Gear unsafe light

[LANCECASPER]

3 hours ago, Andrei Caldararu said:

4) Was left stranded at a completely unattended grass strip in Michigan UP, where not even taxis come, no cell phone service, because the starter decided to do nothing at all. Had to hand prop the plane with just my 12 year old son (not a pilot, obviously) at the controls.

What could possibly go wrong in that scenario?

[KSMooniac]

I wonder if whoever repaired the previous landing incident damage neglected to fully torque the fasteners on the paddle that hits the switch, and it slipped over time until it became a problem.  They might have had to replace the retract rod, and then adjust the paddles and just missed it...

[MikeOH]

2 minutes ago, KSMooniac said:

I wonder if whoever repaired the previous landing incident damage neglected to fully torque the fasteners on the paddle that hits the switch, and it slipped over time until it became a problem.  They might have had to replace the retract rod, and then adjust the paddles and just missed it...

I was on the same train of thought....maybe try to gently move the paddle and see if it is easy to move?

[Kerrville]

Thanks y’all. I spent a bit of time pulling the panels but probably wasn’t wise. I need to get some jacks. Any recommendations as to what kind?

[Kerrville]

28 minutes ago, MikeOH said:

I was on the same train of thought....maybe try to gently move the paddle and see if it is easy to move?

When I opened it. I touched it and it didn’t move but I really didn’t give it a tug because I wasn’t sure what it was supposed to look like yet.  I’d like to mess with it, but I have to restrain myself. I think what I’ve really got to do is get it on jacks. Then I’ve got to find someone who is willing to come look at it. Then I can mess with it and hopefully get the blessing of someone with knowledge and experience to give me the confidence that it is right. 

[KSMooniac]

One of my first tool purchases as a new owner was a set of jacks, I believe from Alpha Aviation?  I don't remember exactly and they were ~$400 for a pair in 2007.  They use import hydraulic cylinders and have a nice very sturdy tripod base/outriggers and locking rings for the ram.  I've been very satisfied with them over the years, even after somehow damaging a cylinder, but I was able to source and buy an inexpensive replacement and install it into the base without issue.  You'll need a set of Mooney jackpoints too... I bought LASAR's excellent tie down/jackpoint kit and leave those in full time... which has been helpful twice with flat tires away from home!  If you search here, you can find some home-brew jacks of varying design quality.  If you come across used/surplus jacks in the wild, make sure they are short enough to work on a Mooney as many are not!  

[Kerrville]

 Do I need two jacks or do they make jack stands?  Do all the alpha jacks work?  I don’t want to order some only to find they won’t fit under the Mooney. Thanks. 

[201Mooniac]

I believe these are the ones from Alpha https://alphaaviation.com/324w-3-ton-low-wing-jack-24-40/

[Kerrville]

Perfect. If my friend’s don’t fit I’m going to get those tomorrow. I also need to get the preload tool and the mm calls for shim stock, can I just use a feeler gauge?

[N201MKTurbo]

You can use a piece of paper. Just cut a slip of paper so it fits (3/8”) in the overcenter link. Gently pull on the paper while looking at the torque wrench and note the torque when it pulls out.

A torque wrench with a dial works best for this.

[KSMooniac]

1 hour ago, Kerrville said:

 Do I need two jacks or do they make jack stands?  Do all the alpha jacks work?  I don’t want to order some only to find they won’t fit under the Mooney. Thanks. 

You need two jacks + an engine cherry picker/hoist to hold the engine or prop.  Harbor Freight or similar (especially used from craigslist or FB Marketplace) work just fine.  Don't forget the jack points that screw into the tie down holes as well.

[Hank]

12 minutes ago, KSMooniac said:

Don't forget the jack points that screw into the tie down holes as well.

In a pinch, socket head cap screws will work (the kind you need an Allen wrench to turn).

[EricJ]

59 minutes ago, Kerrville said:

Perfect. If my friend’s don’t fit I’m going to get those tomorrow. I also need to get the preload tool and the mm calls for shim stock, can I just use a feeler gauge?

It eats feeler gauges, so just use a sheet of paper as described above.

You also need a tail weight to hold the tail down, and there are threads here on creative ways to make tail weights to use during gear swings.   An easy way is to securely sink an anchor bolt in the hangar floor and run a chain to it to hold the tail down.  YMMV.   Others insist on a cherry picker or something else to hold the nose up.   All of these methods are controversial and there are essentialy SBs on all of the various methods that say "don't do it that way", so pick your least abhorrent method and go with that.   Probably most people use tail weights or chain the tail to the floor.

BTW, be careful with the jacks, as many airplanes get damaged by jacks under the wings.    The 24" Alpha Aviation jack is arguably the best choice, but even it is too tall if the tire is flat.   If you borrow a set, check fit before you put it under the wing, and if it has a lock, use it.   The Alpha Aviation jacks have good locks on them.   They're good jacks.

Jacks are a bit like tow bars;  a good policy is that if it isn't in use right now, it shouldn't be under the wing.   A couple of my instructors at A&P school had been career airline people and they said that was their policy even with airliners, as it wasn't unusual for somebody to drop an airliner on a jack and put it through the wing.   My hangar neighbor was weighing his Comanche and had the jacks sitting under the wings, and a dust devil came along and applied just enough force to push the airplane off the scales and onto the jacks, which went through the bottoms of the wings.

[LANCECASPER]

@Kerrville there are a few people on here that are well-qualified to work on the landing gear. Although I own 3 jacks and all of my annuals are done in my hangar, and I’ve owned Mooneys starting in 1993, I am not one of the people on here that is qualified to repair or even rig the landing gear.  I wouldn’t trust my work.

