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[Non-DoD Source] Engine mount rubbers - YAK-50
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mark.bitterlich(at)navy.m
Guest

Posted: Thu Jul 13, 2017 8:03 am Post subject: [Non-DoD Source] Engine mount rubbers - YAK-50

Typically, the rubber used in these engine mounts deteriorates with age.  Personally what I would try to do under your circumstance is to measure a new one with a durometer, and then have a mold constructed and replace them with a polyurethane equivalent.   



You did not ask this, and I am sorry for sticking my nose into the topic and changing the subject somewhat, but I would suggest that you also make sure you have the Russian recording accelerometer installed in your 50, (or a suitable replacement) and are keeping track of the cycles.  The 50 is indeed rated to +9/-6 assuming all the mods are incorporated.  However that was not an unlimited qualification.  Meaning that after so many "cycles" (as documented on the recording accelerometer), it was a requirement to replace the wings.   Considering most 50's that were flown in unlimited events were usually retired under 100 hours of flight time, it might be worth keeping in mind.  



The kind of damage to engine mount rubbers that you are describing is something commonly seen on Sukhoi's flying Unlimited level aerobatic  competition, usually with engines just like yours and MTV9-260 props, thus I suspect you are approaching that kind of G loading.   That said, the Suke construction otherwise is much stronger than the 50.  Another thing that generates this kind of stress is gyroscopic maneuvers usually accompanied by prop shaft seal damage.  



Good luck. 



Mark

   



--

gord(at)thedampub.ca
Guest

Posted: Thu Jul 13, 2017 9:24 am Post subject: [Non-DoD Source] Engine mount rubbers - YAK-50

Mark.  I asked for help .....not a lecture on a subject that I am well versed in nor assumptions that are incorrect

I have solved the problem and I am surprised you did not offer the advice that the sleeve does not require bonding....if it is the correct mounting rubber.  

The rubbers that were supplied and installed by my mechanic do not have the sleeve bonded. In fact the front rubbers do not even have a sleeve.  No wonder they were coming apart. 

A new 'proper' set is being installed this weekend.  I never had this problem with the old engine because it had the correct rubber mounts which were sold with the engine.  

I believe this will solve the problem and I will carry on flying a very aggressive and dynamic AIRSHOW routine that is well within the limits of my airplane which is constantly being inspected. 

 It is not the type of flying that most YAK owners engage in however I am quite at ease flying it this way. I first flew Victor Smolin's  YAK 50 in 1982 and I was taught the Lomcevak by its inventor Ladislav  Bezak in 1980.



[url=tel:331%20826%209942]331 826 9942[/url]. Gord cell Mexico[url=tel:333%20495%205044]333 495 5044[/url] Sandy cell Mexico

[url=tel:519%20375%206233]519 375 6233[/url] Gord cell Canada

[url=tel:519%20378%206800]519 378 6800[/url] Sandy cell Canada

[url=tel:519%20538%202868]519 538 2868[/url] House Canada

[url=tel:226%20777%204383]226 777 4383[/url] Email voice message anywhereSent from my iPhone



On Jul 13, 2017, at 12:00 PM, Bitterlich, Mark G CIV NAVAIR, WD <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)> wrote:

[quote]--> Yak-List message posted by: "Bitterlich, Mark G CIV NAVAIR, WD" <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)>



Typically, the rubber used in these engine mounts deteriorates with age.  Personally what I would try to do under your circumstance is to measure a new one with a durometer, and then have a mold constructed and replace them with a polyurethane equivalent.   



You did not ask this, and I am sorry for sticking my nose into the topic and changing the subject somewhat, but I would suggest that you also make sure you have the Russian recording accelerometer installed in your 50, (or a suitable replacement) and are keeping track of the cycles.  The 50 is indeed rated to +9/-6 assuming all the mods are incorporated.  However that was not an unlimited qualification.  Meaning that after so many "cycles" (as documented on the recording accelerometer), it was a requirement to replace the wings.   Considering most 50's that were flown in unlimited events were usually retired under 100 hours of flight time, it might be worth keeping in mind.  



The kind of damage to engine mount rubbers that you are describing is something commonly seen on Sukhoi's flying Unlimited level aerobatic  competition, usually with engines just like yours and MTV9-260 props, thus I suspect you are approaching that kind of G loading.   That said, the Suke construction otherwise is much stronger than the 50.  Another thing that generates this kind of stress is gyroscopic maneuvers usually accompanied by prop shaft seal damage.  



Good luck. 



Mark

--

pfstelwagon(at)earthlink.
Guest

Posted: Thu Jul 13, 2017 9:50 am Post subject: [Non-DoD Source] Engine mount rubbers - YAK-50

Mark wasnâ€™t lecturing you!Â  He was telling you what he knows from experience (lots of it).Â  It might be safer to listen.

From: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of Gord Price

Sent: Thursday, July 13, 2017 10:22 AM

To: yak-list(at)matronics.com

Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50

Mark.  I asked for help .....not a lecture on a subject that I am well versed in nor assumptions that are incorrect

I have solved the problem and I am surprised you did not offer the advice that the sleeve does not require bonding....if it is the correct mounting rubber.  

The rubbers that were supplied and installed by my mechanic do not have the sleeve bonded. In fact the front rubbers do not even have a sleeve.  No wonder they were coming apart. 

A new 'proper' set is being installed this weekend.  I never had this problem with the old engine because it had the correct rubber mounts which were sold with the engine.  

I believe this will solve the problem and I will carry on flying a very aggressive and dynamic AIRSHOW routine that is well within the limits of my airplane which is constantly being inspected. 

 It is not the type of flying that most YAK owners engage in however I am quite at ease flying it this way. I first flew Victor Smolin's  YAK 50 in 1982 and I was taught the Lomcevak by its inventor Ladislav  Bezak in 1980.

[url=tel:331%20826%209942]331 826 9942[/url]. Gord cell Mexico

[url=tel:333%20495%205044]333 495 5044[/url] Sandy cell Mexico

[url=tel:519%20375%206233]519 375 6233[/url] Gord cell Canada

[url=tel:519%20378%206800]519 378 6800[/url] Sandy cell Canada

[url=tel:519%20538%202868]519 538 2868[/url] House Canada

[url=tel:226%20777%204383]226 777 4383[/url] Email voice message anywhere

Sent from my iPhone

On Jul 13, 2017, at 12:00 PM, Bitterlich, Mark G CIV NAVAIR, WD <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)> wrote:

[quote]

--> Yak-List message posted by: "Bitterlich, Mark G CIV NAVAIR, WD" <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)>

Typically, the rubber used in these engine mounts deteriorates with age.  Personally what I would try to do under your circumstance is to measure a new one with a durometer, and then have a mold constructed and replace them with a polyurethane equivalent.   

You did not ask this, and I am sorry for sticking my nose into the topic and changing the subject somewhat, but I would suggest that you also make sure you have the Russian recording accelerometer installed in your 50, (or a suitable replacement) and are keeping track of the cycles.  The 50 is indeed rated to +9/-6 assuming all the mods are incorporated.  However that was not an unlimited qualification.  Meaning that after so many "cycles" (as documented on the recording accelerometer), it was a requirement to replace the wings.   Considering most 50's that were flown in unlimited events were usually retired under 100 hours of flight time, it might be worth keeping in mind.  

The kind of damage to engine mount rubbers that you are describing is something commonly seen on Sukhoi's flying Unlimited level aerobatic  competition, usually with engines just like yours and MTV9-260 props, thus I suspect you are approaching that kind of G loading.   That said, the Suke construction otherwise is much stronger than the 50.  Another thing that generates this kind of stress is gyroscopic maneuvers usually accompanied by prop shaft seal damage.  

Good luck. 

Mark

--

mark.bitterlich(at)navy.m
Guest

Posted: Thu Jul 13, 2017 10:33 am Post subject: [Non-DoD Source] Engine mount rubbers - YAK-50

Fair enough.  Glad that you got the problem fixed.   As I said, it is common on the Sukes.  There has been an on-going discussion about replacing them with a poly/u substitute.  



My comments regarding the recording system were done publically not as a lecture, but as a notification to anyone that decides to push YAK-50's to their design maximum G loading.  I have seen videos of your airshow flying Gordon and applaud your routine and your aerobatic skills.  I did not, and am not discrediting your skills or intent in any way.  That said, I had no way of knowing that once again someone had installed parts incorrectly into your aircraft.  It is fortunate that you figured that out.   



Regarding counting accelerometers and other stress measurement equipment originally installed in aircraft, the FAA has now written several new Operating Limitations that address this area specifically, and you will find that if your aircraft requires a new set of Operating Limitations, that they will include verbiage that requires the owner to maintain these systems (no removal) and comply with original design specifications, which in our case means wing replacement after maximum cycles are reached, regardless of how good your inspections are.  My intent is not to lecture, but to inform.  Please think back to your landing gear actuators.    



Best of luck. 



Mark

--

gord(at)thedampub.ca
Guest

Posted: Thu Jul 13, 2017 10:33 am Post subject: [Non-DoD Source] Engine mount rubbers - YAK-50

Thanks for the advice Frank however it would be nice on this forum if we could just stick to the topic at hand. 



In this caseâ€¦ the  topic it is a problem with  engine mount rubbers and the fact that the ones supplied did not have the sleeve bonded to the rubber. 



Has anyone ever experienced this? 

 [quote]On Jul 13, 2017, at 1:44 PM, Frank Stelwagon <pfstelwagon(at)earthlink.net (pfstelwagon(at)earthlink.net)> wrote:

Mark wasnâ€™t lecturing you!  He was telling you what he knows from experience (lots of it).  It might be safer to listen.

 

From: owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) [mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)] On Behalf Of Gord PriceSent: Thursday, July 13, 2017 10:22 AMTo: yak-list(at)matronics.com (yak-list(at)matronics.com)Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50

 

Mark.  I asked for help .....not a lecture on a subject that I am well versed in nor assumptions that are incorrect



 



I have solved the problem and I am surprised you did not offer the advice that the sleeve does not require bonding....if it is the correct mounting rubber.  



 



The rubbers that were supplied and installed by my mechanic do not have the sleeve bonded. In fact the front rubbers do not even have a sleeve.  No wonder they were coming apart. 



 



A new 'proper' set is being installed this weekend.  I never had this problem with the old engine because it had the correct rubber mounts which were sold with the engine.  



 



I believe this will solve the problem and I will carry on flying a very aggressive and dynamic AIRSHOW routine that is well within the limits of my airplane which is constantly being inspected. 



