Manually retracting electric gear

[Yetti]

13 hours ago, Vance Harral said:

The only upside of having the LA11C2114 is that because it's technically not called out in the AD and SB, we don't have to strictly adhere to the 200 hour inspection limit.  I don't worry about it if we go something like 210 hours between inspections, especially since our unit has been rebuilt with 40:1 gears.

As we know Dukes stuff tends to explode over time. The ITT has more support for the two gears than the Dukes. For the ITT unit based on what I saw of construction, I would say 200 hours could be extended to a 500 hour.  It's a sealed gear housing not exposed to the elements.    The life of grease is way longer than 2 years/200 hours.

I could see where 10 year old grease in a unit would be a bad thing.   But not 5 year old grease.  And the 40:1 thing was probably not a good way to go.... but that has been fixed.

[Yetti]

For the big Adel clamp around the motor.    Since we know that the unit is under tension when Emergency gear is not being used. And we know that the nuts on my cable are unobtainium.  (I tried McMaster Carr)  We know that the angle on your big motor Adel clamp is telling us something is wrong. (its a bad idea to think the Adel clamp can hold that much tension over surface that may have grease)   And we know the L Brackets are attached via the motor bolt with a longer bolt.   I would build yours using a cable adjuster on the forward L bracket.  Use another cable adjuster on the rear L bracket for a cable guide.

 

http://www.greenskyadventures.com/throttle_cable/itemized09.htm

 

 

[Vance Harral]

I appreciate the ideas, Yetti.  I may be able to get my mechanic to sign off on a minor mod that's more robust next time we have all this stuff apart.

In the mean time, I know we have a few other 1976 M20F owners here on Mooneyspace.  I'd love to see exactly what's installed in their airplanes.  Having seen your picture where the L brackets just attach to the motor end plates - which my actuator has as well - I'm starting to wonder if that Adel clamp was really the factory solution after all.  It's possible some prior owner lost the brackets and/or the magic unobtanium nuts, and the clamp is a kludge fix.

[Vance Harral]

1 hour ago, Yetti said:

And the 40:1 thing was probably not a good way to go.... but that has been fixed.

Can you elaborate on this particular point?  Our unit actually failed the SB-190B inspection a few years ago when it had the 20:1 gears - both the worm gear and the pinion gear were scalloped to the point they had more than a half tooth of lash.  This happened after about 8 years of dutifully pulling and re-greasing every 200-ish hours, so it wasn't due to old grease, just accumulated wear over 30 years.  I definitely saw the gears wearing down over time, and I knew the unit was going to fail the inspection sooner or later.

After 7 years on the 40:1 years I'm already starting to see very slight wear on them, though the system is still very tight, and probably decades away from failing an inspection.  The wear rate anecdotally appears much slower to me vs. the 20:1 gears, so I'm happy to have the higher ratio.  I'm aware it takes twice as long to raise and lower the gear, but the performance impact is negligible in practice.  Curious why you think going to 40:1 gears is a negative.

[Yetti]

Sorry meant 20:1.  Had them reversed.  The business degree fails me....

You can adjust the backlash with the ITT.   do you know if that is being done?   Obviously the lubrication/gear rigging state of the rest of the gear system would dictate the load on the actuator.

And my plane was built towards the end of 1974.  It is interesting that you say I have a newer model actuator. But the little ticks of orange would say that it is all factory.   I have found the orange ticks in other places.

Edited April 6, 2017 by Yetti

[Yetti]

@air cooled dad may have some pics of what his 75 F looks like

[air cooled dad]

This what your looking for?  '75F with the ITT. 

[Hank]

^^^ That looks very much like my '70 C. No pictures, annual was in January.

[Vance Harral]

Thanks air cooled dad.  I see you have the exact model of actuator I do, with the infamous Adel clamp as well.  That gives me at least some confidence our setup isn't just a shade-tree mechanic's kludge fix.

