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Gear Warn breaker popping with Master on! Please help!


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Good evening all, first time posting here but I have been looking everywhere to no avail so here goes:

I have a 1975 Mooney Executive 21 with electric gear Serial number 22-1280.

I just had a DME installed as well as a top overhaul and as soon as I got back in I hit the master to begin the engine start procedure and immediately heard the unmistakable click of a breaker popping, my GEAR WARN CB to be exact. Pressing it back in immediately results in another trip. The gear down light is not illuminated even briefly when the CB is pressed it just immediately trips again. But here's the weird thing: pressing the Test button on the dash makes the GAGES breaker trip. The voltage light on the annunciator is flashing with the master on as is normal and the Landing light light illuminates normally when the landing light is turned on, but when I press the test button it trips my GAGES breaker every time.

Now obviously this sounds like the DME install so we removed everything and to our chagrin it continues. I've inspected the circuit breaker and didn't see anything obvious resting on inspected etc.... I'm completely stumped and a bit scared to fly the aircraft to have it fixed without the annunciator light for the gear. I am also having the Devils own job finding a schematic specific to my aircraft. Please help! Thank you in advance.

-Rhea

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Rhea,

Congrats on your first post...

By the sound of it, you haven’t touched anything and the CB trips... other than turning on the master...

I’m only a PP, not a mechanic...

1) confirm the gear switch is down, or the gear handle is up and locked.  So the gear isn’t trying to move while on the ground...  (do you have electric gear or manual?)

2) Got a POH? The basic wiring diagrams are in there...  gear lights, warning horn, position switch, and throttle position switch are inter-related... sounds like the green gear light is supposed to be on and it is grounding out instead...

3) There is some updated POHs from the mid 70’s in the download section... see what you can find... C,D,E,F, And G will be very similar electrically....

4) Are you handy with a volt meter? Finding a short won’t be too challenging when you know as much as you do already...  follow the wires from the popped CB.... look for burn marks as a hint.... there may be some aroma too...

5) There are standard things that go wrong with the gear CB popping... but that requires trying to raise the gear first....

PP thoughts only, not a mechanic... said it twice.

Good luck with your search...

Best regards,

-a-

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Good evening all, first time posting here but I have been looking everywhere to no avail so here goes:
I have a 1975 Mooney Executive 21 with electric gear Serial number 22-1280.
I just had a DME installed as well as a top overhaul and as soon as I got back in I hit the master to begin the engine start procedure and immediately heard the unmistakable click of a breaker popping, my GEAR WARN CB to be exact. Pressing it back in immediately results in another trip. The gear down light is not illuminated even briefly when the CB is pressed it just immediately trips again. But here's the weird thing: pressing the Test button on the dash makes the GAGES breaker trip. The voltage light on the annunciator is flashing with the master on as is normal and the Landing light light illuminates normally when the landing light is turned on, but when I press the test button it trips my GAGES breaker every time.
Now obviously this sounds like the DME install so we removed everything and to our chagrin it continues. I've inspected the circuit breaker and didn't see anything obvious resting on inspected etc.... I'm completely stumped and a bit scared to fly the aircraft to have it fixed without the annunciator light for the gear. I am also having the Devils own job finding a schematic specific to my aircraft. Please help! Thank you in advance.
-Rhea


Rhea - you must own N6893V. I own 92V. The annunciation panel and the gear warning lights are all interconnected. When you push the test button, it lights up the indicators in the glareshield as well as the gear indicator lights. I suspect they have shorted a wire. Find the glareshield Amp connector. It is the one that you need to disconnect when you remove the glareshield. Disconnect it and see if the breaker pops for the gear warning.

I have a hand drawn schematic for our gear system. I drew it up when I added the gear bypass switch. It should help you find the wires involved. Will post it in a couple of minutes.


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7 minutes ago, Marauder said:

 


Rhea - you must own N6893V. I own 92V. The annunciation panel and the gear warning lights are all interconnected. When you push the test button, it lights up the indicators in the glareshield as well as the gear indicator lights. I suspect they have shorted a wire. Find the glareshield Amp connector. It is the one that you need to disconnect when you remove the glareshield. Disconnect it and see if the breaker pops for the gear warning.

I have a hand drawn schematic for our gear system. I drew it up when I added the gear bypass switch. It should help you find the wires involved. Will post it in a couple of minutes.


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Hah yes I indeed have N6893V that's awesome! As for the glareshield... I'm 95% sure I tried that. It pops with it on or off. Which was leading me to believe it was something wrong with the light display itself.  Though it's worth reiterating that it pops the GAGES breaker instead of the Gear Warn breaker when I hit the test light.