 

 It is not the type of flying that most YAK owners engage in however I am quite at ease flying it this way. I first flew Victor Smolin's  YAK 50 in 1982 and I was taught the Lomcevak by its inventor Ladislav  Bezak in 1980.[url=tel:331%20826%209942]331 826 9942[/url]. Gord cell Mexico

[url=tel:333%20495%205044]333 495 5044[/url] Sandy cell Mexico



[url=tel:519%20375%206233]519 375 6233[/url] Gord cell Canada



[url=tel:519%20378%206800]519 378 6800[/url] Sandy cell Canada



[url=tel:519%20538%202868]519 538 2868[/url] House Canada



[url=tel:226%20777%204383]226 777 4383[/url] Email voice message anywhere

Sent from my iPhone





On Jul 13, 2017, at 12:00 PM, Bitterlich, Mark G CIV NAVAIR, WD <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)> wrote:

[quote]

--> Yak-List message posted by: "Bitterlich, Mark G CIV NAVAIR, WD" <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)>Typically, the rubber used in these engine mounts deteriorates with age.  Personally what I would try to do under your circumstance is to measure a new one with a durometer, and then have a mold constructed and replace them with a polyurethane equivalent.   You did not ask this, and I am sorry for sticking my nose into the topic and changing the subject somewhat, but I would suggest that you also make sure you have the Russian recording accelerometer installed in your 50, (or a suitable replacement) and are keeping track of the cycles.  The 50 is indeed rated to +9/-6 assuming all the mods are incorporated.  However that was not an unlimited qualification.  Meaning that after so many "cycles" (as documented on the recording accelerometer), it was a requirement to replace the wings.   Considering most 50's that were flown in unlimited events were usually retired under 100 hours of flight time, it might be worth keeping in mind.  The kind of damage to engine mount rubbers that you are describing is something commonly seen on Sukhoi's flying Unlimited level aerobatic  competition, usually with engines just like yours and MTV9-260 props, thus I suspect you are approaching that kind of G loading.   That said, the Suke construction otherwise is much stronger than the 50.  Another thing that generates this kind of stress is gyroscopic maneuvers usually accompanied by prop shaft seal damage.  Good luck. Mark--

mark.bitterlich(at)navy.m
Guest

Posted: Thu Jul 13, 2017 11:08 am Post subject: [Non-DoD Source] Engine mount rubbers - YAK-50

You said: "we have just found some engine mount rubbers  are being torn up because the metal sleeve is moving and cutting the rubber.  The airplane is being flown under the G limits however during the air show sequence I am sometimes seeing +8 and -5 G."  



You then said:  " I have solved the problem and I am surprised you did not offer the advice that the sleeve does not require bonding....if it is the correct mounting rubber. "



You then said:  " The rubbers that were supplied and installed by my mechanic do not have the sleeve bonded. In fact the front rubbers do not even have a sleeve.  No wonder they were coming apart."



You then said:  "it would be nice on this forum if we could just stick to the topic at hand."



You then said:   " the  topic it is a problem with  engine mount rubbers and the fact that the ones supplied did not have the sleeve bonded to the rubber."



Finally you end with: " Has anyone ever experienced this?"



Answer:  Why yes.  I have.  



Mark Bitterlich

   



--

richard.goode(at)russiana
Guest

Posted: Thu Jul 13, 2017 10:23 pm Post subject: [Non-DoD Source] Engine mount rubbers - YAK-50

Firstly I would like to make it clear that we supplied the engine together with the engine mount rubbers to Gordon Price. But we have used exactly the same rubbers on around 300 engines that we have supplied to a wide variety of aircraft, including competition Sukhois and have never had this problem before. But we will sort it out, and we know from Gordon that the engine is performing spectacularly well.

 

But it raises an issue which I think is far more important, and that is flying a Yak 50 to its design limits of plus 9G and minus 6G. I have done a lot of research on this topic, and the 50 was unfortunate in that it was introduced at a time that aerobatics changing from being big graceful manoeuvres to sharp angles. The Russian team was well funded and incredibly well motivated, and they were flying them Â beyond these limits, and had four fatal accidents to team members. During this period Yakovlev issued a series of service bulletins to reinforce the last bit of the aircraft that had broken, culminating in bulletin 79 â€“ a 4.5 mm steel plate on top and bottom of the centre section.

 

But firstly, remember that the Russian pilots were all relatively light; the aeroplane was flown only with one fuel tank; no generator; air compressor; a light battery. Then, the TOTAL service life of a team aircraft was 47 hours. After that it was scrapped. And for any other aircraft, the total service life was 300 hours, and then it was scrapped!

 

I have a serious concern that many pilots today are flying aircraft that have done far more hours than this; are ignorant of these issues, and yet feel that they still have a plus 9G aircraft, with a heavy Western pilot; smoke system; both fuel tanks et cetera!

 

I prepared a detailed paper some years ago following discussions with Yakovlev describing the individual failures and then the subsequent service bulletins. I will send this to anyone who is interested.

 

Richard Goode Aerobatics

Rhodds Farm

Lyonshall

Hereford

HR5 3LW

 

Tel:Â  +44 (0) 1544 340120

Fax: +44 (0) 1544 340129

www.russianaeros.com



 

From: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of Gordon Price

Sent: 13 July 2017 19:31

To: yak-list(at)matronics.com

Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50

 

Thanks for the advice Frank however it would be nice on this forum if we could just stick to the topic at hand. 



 



In this caseâ€¦ the  topic it is a problem with  engine mount rubbers and the fact that the ones supplied did not have the sleeve bonded to the rubber. 



 



Has anyone ever experienced this? 



 [quote]

On Jul 13, 2017, at 1:44 PM, Frank Stelwagon <pfstelwagon(at)earthlink.net (pfstelwagon(at)earthlink.net)> wrote:



 

Mark wasnâ€™t lecturing you!  He was telling you what he knows from experience (lots of it).  It might be safer to listen.



 



From: owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) [mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)] On Behalf Of Gord Price

Sent: Thursday, July 13, 2017 10:22 AM

To: yak-list(at)matronics.com (yak-list(at)matronics.com)

Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50



 



Mark.  I asked for help .....not a lecture on a subject that I am well versed in nor assumptions that are incorrect

 

I have solved the problem and I am surprised you did not offer the advice that the sleeve does not require bonding....if it is the correct mounting rubber.  

 

The rubbers that were supplied and installed by my mechanic do not have the sleeve bonded. In fact the front rubbers do not even have a sleeve.  No wonder they were coming apart. 

 

A new 'proper' set is being installed this weekend.  I never had this problem with the old engine because it had the correct rubber mounts which were sold with the engine.  

 

I believe this will solve the problem and I will carry on flying a very aggressive and dynamic AIRSHOW routine that is well within the limits of my airplane which is constantly being inspected. 

 

 It is not the type of flying that most YAK owners engage in however I am quite at ease flying it this way. I first flew Victor Smolin's  YAK 50 in 1982 and I was taught the Lomcevak by its inventor Ladislav  Bezak in 1980.

[url=tel:331%20826%209942]331 826 9942[/url]. Gord cell Mexico



[url=tel:333%20495%205044]333 495 5044[/url] Sandy cell Mexico

[url=tel:519%20375%206233]519 375 6233[/url] Gord cell Canada

[url=tel:519%20378%206800]519 378 6800[/url] Sandy cell Canada

[url=tel:519%20538%202868]519 538 2868[/url] House Canada

[url=tel:226%20777%204383]226 777 4383[/url] Email voice message anywhere



Sent from my iPhone



On Jul 13, 2017, at 12:00 PM, Bitterlich, Mark G CIV NAVAIR, WD <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)> wrote:

[quote]

--> Yak-List message posted by: "Bitterlich, Mark G CIV NAVAIR, WD" <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)>



Typically, the rubber used in these engine mounts deteriorates with age.  Personally what I would try to do under your circumstance is to measure a new one with a durometer, and then have a mold constructed and replace them with a polyurethane equivalent.   



You did not ask this, and I am sorry for sticking my nose into the topic and changing the subject somewhat, but I would suggest that you also make sure you have the Russian recording accelerometer installed in your 50, (or a suitable replacement) and are keeping track of the cycles.  The 50 is indeed rated to +9/-6 assuming all the mods are incorporated.  However that was not an unlimited qualification.  Meaning that after so many "cycles" (as documented on the recording accelerometer), it was a requirement to replace the wings.   Considering most 50's that were flown in unlimited events were usually retired under 100 hours of flight time, it might be worth keeping in mind.  



The kind of damage to engine mount rubbers that you are describing is something commonly seen on Sukhoi's flying Unlimited level aerobatic  competition, usually with engines just like yours and MTV9-260 props, thus I suspect you are approaching that kind of G loading.   That said, the Suke construction otherwise is much stronger than the 50.  Another thing that generates this kind of stress is gyroscopic maneuvers usually accompanied by prop shaft seal damage.  



Good luck. 



Mark

--

Dawg

Joined: 19 May 2013
Posts: 355

Posted: Fri Jul 14, 2017 3:23 am Post subject: [Non-DoD Source] Engine mount rubbers - YAK-50

Richard,

Is it possible to get a copy of the service bulletins? (new Yak 50 owner)



Bill

[quote]On Jul 14, 2017, at 00:20, That's looking at his note <richard.goode(at)russianaeros.com (richard.goode(at)russianaeros.com)> wrote:

Firstly I would like to make it clear that we supplied the engine together with the engine mount rubbers to Gordon Price. But we have used exactly the same rubbers on around 300 engines that we have supplied to a wide variety of aircraft, including competition Sukhois and have never had this problem before. But we will sort it out, and we know from Gordon that the engine is performing spectacularly well.

 

But it raises an issue which I think is far more important, and that is flying a Yak 50 to its design limits of plus 9G and minus 6G. I have done a lot of research on this topic, and the 50 was unfortunate in that it was introduced at a time that aerobatics changing from being big graceful manoeuvres to sharp angles. The Russian team was well funded and incredibly well motivated, and they were flying them  beyond these limits, and had four fatal accidents to team members. During this period Yakovlev issued a series of service bulletins to reinforce the last bit of the aircraft that had broken, culminating in bulletin 79 â€“ a 4.5 mm steel plate on top and bottom of the centre section.

 

But firstly, remember that the Russian pilots were all relatively light; the aeroplane was flown only with one fuel tank; no generator; air compressor; a light battery. Then, the TOTAL service life of a team aircraft was 47 hours. After that it was scrapped. And for any other aircraft, the total service life was 300 hours, and then it was scrapped!

 

I have a serious concern that many pilots today are flying aircraft that have done far more hours than this; are ignorant of these issues, and yet feel that they still have a plus 9G aircraft, with a heavy Western pilot; smoke system; both fuel tanks et cetera!

 

I prepared a detailed paper some years ago following discussions with Yakovlev describing the individual failures and then the subsequent service bulletins. I will send this to anyone who is interested.

 

Richard Goode Aerobatics

Rhodds Farm

Lyonshall

Hereford

HR5 3LW

 

Tel:  +44 (0) 1544 340120

Fax: +44 (0) 1544 340129

www.russianaeros.com



 

From: owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) [mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)] On Behalf Of Gordon PriceSent: 13 July 2017 19:31To: yak-list(at)matronics.com (yak-list(at)matronics.com)Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50

 

Thanks for the advice Frank however it would be nice on this forum if we could just stick to the topic at hand. 



 



In this caseâ€¦ the  topic it is a problem with  engine mount rubbers and the fact that the ones supplied did not have the sleeve bonded to the rubber. 



 



Has anyone ever experienced this? 



