Gear unsafe light

[Kerrville]

Fixed my last problem and after my last landing (was not hard), gear unsafe light and horn came on and the gr act breaker popped. Taxiied clear and shut down after verifying that the floor indicator showed gear down (it does). Reset breaker, it pops again and horn comes on. Any ideas?

 

also what is this switch by the left wing root fairing?

[KSMooniac]

That circled hootie is actually a drain for the pitot line coming from your pitot probe.  You can drain out accumulated moisture there.  There is another one on the left side, aft of the wing, for the static system.

Regarding your gear issue, it is time to put it on jacks and open up the belly.  I would use the maintenance manual procedure to exercise the gear, and crank it down until the light comes on and check pre-loads.  Inspect the limit switches, and the retract tubes that have the paddles for the switches and make sure they're not bowed/bent/buckled anywhere.  If all of that checks out, then you might have a worn-out gear motor that is drawing too much power and popping the breaker.  I would not fly again until you get this solved.

[Kerrville]

I pulled the belly panel and see the paddles that you are referring to. Should one be compressed?  I assume yes. I’m guessing they are up and down limits for the gear motor.  As of now, both are open. 

[PT20J]

Hard to tell from your description what is going on. Usually the thing that pops the gear actuator breaker is the emergency gear extension lever being engaged. But you said this happened after landing and nothing should be running then. From your description it sounds like the gear is not currently fully down. I would get it on jacks and check it out thoroughly. It didn't collapse when you taxied it after landing, so there must be some preload left on the gear, but there is no telling how much.

[Kerrville]

Do you really think there is a preload issue?  The mechanical indicator on the floor shows fully down and locked. I’m guessing for some reason the down limit switch is not compressed. 

[KSMooniac]

Yes, the paddles should close the limit switches at each end of the travel.  I suppose it is possible the down limit switch paddle has slipped, and that caused your motor to over-run and really jam the gear down while tripping the breaker.  You said the floor indicator showed it "down" so I'll ask if it stopped in the same place as it usually does... or did it go further?  Mine stops and the two lines are precisely lined up.  I think you really need to jack it up and do all of the gear rigging checks per the manual, especially after cranking down the gear until the indicator says done, and then check the preload.  That will tell you if everything is rigged correctly, and then you can verify the limit switches are working and the paddles are rigged correctly.  You want the motor to stop before it jams the system with extra preload...

[Kerrville]

The indicator in the floor looks normal, but the aft paddle looks like it rotated down. 

[PT20J]

I should have asked about the floor indicator. If it is aligned, and the preloads are properly adjusted, then it should be safely down. If something is amiss with the down limit switch the motor can overrun and jam and that would trip the breaker. The proper thing to do is to put it on jacks and check the rigging according to the Service Manual.

[LANCECASPER]

4 hours ago, Kerrville said:

Fixed my last problem and after my last landing (was not hard), gear unsafe light and horn came on and the gr act breaker popped. Taxiied clear and shut down after verifying that the floor indicator showed gear down (it does). Reset breaker, it pops again and horn comes on. Any ideas?

 

also what is this switch by the left wing root fairing?

If you're in Kerrville, get it in to Dugosh. David will know exactly what to do.

[KSMooniac]

6 minutes ago, LANCECASPER said:

If you're in Kerrville, get it in to Dugosh. David will know exactly what to do.

Absolutely.  Don't mess around and listen to us clowns on the internet.    

[1980Mooney]

2 hours ago, KSMooniac said:

Yes, the paddles should close the limit switches at each end of the travel.  I suppose it is possible the down limit switch paddle has slipped, and that caused your motor to over-run and really jam the gear down while tripping the breaker.  You said the floor indicator showed it "down" so I'll ask if it stopped in the same place as it usually does... or did it go further?  Mine stops and the two lines are precisely lined up.  I think you really need to jack it up and do all of the gear rigging checks per the manual, especially after cranking down the gear until the indicator says done, and then check the preload.  That will tell you if everything is rigged correctly, and then you can verify the limit switches are working and the paddles are rigged correctly.  You want the motor to stop before it jams the system with extra preload...

 

2 hours ago, Kerrville said:

The indicator in the floor looks normal, but the aft paddle looks like it rotated down. 

 

1 hour ago, PT20J said:

I should have asked about the floor indicator. If it is aligned, and the preloads are properly adjusted, then it should be safely down. If something is amiss with the down limit switch the motor can overrun and jam and that would trip the breaker. The proper thing to do is to put it on jacks and check the rigging according to the Service Manual.

