PC aileron servo removal

[Cloudmirth]

I am in need of your collective wisdom on the above captioned subject.  I am working with my trusted IA to restore the PC system in my '69 C to working order.  We have conducted the requisite tests and it appears that the problem is a leaking port wing servo.  After removing the wing access panel we are at a loss as to how to get the servo out.  While there is an access hold behind the aileron it does not line up with the servo mounting bolt so how to access the bolt is problematic.  Also, the connector for the vacuum line is located behind the servo mounting bracket where it seem impossible to get access.  So, while we are certain there is a way to remove the servo, we are perplexed as to how.  Would anyone care to share the secret?  Many thanks.

[Vance Harral]

On our airplane, you disconnect the linkage to the aileron, fold the aileron up out of the way, and remove the mounting bolt via that access hole you're referring to.  But if the hole doesn't line up with the bolt, that sounds ugly.

If the access hole is only slightly mis-aligned with the mounting bolt, perhaps a crow's foot wrench might do the trick?

[Mooneymite]

On 9/10/2021 at 4:43 PM, Cloudmirth said:

  Would anyone care to share the secret?  Many thanks.

I have removed, repaired and replaced both the left and right aileron servos.  After considerable study, I was not able to discover any trick, or secret.  It was a miserable job from beginning to end.  I considered using a small handed 10 year old child to access the hardware, but that certainly would have been considered child  abuse!

I will follow this thread to see if anyone else has come up with a better way...

Edited September 11, 2021 by Mooneymite

[Igor_U]

2 hours ago, Cloudmirth said:

 Would anyone care to share the secret?  Many thanks.

Having small hands would help. 

I used the 1/2" stubby articulated ratcheting wrench bought at Sears. Once you reach and find the nut attaching the servo, it's easy. 

[211º]

In addition to the 1/2” short handled ratchet wrench, push a camera up in the hole to take a video of the area for when you hear the washer fall off and you’re not surprised. After the servo is disconnected, you should be able to wiggle the servo around and out of the access hole so that you can use a 3/8” open end wrench to remove the hose. Also pay attention to the chain and which way it faces and which links are used. 
if you look in the pictures link here https://www.windfield.farm/brittain-autopilot and scroll down you’ll see a sample of the servo connection (outside of the wing). 

[JoeM]

My E does not have the opening under the aileron, so I had to do it from the underwing inspection opening. To undo the rear facing nut, I bought and tried both crows feet wrenches and ratchet wrenches, but ended up using a simple,  long 1/2” open end, flipping it over each micro-turn. My arms and hands took a bruising from the sharp sides of the opening, but eventually the nut came off. I used an adjustable magnet to lift the nut and washer off, but lost them both when trying to get the threads started on reinstalling it. It truly is a job for small hands and looong tempers. I took many breaks to rest and re-calm myself.  

After doing all that, I discovered the servo was fine and someone had slipped a larger hose over the small one causing the leak. So…..when you say you have done the requisite tests, be sure to localize the problem precisely before removing servos. The job is too hard to make the same mistake I did. 

[Raymond J1]

Small tip, so as not to hear the nut and washer fall... Put a little grease on the eye of the key...

[Cloudmirth]

After reading the responses so far I have come to a few conclusions.  First, the person who designed the layout for the wing servo installation obviously  gave no thought to servicing same.  Second, said person may actually have been a sadist.  Third, after said person presented  the plans for the servo installation to his boss, he should have been taken aside, given a polite but firm lecture on design criteria with  later servicing in mind and then taken out and shot!  Seriously, if you are going to go the the effort to put an access hole behind the aileron would it not make sense to have it line up with the servo retaining bolt?   It also occurs to me that if you are lucky enough to actually get the servo out, how in Gods green earth would you ever get the retaining nut and washer back on? I truly appreciate the input so far and agree with Joe M that nailing down whether or not the wing servos are actually leaking before trying to pull them out is absolutely mandatory.  Maybe I should just ditch flying and just take up needlework!

[carusoam]

Balance that with how often these things even get touched…

The wing was designed long before the wing leveler was introduced…

Theory of manufacturing was still in its infancy when many Mooneys were built…

1965 was a big year for incorporating changes to include the PC system…

 

Next steps were probably to include an electric BK AP…. With a corporate budget… 

Compare making updates to the Brittain system to installing a GFC500…

 

Note…. I got my M20C with no PC button in the yoke…. Never found out if it worked or not… MS wasn’t around for another decade…

GO MS!

Best regards,

-a-

[jamesm]

Are you going to permanently remove the wing  servos or is this removal for repair of the wing servo? (I couldn't by the tell the title of the post.)

If you are going to permanently remove the  servos there are 4 or 5 rivets  on the top and bottom of the wing. drill them out remove the whole  servo assembly. You will have re-rivet the drilled out holes on top and  bottom of the wing. My IA and I did this about 4 years ago on '67C.

But as others have stated removing them for repair can be a bear. I had to grind down a wrench to get thin enough to fit between the mounting bracket and the servo. to get  rudder servo come out the mounting bracket in the tail. took a lot patience and many half turns and  1/4 turns of the wrench to get the nut on the back of the servo to finally to get to come out. In my case the nut on the servo probably had moved in nearly 50 plus years and probably had little bit help of corrosion of not wanting to come off easily. You may have modify a wrench to fit your needs. This were harbor freight wrench and grinder,  bottle yellow propane and good quality heavy duty shop vise comes in handy you  can bend/grind wrench (or most tool(s)) to fit most of your needs.

FWIW

Good luck on your project.

James '67C

[TomM20F]

Long open end box wrench, 1/4" drive stubby ratchet with fine mechanism, 12 pt socket, short wobble extension. Pretty much used them all at one point or other. Accessed from bottom inspection panel. patience. Not a fun job, pretty much blind and by feel. but it is possible.

[Mooneymite]

There are a lot of mechanical tasks that the Mooney engineers could have made lots easier.  The wing servo is just one example of lack of concern about maintainability.

Checking the suction screen at each oil change is another example of little concern about maintainability.

There's a reason so many aircraft shops hate to work on Mooneys.

[Guest]

25 minutes ago, Mooneymite said:

There are a lot of mechanical tasks that the Mooney engineers could have made lots easier.  The wing servo is just one example of lack of concern about maintainability.

Checking the suction screen at each oil change is another example of little concern about maintainability.

There's a reason so many aircraft shops hate to work on Mooneys.

Mooney is not particularly unique in this regard.  Most airframes include tasks which are a pain to complete.

Clarence

[Shadrach]

I’ve never had to remove a wing servo but in general find that electric ratchets are well worth the investment, especially when working on a Mooney.

[Cloudmirth]

In response to James M, the game plan is to determine, if in fact, the servos are leaking and if so, replace them to get the PC system back in operation.  However, given the onerous nature of the task the juice may not be worth the squeeze.  Next plan is to break the hose connections at the wing juncture and run a vacuum test from there.  If it holds vacuum at leak I'll know that the wing servos are tight (but after 50 years you know what the odds of that are).

[TonyK]

On 9/10/2021 at 4:49 PM, Vance Harral said:

On our airplane, you disconnect the linkage to the aileron, fold the aileron up out of the way, and remove the mounting bolt via that access hole you're referring to.  But if the hole doesn't line up with the bolt, that sounds ugly.

If the access hole is only slightly mis-aligned with the mounting bolt, perhaps a crow's foot wrench might do the trick?

This is how I did it.  With the crows foot it took about 5 minutes.  After spending hours trying to contort my arm into the space and depositing the requisite blood sacrifice.