Removing the Undercarriage.

[Denis Mexted]

Well, I know almost all of you will called it ‘Removing the Landing Gear’.  
But seriously, what’s involved?

I’ve done the first two steps, had some jacking pads turned and par read the service manual. A print out of the physical manual and more thorough read this week prior to tackling the job in a week.

Does anyone have notes of when they did the job? Any secrets or traps for young players?

I once did the same in a Bonanza and found the ABS gear notes invaluable. Would someone have done the same for the Mooney? All advice by this novice gratefully received.

Thanks,

Denis.

 

[Kelpro999]

42 minutes ago, Denis Mexted said:

Well, I know almost all of you will called it ‘Removing the Landing Gear’.  
But seriously, what’s involved?

I’ve done the first two steps, had some jacking pads turned and par read the service manual. A print out of the physical manual and more thorough read this week prior to tackling the job in a week.

Does anyone have notes of when they did the job? Any secrets or traps for young players?

I once did the same in a Bonanza and found the ABS gear notes invaluable. Would someone have done the same for the Mooney? All advice by this novice gratefully received.

Thanks,

Denis.

 

First verify the jack pad base fits tightly against your wing. I think mine were damaged by lifting loose some time in its life. I turned mine to minor diameter  the last 1/2” from base so they pass through yet won’t fall off the wing .

 Following for the rest of this adventure 

Edited February 18, 2023 by Kelpro999

[Fly Boomer]

1 hour ago, Kelpro999 said:

First verify the jack pad base fits tightly against your wing. I think mine were damaged by lifting loose some time in its life. I turned mine to minor diameter  the last 1/2” from base so they pass through yet won’t fall off the wing .

 Following for the rest of this adventure 

I'm sure you all are aware that the original jack points were not threaded.  The shaft was small enough to slip up into the tie-down threads, but not engage the threads.  I don't know why it was done that way, but you are now planning to support all the weight on the threads and, from the look of your jack points, not support any of the weight on the flat face of the jack point at the bottom of the threaded area.  I'm basing this on the fact that your threads don't go all the way down to the flat face.  I don't have any reason to suspect that this is a problem, but it is different to the way Mooney designed them (at least in 1989).

[N201MKTurbo]

The nose gear is easy, just start taking it apart until until you are holding it in your hands.

The mains are a little tricker because of the spring. Mooney has a tool for that, and I have one, but it doesn’t work very well. The washer trick works better. With the wheels down, shove as many washers into the coils of the springs as you can, then swing the gear up with the gear doors off and remove the bolt on the question mark shaped link and remove the spring. Set it aside with the washers in place. 
 

Once you have all the retract links and brake lines disconnected, remove the four bolts holding the rear bearing plate on. Remove the bearing and backing plate, slide the leg back out of the front bearing and you are done.

It is easier if you take the doughnuts out while the gear is on the plane.

If you are going to take it all apart, you must strip and paint it all.

[Denis Mexted]

I'm sure you all are aware that the original jack points were not threaded. 

Very interesting. No I was not. But yes there is some insertion rubber yet to go on and yes I'll make sure they're not thread bound. Well now not thread bound and loose on the threads.

N201MKTurbo: Great thanks for the advice. Any little tidbits to make this easier are welcome. 

Yes, I will completely strip it and repaint. Which leads me to another discussion. I've always been hesitant to powder coat things on aircraft, but I read elsewhere on this forum that many do. Any difference in wear rates between powder coating and 2 pack polyurethane ?

Also I see earlier 'GeeBee' as a member online. When I pulled the gear out of a Bonanza once he supplied the most beautiful stainless tubes and flex lines. I assume it's the same guy.

[Guest]

We have a GeeBee and we had a Gee Bee Aeroproducts, the later doesn’t hang out here anymore. You can find him at www.csobeech.com

LASAR combination tie down/ jack point is threaded.

[cliffy]

I've used an 8 grade bolt with washers underneath for years as jack points. works fine but your machined ones look pretty. 

[EricJ]

The tie down rings that normally go there are threaded.   They're made to take stress.   A washer on the jack points shown would take up the unthreaded shank if needed.

[Kelpro999]

18 hours ago, Fly Boomer said:

I'm sure you all are aware that the original jack points were not threaded.  The shaft was small enough to slip up into the tie-down threads, but not engage the threads.  I don't know why it was done that way, but you are now planning to support all the weight on the threads and, from the look of your jack points, not support any of the weight on the flat face of the jack point at the bottom of the threaded area.  I'm basing this on the fact that your threads don't go all the way down to the flat face.  I don't have any reason to suspect that this is a problem, but it is different to the way Mooney designed them (at least in 1989).

Precisely why I suggest removing material down to the thread minor diameter within 1/2” of base. On mine I left a 1/4” of the shank ends threaded so they screw all the way through the nuts and won’t fall out while positioning the jack. No compression load on threads at any time.