 

 

@Kerrville Your profile shows N201JK which was built in 1976 serial number 24-0040.  The early J's had Dukes gear actuators, emergency extension handle on the pilot's left side and a squat switch.  Later models had the Avionics Products (bought by Eaton) and Plessey with T handle emergency extension and an air-speed switch.

That said, I see that your Mooney had a nasty botched landing by the previous owner in 2020 about a year before it was registered to you.  

• "on touchdown, there were some "sudden gusts," and as he added normal braking, the right tire failed, which caused a loss of directional control and subsequent skid. The left main landing gear collapsed, and the airplane slid to a stop on the taxiway. The aft fuselage was substantially damaged."
• Collapsing one main gear in a sideways skid would have torn up a lot of the landing gear rod linkage, bellcranks and maybe the actuator.  
• This plane therefore had a lot of work on the entire landing gear mechanism.
  • Do you know if they replaced everything back to 1976 Dukes spec with squat switches? (It could have some bespoke repair)
  • Does your current mechanic know the differences in the M20J landing gear actuators and controls?
    • Dukes was installed thru 24-0377 (Avioncs/Eaton after that)
    • Squat switches were installed through 24-0237 (air speed switch after that)
    • 24-0238 through 24-0377 had Dukes actuator with Air Speed switch
    • The rigging of each is different - see Chapter 32 in the Service Manual

https://aviation-safety.net/wikibase/249363

https://www.donmaxwell.com/ad-75-23-04-sb-m20-190

 

Edited December 13, 2023 by 1980Mooney

[Kerrville]

Unfortunately my mechanic can’t see my plane until February. So I am doing my best until then to figure it out. Thanks for the good link. I was aware of the accident from the prior owner, but never was able to read an official report of it. 

[LANCECASPER]

Unfortunately my mechanic can’t see my plane until February. So I am doing my best until then to figure it out. Thanks for the good link. I was aware of the accident from the prior owner, but never was able to read an official report of it. 

I wouldn't even tow it with a tow bar until someone looks at it. I've seen a nose gear collapse while using a tow bar on an M20R that had an intermittent gear unsafe light

[Kerrville]

Shoot. I did everything wrong. After the light came on, taxied to the hangar and pushed it in with a tow bar.  Looks like after reading the book I am going to need some jacks and a preload tool. Any suggestions on where to get these?  I knew this airplane might be a can of worms, but it’s got more worms than I had hoped. Oh well, I like the plane and want to get it right. 

[LANCECASPER]

20 minutes ago, Kerrville said:

 Oh well, I like the plane and want to get it right. 

If you've never done it before, this is one job you want to leave to someone with Mooney landing gear experience. Observe and learn from them. A few hours of their time will be well worth it.

[AndreiC]

1 hour ago, Kerrville said:

I knew this airplane might be a can of worms, but it’s got more worms than I had hoped. Oh well, I like the plane and want to get it right. 

I'm afraid this is what *any* airplane ownership is like. The first 6 months to a year of your ownership, all goes wrong (hopefully no gear collapse, which you seem to have avoided!) For some reason this is what seems to always happen. Some are things you may have known when you bought the plane (if you had a good pre-purchase inspection), others are just stuff you find out. But after you clean up the gremlins, you can hope to have many years with just an annual inspection and minor inconveniences here and there.

This has been my experience with every plane I owned. Here's a small example, just for fun. One of the planes I owned, and which I feel was more trouble-free than most, was a 1967 Cherokee 180. Had trouble starting from day one. Here is a list of things that went wrong in just this one maintenance area:

1) Replaced starter with a nice new lightweight SkyTec. Helped for a few months, and then back to slow starting.

2) New battery. Same as before, better starting for a while, back to ground zero.

3) Managed to forget to take out the cowl plugs when starting the plane (big booboo!) someplace 8 hours driving from home. Alternator belt messed up, had to have a mechanic at a different field pull off the prop, put on a temporary automotive belt to make it home.

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.

5) Replaced battery box. Slightly better, not much.

6) Bit the bullet and replaced the aluminum battery cables with copper. Hurray! Now we're talking...

This all took 3-4 years of bad experiences... The only thing to avoid is to sell your plane right after you got all the bugs fixed.

