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Gearbox Bearing limits at the Flange

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italianjon

Joined: 05 Aug 2015
Posts: 68

Posted: Sun Mar 26, 2017 4:12 am Post subject: Gearbox Bearing limits at the Flange

Hi all,



I checked the manual (Heavy Maintenance) but can't find information on the specific bearing.



If I pull/push the propeller there is a small amount of play between propeller gearbox shaft and the gearbox housing. 



Also if I lift the propeller vertically there is a small amount of play, it is repeatable in all radial directions. It's not the gear play in the propeller rotation plane - I'm not that silly 

Obviously the shaft passes a bearing at the front of the gearbox, so there should be some play, but I can't find what the limit should be. I have a low frequency vibration in flight and am trying to find the source.



Cheers



Jon

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Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Sun Mar 26, 2017 6:16 am Post subject: Re: Gearbox Bearing limits at the Flange

Hi Jon,



Is it a 912 ULS 100 HP or a 912UL 80 HP? About what year is the engine? (These two questions tell me if it has an overload clutch)  How many hours on the gearbox? Any strikes? Oil type and change intervals?



The straight answer to your question is no the box should have none of those. You may have a tiny bit of backlash if moving the prop in its rotational plane, but very little. No side to side play.



The gearbox needs servicing and most likely the bearing and oils seal need replacement. It will get shimmed at the same time and most likely new bellville washers.

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_________________
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Tucson, Az.
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Light Sport Repairman
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Guest

Posted: Sun Mar 26, 2017 9:07 am Post subject: Gearbox Bearing limits at the Flange

Worn clutch dogs, just had the gearbox rebuilt and it cured the vibration on 

throttle back.

Jim



--

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italianjon

Joined: 05 Aug 2015
Posts: 68

Posted: Sun Mar 26, 2017 10:41 am Post subject: Re: Gearbox Bearing limits at the Flange

Hi both,



Thanks for the info. I went back out to the plane in the afternoon and tried to be a bit more specific on the amount of play.



I am not fully convinced that there is the previously mentioned up/down/left/right play. I can't be sure whether I am slightly rotating the propeller as I do the test, and therefore I can't be sure is if what I feel is actually just the play in the gears on through the rotation axis.



But, Roger to answer your questions: It's the 80Hp, with 1090 hours on it, the engine is from 1995, and it does have the overload clutch fitted in the gearbox. No strikes, and Aeroshell Sport plus 4, changed annually or 50 hours. Normally run on Mogas, but has had Avgas.



Returning to the play, I can be sure that there is forward/backward play. It's not easy to measure, so I have to guess at about 0.2 to 0.3 mm.



Also, what I was trying to do today, was install a Warpdrive Propeller, in place of my Arplast PV50. The reason is that I have a low frequency vibration that you can feel in flight, at the rudder pedals and if you place your hand on the fuselage, and I wanted to fly with another propeller to check if it remains, and therefore indicates the propeller... but for love nor money, I can not dynamically balance a brand new warpdrive, I get 0.3 to 0.4 IPS whatever I try to do...



The Arplast is balanced better, but there is a large mass difference between the propellers, and this is leading me to think that the source of the vibration is somewhere else and not directly the propeller. Just that the extra mass of the Arplast helps somehow...



I think I'll get the gearbox looked at, but any ideas with the extra info above?



Best



Jon

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lyleapgmc

Joined: 19 Feb 2014
Posts: 57

Posted: Sun Mar 26, 2017 1:07 pm Post subject: Gearbox Bearing limits at the Flange

Jon,



I think you really need to beg, borrow or buy a dial indicator. Using 

that you will get a definitive indication of the real play both radially 

and axial in the gear box.  Get a dial indicator and a mount of some 

sort.  Magnetic mounts are handy but there may not be any steel near 

enough to use one.  You may have to remove a bolt and put some sort of 

bracket under the bolt.  The mount has to be stable so the flexing of it 

doesn't give false readings.



Harbor Freight has both indicators and mounts.  Northern Tool may have 

them too if you want to spend more money.  You could go to a machine 

tool supply and get a Starrett if you want to spend some real money.



Lyle



On 3/26/2017 1:41 PM, italianjon wrote:

 	  Quote: 	
		   



 Hi both,



 Thanks for the info. I went back out to the plane in the afternoon and tried to be a bit more specific on the amount of play.