[A64Pilot]

5 hours ago, EricJ said:

The tie down rings that normally go there are threaded.   They're made to take stress.   A washer on the jack points shown would take up the unthreaded shank if needed.

They are made to be pulled on, so they must be threaded, but typically jack points aren’t because if they aren’t real tight you run the chance of damaging the threads.

Very often people will cut the threaded portion of bolts off that are one size smaller and simply push them into the jack point, it works fine, just have to hold the bolt in place until the jack takes up the slack.

I bought the LASAR jack points largely because I like the way they look, silly I know.

If your pulling gear and disassembling I’d strongly recommend powder coating as it will last a lot longer than paint

I had all the tubing, fuselage, engine mounts, landing gear etc for the Thrush powder coated with gloss white anti-graffiti powder coat, the anti-graffiti is very tough and slick, you can literally remove spray paint from it with a solvent dampened rag. Look it up, it’s really a thing. It’s a very slick coating nothing sticks to it.

It eliminated the rusting issues we were getting within a few years, I stole the idea from Maule who started powder coating their fuselages because float planes in the Bahamas fuselages and elevators were rusting from the salt water

[Denis Mexted]

Thanks for the knowledge on the jacking pads. I'll modify mine so as not to be taking weight on the threads.

Re powder coating. I'm thinking of stripping, bead blasting and immediately priming with BMS 1011 or equivalent. Then could I give them to the powder coating man? Or am I overthinking this. 

I see in the notes by the guy who has periodically run the engine and kept the critters out of the airframe that the aircraft has nose wheel shimmy. What are the sources of nose wheel shimmy in a Mooney?

I also see in another thread on 'Mooneyspace' gear up landings. Are any of these attributed to gear failure? (I know ABS recommends changing out a rod end on the nose gear actuator due frequent failure)

[A64Pilot]

If your not an A&P I’d strongly suggest the gear goes together under the supervision of a A&P with Mooney gear experience as I’m sure some of the gear ups are because of incorrectly rigged gear, or probably more likely gear collapses.

Powder Coat wise, I’m no powder coat man but I was led to believe that ideally any steel tubing is powder coated immediately after the blasting with no delay, so I’d degrease them but have the powder coater bead blast them

We had Moultrie Manufacturing in Moultrie Ga do our powder coating, I don’t believe he has a website, but if called I’m certain he would tell you the product used on both Maule and Thrush airframes. He had an old 40’ truck trailer for an oven so our fuselage would fit, we had to go through the song and dance with the FAA of course writing specifications and having them accepted as we were a manufacturer, but the heat level for powder coating is no where near the heat that will change 4130 heat treat.

Some believe that powder coating hides cracks, Thrush have very few issues with cracks, but the rare ones did crack the powder coat, and since we used gloss white powder coat the thin rust line from the crack made finding cracks much easier than the grey paint we used to use. Maybe some powder coat is softer and more flexible than what we used and could hide cracks.

Oh, and I don’t think you need to modify the jack pads, just be sure they tighten up on the bottom of the wing is all, the LASAR pads are threaded and I’m sure there are many in use with no problems.

Just take anything I post as an opinion, validate everything yourself

[A64Pilot]

Gear shimmy is a whole other thing, I believe there is an SB that addresses that, but also I believe wear could aggravate it. I believe a tiny bit just as the nose touches down in a cross wind is normal, or mine does anyway, but real shimmy could cause you to lose control and run off of the runway, it’s happened.

[Guest]

It going to be hard to get an A&P licences to work on an Australian airplane.  I think they like most commonwealth countries call us Aircraft Maintenance Engineer.

[Guest]

1 hour ago, Denis Mexted said:

Thanks for the knowledge on the jacking pads. I'll modify mine so as not to be taking weight on the threads.

Re powder coating. I'm thinking of stripping, bead blasting and immediately priming with BMS 1011 or equivalent. Then could I give them to the powder coating man? Or am I overthinking this. 

I see in the notes by the guy who has periodically run the engine and kept the critters out of the airframe that the aircraft has nose wheel shimmy. What are the sources of nose wheel shimmy in a Mooney?

I also see in another thread on 'Mooneyspace' gear up landings. Are any of these attributed to gear failure? (I know ABS recommends changing out a rod end on the nose gear actuator due frequent failure)

This is what should be inside your wing.  In some cases the thread get stripped out and Helicoil is installed.  SB M20-202 covers shimmy.

https://www.mooney.com/wp-content/uploads/2020/12/SBM20-202.pdf

[carusoam]

Additional thoughts…

1) nice Jack points!

2) Jack points typically sit against the painted surface… something to consider while trying to be friendly to the paint.