[EricJ]

2 hours ago, Kerrville said:

Shoot. I did everything wrong. After the light came on, taxied to the hangar and pushed it in with a tow bar.  Looks like after reading the book I am going to need some jacks and a preload tool. Any suggestions on where to get these?  I knew this airplane might be a can of worms, but it’s got more worms than I had hoped. Oh well, I like the plane and want to get it right. 

It sounds like the stop switch didn't engage, so the motor kept running after the gear was down.   That just jams the motor at the end of the gear travel so it popped the breaker.

The electric gear won't back-run and let the gear collapse, and it's likely that the gear is past what it needs to be overcenter and safe, especially since the floor indicator is indicating locked.    You *probably* didn't have much to fear by handling it on the ground, but it's best to not push your luck now that it's in your hangar.

It also sounds like probably all that's wrong is to fix the stop switch issue, which may not be too difficult, but I agree that you want some competent eyes to do that and check everything (preloads, etc.) along the way.   Some gear swings on jacks will be in order, for sure.

Checking the gear preload isn't too difficult, but shouldn't be done in its current state with the motor likely over-run past the normal stop point.   You'll want to get the stop switch fixed, then check the preloads and make sure everything is still where it needs to be.

Mooney gear is low maintenance with respect to the suspension (pucks rather than oleos) and the actuation system (electric motor or Johnson bar as opposed to electro-hydraulic or whatever), but rigging it properly, including the stop switch, is a little tedious and requires some attention to detail.  It's not really worse than most other airplanes, it's just one of the areas of Mooney maintenance where some experience can be very valuable.

[Kerrville]

2 hours ago, LANCECASPER said:

If you've never done it before, this is one job you want to leave to someone with Mooney landing gear experience. Observe and learn from them. A few hours of their time will be well worth it.

Hopefully I can find someone near me (KCXO) that has some experience, because now I’m terrified of sneezing on it…

[Kerrville]

I’ve got the belly pan off and I can see that the paddle is definitely not contacting the down limit switch. I wonder how it could have come off?  My last landing was a bounce, but it was one of those super soft bounces, more like a touch and I added power and the final touchdown was very soft as well, so I imagine this didn’t move that paddle. I just wonder what could have caused it to rotate out of the plane of the switch because it must have been touching prior to that, as everything was working fine. 
 

I reset the gear actuator CB twice at my hangar before doing much research, so I imagine that the motor probably has overrun whatever limits it has and probably calls for a complete gear system rerig.  
 

Big problem is I now need someone to come to me. Is there any way to pin these gear so that it is safe to move?

[Ragsf15e]

9 minutes ago, Kerrville said:

Hopefully I can find someone near me (KCXO) that has some experience, because now I’m terrified of sneezing on it…

I think there’s a Mooney knowledgeable guy down at KDWH that you might be able to get to drive up and help you.  Possibly someone here remembers his name?  Someone else here keeps their airplane at David Wayne Hooks….

[Kerrville]

33 minutes ago, EricJ said:

It sounds like the stop switch didn't engage, so the motor kept running after the gear was down.   That just jams the motor at the end of the gear travel so it popped the breaker.

The electric gear won't back-run and let the gear collapse, and it's likely that the gear is past what it needs to be overcenter and safe, especially since the floor indicator is indicating locked.    You *probably* didn't have much to fear by handling it on the ground, but it's best to not push your luck now that it's in your hangar.

It also sounds like probably all that's wrong is to fix the stop switch issue, which may not be too difficult, but I agree that you want some competent eyes to do that and check everything (preloads, etc.) along the way.   Some gear swings on jacks will be in order, for sure.

Checking the gear preload isn't too difficult, but shouldn't be done in its current state with the motor likely over-run past the normal stop point.   You'll want to get the stop switch fixed, then check the preloads and make sure everything is still where it needs to be.

Mooney gear is low maintenance with respect to the suspension (pucks rather than oleos) and the actuation system (electric motor or Johnson bar as opposed to electro-hydraulic or whatever), but rigging it properly, including the stop switch, is a little tedious and requires some attention to detail.  It's not really worse than most other airplanes, it's just one of the areas of Mooney maintenance where some experience can be very valuable.

Thanks for the encouragement. My Dad told me the first 3 years are going to be miserable. It’s to bad because on the now seemingly rare occasions when it flies, it is a lot of fun. Working on it is fun to. Figuring out what to do, not so much. 

[Kerrville]

20 minutes ago, Ragsf15e said:

I think there’s a Mooney knowledgeable guy down at KDWH that you might be able to get to drive up and help you.  Possibly someone here remembers his name?  Someone else here keeps their airplane at David Wayne Hooks….