 

[quote]On Jul 13, 2017, at 1:44 PM, Frank Stelwagon <pfstelwagon(at)earthlink.net (pfstelwagon(at)earthlink.net)> wrote:



 

Mark wasnâ€™t lecturing you!  He was telling you what he knows from experience (lots of it).  It might be safer to listen.



 



From: owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) [mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)] On Behalf Of Gord PriceSent: Thursday, July 13, 2017 10:22 AMTo: yak-list(at)matronics.com (yak-list(at)matronics.com)Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50



 



Mark.  I asked for help .....not a lecture on a subject that I am well versed in nor assumptions that are incorrect

 

I have solved the problem and I am surprised you did not offer the advice that the sleeve does not require bonding....if it is the correct mounting rubber.  

 

The rubbers that were supplied and installed by my mechanic do not have the sleeve bonded. In fact the front rubbers do not even have a sleeve.  No wonder they were coming apart. 

 

A new 'proper' set is being installed this weekend.  I never had this problem with the old engine because it had the correct rubber mounts which were sold with the engine.  

 

I believe this will solve the problem and I will carry on flying a very aggressive and dynamic AIRSHOW routine that is well within the limits of my airplane which is constantly being inspected. 

 



 It is not the type of flying that most YAK owners engage in however I am quite at ease flying it this way. I first flew Victor Smolin's  YAK 50 in 1982 and I was taught the Lomcevak by its inventor Ladislav  Bezak in 1980.[url=tel:331%20826%209942]331 826 9942[/url]. Gord cell Mexico



[url=tel:333%20495%205044]333 495 5044[/url] Sandy cell Mexico

[url=tel:519%20375%206233]519 375 6233[/url] Gord cell Canada

[url=tel:519%20378%206800]519 378 6800[/url] Sandy cell Canada

[url=tel:519%20538%202868]519 538 2868[/url] House Canada

[url=tel:226%20777%204383]226 777 4383[/url] Email voice message anywhere



Sent from my iPhone



On Jul 13, 2017, at 12:00 PM, Bitterlich, Mark G CIV NAVAIR, WD <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)> wrote:

[quote]

--> Yak-List message posted by: "Bitterlich, Mark G CIV NAVAIR, WD" <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)>Typically, the rubber used in these engine mounts deteriorates with age.  Personally what I would try to do under your circumstance is to measure a new one with a durometer, and then have a mold constructed and replace them with a polyurethane equivalent.   You did not ask this, and I am sorry for sticking my nose into the topic and changing the subject somewhat, but I would suggest that you also make sure you have the Russian recording accelerometer installed in your 50, (or a suitable replacement) and are keeping track of the cycles.  The 50 is indeed rated to +9/-6 assuming all the mods are incorporated.  However that was not an unlimited qualification.  Meaning that after so many "cycles" (as documented on the recording accelerometer), it was a requirement to replace the wings.   Considering most 50's that were flown in unlimited events were usually retired under 100 hours of flight time, it might be worth keeping in mind.  The kind of damage to engine mount rubbers that you are describing is something commonly seen on Sukhoi's flying Unlimited level aerobatic  competition, usually with engines just like yours and MTV9-260 props, thus I suspect you are approaching that kind of G loading.   That said, the Suke construction otherwise is much stronger than the 50.  Another thing that generates this kind of stress is gyroscopic maneuvers usually accompanied by prop shaft seal damage.  Good luck. Mark--

_________________
Dawg

gord(at)thedampub.ca
Guest

Posted: Fri Jul 14, 2017 4:42 am Post subject: [Non-DoD Source] Engine mount rubbers - YAK-50

As I recall Richard you did say that the YAK 50 could be flown forever at +5 and -3.



As I said SOMETIMES I see +8 and -5 G.  Just being honest.  A normal airshow routine is +6 and -4 and yes the airplane has all the mods and lightweight equipment. As for the pilot weightâ€¦ I am always working on that.



You are right . The engine is spectacular and increased power has changed the flying characteristics of the airplane which I am still getting used to.  I should be fully up to speed by the end of August when I fly the CNE  Canadian International Air Show in Toronto.

Back to the subject I have been to introduce for discussionâ€¦â€¦â€¦..

Attached is a picture of the different engine mount rubbers.



On the left 2 new ones with the rubber bonded to the steel insert  and on the right one of the damaged mounts where the steel insert is not bonded and can turn and cut the rubber.



[img]cid:670FE21D-1044-4710-A2A2-FAFD9DC8C226[/img] 

  

 [quote]On Jul 14, 2017, at 2:20 AM, That's looking at his note <richard.goode(at)russianaeros.com (richard.goode(at)russianaeros.com)> wrote:

Firstly I would like to make it clear that we supplied the engine together with the engine mount rubbers to Gordon Price. But we have used exactly the same rubbers on around 300 engines that we have supplied to a wide variety of aircraft, including competition Sukhois and have never had this problem before. But we will sort it out, and we know from Gordon that the engine is performing spectacularly well.

 

But it raises an issue which I think is far more important, and that is flying a Yak 50 to its design limits of plus 9G and minus 6G. I have done a lot of research on this topic, and the 50 was unfortunate in that it was introduced at a time that aerobatics changing from being big graceful manoeuvres to sharp angles. The Russian team was well funded and incredibly well motivated, and they were flying them  beyond these limits, and had four fatal accidents to team members. During this period Yakovlev issued a series of service bulletins to reinforce the last bit of the aircraft that had broken, culminating in bulletin 79 â€“ a 4.5 mm steel plate on top and bottom of the centre section.

 

But firstly, remember that the Russian pilots were all relatively light; the aeroplane was flown only with one fuel tank; no generator; air compressor; a light battery. Then, the TOTAL service life of a team aircraft was 47 hours. After that it was scrapped. And for any other aircraft, the total service life was 300 hours, and then it was scrapped!

 

I have a serious concern that many pilots today are flying aircraft that have done far more hours than this; are ignorant of these issues, and yet feel that they still have a plus 9G aircraft, with a heavy Western pilot; smoke system; both fuel tanks et cetera!

 

I prepared a detailed paper some years ago following discussions with Yakovlev describing the individual failures and then the subsequent service bulletins. I will send this to anyone who is interested.

 

Richard Goode Aerobatics

Rhodds Farm

Lyonshall

Hereford

HR5 3LW

 

Tel:  +44 (0) 1544 340120

Fax: +44 (0) 1544 340129

www.russianaeros.com



 

From: owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) [mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)] On Behalf Of Gordon PriceSent: 13 July 2017 19:31To: yak-list(at)matronics.com (yak-list(at)matronics.com)Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50

 

Thanks for the advice Frank however it would be nice on this forum if we could just stick to the topic at hand. 



 



In this caseâ€¦ the  topic it is a problem with  engine mount rubbers and the fact that the ones supplied did not have the sleeve bonded to the rubber. 



 



Has anyone ever experienced this? 



 

[quote]On Jul 13, 2017, at 1:44 PM, Frank Stelwagon <pfstelwagon(at)earthlink.net (pfstelwagon(at)earthlink.net)> wrote:



 

Mark wasnâ€™t lecturing you!  He was telling you what he knows from experience (lots of it).  It might be safer to listen.



 



From: owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) [mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)] On Behalf Of Gord PriceSent: Thursday, July 13, 2017 10:22 AMTo: yak-list(at)matronics.com (yak-list(at)matronics.com)Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50



 



Mark.  I asked for help .....not a lecture on a subject that I am well versed in nor assumptions that are incorrect

 

I have solved the problem and I am surprised you did not offer the advice that the sleeve does not require bonding....if it is the correct mounting rubber.  

 

The rubbers that were supplied and installed by my mechanic do not have the sleeve bonded. In fact the front rubbers do not even have a sleeve.  No wonder they were coming apart. 

 

A new 'proper' set is being installed this weekend.  I never had this problem with the old engine because it had the correct rubber mounts which were sold with the engine.  

 

I believe this will solve the problem and I will carry on flying a very aggressive and dynamic AIRSHOW routine that is well within the limits of my airplane which is constantly being inspected. 

 



 It is not the type of flying that most YAK owners engage in however I am quite at ease flying it this way. I first flew Victor Smolin's  YAK 50 in 1982 and I was taught the Lomcevak by its inventor Ladislav  Bezak in 1980.[url=tel:331%20826%209942]331 826 9942[/url]. Gord cell Mexico



[url=tel:333%20495%205044]333 495 5044[/url] Sandy cell Mexico

[url=tel:519%20375%206233]519 375 6233[/url] Gord cell Canada

[url=tel:519%20378%206800]519 378 6800[/url] Sandy cell Canada

[url=tel:519%20538%202868]519 538 2868[/url] House Canada

[url=tel:226%20777%204383]226 777 4383[/url] Email voice message anywhere



Sent from my iPhone



On Jul 13, 2017, at 12:00 PM, Bitterlich, Mark G CIV NAVAIR, WD <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)> wrote:

[quote]

--> Yak-List message posted by: "Bitterlich, Mark G CIV NAVAIR, WD" <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)>Typically, the rubber used in these engine mounts deteriorates with age.  Personally what I would try to do under your circumstance is to measure a new one with a durometer, and then have a mold constructed and replace them with a polyurethane equivalent.   You did not ask this, and I am sorry for sticking my nose into the topic and changing the subject somewhat, but I would suggest that you also make sure you have the Russian recording accelerometer installed in your 50, (or a suitable replacement) and are keeping track of the cycles.  The 50 is indeed rated to +9/-6 assuming all the mods are incorporated.  However that was not an unlimited qualification.  Meaning that after so many "cycles" (as documented on the recording accelerometer), it was a requirement to replace the wings.   Considering most 50's that were flown in unlimited events were usually retired under 100 hours of flight time, it might be worth keeping in mind.  The kind of damage to engine mount rubbers that you are describing is something commonly seen on Sukhoi's flying Unlimited level aerobatic  competition, usually with engines just like yours and MTV9-260 props, thus I suspect you are approaching that kind of G loading.   That said, the Suke construction otherwise is much stronger than the 50.  Another thing that generates this kind of stress is gyroscopic maneuvers usually accompanied by prop shaft seal damage.  Good luck. Mark--

rubber.jpeg

Description:

Filesize:

49.67 KB

Viewed:

10520 Time(s)

HawkerPilot2015

Joined: 10 Jan 2006
Posts: 503

Posted: Fri Jul 14, 2017 7:33 am Post subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50

Mark is a wealth of information and I would be willing to bet, has owned and operated a -50 longer than anyone else in the US..maybe even the world. His input has served this community well. Richard is always good for a dose of common sense. Ignore it at your own peril. 



Out of the 30+ types of aircraft I have flown, the -50 was quite possibly, the finest! What a hoot!

dougsappllc(at)gmail.com
Guest

Posted: Fri Jul 14, 2017 7:57 am Post subject: [Non-DoD Source] Engine mount rubbers - YAK-50

Gents,Addressing the "mount rubber" issue only. Â 

Are we 100% sure that the bonding or the failure of bonding to the washer or to the bushing is the problem here?Â  I suspect that it is not.Â  I suspect that the mount rubber were incorrectly installed.Â  Since there is no actual torque value stated in anything I have read it seems that there exists a large opportunity to install them without enough torque, meaning not tight enough.Â  In a "normal situation" (gentleman's acro) I would think that proper installation would not be as critical as is would be in this rather unusual Â high g loading situation.Â  This would help explain why this problem/situation has not been seen much in the past. Â 

Just a WAG on my part, YMMV.