Yetti, I shouldn't have said you have a "newer" actuator, just a "different" one.  I assumed the LAC2116 in your airplane was newer than the LAC2114 in mine because the number was bigger.  But that appears to not be the case.

We have never adjusted the backlash on our actuator.  I'm not entirely sure what you mean by that.  I understand "backlash" to mean the space between the worm and pinion gears.  Maybe you're referring to adjusting the emergency engagement lever?  If so, no, we've never adjusted that either.  All I know is the entire actuator was rebuilt by LASAR a few years back (they did more than just install the 40:1 gears).  I'm inclined to assume it was adjusted at the time.

[Yetti]

Talking with someone they said there was a way to adjust backlash or maybe run out.  There are several shim washers in the bearings so maybe that is the way to adjust things.

It is interesting how much the factory was playing around with different things while starting the J program.

[carusoam]

Machines and gear boxes get the backlash adjusted using various spacers.  I believe this is a way to get the gear faces to contact each other in the right place for better strength, and wear.

Best regards,

-a-

[corvar01]

Vance,

I am doing my first annual. I am an A&P and I am getting used to Mooney maintenance. You noted you have a 1974 F as do I. I noticed in your comment from last year you have removed your gear motor multiple times. I have a question about the heim bearing that is attached to the bellcrank. The way I am reading the AD/SB the bearing should be in the center of the space where the bearing mounts to the bellcrank based on Figure 3. Upon inspection mine has the washers all on one side. Am I reading it wrong? Also would love to chat with you on the phone if your time permits sometime.

Thanks

sbm20-190B.pdf

[carusoam]

Paging @Vance Harral....   ^^^

the @ sign lights a notification on the MSer’s screen...

-a-

[Yetti]

since we are back on this thread here are some more pics to help folks.

[carusoam]

Great pics and notations, Yetti!

I just realized there is another relay hiding in there as well.

Best regards,

-a-

[RobertGary1]

On 4/5/2017 at 12:20 PM, Dream to fly said:

Sorry,  I've got more questions...  I had a customer come into my shop today and noticed me working on parts to my plane.  He then starts informing me about all his experiences and time with everything from the war birds of the ice age all the way to the space shuttle.  He did say something that made me think.  He said that Mooney electric gear is fine but the manual levers are only good for a hand full of uses.  Is this true? and if so is there a way to make it reliable?  I can't picture it being sub-par but this guy could sell ice to an eskimo.

Yes, he is correct. The only value in the manual extension is if the gear motor itself is not working. Any other issue of the gear jamming, etc won't be any better with the manual extension over the electrical. Also, the design of the Mooney gear is that if one gear jams they will all jam. However, in practice this seems to rarely be an issue so I wouldnt worry too much.

 

-Robert

[Vance Harral]

5 hours ago, corvar01 said:

I am doing my first annual. I am an A&P and I am getting used to Mooney maintenance. You noted you have a 1974 F as do I. I noticed in your comment from last year you have removed your gear motor multiple times. I have a question about the heim bearing that is attached to the bellcrank. The way I am reading the AD/SB the bearing should be in the center of the space where the bearing mounts to the bellcrank based on Figure 3. Upon inspection mine has the washers all on one side. Am I reading it wrong? Also would love to chat with you on the phone if your time permits sometime.

We actually have a 1976 F, not a 1974.  As noted in this thread, there was some variety in the electric gear system around these years.

That said, I think your question about the Heim joint connection to the bellcrank has a universal answer.  But note that I'm not a licensed A&P, just an owner-assisted annual guy.