Hopefully I can meet the guy at DWH. I used to fly out of there all the time, but sadly I never met any Mooney guys down there. 

[1980Mooney]

37 minutes ago, EricJ said:

It sounds like the stop switch didn't engage, so the motor kept running after the gear was down.   That just jams the motor at the end of the gear travel so it popped the breaker.

The electric gear won't back-run and let the gear collapse, and it's likely that the gear is past what it needs to be overcenter and safe, especially since the floor indicator is indicating locked.    You *probably* didn't have much to fear by handling it on the ground, but it's best to not push your luck now that it's in your hangar.

It also sounds like probably all that's wrong is to fix the stop switch issue, which may not be too difficult, but I agree that you want some competent eyes to do that and check everything (preloads, etc.) along the way.   Some gear swings on jacks will be in order, for sure.

Checking the gear preload isn't too difficult, but shouldn't be done in its current state with the motor likely over-run past the normal stop point.   You'll want to get the stop switch fixed, then check the preloads and make sure everything is still where it needs to be.

Mooney gear is low maintenance with respect to the suspension (pucks rather than oleos) and the actuation system (electric motor or Johnson bar as opposed to electro-hydraulic or whatever), but rigging it properly, including the stop switch, is a little tedious and requires some attention to detail.  It's not really worse than most other airplanes, it's just one of the areas of Mooney maintenance where some experience can be very valuable.

 

16 minutes ago, Kerrville said:

I’ve got the belly pan off and I can see that the paddle is definitely not contacting the down limit switch. I wonder how it could have come off?  My last landing was a bounce, but it was one of those super soft bounces, more like a touch and I added power and the final touchdown was very soft as well, so I imagine this didn’t move that paddle. I just wonder what could have caused it to rotate out of the plane of the switch because it must have been touching prior to that, as everything was working fine. 
 

I reset the gear actuator CB twice at my hangar before doing much research, so I imagine that the motor probably has overrun whatever limits it has and probably calls for a complete gear system rerig.  
 

Big problem is I now need someone to come to me. Is there any way to pin these gear so that it is safe to move?

 

3 minutes ago, Kerrville said:

Thanks for the encouragement. My Dad told me the first 3 years are going to be miserable. It’s to bad because on the now seemingly rare occasions when it flies, it is a lot of fun. Working on it is fun to. Figuring out what to do, not so much. 

The first M20J's had the landing gear, throttle quadrant, etc of the M20F as they phased in the aerodynamic improvements.  Here is a video and post from @Yetti who has a M20F with the Dukes landing gear actuator (like yours)/

Here is another post - the picture on the second page appears to be a Dukes actuator - it shows the microswitches

 

Here is another post that shows the gear up stop microswitch on an Eaton actuator in a 1978 J

Here are 2 more that show the stop micro switches on an Eaton

 

[EricJ]

1 hour ago, Kerrville said:

Thanks for the encouragement. My Dad told me the first 3 years are going to be miserable. It’s to bad because on the now seemingly rare occasions when it flies, it is a lot of fun. Working on it is fun to. Figuring out what to do, not so much. 

The Service Maintenance Manual for the J is available free online.   It's not necessarily fun reading, but it has all of the procedures including gear rigging, which is a slog of a read:

http://mooney.free.fr/Manuels M20J/M20J/Mooney Service Manuel M20J Vol. 1 of 2.pdf

http://mooney.free.fr/Manuels M20J/M20J/Mooney Service Manuel M20J Vol. 2 of 2.pdf

[LANCECASPER]

6 hours ago, Kerrville said:

I’ve got the belly pan off and I can see that the paddle is definitely not contacting the down limit switch. I wonder how it could have come off?  My last landing was a bounce, but it was one of those super soft bounces, more like a touch and I added power and the final touchdown was very soft as well, so I imagine this didn’t move that paddle. I just wonder what could have caused it to rotate out of the plane of the switch because it must have been touching prior to that, as everything was working fine. 
 

I reset the gear actuator CB twice at my hangar before doing much research, so I imagine that the motor probably has overrun whatever limits it has and probably calls for a complete gear system rerig.  
 

Big problem is I now need someone to come to me. Is there any way to pin these gear so that it is safe to move?

I would get it up on jacks before you go crawling under there . . . Unless you think you can hold it up with one hand and call 9-1-1 with the other.