Doug

On Fri, Jul 14, 2017 at 5:32 AM, Gordon Price <gord(at)thedampub.ca (gord(at)thedampub.ca)> wrote:

[quote]As I recall Richard you did say that the YAK 50 could be flown forever at +5 and -3.

As I said SOMETIMES I see +8 and -5 G.Â  Just being honest.Â  A normal airshow routine is +6 and -4 and yes the airplane has all the mods and lightweight equipment. As for the pilot weightâ€¦ I am always working on that.

You are right . The engine is spectacular and increased power has changed the flying characteristics of the airplane which I am still getting used to.Â  I should be fully up to speed by the end of August when I fly the CNE Â Canadian International Air Show in Toronto.





Back to the subject I have been to introduce for discussionâ€¦â€¦â€¦..





Attached is a picture of the different engine mount rubbers.

On the left 2 new ones with the rubber bonded to the steel insert Â and on the right one of the damaged mounts where the steel insert is not bonded and can turn and cut the rubber.

[img]cid:670FE21D-1044-4710-A2A2-FAFD9DC8C226[/img]

 



  

 

[quote]On Jul 14, 2017, at 2:20 AM, That's looking at his note <richard.goode(at)russianaeros.com (richard.goode(at)russianaeros.com)> wrote:

Firstly I would like to make it clear that we supplied the engine together with the engine mount rubbers to Gordon Price. But we have used exactly the same rubbers on around 300 engines that we have supplied to a wide variety of aircraft, including competition Sukhois and have never had this problem before. But we will sort it out, and we know from Gordon that the engine is performing spectacularly well.

Â 

But it raises an issue which I think is far more important, and that is flying a Yak 50 to its design limits of plus 9G and minus 6G. I have done a lot of research on this topic, and the 50 was unfortunate in that it was introduced at a time that aerobatics changing from being big graceful manoeuvres to sharp angles. The Russian team was well funded and incredibly well motivated, and they were flying them Â beyond these limits, and had four fatal accidents to team members. During this period Yakovlev issued a series of service bulletins to reinforce the last bit of the aircraft that had broken, culminating in bulletin 79 â€“ a 4.5 mm steel plate on top and bottom of the centre section.

Â 

But firstly, remember that the Russian pilots were all relatively light; the aeroplane was flown only with one fuel tank; no generator; air compressor; a light battery. Then, the TOTAL service life of a team aircraft was 47 hours. After that it was scrapped. And for any other aircraft, the total service life was 300 hours, and then it was scrapped!

Â 

I have a serious concern that many pilots today are flying aircraft that have done far more hours than this; are ignorant of these issues, and yet feel that they still have a plus 9G aircraft, with a heavy Western pilot; smoke system; both fuel tanks et cetera!

Â 

I prepared a detailed paper some years ago following discussions with Yakovlev describing the individual failures and then the subsequent service bulletins. I will send this to anyone who is interested.

Â 

Richard Goode Aerobatics

Rhodds Farm

Lyonshall

Hereford

HR5 3LW

Â 

Tel:Â  [url=tel:+44%201544%20340120]+44 (0) 1544 340120[/url]

Fax: [url=tel:+44%201544%20340129]+44 (0) 1544 340129[/url]

www.russianaeros.com



Â 

From:Â owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)Â [mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)]Â On Behalf OfÂ Gordon Price

Sent:Â 13 July 2017 19:31

To:Â yak-list(at)matronics.com (yak-list(at)matronics.com)

Subject:Â Re: [Non-DoD Source] Yak-List: Engine mount rubbers - YAK-50

Â 

Thanks for the advice Frank however it would be nice on this forum if we could just stick to the topic at hand.Â 



Â 



In this caseâ€¦ the Â topic it is a problem with Â engine mount rubbers and the fact that the ones supplied did not have the sleeve bonded to the rubber.Â 



Â 



Has anyone ever experienced this?Â 



Â 

[quote]On Jul 13, 2017, at 1:44 PM, Frank Stelwagon <pfstelwagon(at)earthlink.net (pfstelwagon(at)earthlink.net)> wrote:



Â 

Mark wasnâ€™t lecturing you!Â  He was telling you what he knows from experience (lots of it).Â  It might be safer to listen.



Â 



From:Â owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)Â [mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)]Â On Behalf OfÂ Gord Price

Sent:Â Thursday, July 13, 2017 10:22 AM

To:Â yak-list(at)matronics.com (yak-list(at)matronics.com)

Subject:Â Re: [Non-DoD Source] Engine mount rubbers - YAK-50



Â 



Mark.Â  I asked for help .....not a lecture on a subject that I am well versed in nor assumptions that are incorrect

Â 

I have solved the problem and I am surprised you did not offer the advice that the sleeve does not require bonding...if it is the correct mounting rubber. Â 

Â 

The rubbers that were supplied and installed by my mechanic do not have the sleeve bonded. In fact the front rubbers do not even have a sleeve.Â  No wonder they were coming apart.Â 

Â 

A new 'proper' set is being installed this weekend.Â  I never had this problem with the old engine because it had the correct rubber mounts which were sold with the engine. Â 

Â 

I believe this will solve the problem and I will carry on flying a very aggressive and dynamic AIRSHOW routine that is well within the limits of my airplane which is constantly being inspected.Â 

Â 



Â It is not the type of flying that most YAK owners engage in however I am quite at ease flying it this way. I first flew Victor Smolin's Â YAK 50 in 1982 and I was taught the Lomcevak by its inventor Ladislav Â Bezak in 1980.[url=tel:331%20826%209942]331 826 9942[/url]. Gord cell Mexico



[url=tel:333%20495%205044]333 495 5044[/url]Â Sandy cell Mexico

[url=tel:519%20375%206233]519 375 6233[/url]Â Gord cell Canada

[url=tel:519%20378%206800]519 378 6800[/url]Â Sandy cell Canada

[url=tel:519%20538%202868]519 538 2868[/url]Â House Canada

[url=tel:226%20777%204383]226 777 4383[/url]Â Email voice message anywhere



Sent from my iPhone

On Jul 13, 2017, at 12:00 PM, Bitterlich, Mark G CIV NAVAIR, WD <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)> wrote:

[quote]

--> Yak-List message posted by: "Bitterlich, Mark G CIV NAVAIR, WD" <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)>



Typically, the rubber used in these engine mounts deteriorates with age.Â  Personally what I would try to do under your circumstance is to measure a new one with a durometer, and then have a mold constructed and replace them with a polyurethane equivalent. Â Â 



You did not ask this, and I am sorry for sticking my nose into the topic and changing the subject somewhat, but I would suggest that you also make sure you have the Russian recording accelerometer installed in your 50, (or a suitable replacement) and are keeping track of the cycles.Â  The 50 is indeed rated to +9/-6 assuming all the mods are incorporated.Â  However that was not an unlimited qualification.Â  Meaning that after so many "cycles" (as documented on the recording accelerometer), it was a requirement to replace the wings. Â Â Considering most 50's that were flown in unlimited events were usually retired under 100 hours of flight time, it might be worth keeping in mind. Â 



The kind of damage to engine mount rubbers that you are describing is something commonly seen on Sukhoi's flying Unlimited level aerobatic Â competition, usually with engines just like yours and MTV9-260 props, thus I suspect you are approaching that kind of G loading. Â Â That said, the Suke construction otherwise is much stronger than the 50.Â  Another thing that generates this kind of stress is gyroscopic maneuvers usually accompanied by prop shaft seal damage. Â 



Good luck.Â 



Mark

--

rubber.jpeg

Description:

Filesize:

49.67 KB

Viewed:

10511 Time(s)

gord(at)thedampub.ca
Guest

Posted: Fri Jul 14, 2017 8:38 am Post subject: [Non-DoD Source] Engine mount rubbers - YAK-50

Thanks HawkerPilot2015.  Richard I used to compete back in the 80â€™s.  I know him fairly well and certainly respect his advice.



Do you have any experience with the rubber mounts? Are the sleeves on your YAK -50 bonded to the rubber? 



Gord



 	  Quote: 	
		   On Jul 14, 2017, at 11:33 AM, HawkerPilot2015 <timsmiscaz(at)gmail.com> wrote:

 

 

 

 Richard is always good for a dose of common sense. Ignore it at your own peril. 

 

 Out of the 30+ types of aircraft I have flown, the -50 was quite possibly, the finest! What a hoot!

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=470991#470991

gord(at)thedampub.ca
Guest

Posted: Fri Jul 14, 2017 8:41 am Post subject: [Non-DoD Source] Engine mount rubbers - YAK-50

Good point Doug and thank you for that.  There is a measurement of 34.5 mm on the plans sent to me by George Coy.   At that point should the metal sleeves inside touch?   



Does anyone have method of torquing  that would be helpful or sod you just compress to 34.5 mm.



Could not enough torque could cause this problem?  Could too much torque cause the problem?  We donâ€™t know so if someone has experience please let us know.



We have yet to remove the engine since work is backed up in the shop however I am told that the forward rubber mounts that are installed did not have the washer with a sleeve. Only a washer..no sleeve. 



Also, which mounts do you sell Doug?  With or without the sleeve?



Thanks  



Gord

  

 [quote]On Jul 14, 2017, at 11:54 AM, doug sapp <dougsappllc(at)gmail.com (dougsappllc(at)gmail.com)> wrote:

Gents,Addressing the "mount rubber" issue only.  

Are we 100% sure that the bonding or the failure of bonding to the washer or to the bushing is the problem here?  I suspect that it is not.  I suspect that the mount rubber were incorrectly installed.  Since there is no actual torque value stated in anything I have read it seems that there exists a large opportunity to install them without enough torque, meaning not tight enough.  In a "normal situation" (gentleman's acro) I would think that proper installation would not be as critical as is would be in this rather unusual  high g loading situation.  This would help explain why this problem/situation has not been seen much in the past.  



Just a WAG on my part, YMMV.



Doug



On Fri, Jul 14, 2017 at 5:32 AM, Gordon Price <gord(at)thedampub.ca (gord(at)thedampub.ca)> wrote:[quote]As I recall Richard you did say that the YAK 50 could be flown forever at +5 and -3.



As I said SOMETIMES I see +8 and -5 G.  Just being honest.  A normal airshow routine is +6 and -4 and yes the airplane has all the mods and lightweight equipment. As for the pilot weightâ€¦ I am always working on that.



You are right . The engine is spectacular and increased power has changed the flying characteristics of the airplane which I am still getting used to.  I should be fully up to speed by the end of August when I fly the CNE  Canadian International Air Show in Toronto.

Back to the subject I have been to introduce for discussionâ€¦â€¦â€¦..

Attached is a picture of the different engine mount rubbers.



On the left 2 new ones with the rubber bonded to the steel insert  and on the right one of the damaged mounts where the steel insert is not bonded and can turn and cut the rubber.