If you look at the picture in SB M20-190B, you'll see there's quite a bit of space between the rod end and the "ears" of the bellcrank, right where the blue arrows point:

That space allows the rod end to rotate around the bolt.  A little rotation of the joint is good, as it prevents the inner diameter from binding on the bolt.  Too much is bad, as it allows the outer diameter to contact the bellcrank ears, and possibly bind there.  I think the washer arrangement spec'd in the SB is intended to control the amount of rotation.  In particular, the AN960-716L washers have an inner diameter that's actually larger than the bolt, and they nestle up against the "ball" of the rod end.  With one of those on each side of the rod end, accompanied by some number of bolt-sized AN960-616 washers between the AN960-716Ls and the bellcrank ears, rotation of the joint is limited.  Presumably Mooney thinks this limits the rotation to "just enough, but not too much".  As for how many washers are on each side, I try to use even numbers, but I don't think it's a big deal if the rod end winds up slightly left or right of dead center.

I do think it's "bad" if all the washers are on one side, as this could allow the outer diameter of the rod end to contact the bellcrank, and possibly bind.  It's hard to quantify the risk, and I don't think you were perilously close to a landing gear failure with your current arrangement.  But on reassembly, I'd follow the guidance in the SB: one AN960-716L on either side of the rod end, then fill the remaining space with AN960-616s "as required".

I can see how this got to be confusing, as the "F" and "J" parts manuals don't actually show where the washers go.  The specific parts manual for my airplane spec's 1 AN960-716L and 5 AN960-616s, but it doesn't say or show on which side of the rod end they're supposed to be placed.  My guess is that Mooney originally thought this wasn't critical, then later changed their mind about it when publishing the SB.  Whoever put yours together last may have done so in good faith to the parts manual, but without looking at the details of the SB.

Hope that helps.  Feel free to call me if you want to chat further, I'll PM you my phone number.

[Yetti]

One of the reasons to do the gear video is to check and see if anything was binding.   And not have anyone under the plane while running the gear. Yes I know the bolt was not tight.   Get a camera and make it the way you like it.

 

[RobertGary1]

1 hour ago, Vance Harral said:

 

That space allows the rod end to rotate around the bolt.  A little rotation of the joint is good, as it prevents the inner diameter from binding on the bolt.  Too much is bad, as it allows the outer diameter to contact the bellcrank ears, and possibly bind there.  

I'm not sure I agree with that. Its not uncommon or problematic for the rod-end bearings to rotate very easily. Its kind of how they are designed.

 

-Robert

Edited April 30, 2018 by RobertGary1

[Igor_U]

2 hours ago, Vance Harral said:

 

That space allows the rod end to rotate around the bolt.  A little rotation of the joint is good, as it prevents the inner diameter from binding on the bolt.  Too much is bad, as it allows the outer diameter to contact the bellcrank ears, and possibly bind there.

 

42 minutes ago, RobertGary1 said:

I'm not sure I agree with that. Its not uncommon or problematic for the rod-end bearings to rotate very easily. Its kind of how they are designed.

 

-Robert

Robert,

I agree wit this. What the picture shows (and what designer intention was) is to use AN960-616 washers as a "shim remaining space" on both sides of the spherical ball bearing. Note on picture, by design, calls for centering the ball joint to allow maximum rotation as you mentioned.

Using washers is simple way to prevent bending of the clevis (sides of the bellcrank) when you torque the bolt to the spec. There are other ways to do that, notably with shoulder bushings in the clevis and sliding bushing that clamps the rod end with ball joint to one side but doesn't lad the clevis sides; these are more expensive and bulkier (heavier) and used on bigger Part 25 planes.

 

 

[N201MKTurbo]

While the center is the safe place to put it, it might not be the best place to put it. Let it sit in its natural position and see if it wants to be biased to one side or the other. Put the washers in to get it to its happy spot then cycle the gear by spinning the rubber coupler with your fingers through its whole stroke. You will feel any binding while spinning the coupler and you will be able to watch it throughout the whole stroke. If it does bind, shim it away from the bind until it doesn't bind any more.

Sorry about the cramp in your thumb and forefinger.

[carusoam]

Somebody posted a bent retract rod today...

I’ll see if I can find that post.  They need to see this...

Best regards,

-a-

[carusoam]

@David Perry

invitation to get up to speed with your bent rod challenge....  check out the details in this thread!

Best regards,

-a-