There are more people on here that are qualified to properly jack up a Mooney safely and do a gear retraction or do preventive maintenance under the airplane on jacks. I do feel I can do it, but only because I’ve helped many times under supervision. I still don’t do it if I am the only person in the hangar. 

If you have never used jacks on a Mooney, absolutely no offense intended, you’re not qualified to do what you are trying to do. You may be a good auto mechanic - but this is completely different. After working on it and not getting it right, you can’t pull over to the side of the road in your Mooney and figure it out. Since there is already something wrong, this does not fall under preventive maintenance in the FARS - so you are also not legally qualified to do what you are trying to do. I definitely wouldn’t be posting that you are doing it or planning on doing it on a public forum.

The thread below on the first post used to show a video of a jack going through the wing of a Mooney - not a pretty sight. Someone on here probably still has a still shot of that.

 These accidents happen even at well-qualified shops;

 

[Kerrville]

I agree. I’m not qualified to do any of this work, but I want to get everything I need set for whoever is. I have a few IA friends who can help, but they are not Mooney guys. I really hope I can find a Mooney guy at my airport seeing as the plane is unmovable.  I have the engine hoist. I just want to get the rest ready to Jack when I do find someone. I want to get it done sooner than later, but I’m starting to get the feeling this could take months. 

[EricJ]

1 hour ago, Kerrville said:

I agree. I’m not qualified to do any of this work, but I want to get everything I need set for whoever is. I have a few IA friends who can help, but they are not Mooney guys. I really hope I can find a Mooney guy at my airport seeing as the plane is unmovable.  I have the engine hoist. I just want to get the rest ready to Jack when I do find someone. I want to get it done sooner than later, but I’m starting to get the feeling this could take months. 

If you're going to use a hoist, strap it through the engine mounts rather than the engine lift point or the prop.   I think Maxwells do it this way.

 

[PT20J]

I think we may be overthinking this. Here are the facts as I understand them from this thread.

1. The gear has been operating normally since the OP purchased the airplane recently.

2. After a bounced landing, the gear unsafe annunciator illuminated and the gear actuator breaker popped.

3. Upon inspection, it was found that the gear down limit switch mechanical actuator (paddle? Mooney calls it a lug) was loose. (It would be nice to have some pictures).

4. The floor indicator shows that the gear is fully extended.

Given the above, a likely scenario is that the gear fully extended normally before the landing. Upon landing, the gear down limit switch lug moved (maybe it wasn't tightened properly?). This caused the motor to run until it hit the mechanical down stop (it won't turn far -- maybe not even a full revolution) and jammed which caused the breaker to trip.

If the preloads were correct before the incident, they will still be correct, or maybe slightly higher because of the motor overrun. There is no reason to think that the gear is in an unsafe position, if all the above is true. Checking the nose gear preload requires partially retracting the gear, and since it is most probably safe now, it might be best not to mess with anything. 

Obviously, the best thing to do is jack it up and have a mechanic check the gear rigging and readjust the down limit switch.

Skip

 

[Kerrville]

I can buy that scenario. Since I landed taxied and pushed it in with no issue. I’m thinking i can just put the paddle back on the switch and have a mechanic just swing the gear a few times?

[PT20J]

Just now, Kerrville said:

I can buy that scenario. Since I landed taxied and pushed it in with no issue. I’m thinking i can just put the paddle back on the switch and have a mechanic just swing the gear a few times?

You cannot set the down limit switch correctly now if the gear motor has overrun. It needs to be set as part of the rigging check. I would just leave the whole thing as is for the mechanic to sort out.

[EricJ]

Just now, Kerrville said:

I can buy that scenario. Since I landed taxied and pushed it in with no issue. I’m thinking i can just put the paddle back on the switch and have a mechanic just swing the gear a few times?

The down switch needs to be properly rigged so that the gear stops at the right spot with the proper preload.    There's a procedure in the SMM regarding how to do this, and the switch stop (paddle) should be inspected to make sure it's secure and in the right spot.   The procedure for rigging the down-limit switch requires the airplane to be on jacks so that the gear can be moved and set to the measurements outlined in the SMM.

I think that's the majority of the issue, other than just making sure nothing got tweaked by the over-run, which is where checking the rigging preloads comes in.   It needs to be on jacks to rig the down-limit switch, so it's not hard to check the preloads at the same time to make sure nothing got tweaked.   It's possible that the paddle wasn't in the exact right spot so re-rigging may require some readjustments.  

[Kerrville]

That’s kind of what I thought. Need a full rerig. Found a mexhanic who might be able to do it, but they have no Mooney experience. Right now that’s the best I can do…

[Kerrville]

Mechanic pretty much straight up told me that he doesn’t want the liability of rerigging Mooney gear…

[ArtVandelay]

For this kind of work I would either go to a Mooney service shop or one known as a place to go. I used a shop who has a mechanic who owns a 78J.

[LANCECASPER]

36 minutes ago, Kerrville said:

Mechanic pretty much straight up told me that he doesn’t want the liability of rerigging Mooney gear…

Thank him for that. You want someone that is not learning on your airplane.

[MikeOH]

Wow!  This saga just won't conclude...

The summary:

1) The SGOTI are saying don't touch, let alone move the plane

2) The SGOTI are saying take it to an expert

Since 2 kinda contradicts 1, what do the SGOTI suggest @Kerrville do at this point because, apparently, the Mooney gear is so complex that competent experts are few and far between?

Surely, there is SGOTI that knows an 'expert' near Kerrville that could travel to his hangar?  Anyone, ..Bueller????