<rubber.jpeg> 

  

 [quote]On Jul 14, 2017, at 2:20 AM, That's looking at his note <richard.goode(at)russianaeros.com (richard.goode(at)russianaeros.com)> wrote:

Firstly I would like to make it clear that we supplied the engine together with the engine mount rubbers to Gordon Price. But we have used exactly the same rubbers on around 300 engines that we have supplied to a wide variety of aircraft, including competition Sukhois and have never had this problem before. But we will sort it out, and we know from Gordon that the engine is performing spectacularly well.

 

But it raises an issue which I think is far more important, and that is flying a Yak 50 to its design limits of plus 9G and minus 6G. I have done a lot of research on this topic, and the 50 was unfortunate in that it was introduced at a time that aerobatics changing from being big graceful manoeuvres to sharp angles. The Russian team was well funded and incredibly well motivated, and they were flying them  beyond these limits, and had four fatal accidents to team members. During this period Yakovlev issued a series of service bulletins to reinforce the last bit of the aircraft that had broken, culminating in bulletin 79 â€“ a 4.5 mm steel plate on top and bottom of the centre section.

 

But firstly, remember that the Russian pilots were all relatively light; the aeroplane was flown only with one fuel tank; no generator; air compressor; a light battery. Then, the TOTAL service life of a team aircraft was 47 hours. After that it was scrapped. And for any other aircraft, the total service life was 300 hours, and then it was scrapped!

 

I have a serious concern that many pilots today are flying aircraft that have done far more hours than this; are ignorant of these issues, and yet feel that they still have a plus 9G aircraft, with a heavy Western pilot; smoke system; both fuel tanks et cetera!

 

I prepared a detailed paper some years ago following discussions with Yakovlev describing the individual failures and then the subsequent service bulletins. I will send this to anyone who is interested.

 

Richard Goode Aerobatics

Rhodds Farm

Lyonshall

Hereford

HR5 3LW

 

Tel:  [url=tel:+44%201544%20340120]+44 (0) 1544 340120[/url]

Fax: [url=tel:+44%201544%20340129]+44 (0) 1544 340129[/url]

www.russianaeros.com



 

From: owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) [mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)] On Behalf Of Gordon PriceSent: 13 July 2017 19:31To: yak-list(at)matronics.com (yak-list(at)matronics.com)Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50

 

Thanks for the advice Frank however it would be nice on this forum if we could just stick to the topic at hand. 



 



In this caseâ€¦ the  topic it is a problem with  engine mount rubbers and the fact that the ones supplied did not have the sleeve bonded to the rubber. 



 



Has anyone ever experienced this? 



 

[quote]On Jul 13, 2017, at 1:44 PM, Frank Stelwagon <pfstelwagon(at)earthlink.net (pfstelwagon(at)earthlink.net)> wrote:



 

Mark wasnâ€™t lecturing you!  He was telling you what he knows from experience (lots of it).  It might be safer to listen.



 



From: owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) [mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)] On Behalf Of Gord PriceSent: Thursday, July 13, 2017 10:22 AMTo: yak-list(at)matronics.com (yak-list(at)matronics.com)Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50



 



Mark.  I asked for help .....not a lecture on a subject that I am well versed in nor assumptions that are incorrect

 

I have solved the problem and I am surprised you did not offer the advice that the sleeve does not require bonding....if it is the correct mounting rubber.  

 

The rubbers that were supplied and installed by my mechanic do not have the sleeve bonded. In fact the front rubbers do not even have a sleeve.  No wonder they were coming apart. 

 

A new 'proper' set is being installed this weekend.  I never had this problem with the old engine because it had the correct rubber mounts which were sold with the engine.  

 

I believe this will solve the problem and I will carry on flying a very aggressive and dynamic AIRSHOW routine that is well within the limits of my airplane which is constantly being inspected. 

 



 It is not the type of flying that most YAK owners engage in however I am quite at ease flying it this way. I first flew Victor Smolin's  YAK 50 in 1982 and I was taught the Lomcevak by its inventor Ladislav  Bezak in 1980.[url=tel:331%20826%209942]331 826 9942[/url]. Gord cell Mexico



[url=tel:333%20495%205044]333 495 5044[/url] Sandy cell Mexico

[url=tel:519%20375%206233]519 375 6233[/url] Gord cell Canada

[url=tel:519%20378%206800]519 378 6800[/url] Sandy cell Canada

[url=tel:519%20538%202868]519 538 2868[/url] House Canada

[url=tel:226%20777%204383]226 777 4383[/url] Email voice message anywhere



Sent from my iPhone



On Jul 13, 2017, at 12:00 PM, Bitterlich, Mark G CIV NAVAIR, WD <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)> wrote:

[quote]

--> Yak-List message posted by: "Bitterlich, Mark G CIV NAVAIR, WD" <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)>Typically, the rubber used in these engine mounts deteriorates with age.  Personally what I would try to do under your circumstance is to measure a new one with a durometer, and then have a mold constructed and replace them with a polyurethane equivalent.   You did not ask this, and I am sorry for sticking my nose into the topic and changing the subject somewhat, but I would suggest that you also make sure you have the Russian recording accelerometer installed in your 50, (or a suitable replacement) and are keeping track of the cycles.  The 50 is indeed rated to +9/-6 assuming all the mods are incorporated.  However that was not an unlimited qualification.  Meaning that after so many "cycles" (as documented on the recording accelerometer), it was a requirement to replace the wings.   Considering most 50's that were flown in unlimited events were usually retired under 100 hours of flight time, it might be worth keeping in mind.  The kind of damage to engine mount rubbers that you are describing is something commonly seen on Sukhoi's flying Unlimited level aerobatic  competition, usually with engines just like yours and MTV9-260 props, thus I suspect you are approaching that kind of G loading.   That said, the Suke construction otherwise is much stronger than the 50.  Another thing that generates this kind of stress is gyroscopic maneuvers usually accompanied by prop shaft seal damage.  Good luck. Mark--

dougsappllc(at)gmail.com
Guest

Posted: Fri Jul 14, 2017 9:17 am Post subject: [Non-DoD Source] Engine mount rubbers - YAK-50

Sorry to say, but I am out of stock on the M14P style mount rubbers at this time.Â  I do have good stock on the 285 hp style. Â 



We are however actively looking into an alternative mount material which may work well for both applications, but have no solid info to share at this time.

Best,

Doug

On Fri, Jul 14, 2017 at 9:31 AM, Gordon Price <gord(at)thedampub.ca (gord(at)thedampub.ca)> wrote:

[quote]

 Good point Doug and thank you for that.Â  There is a measurement of 34.5 mm on the plans sent to me by George Coy. Â  At that point should the metal sleeves inside touch? Â Â 

Does anyone have method of torquing Â that would be helpful or sod you just compress to 34.5 mm.

Could not enough torque could cause this problem?Â  Could too much torque cause the problem?Â  We donâ€™t know so if someone has experience please let us know.

We have yet to remove the engine since work is backed up in the shop however I am told that the forward rubber mounts that are installed did not have the washer with a sleeve. Only a washer..no sleeve.Â 

Also, which mounts do you sell Doug?Â  With or without the sleeve?

Thanks Â 

Gord

  

 

[quote]On Jul 14, 2017, at 11:54 AM, doug sapp <dougsappllc(at)gmail.com (dougsappllc(at)gmail.com)> wrote:

Gents,Addressing the "mount rubber" issue only. Â 

Are we 100% sure that the bonding or the failure of bonding to the washer or to the bushing is the problem here?Â  I suspect that it is not.Â  I suspect that the mount rubber were incorrectly installed.Â  Since there is no actual torque value stated in anything I have read it seems that there exists a large opportunity to install them without enough torque, meaning not tight enough.Â  In a "normal situation" (gentleman's acro) I would think that proper installation would not be as critical as is would be in this rather unusual Â high g loading situation.Â  This would help explain why this problem/situation has not been seen much in the past. Â 

Just a WAG on my part, YMMV.

Doug

On Fri, Jul 14, 2017 at 5:32 AM, Gordon Price <gord(at)thedampub.ca (gord(at)thedampub.ca)> wrote:

[quote]As I recall Richard you did say that the YAK 50 could be flown forever at +5 and -3.

As I said SOMETIMES I see +8 and -5 G.Â  Just being honest.Â  A normal airshow routine is +6 and -4 and yes the airplane has all the mods and lightweight equipment. As for the pilot weightâ€¦ I am always working on that.

You are right . The engine is spectacular and increased power has changed the flying characteristics of the airplane which I am still getting used to.Â  I should be fully up to speed by the end of August when I fly the CNE Â Canadian International Air Show in Toronto.





Back to the subject I have been to introduce for discussionâ€¦â€¦â€¦..





Attached is a picture of the different engine mount rubbers.

On the left 2 new ones with the rubber bonded to the steel insert Â and on the right one of the damaged mounts where the steel insert is not bonded and can turn and cut the rubber.

<rubber.jpeg>

 



  

 

[quote]On Jul 14, 2017, at 2:20 AM, That's looking at his note <richard.goode(at)russianaeros.com (richard.goode(at)russianaeros.com)> wrote:

Firstly I would like to make it clear that we supplied the engine together with the engine mount rubbers to Gordon Price. But we have used exactly the same rubbers on around 300 engines that we have supplied to a wide variety of aircraft, including competition Sukhois and have never had this problem before. But we will sort it out, and we know from Gordon that the engine is performing spectacularly well.

Â 

But it raises an issue which I think is far more important, and that is flying a Yak 50 to its design limits of plus 9G and minus 6G. I have done a lot of research on this topic, and the 50 was unfortunate in that it was introduced at a time that aerobatics changing from being big graceful manoeuvres to sharp angles. The Russian team was well funded and incredibly well motivated, and they were flying them Â beyond these limits, and had four fatal accidents to team members. During this period Yakovlev issued a series of service bulletins to reinforce the last bit of the aircraft that had broken, culminating in bulletin 79 â€“ a 4.5 mm steel plate on top and bottom of the centre section.

Â 

But firstly, remember that the Russian pilots were all relatively light; the aeroplane was flown only with one fuel tank; no generator; air compressor; a light battery. Then, the TOTAL service life of a team aircraft was 47 hours. After that it was scrapped. And for any other aircraft, the total service life was 300 hours, and then it was scrapped!

Â 

I have a serious concern that many pilots today are flying aircraft that have done far more hours than this; are ignorant of these issues, and yet feel that they still have a plus 9G aircraft, with a heavy Western pilot; smoke system; both fuel tanks et cetera!

Â 

I prepared a detailed paper some years ago following discussions with Yakovlev describing the individual failures and then the subsequent service bulletins. I will send this to anyone who is interested.

