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Yak-52 heavy spar

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richard.goode(at)russiana
Guest

Posted: Fri Aug 29, 2008 8:42 am Post subject: Yak-52 heavy spar

I see there is another enquiry about how to identify the heavy spar on the Yak-52.   

It is a great pity that this simplistic notion still continues.   

To confirm:   

Yak-52 is a very tough aeroplane but when it began being flown hard, a number of structural problems emerged.  As they emerged, Yakovlev instituted a series of mandatory Service Bulletins to allow the aeroplane to continue to fly at the same G limits.  

Unfortunately, many aeroplanes have not been modified; some logbooks have been falsified etc.  

There are actually 114 Service Bulletins, of which many are trivial.  

Our view is that there are 31 serious structural Bulletins, which really should be installed on any 52s doing aerobatics at more than (say) 4G.  

The list of these important Bulletins is as follows:  

  

9       48      71     

 18      53      72     

 28      54      75     

 34      59      80     

 36      60      82     

 37      62      92     

 38      66      93     

 41      67      99     

 45      69      100    

 47      70      106    

                 107    

   

The critical wing Bulletins are:   

59 for stronger wing mountings  

60 for stronger centre section  

107 – external (underneath) spar-strap   

59 and 60 came out together in 1987 and 107 in 1991  

So the practicality is that an aeroplane built after the middle of 1991 SHOULD have all SBs incorporated.   

Also, any aeroplanes incorporating 107 are almost certainly incorporating all earlier Bulletins.   

107 can be identified by being a metal plate, about 4’ long, bolted under the wing to the main spar, but proud of the under-wing surface. 

  

Richard Goode Aerobatics  

Rhodds Farm  

Lyonshall  

Hereford  

HR5 3LW  

United Kingdom  

   

Tel:   +44 (0) 1544 340120  

Fax:  +44 (0) 1544 340129  

www.russianaeros.com  

     [quote][b]

f4ffm2(at)adelphia.net
Guest

Posted: Fri Aug 29, 2008 4:04 pm Post subject: Yak-52 heavy spar

Richard,

     Nice of you to chime in on this matter, but you did not answer the mans question.  I don't think I quite follow you when you say "It is a great pity that this simplistic notion still continues".  To what "simplistic notion" were your referring? 



     I would be interested in knowing what the "number of structural problems" that emerged actually were.  Does anyone (such as yourself) have a verified list of the actual structual problems that are supposed to have been occuring on Yak 52's?  If so, is there any independant verification that these problems were truly occuring in the real world.



     I do know the trail that led to Bulletin #107 and from that, I believe that  bulletin 107 is nonsense....written in an attempt to raise some money at the bureau in those dark days of the early to mid 90's when they had no funding from anybody.  If you know different, I would appreciate hearing about it.



     So far as I know, NO Yak 52, with or without the wing attach and spar carry through modifications mandated by 59 and 60, has crashed due to structural failure.



Roger Baker



     

On Aug 29, 2008, at 9:41 AM, Richard Goode wrote:

[quote]   



I see there is another enquiry about how to identify the heavy spar on the Yak-52.  

It is a great pity that this simplistic notion still continues. 

To confirm: 

Yak-52 is a very tough aeroplane but when it began being flown hard, a number of structural problems emerged.  As they emerged, Yakovlev instituted a series of mandatory Service Bulletins to allow the aeroplane to continue to fly at the same G limits.

Unfortunately, many aeroplanes have not been modified; some logbooks have been falsified etc. 

There are actually 114 Service Bulletins, of which many are trivial. 

Our view is that there are 31 serious structural Bulletins, which really should be installed on any 52s doing aerobatics at more than (say) 4G.

The list of these important Bulletins is as follows:  



9       48      71     

 18      53      72     

 28      54      75     

 34      59      80     

 36      60      82     

 37      62      92     

 38      66      93     

 41      67      99     

 45      69      100    

 47      70      106    

                 107    

  

The critical wing Bulletins are: 

59 for stronger wing mountings 

60 for stronger centre section 

107 – external (underneath) spar-strap 

59 and 60 came out together in 1987 and 107 in 1991 

So the practicality is that an aeroplane built after the middle of 1991 SHOULD have all SBs incorporated. 

Also, any aeroplanes incorporating 107 are almost certainly incorporating all earlier Bulletins. 

107 can be identified by being a metal plate, about 4’ long, bolted under the wing to the main spar, but proud of the under-wing surface. 



Richard Goode Aerobatics 

Rhodds Farm 

Lyonshall 

Hereford 

HR5 3LW 

United Kingdom 

  

Tel:   +44 (0) 1544 340120 

Fax:  +44 (0) 1544 340129 

www.russianaeros.com  

  	  Quote: 	
		  

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[b]

richard.goode(at)russiana
Guest

Posted: Sat Aug 30, 2008 12:13 am Post subject: Yak-52 heavy spar

The "simplistic notion" is that there is  something called a "heavy spar" that makes a 52 safe to fly hard.I'm simply  making it clear that there is a range of mandatory SB's that you must have to  fly a 52 to its design limits.