 I am not fully convinced that there is the previously mentioned up/down/left/right play. I can't be sure whether I am slightly rotating the propeller as I do the test, and therefore I can't be sure is if what I feel is actually just the play in the gears on through the rotation axis.



 But, Roger to answer your questions: It's the 80Hp, with 1090 hours on it, the engine is from 1995, and it does have the overload clutch fitted in the gearbox. No strikes, and Aeroshell Sport plus 4, changed annually or 50 hours. Normally run on Mogas, but has had Avgas.



 Returning to the play, I can be sure that there is forward/backward play. It's not easy to measure, so I have to guess at about 0.2 to 0.3 mm.



 Also, what I was trying to do today, was install a Warpdrive Propeller, in place of my Arplast PV50. The reason is that I have a low frequency vibration that you can feel in flight, at the rudder pedals and if you place your hand on the fuselage, and I wanted to fly with another propeller to check if it remains, and therefore indicates the propeller... but for love nor money, I can not dynamically balance a brand new warpdrive, I get 0.3 to 0.4 IPS whatever I try to do...



 The Arplast is balanced better, but there is a large mass difference between the propellers, and this is leading me to think that the source of the vibration is somewhere else and not directly the propeller. Just that the extra mass of the Arplast helps somehow...



 I think I'll get the gearbox looked at, but any ideas with the extra info above?



 Best



 Jon





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Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Sun Mar 26, 2017 3:19 pm Post subject: Re: Gearbox Bearing limits at the Flange

There should be no fore or aft push/pull play. Just a tad of backlash play when you rotate it back and forth.  That part is normal.

If it has that many hours on the engine it is overdue for a gearbox inspection, new bellville washers and shims. You should also have the bearing replaced. That part isn't expensive.

Warp Drive props shouldn't be over 68" long and never have nickeled leading edges. Most planes when flying have a little vibration in the frame. A 2 blade has a different vibration over a 3 blade. A 2 blade has a wider vibration frequency and the 3 blade is finer. Some people can feel this and some not. Vibration can absolutely be caused by a worn gearbox.

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_________________
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Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

rickofudall

Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA

Posted: Tue Mar 28, 2017 10:59 am Post subject: Gearbox Bearing limits at the Flange

Harbor Freight indicators don't have the range to do the job, IMHO. You

want something that has a resolution of at least .0001" to get accuracy at

the level you want it. Mitutoyo, Starret, Brown and Sharpe, Alina....Take

your pick.

As for an indicator mount, the Harbor Freight magnetic base is just fine

for $10 AND you can unscrew the post from the magnet and screw it right

into any of the M8 bosses on the propeller gearbox. Makes for a very steady

mount for the indicator.

Rick Girard

On Sun, Mar 26, 2017 at 4:04 PM, Lyle Peterson <lyleap(at)centurylink.net>

wrote:

[quote] 

 lyleap(at)centurylink.net>

 Jon,

 I think you really need to beg, borrow or buy a dial indicator. Using that

 you will get a definitive indication of the real play both radially and

 axial in the gear box.  Get a dial indicator and a mount of some sort.

 Magnetic mounts are handy but there may not be any steel near enough to use

 one.  You may have to remove a bolt and put some sort of bracket under the

 bolt.  The mount has to be stable so the flexing of it doesn't give false

 readings.

 Harbor Freight has both indicators and mounts.  Northern Tool may have

 them too if you want to spend more money.  You could go to a machine tool

 supply and get a Starrett if you want to spend some real money.

 Lyle

 On 3/26/2017 1:41 PM, italianjon wrote:

> 

> jon.catilli(at)gmail.com>

>

> Hi both,

>

> Thanks for the info. I went back out to the plane in the afternoon and

> tried to be a bit more specific on the amount of play.

>

> I am not fully convinced that there is the previously mentioned

> up/down/left/right play. I can't be sure whether I am slightly rotating the

> propeller as I do the test, and therefore I can't be sure is if what I feel

> is actually just the play in the gears on through the rotation axis.

>

> But, Roger to answer your questions: It's the 80Hp, with 1090 hours on

> it, the engine is from 1995, and it does have the overload clutch fitted in

> the gearbox. No strikes, and Aeroshell Sport plus 4, changed annually or 50

> hours. Normally run on Mogas, but has had Avgas.

>

> Returning to the play, I can be sure that there is forward/backward play

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