Â 

Richard Goode Aerobatics

Rhodds Farm

Lyonshall

Hereford

HR5 3LW

Â 

Tel:Â  [url=tel:+44%201544%20340120]+44 (0) 1544 340120[/url]

Fax: [url=tel:+44%201544%20340129]+44 (0) 1544 340129[/url]

www.russianaeros.com



Â 

From:Â owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)Â [mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)]Â On Behalf OfÂ Gordon Price

Sent:Â 13 July 2017 19:31

To:Â yak-list(at)matronics.com (yak-list(at)matronics.com)

Subject:Â Re: [Non-DoD Source] Engine mount rubbers - YAK-50

Â 

Thanks for the advice Frank however it would be nice on this forum if we could just stick to the topic at hand.Â 



Â 



In this caseâ€¦ the Â topic it is a problem with Â engine mount rubbers and the fact that the ones supplied did not have the sleeve bonded to the rubber.Â 



Â 



Has anyone ever experienced this?Â 



Â 

[quote]On Jul 13, 2017, at 1:44 PM, Frank Stelwagon <pfstelwagon(at)earthlink.net (pfstelwagon(at)earthlink.net)> wrote:



Â 

Mark wasnâ€™t lecturing you!Â  He was telling you what he knows from experience (lots of it).Â  It might be safer to listen.



Â 



From:Â owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)Â [mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)]Â On Behalf OfÂ Gord Price

Sent:Â Thursday, July 13, 2017 10:22 AM

To:Â yak-list(at)matronics.com (yak-list(at)matronics.com)

Subject:Â Re: [Non-DoD Source] Engine mount rubbers - YAK-50



Â 



Mark.Â  I asked for help .....not a lecture on a subject that I am well versed in nor assumptions that are incorrect

Â 

I have solved the problem and I am surprised you did not offer the advice that the sleeve does not require bonding....if it is the correct mounting rubber. Â 

Â 

The rubbers that were supplied and installed by my mechanic do not have the sleeve bonded. In fact the front rubbers do not even have a sleeve.Â  No wonder they were coming apart.Â 

Â 

A new 'proper' set is being installed this weekend.Â  I never had this problem with the old engine because it had the correct rubber mounts which were sold with the engine. Â 

Â 

I believe this will solve the problem and I will carry on flying a very aggressive and dynamic AIRSHOW routine that is well within the limits of my airplane which is constantly being inspected.Â 

Â 



Â It is not the type of flying that most YAK owners engage in however I am quite at ease flying it this way. I first flew Victor Smolin's Â YAK 50 in 1982 and I was taught the Lomcevak by its inventor Ladislav Â Bezak in 1980.[url=tel:331%20826%209942]331 826 9942[/url]. Gord cell Mexico



[url=tel:333%20495%205044]333 495 5044[/url]Â Sandy cell Mexico

[url=tel:519%20375%206233]519 375 6233[/url]Â Gord cell Canada

[url=tel:519%20378%206800]519 378 6800[/url]Â Sandy cell Canada

[url=tel:519%20538%202868]519 538 2868[/url]Â House Canada

[url=tel:226%20777%204383]226 777 4383[/url]Â Email voice message anywhere



Sent from my iPhone

On Jul 13, 2017, at 12:00 PM, Bitterlich, Mark G CIV NAVAIR, WD <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)> wrote:

[quote]

--> Yak-List message posted by: "Bitterlich, Mark G CIV NAVAIR, WD" <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)>



Typically, the rubber used in these engine mounts deteriorates with age.Â  Personally what I would try to do under your circumstance is to measure a new one with a durometer, and then have a mold constructed and replace them with a polyurethane equivalent. Â Â 



You did not ask this, and I am sorry for sticking my nose into the topic and changing the subject somewhat, but I would suggest that you also make sure you have the Russian recording accelerometer installed in your 50, (or a suitable replacement) and are keeping track of the cycles.Â  The 50 is indeed rated to +9/-6 assuming all the mods are incorporated.Â  However that was not an unlimited qualification.Â  Meaning that after so many "cycles" (as documented on the recording accelerometer), it was a requirement to replace the wings. Â Â Considering most 50's that were flown in unlimited events were usually retired under 100 hours of flight time, it might be worth keeping in mind. Â 



The kind of damage to engine mount rubbers that you are describing is something commonly seen on Sukhoi's flying Unlimited level aerobatic Â competition, usually with engines just like yours and MTV9-260 props, thus I suspect you are approaching that kind of G loading. Â Â That said, the Suke construction otherwise is much stronger than the 50.Â  Another thing that generates this kind of stress is gyroscopic maneuvers usually accompanied by prop shaft seal damage. Â 



Good luck.Â 



Mark

--

mark.bitterlich(at)navy.m
Guest

Posted: Fri Jul 14, 2017 11:05 am Post subject: [Non-DoD Source] Engine mount rubbers - YAK-50

Mr. Price and list members:   I have a few suggestions.  



1.  Richard Goode provided the engine and the rubbers to Mr. Price.   Richard is considered the de-facto expert on this make & model and other Russian aircraft as well.  His reputation is well earned, and I respect him completely.  Mr. Price has actually accused Richard (by proxy) of supplying him with incorrectly constructed engine rubbers.  Without knowing the exact cause of the failure of these parts, it is wrong for Mr. Price to insinuate this kind of thing in public.   



2.  I suggest Mr. Price that you take this conversation off-line and deal directly with the person who provided you with the material, is an expert on the material, and is more than willing to work out any problems that you have with the material , and has so stated in his message.   Ignoring that offer makes no sense.  



You mention that Richard Goode told you that +5/-3 could be flown forever with a YAK-50.    That in fact is correct, and these are numbers I have been careful to observe in my own 50, since 1999, and for over 800 hours in the model.      



What I have tried to gently relate to you (and other 50 owners) is that pulling +8/-5 in this aircraft is dangerous, and you could end up killing yourself and worse yet someone in the audience.  You have made it very clear that you believe your aircraft is perfectly safe to "occasionally" pull +8/-5, that +6/-4 is the norm, and that your aircraft is the exception to the rule, that your inspections make you safe, that I do not know what I am talking about.  What this really boils down to in my opinion is that anything that implies you might be pushing the envelope in this aircraft is to either be ignored, scoffed at, or the messenger who tells you what you don't want to hear; attacked.  



Mr. Price, I respect you as a pilot and an Airshow performer.  But pushing YAK-50 serial number ONE, to +8/-5 G's is too much, even once in a while, especially with an engine and prop that it was never designed for.    It is not a matter of being right or wrong, it is a matter of public safety.  

Mark Bitterlich 

--

GeorgeCoy

Joined: 02 Dec 2010
Posts: 310

Posted: Fri Jul 14, 2017 12:26 pm Post subject: [Non-DoD Source] Engine mount rubbers - YAK-50

Just to let you guys know, We can supply new production motor mount sets and all new hardware if needed, The part numbers and quantities are as follows for a complete set:: 

Qty. Â 24 ofÂ  508400-05 

Qty. Â 2 if the 506400-35. 

The -35 mounts are slightly smaller go on the rear by the magnetos and allow better access to the Magneto timing bolts. Contact me off list and I can supply pricing as well as a drawing showing the part numbers for all the bits and where they go. 

George Coy

From: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of doug sapp

Sent: Friday, July 14, 2017 1:14 PM

To: yak-list(at)matronics.com

Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50

 

Sorry to say, but I am out of stock on the M14P style mount rubbers at this time.  I do have good stock on the 285 hp style.  

 



We are however actively looking into an alternative mount material which may work well for both applications, but have no solid info to share at this time.



 



Best,



Doug

 

On Fri, Jul 14, 2017 at 9:31 AM, Gordon Price <gord(at)thedampub.ca (gord(at)thedampub.ca)> wrote:[quote]

 

Good point Doug and thank you for that.  There is a measurement of 34.5 mm on the plans sent to me by George Coy.   At that point should the metal sleeves inside touch?   



 



Does anyone have method of torquing  that would be helpful or sod you just compress to 34.5 mm.



 



Could not enough torque could cause this problem?  Could too much torque cause the problem?  We donâ€™t know so if someone has experience please let us know.



 



We have yet to remove the engine since work is backed up in the shop however I am told that the forward rubber mounts that are installed did not have the washer with a sleeve. Only a washer..no sleeve. 



 



Also, which mounts do you sell Doug?  With or without the sleeve?



 



Thanks  



 



Gord

 [quote]

On Jul 14, 2017, at 11:54 AM, doug sapp <dougsappllc(at)gmail.com (dougsappllc(at)gmail.com)> wrote:



 

Gents,

Addressing the "mount rubber" issue only.  



Are we 100% sure that the bonding or the failure of bonding to the washer or to the bushing is the problem here?  I suspect that it is not.  I suspect that the mount rubber were incorrectly installed.  Since there is no actual torque value stated in anything I have read it seems that there exists a large opportunity to install them without enough torque, meaning not tight enough.  In a "normal situation" (gentleman's acro) I would think that proper installation would not be as critical as is would be in this rather unusual  high g loading situation.  This would help explain why this problem/situation has not been seen much in the past.  



 



Just a WAG on my part, YMMV.



 



Doug

 

On Fri, Jul 14, 2017 at 5:32 AM, Gordon Price <gord(at)thedampub.ca (gord(at)thedampub.ca)> wrote:[quote]

As I recall Richard you did say that the YAK 50 could be flown forever at +5 and -3.



 



As I said SOMETIMES I see +8 and -5 G.  Just being honest.  A normal airshow routine is +6 and -4 and yes the airplane has all the mods and lightweight equipment. As for the pilot weightâ€¦ I am always working on that.



 



You are right . The engine is spectacular and increased power has changed the flying characteristics of the airplane which I am still getting used to.  I should be fully up to speed by the end of August when I fly the CNE  Canadian International Air Show in Toronto.



 



 



Back to the subject I have been to introduce for discussionâ€¦â€¦â€¦..



 



 



Attached is a picture of the different engine mount rubbers.



 



On the left 2 new ones with the rubber bonded to the steel insert  and on the right one of the damaged mounts where the steel insert is not bonded and can turn and cut the rubber.



 



<rubber.jpeg>

 

 

 [quote]

On Jul 14, 2017, at 2:20 AM, That's looking at his note <richard.goode(at)russianaeros.com (richard.goode(at)russianaeros.com)> wrote:



 

Firstly I would like to make it clear that we supplied the engine together with the engine mount rubbers to Gordon Price. But we have used exactly the same rubbers on around 300 engines that we have supplied to a wide variety of aircraft, including competition Sukhois and have never had this problem before. But we will sort it out, and we know from Gordon that the engine is performing spectacularly well.



 



But it raises an issue which I think is far more important, and that is flying a Yak 50 to its design limits of plus 9G and minus 6G. I have done a lot of research on this topic, and the 50 was unfortunate in that it was introduced at a time that aerobatics changing from being big graceful manoeuvres to sharp angles. The Russian team was well funded and incredibly well motivated, and they were flying them  beyond these limits, and had four fatal accidents to team members. During this period Yakovlev issued a series of service bulletins to reinforce the last bit of the aircraft that had broken, culminating in bulletin 79 â€“ a 4.5 mm steel plate on top and bottom of the centre section.



 



But firstly, remember that the Russian pilots were all relatively light; the aeroplane was flown only with one fuel tank; no generator; air compressor; a light battery. Then, the TOTAL service life of a team aircraft was 47 hours. After that it was scrapped. And for any other aircraft, the total service life was 300 hours, and then it was scrapped!