 Yes ,I have discussed the whole issue of  52[and50/55] structural integrity for many hours over a number of meetings with  Dimitry Dratch [Yak chief designer for light aircraft] and his designers in  Moscow.

 They had no vested interest to imagine or  create problems that did not exist,and each structural SB was brought about by a  specific problem across a huge fleet [1200] of aircraft.

 107SB is a complex issue but the point that  it was issued to make money is absurd!It came out in 1990 when Yak was well  funded,and importantly they would get NO money from it since they did not make  the 107 kits!

 You are correct,and there have been no total  failures in 52s,BUT there have been a wide variety of serious problems  begining-and I have seen the reports and photos.The reason that the 52 remained  safe was the introduction of the SBs.Also because few pilots fly them at their  design limits-AND because most 52s have been modified.

 If you have any doubts about the seriosness  of the approach of Yak,you should consider the history of the 50,with 4 fatal  crashes due to structural problems,and many more prevented by very diligent  inspections and,of course a raft of SBs.

  

 Richard

  

 Richard Goode Aerobatics

Rhodds Farm

Lyonshall

Hereford

HR5  3LW

United Kingdom

  

 Tel:   +44 (0) 1544 340120

Fax:  +44 (0) 1544  340129

www.russianaeros.com



 [quote]   ---

tjyak50

Joined: 31 May 2007
Posts: 81
Location: Phoenix, AZ

Posted: Sat Aug 30, 2008 6:27 am Post subject: Re: Yak-52 heavy spar

Richard:

The tone of your email implies that we, U.S. Americans..., are unfamiliar with the modifications of the Yak 52.   



When a person uses the term "Heavy Spar" what they mean (generally) is Service Bulletin 59 and 60.  



Service Bulletin 59 and 60 clearly are more massive (slightly greater weight) and also increase overall strength and hence we assign the adjective "Heavy".  It is a colloquialism of sorts.



In my opinion, a Yak 52 with the "Heavy Spar" is indeed safe to fly "hard".

Many others, possibly including yourself, agree with me (us).



Perhaps your misunderstanding is due to the language barrier between this American Yak-list and your native language in the U.K.



Have a nice weekend.

Tom Johnson (signed).

richard.goode(at)russiana
Guest

Posted: Sat Aug 30, 2008 9:14 am Post subject: Yak-52 heavy spar

Again,this is too simplistic!The SBs  subsequent to 59 & 60 are there because there have been real problems  with the structure when flown at the design limits.You can be sure that EVERY 52  that was flown in the East was flown at or very near these limits.

 Also,I have seen various Logs saying that  the 52 concerned had the various SBs embodied whe they had not,and unless you  really know what to look for,it is very hard to know if they have or  not.

 If a 52 has not had ALL the SBs embodied my  firm conviction is that it should not be flown hard.I do not consider a 52 with  only 59 & 60 to be fully modified.

 It is possible that I am over-cautious but I  did spend 4 months in one hospital bed after airframe failure [not a Yak],and I  would not wish that on anyone.I have also spent a lot of time with the Yakovlev  designers,and I am sure that every SB is there because it is needed IF the plane  is flown as was intended!!

 Richard

  

 Richard Goode Aerobatics

Rhodds Farm

Lyonshall

Hereford

HR5  3LW

United Kingdom

  

 Tel:   +44 (0) 1544 340120

Fax:  +44 (0) 1544  340129

www.russianaeros.com



 [quote]   ---

vectorwarbirds(at)aol.com
Guest

Posted: Sat Aug 30, 2008 4:58 pm Post subject: Yak-52 heavy spar

Richard,

 

 I for one appreciate your knowledge and advice on this matter, I feel as you do that you cannot be too safe.  As we are looking for a 52 to add to our Nanchang stable your, as well as others, experience and real world problems have helped us greatly, and I just want you to know that there are many of us out here that listen carefully to what you and others have to say.  And I for one take those things to heart.  Fly Safe Comrade and thank you!!

 

 Gary Bunn

 Vector Warbirds USA

 

 

   

 

   

 

 --

heaysr(at)telus.net
Guest

Posted: Sat Aug 30, 2008 5:35 pm Post subject: Yak-52 heavy spar

Hello Richard,  

   

Do you have a similar list of SB’s for the Yak 55M that you could post, and if yes, do you have each one of them available in English  

   

Royden Heays  

Vancouver BC  

Canada  

   

--

drc(at)wscare.com
Guest

Posted: Sat Aug 30, 2008 8:38 pm Post subject: Yak-52 heavy spar

Yes you mentioned the 50 and the 55 in a previous email - i would ask for the same info for the 55 and others on the list may want to see a list for the 50.