3) Steel tubes have two surfaces… probably no coating on the inside… especially where the tow bar slides in…

4) there are a few threads around here where people have detailed R&R of their gear… in order to paint them…

5) Soooo long ago, the pictures probably have been lost…

6) If it is possible to document the process of bringing the gear back to new… more people would love to have this service done…

7) I don’t think the gear are known to crack…. So hiding a potential crack with powder coating would be less of an issue…

8) Gear rigging, when done… is super important… a couple of small tools are used for that…

9) Changing rubber donuts…   The mains are done using the weight of the plane… the nose gear, some people have built a hydraulic press device for that….

10) gear shimmy is a sign of wear, or the nose gear not being set up properly… find the plumb bob procedure…

11) Lasar has been the resource for having the nose gear OH’d…

Get ready to post before and after pics!

 

PP thoughts only, not a mechanic…

Best regards,

-a-

[A64Pilot]

14 minutes ago, M20Doc said:

It going to be hard to get an A&P licences to work on an Australian airplane.  I think they like most commonwealth countries call us Aircraft Maintenance Engineer.

They have equalivents it seems most nations call them Engineers. 

[Denis Mexted]

Thanks guys. Yes I'm in the gathering of information stage before we launch into this in about 8 days. Yes we call them LAME's (pronounced LA - ME) which is a Licensed Aircraft Maintenance Engineer. And although I technically am a LAME, in practice my only competency is flying Airliners. So I've a very experienced LAME friend flying down to stay a week and we'll do the pulling things apart phase, to reconvene a few months later for the tedious stage. Putting back together. 

A64Pilot, thanks for all. So rigging issues, rather than points of failure are the most common cause of gear failure. Good to know. 

Yes, that's a hefty steel undercarriage and I would be very comfortable powder coating them. 

I did see the SB re nose wheel. More reading in the next few days. 

 

Thanks all. And I'll try to take many pics.

[Denis Mexted]

M20Doc. This is what should be inside your wing.

Excellent, thank you. I was going to get in there today but strangely it involves drilling of an inspection panel. 

 

Why would Mooney, or anyone else pop rivet an inspection panel?

 

[Kelpro999]

By far the most common gear ups are not of the machine but of the mind.

[Guest]

12 hours ago, Denis Mexted said:

M20Doc. This is what should be inside your wing.

Excellent, thank you. I was going to get in there today but strangely it involves drilling of an inspection panel. 

 

Why would Mooney, or anyone else pop rivet an inspection panel?

 

Mooney has gone through many variations on inspection panels.  Early ones had the nutplates riveted to the inspection cover, the cover was slipped inside the wing and screws driven through the wing skin and into the cover resulting in a near perfectly flush installation. Every panel was removable.

Later they installed clip nuts on the wing skin and installed the cover over top making it a bumpy wing, somewhat like a Piper Cherokee or Cessna 172, some panels were riveted on.

Still later they riveted a backup ring to the inside of the wing skin, and installed a flush fitting inspection cover with nut plates and screws, and some panels riveted on the inside of the wing.  These panels are made of “O” too thin and “O” too soft alloy.  There is a recent thread on these.

[1980Mooney]

1 hour ago, M20Doc said:

Mooney has gone through many variations on inspection panels.  Early ones had the nutplates riveted to the inspection cover, …..There is a recent thread on these.

Here @Denis Mexted

 

Edited February 20, 2023 by 1980Mooney

[EricJ]

9 hours ago, M20Doc said:

Mooney has gone through many variations on inspection panels.  Early ones had the nutplates riveted to the inspection cover, the cover was slipped inside the wing and screws driven through the wing skin and into the cover resulting in a near perfectly flush installation. Every panel was removable.

Later they installed clip nuts on the wing skin and installed the cover over top making it a bumpy wing, somewhat like a Piper Cherokee or Cessna 172, some panels were riveted on.

Still later they riveted a backup ring to the inside of the wing skin, and installed a flush fitting inspection cover with nut plates and screws, and some panels riveted on the inside of the wing.  These panels are made of “O” too thin and “O” too soft alloy.  There is a recent thread on these.

That sounds like backwards progression.   

[65MooneyPilot]

When you get the airplane up on jacks, check the nose gear by grabbing the axle on both sides and lifting up. When I did that on my plane the nose gear moved up and down about and inch. It was totally worn out. I replaced it with a LASAR rebuilt one and no more shimmy and all the steering issues after landing were fixed. It was like getting a new plane. I also installed the LASAR steering horn mod. 
When I removed my main gear I used a hydraulic press to get the shock discs out and it it worked well. Putting large washers in the spring is a great idea, I made a tool similar the one in the manual which worked ok. Just let us know if you run into an issue as usual there is always one of us that has been thru it before. 

[Denis Mexted]

Well after all that debate on whether to pull down by the tail or lift at the front I did both. 

 

And I like to brace for any lateral movement. I'm hoping jacks only for 2/3 months, but there will be a bit of in and out in the cabin. It's sitting pretty solid at the moment.