 



I have a serious concern that many pilots today are flying aircraft that have done far more hours than this; are ignorant of these issues, and yet feel that they still have a plus 9G aircraft, with a heavy Western pilot; smoke system; both fuel tanks et cetera!



 



I prepared a detailed paper some years ago following discussions with Yakovlev describing the individual failures and then the subsequent service bulletins. I will send this to anyone who is interested.



 



Richard Goode Aerobatics



Rhodds Farm



Lyonshall



Hereford



HR5 3LW



 



Tel:  [url=tel:+44%201544%20340120]+44 (0) 1544 340120[/url]



Fax: [url=tel:+44%201544%20340129]+44 (0) 1544 340129[/url]



www.russianaeros.com

 



From: owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) [mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)] On Behalf Of Gordon Price

Sent: 13 July 2017 19:31

To: yak-list(at)matronics.com (yak-list(at)matronics.com)

Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50



 



Thanks for the advice Frank however it would be nice on this forum if we could just stick to the topic at hand. 

 

In this caseâ€¦ the  topic it is a problem with  engine mount rubbers and the fact that the ones supplied did not have the sleeve bonded to the rubber. 

 

Has anyone ever experienced this? 

 

[quote]

On Jul 13, 2017, at 1:44 PM, Frank Stelwagon <pfstelwagon(at)earthlink.net (pfstelwagon(at)earthlink.net)> wrote:

 



Mark wasnâ€™t lecturing you!  He was telling you what he knows from experience (lots of it).  It might be safer to listen.

 

From: owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) [mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)] On Behalf Of Gord Price

Sent: Thursday, July 13, 2017 10:22 AM

To: yak-list(at)matronics.com (yak-list(at)matronics.com)

Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50





 

Mark.  I asked for help .....not a lecture on a subject that I am well versed in nor assumptions that are incorrect



 



I have solved the problem and I am surprised you did not offer the advice that the sleeve does not require bonding....if it is the correct mounting rubber.  



 



The rubbers that were supplied and installed by my mechanic do not have the sleeve bonded. In fact the front rubbers do not even have a sleeve.  No wonder they were coming apart. 



 



A new 'proper' set is being installed this weekend.  I never had this problem with the old engine because it had the correct rubber mounts which were sold with the engine.  



 



I believe this will solve the problem and I will carry on flying a very aggressive and dynamic AIRSHOW routine that is well within the limits of my airplane which is constantly being inspected. 



 



 It is not the type of flying that most YAK owners engage in however I am quite at ease flying it this way. I first flew Victor Smolin's  YAK 50 in 1982 and I was taught the Lomcevak by its inventor Ladislav  Bezak in 1980.

[url=tel:331%20826%209942]331 826 9942[/url]. Gord cell Mexico

[url=tel:333%20495%205044]333 495 5044[/url] Sandy cell Mexico



[url=tel:519%20375%206233]519 375 6233[/url] Gord cell Canada



[url=tel:519%20378%206800]519 378 6800[/url] Sandy cell Canada



[url=tel:519%20538%202868]519 538 2868[/url] House Canada



[url=tel:226%20777%204383]226 777 4383[/url] Email voice message anywhere

Sent from my iPhone

On Jul 13, 2017, at 12:00 PM, Bitterlich, Mark G CIV NAVAIR, WD <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)> wrote:

[quote]

--> Yak-List message posted by: "Bitterlich, Mark G CIV NAVAIR, WD" <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)>



Typically, the rubber used in these engine mounts deteriorates with age.  Personally what I would try to do under your circumstance is to measure a new one with a durometer, and then have a mold constructed and replace them with a polyurethane equivalent.   



You did not ask this, and I am sorry for sticking my nose into the topic and changing the subject somewhat, but I would suggest that you also make sure you have the Russian recording accelerometer installed in your 50, (or a suitable replacement) and are keeping track of the cycles.  The 50 is indeed rated to +9/-6 assuming all the mods are incorporated.  However that was not an unlimited qualification.  Meaning that after so many "cycles" (as documented on the recording accelerometer), it was a requirement to replace the wings.   Considering most 50's that were flown in unlimited events were usually retired under 100 hours of flight time, it might be worth keeping in mind.  



The kind of damage to engine mount rubbers that you are describing is something commonly seen on Sukhoi's flying Unlimited level aerobatic  competition, usually with engines just like yours and MTV9-260 props, thus I suspect you are approaching that kind of G loading.   That said, the Suke construction otherwise is much stronger than the 50.  Another thing that generates this kind of stress is gyroscopic maneuvers usually accompanied by prop shaft seal damage.  



Good luck. 



Mark

--

gord(at)thedampub.ca
Guest

Posted: Fri Jul 14, 2017 12:41 pm Post subject: [Non-DoD Source] Engine mount rubbers - YAK-50

Thanks Mark



Your opinions are noted



If you have any knowledge about the different mount rubbers and any failures please pass it on



Gord

[quote] On Jul 14, 2017, at 3:02 PM, Bitterlich, Mark G CIV NAVAIR, WD <mark.bitterlich(at)navy.mil> wrote:

 

 

 

 Mr. Price and list members:   I have a few suggestions.  

 

 1.  Richard Goode provided the engine and the rubbers to Mr. Price.   Richard is considered the de-facto expert on this make & model and other Russian aircraft as well.  His reputation is well earned, and I respect him completely.  Mr. Price has actually accused Richard (by proxy) of supplying him with incorrectly constructed engine rubbers.  Without knowing the exact cause of the failure of these parts, it is wrong for Mr. Price to insinuate this kind of thing in public.   

 

 2.  I suggest Mr. Price that you take this conversation off-line and deal directly with the person who provided you with the material, is an expert on the material, and is more than willing to work out any problems that you have with the material , and has so stated in his message.   Ignoring that offer makes no sense.  

 

 You mention that Richard Goode told you that +5/-3 could be flown forever with a YAK-50.    That in fact is correct, and these are numbers I have been careful to observe in my own 50, since 1999, and for over 800 hours in the model.      

 

 What I have tried to gently relate to you (and other 50 owners) is that pulling +8/-5 in this aircraft is dangerous, and you could end up killing yourself and worse yet someone in the audience.  You have made it very clear that you believe your aircraft is perfectly safe to "occasionally" pull +8/-5, that +6/-4 is the norm, and that your aircraft is the exception to the rule, that your inspections make you safe, that I do not know what I am talking about.  What this really boils down to in my opinion is that anything that implies you might be pushing the envelope in this aircraft is to either be ignored, scoffed at, or the messenger who tells you what you don't want to hear; attacked.  

 

 Mr. Price, I respect you as a pilot and an Airshow performer.  But pushing YAK-50 serial number ONE, to +8/-5 G's is too much, even once in a while, especially with an engine and prop that it was never designed for.    It is not a matter of being right or wrong, it is a matter of public safety.  

 

 

 Mark Bitterlich 

 

 

 --

Viperdoc

Joined: 19 Apr 2014
Posts: 484
Location: 08A

Posted: Sun Jul 16, 2017 5:16 am Post subject: [Non-DoD Source] Engine mount rubbers - YAK-50

ðŸ‘ðŸ‘ðŸ‘ðŸ‘ðŸ‘, Doug.

Doc



Sent from my iPad



On Jul 14, 2017, at 10:54 AM, doug sapp <dougsappllc(at)gmail.com (dougsappllc(at)gmail.com)> wrote:

[quote]Gents,Addressing the "mount rubber" issue only.  

Are we 100% sure that the bonding or the failure of bonding to the washer or to the bushing is the problem here?  I suspect that it is not.  I suspect that the mount rubber were incorrectly installed.  Since there is no actual torque value stated in anything I have read it seems that there exists a large opportunity to install them without enough torque, meaning not tight enough.  In a "normal situation" (gentleman's acro) I would think that proper installation would not be as critical as is would be in this rather unusual  high g loading situation.  This would help explain why this problem/situation has not been seen much in the past.  

Just a WAG on my part, YMMV.

Doug

On Fri, Jul 14, 2017 at 5:32 AM, Gordon Price <gord(at)thedampub.ca (gord(at)thedampub.ca)> wrote:

[quote]As I recall Richard you did say that the YAK 50 could be flown forever at +5 and -3.

As I said SOMETIMES I see +8 and -5 G.  Just being honest.  A normal airshow routine is +6 and -4 and yes the airplane has all the mods and lightweight equipment. As for the pilot weightâ€¦ I am always working on that.

You are right . The engine is spectacular and increased power has changed the flying characteristics of the airplane which I am still getting used to.  I should be fully up to speed by the end of August when I fly the CNE  Canadian International Air Show in Toronto.





Back to the subject I have been to introduce for discussionâ€¦â€¦â€¦..





Attached is a picture of the different engine mount rubbers.

On the left 2 new ones with the rubber bonded to the steel insert  and on the right one of the damaged mounts where the steel insert is not bonded and can turn and cut the rubber.

<rubber.jpeg>

 



  

 

[quote]On Jul 14, 2017, at 2:20 AM, That's looking at his note <richard.goode(at)russianaeros.com (richard.goode(at)russianaeros.com)> wrote:

Firstly I would like to make it clear that we supplied the engine together with the engine mount rubbers to Gordon Price. But we have used exactly the same rubbers on around 300 engines that we have supplied to a wide variety of aircraft, including competition Sukhois and have never had this problem before. But we will sort it out, and we know from Gordon that the engine is performing spectacularly well.

 

But it raises an issue which I think is far more important, and that is flying a Yak 50 to its design limits of plus 9G and minus 6G. I have done a lot of research on this topic, and the 50 was unfortunate in that it was introduced at a time that aerobatics changing from being big graceful manoeuvres to sharp angles. The Russian team was well funded and incredibly well motivated, and they were flying them  beyond these limits, and had four fatal accidents to team members. During this period Yakovlev issued a series of service bulletins to reinforce the last bit of the aircraft that had broken, culminating in bulletin 79 â€“ a 4.5 mm steel plate on top and bottom of the centre section.

 

But firstly, remember that the Russian pilots were all relatively light; the aeroplane was flown only with one fuel tank; no generator; air compressor; a light battery. Then, the TOTAL service life of a team aircraft was 47 hours. After that it was scrapped. And for any other aircraft, the total service life was 300 hours, and then it was scrapped!

 

I have a serious concern that many pilots today are flying aircraft that have done far more hours than this; are ignorant of these issues, and yet feel that they still have a plus 9G aircraft, with a heavy Western pilot; smoke system; both fuel tanks et cetera!

 

I prepared a detailed paper some years ago following discussions with Yakovlev describing the individual failures and then the subsequent service bulletins. I will send this to anyone who is interested.

 

Richard Goode Aerobatics

Rhodds Farm

Lyonshall

Hereford

HR5 3LW

 

Tel:  [url=tel:+44%201544%20340120]+44 (0) 1544 340120[/url]

Fax: [url=tel:+44%201544%20340129]+44 (0) 1544 340129[/url]

www.russianaeros.com



 

From: owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) [mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)] On Behalf Of Gordon Price

Sent: 13 July 2017 19:31

To: yak-list(at)matronics.com (yak-list(at)matronics.com)

Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50

 

Thanks for the advice Frank however it would be nice on this forum if we could just stick to the topic at hand. 