Thanks,

herb





On Aug 30, 2008, at 8:34 PM, Royden Heays wrote:

[quote]Hello Richard,



 Do you have a similar list of SB’s for the Yak 55M that you could post, and if yes, do you have each one of them available in English



 Royden Heays

Vancouver BC

Canada



 --

aeroconcept

Joined: 13 Jun 2008
Posts: 3

Posted: Sun Aug 31, 2008 12:17 am Post subject: Re: Yak-52 heavy spar

The issue of bulletins is quite less complicated than it sometimes appears to be. In fact, the complete lists are available from Yakovlev. For my part, I have translated and put them on my Web site years ago â€“ this is where one realizes that his referencing is probably not optimized, euhâ€¦ Anyway, take a look at:



http://www.aero-concept.com/Pages/Pages_reserved/52_pages/52_SB.html

http://www.aero-concept.com/Pages/Pages_reserved/50_pages/50_SB.html



These lists are quite self-explanatory. I would not attempt to range them according to their importance. The lettering comes from the history of their implementation, with E-bulletins clearly concerning the changes in documentation only. Anyway, for Yakovlev they are all applicable, hence have to be implemented during OHs at the Yakovlev certified facilities, the meaning of certification.



One remarks that the lists have the serial numbers concerned. For instance, the famous 59R/60R couple was introduced in production at Bacau somewhere in mid-1986, theoretically starting with # 866501, although I know of a few of later 1986 serials that were still manufactured with the light spar. The reason is the discrepancy between the times of manufacture of the airframes and of the finished aircraft, i.e. some earlier manufactured airframes were completed later than others.



It may be less easy to judge oneâ€™s aircraft compliance.

After checking your serial against the SB list, the next step is to check the original (Russian) airframe logbook which lists all SBs applied during overhauls.

Unfortunately, this can not be enough. I agree that some of the logbooks have been faked or incomplete, hence a visual check can be necessary, starting with the most known 59/60 and 107. If you have any problems in reading the logbooks, feel free to send me copies of relevant pages, for second opinion.



I do have a list of bulletins for Yak-55, I will put it on my site in near future. In between, I can send them individually on request.



Ilia Palamodov

Aeroconcept Trading

Phone +33614487585

www.aero-concept.com

mikspin

Joined: 12 Aug 2007
Posts: 66

Posted: Sun Aug 31, 2008 8:23 am Post subject: Re: Yak-52 heavy spar

Richard,



With respect to these SB's, I do not question their validity.  However, could you please respond with what was found to be wrong with the aircraft in the past that prompted the respective SB?  I have not found in your past posts any descriptions of what was found.  



Again, I do not question their validity, I just would like to know the failure mode(s) for inspection/maintenance as well as educational purposes.  I am assuming that your discussions with Dimitry Dratch and co. would have given you access to this information.



Thank you in advance,



Mike Hastings

richard.goode(at)russiana
Guest

Posted: Tue Sep 02, 2008 6:53 am Post subject: Yak-52 heavy spar

Hi Herb-I assume you saw the link to the 50  and 55 Service Bulletins!

 Richard

  

 Richard Goode Aerobatics

Rhodds Farm

Lyonshall

Hereford

HR5  3LW

United Kingdom

  

 Tel:   +44 (0) 1544 340120

Fax:  +44 (0) 1544  340129

www.russianaeros.com



 [quote]   ---

Pete M

Joined: 21 Apr 2006
Posts: 4
Location: Kent, UK

Posted: Fri Sep 05, 2008 12:56 pm Post subject: Re: Yak-52 heavy spar

Richard,



What do you know about main spar corrosion?



We recently trashed a 1983 build 52 because of it.



Is there an issue with the quality of metal used?

Last edited by Pete M on Sat Sep 06, 2008 8:59 am; edited 1 time in total

richard.goode(at)russiana
Guest

Posted: Sat Sep 06, 2008 12:25 am Post subject: Yak-52 heavy spar

Pete-It does seem to be a problem with older  planes that are in the open;

 near the sea,and also some types of  industry.But,I've only heard of 3/4 cases alltogether.

 I'd be interested in more  information.

 Richard

  

 Richard Goode Aerobatics

Rhodds Farm

Lyonshall

Hereford

HR5  3LW

United Kingdom

  

 Tel:   +44 (0) 1544 340120

Fax:  +44 (0) 1544  340129

www.russianaeros.com



 [quote]   ---

Pete M

Joined: 21 Apr 2006
Posts: 4
Location: Kent, UK

Posted: Sat Sep 06, 2008 8:58 am Post subject: Re: Yak-52 heavy spar

Richard,



The aircraft was originally made in 1983 but rebuilt in Lithuania 1994. Total time on airframe was around 1700 hours and it lived outside in Southern England all its western life.



During those hours it had been used for aerobatic competitions and more later a few flying displays as well as chugging around in a more civilised manner.



During the annual check 'bad' corrosion was found in the left wing and to a lesser extent in the right. We were advised that we needed 2 new lower wing spars.



As the machine was looking a bit shabby and in need of a re-paint the cost of the re-spar was expected to be close to its market value. So the group decided to bin it for what we could get. It is now in Germany with another 52 and we are told its going to be repaired. 



At the time I believe that there was another 52 suffering the same problem, although a slightly later production year. This could well be the other one that went to Germany (in fact I am fairly certain)

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