 



In this caseâ€¦ the  topic it is a problem with  engine mount rubbers and the fact that the ones supplied did not have the sleeve bonded to the rubber. 



 



Has anyone ever experienced this? 



 

[quote]On Jul 13, 2017, at 1:44 PM, Frank Stelwagon <pfstelwagon(at)earthlink.net (pfstelwagon(at)earthlink.net)> wrote:



 

Mark wasnâ€™t lecturing you!  He was telling you what he knows from experience (lots of it).  It might be safer to listen.



 



From: owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) [mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)] On Behalf Of Gord Price

Sent: Thursday, July 13, 2017 10:22 AM

To:  Re: [Non-DoD Source] Yak-List: Engine mount rubbers - YAK-50



 



Mark.  I asked for help .....not a lecture on a subject that I am well versed in nor assumptions that are incorrect

 

I have solved the problem and I am surprised you did not offer the advice that the sleeve does not require bonding....if it is the correct mounting rubber.  

 

The rubbers that were supplied and installed by my mechanic do not have the sleeve bonded. In fact the front rubbers do not even have a sleeve.  No wonder they were coming apart. 

 

A new 'proper' set is being installed this weekend.  I never had this problem with the old engine because it had the correct rubber mounts which were sold with the engine.  

 

I believe this will solve the problem and I will carry on flying a very aggressive and dynamic AIRSHOW routine that is well within the limits of my airplane which is constantly being inspected. 

 



 It is not the type of flying that most YAK owners engage in however I am quite at ease flying it this way. I first flew Victor Smolin's  YAK 50 in 1982 and I was taught the Lomcevak by its inventor Ladislav  Bezak in 1980.[url=tel:331%20826%209942]331 826 9942[/url]. Gord cell Mexico



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[url=tel:519%20375%206233]519 375 6233[/url] Gord cell Canada

[url=tel:519%20378%206800]519 378 6800[/url] Sandy cell Canada

[url=tel:519%20538%202868]519 538 2868[/url] House Canada

[url=tel:226%20777%204383]226 777 4383[/url] Email voice message anywhere



Sent from my iPhone

On Jul 13, 2017, at 12:00 PM, Bitterlich, Mark G CIV NAVAIR, WD <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)> wrote:



[quote]

--> Yak-List message posted by: "Bitterlich, Mark G CIV NAVAIR, WD" <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)>



Typically, the rubber used in these engine mounts deteriorates with age.  Personally what I would try to do under your circumstance is to measure a new one with a durometer, and then have a mold constructed and replace them with a polyurethane equivalent.   



You did not ask this, and I am sorry for sticking my nose into the topic and changing the subject somewhat, but I would suggest that you also make sure you have the Russian recording accelerometer installed in your 50, (or a suitable replacement) and are keeping track of the cycles.  The 50 is indeed rated to +9/-6 assuming all the mods are incorporated.  However that was not an unlimited qualification.  Meaning that after so many "cycles" (as documented on the recording accelerometer), it was a requirement to replace the wings.   Considering most 50's that were flown in unlimited events were usually retired under 100 hours of flight time, it might be worth keeping in mind.  



The kind of damage to engine mount rubbers that you are describing is something commonly seen on Sukhoi's flying Unlimited level aerobatic  competition, usually with engines just like yours and MTV9-260 props, thus I suspect you are approaching that kind of G loading.   That said, the Suke construction otherwise is much stronger than the 50.  Another thing that generates this kind of stress is gyroscopic maneuvers usually accompanied by prop shaft seal damage.  



Good luck. 



Mark

--

_________________
Viperdoc

Viperdoc

Joined: 19 Apr 2014
Posts: 484
Location: 08A

Posted: Sun Jul 16, 2017 5:21 am Post subject: [Non-DoD Source] Engine mount rubbers - YAK-50

Gord,

The instructions I got were to compress to 44.5 mm.

Doc



Sent from my iPad



[quote] On Jul 14, 2017, at 11:31 AM, Gordon Price <gord(at)thedampub.ca> wrote:

 

 

 Good point Doug and thank you for that.  There is a measurement of 34.5 mm on the plans sent to me by George Coy.   At that point should the metal sleeves inside touch?   

 

 Does anyone have method of torquing  that would be helpful or sod you just compress to 34.5 mm.

 

 Could not enough torque could cause this problem?  Could too much torque cause the problem?  We donâ€™t know so if someone has experience please let us know.

 

 We have yet to remove the engine since work is backed up in the shop however I am told that the forward rubber mounts that are installed did not have the washer with a sleeve. Only a washer..no sleeve. 

 

 Also, which mounts do you sell Doug?  With or without the sleeve?

 

 Thanks  

 

 Gord

 

> On Jul 14, 2017, at 11:54 AM, doug sapp <dougsappllc(at)gmail.com> wrote:

> 

> Gents,

> Addressing the "mount rubber" issue only.  

> Are we 100% sure that the bonding or the failure of bonding to the washer or to the bushing is the problem here?  I suspect that it is not.  I suspect that the mount rubber were incorrectly installed.  Since there is no actual torque value stated in anything I have read it seems that there exists a large opportunity to install them without enough torque, meaning not tight enough.  In a "normal situation" (gentleman's acro) I would think that proper installation would not be as critical as is would be in this rather unusual  high g loading situation.  This would help explain why this problem/situation has not been seen much in the past.  

> 

> Just a WAG on my part, YMMV.

> 

> Doug

> 

>> On Fri, Jul 14, 2017 at 5:32 AM, Gordon Price <gord(at)thedampub.ca> wrote:

>> As I recall Richard you did say that the YAK 50 could be flown forever at +5 and -3.

>> 

>> As I said SOMETIMES I see +8 and -5 G.  Just being honest.  A normal airshow routine is +6 and -4 and yes the airplane has all the mods and lightweight equipment. As for the pilot weightâ€¦ I am always working on that.

>> 

>> You are right . The engine is spectacular and increased power has changed the flying characteristics of the airplane which I am still getting used to.  I should be fully up to speed by the end of August when I fly the CNE  Canadian International Air Show in Toronto.

>> 

>> 

>> Back to the subject I have been to introduce for discussionâ€¦â€¦â€¦..

>> 

>> 

>> Attached is a picture of the different engine mount rubbers.

>> 

>> On the left 2 new ones with the rubber bonded to the steel insert  and on the right one of the damaged mounts where the steel insert is not bonded and can turn and cut the rubber.

>> 

>> <rubber.jpeg>

>> 

>> 

>> 

>>> On Jul 14, 2017, at 2:20 AM, That's looking at his note <richard.goode(at)russianaeros.com> wrote:

>>> 

>>> Firstly I would like to make it clear that we supplied the engine together with the engine mount rubbers to Gordon Price. But we have used exactly the same rubbers on around 300 engines that we have supplied to a wide variety of aircraft, including competition Sukhois and have never had this problem before. But we will sort it out, and we know from Gordon that the engine is performing spectacularly well.

>>>  

>>> But it raises an issue which I think is far more important, and that is flying a Yak 50 to its design limits of plus 9G and minus 6G. I have done a lot of research on this topic, and the 50 was unfortunate in that it was introduced at a time that aerobatics changing from being big graceful manoeuvres to sharp angles. The Russian team was well funded and incredibly well motivated, and they were flying them  beyond these limits, and had four fatal accidents to team members. During this period Yakovlev issued a series of service bulletins to reinforce the last bit of the aircraft that had broken, culminating in bulletin 79 â€“ a 4.5 mm steel plate on top and bottom of the centre section.

>>>  

>>> But firstly, remember that the Russian pilots were all relatively light; the aeroplane was flown only with one fuel tank; no generator; air compressor; a light battery. Then, the TOTAL service life of a team aircraft was 47 hours. After that it was scrapped. And for any other aircraft, the total service life was 300 hours, and then it was scrapped!

>>>  

>>> I have a serious concern that many pilots today are flying aircraft that have done far more hours than this; are ignorant of these issues, and yet feel that they still have a plus 9G aircraft, with a heavy Western pilot; smoke system; both fuel tanks et cetera!

>>>  

>>> I prepared a detailed paper some years ago following discussions with Yakovlev describing the individual failures and then the subsequent service bulletins. I will send this to anyone who is interested.

>>>  

>>> Richard Goode Aerobatics

>>> Rhodds Farm

>>> Lyonshall

>>> Hereford

>>> HR5 3LW

>>>  

>>> Tel:  +44 (0) 1544 340120

>>> Fax: +44 (0) 1544 340129

>>> www.russianaeros.com

>>>  

>>> From: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of Gordon Price

>>> Sent: 13 July 2017 19:31

>>> To: yak-list(at)matronics.com

>>> Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50

>>>  

>>> Thanks for the advice Frank however it would be nice on this forum if we could just stick to the topic at hand. 

>>>  

>>> In this caseâ€¦ the  topic it is a problem with  engine mount rubbers and the fact that the ones supplied did not have the sleeve bonded to the rubber. 

>>>  

>>> Has anyone ever experienced this? 

>>>  

>>>> On Jul 13, 2017, at 1:44 PM, Frank Stelwagon <pfstelwagon(at)earthlink.net> wrote:

>>>>  

>>>> Mark wasnâ€™t lecturing you!  He was telling you what he knows from experience (lots of it).  It might be safer to listen.

>>>>  

>>>> From: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of Gord Price

>>>> Sent: Thursday, July 13, 2017 10:22 AM

>>>> To: yak-list(at)matronics.com

>>>> Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50

>>>>  

>>>> Mark.  I asked for help .....not a lecture on a subject that I am well versed in nor assumptions that are incorrect

>>>>  

>>>> I have solved the problem and I am surprised you did not offer the advice that the sleeve does not require bonding....if it is the correct mounting rubber.  

>>>>  

>>>> The rubbers that were supplied and installed by my mechanic do not have the sleeve bonded. In fact the front rubbers do not even have a sleeve.  No wonder they were coming apart. 

>>>>  

>>>> A new 'proper' set is being installed this weekend.  I never had this problem with the old engine because it had the correct rubber mounts which were sold with the engine.  

>>>>  

>>>> I believe this will solve the problem and I will carry on flying a very aggressive and dynamic AIRSHOW routine that is well within the limits of my airplane which is constantly being inspected. 

>>>>  

>>>>  It is not the type of flying that most YAK owners engage in however I am quite at ease flying it this way. I first flew Victor Smolin's  YAK 50 in 1982 and I was taught the Lomcevak by its inventor Ladislav  Bezak in 1980

_________________
Viperdoc

gord(at)thedampub.ca
Guest

Posted: Sun Jul 16, 2017 5:59 am Post subject: [Non-DoD Source] Engine mount rubbers - YAK-50

Thanks Doc 

That is a big difference!



Here is the drawing George Coy sent to me.



Do you know if the rubber is bonded to the sleeve and are there sleeves on both the front and back rubbers?



We will know more once we get the engine off the mount on Wednesday.



Gord

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