Edited by Flyingfisher
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Hmm, this sounds VERY similar to what happened to me recently.  Not coincidently, right after the avionics shop messed behind my panel!

Same symptom, the gear warning CB popped and would NOT reset (like yours, immediately popped again): dead short.

There is a control box just under the glare shield on the pilot's side.  Inside is a bundle of wires held by an Adel clamp.  In my case, ONE wire (the one in the gear warning system) had been clamped UNDER the metal part of the Adel clamp (NOT inside the rubber grommet insulated part like all the other wires). This was pretty clearly a factory error: the insulation was crushed during assembly and it took nearly 50 years to wear through!  The shop moving things around must have been the last straw.

Odds of it being the same cause in your case...?????

Here's what I did to troubleshoot: Remove the glare shield, locate the control box and you will find a bundle of white wires exiting the box to a connector close by.  Disconnect the connector and turn on the master.  In my case, the CB no longer tripped.  I'd have to go back and look at the schematic, but I'm pretty sure that it was conclusive that meant the short had to be within the box.

Another MSer provided me a schematic of the control box.  If you troubleshoot down to the control box being the issue, let me know and I can get you the schematic.  Frankly, while learning how the box worked was fun, the reality is I found the problem by a VERY careful visual examination.

Good luck!

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12 minutes ago, carusoam said:

Rhea,

Congrats on your first post...

By the sound of it, you haven’t touched anything and the CB trips...

I’m only a PP, not a mechanic...

1) confirm the gear switch is down.  So the gear isn’t trying to move while on the ground...

2) Got a POH? The basic wiring diagrams are in there...

3) There is some updated POHs from the mid 70’s in the download section... see what you can find... C,D,E,F, And G will be very similar electrically....

4) Are you handy with a volt meter? Finding a short won’t be too challenging when you know as much as you do already...  follow the wires from the popped CB.... look for burn marks as a hint.... there may be some aroma too...

5) There are standard things that go wrong with the gear CB popping... but that requires trying to raise the gear first....

PP thoughts only, not a mechanic... said it twice.

Good luck with your search...

Best regards,

-a-

Oh the POH is a good idea. I'm decent with a voltmeter and come from a motorcycle background and tend to be pretty handy but I feel so far over my head here... my F has a modern windscreen on it and it's hell getting under the panel so it's very intimidating "following a wire." Feels like 40 years of avionics leftovers under there.

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1 minute ago, MikeOH said:

Hmm, this sounds VERY similar to what happened to me recently.  Not coincidently, right after the avionics shop messed behind my panel!

Same symptom, the gear warning CB popped and would NOT reset (like yours, immediately popped again): dead short.

There is a control box just under the glare shield on the pilot's side.  Inside is a bundle of wires held by an Adel clamp.  In my case, ONE wire (the one in the gear warning system) had been clamped UNDER the metal part of the Adel clamp (NOT inside the rubber grommet insulated part like all the other wires). This was pretty clearly a factory error: the insulation was crushed during assembly and it took nearly 50 years to wear through!  The shop moving things around must have been the last straw.

Odds of it being the same cause in your case...?????

Here's what I did to troubleshoot: Remove the glare shield, locate the control box and you will find a bundle of white wires exiting the box to a connector close by.  Disconnect the connector and turn on the master.  In my case, the CB no longer tripped.  I'd have to go back and look at the schematic, but I'm pretty sure that it was conclusive that meant the short had to be within the box.

Another MSer provided me a schematic of the control box.  If you troubleshoot down to the control box being the issue, let me know and I can get you the schematic.  Frankly, while learning how the box worked was fun, the reality is I found the problem by a VERY careful visual examination.

Good luck!

Oh I think I read your thread, I'm glad you chimed in. When I remove the glareshield pilot side I see right behind the annunciator lights for the gear and the gear lever itself a glob of what looks like silicone and then a mass of wires that leads to a connector. Disconnect that one? What if it that works and it narrows it down to the box itself, then what? Thanks! 

-Rhea

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Oh the POH is a good idea. I'm decent with a voltmeter and come from a motorcycle background and tend to be pretty handy but I feel so far over my head here... my F has a modern windscreen on it and it's hell getting under the panel so it's very intimidating "following a wire." Feels like 40 years of avionics leftovers under there.


If the plane has not had a wire clean up like mine, it will be a rat’s nest under there. I would check the breaker panel really carefully. They probably added a breaker for the DME so they were in that area.


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Oh I think I read your thread, I'm glad you chimed in. When I remove the glareshield pilot side I see right behind the annunciator lights for the gear and the gear lever itself a glob of what looks like silicone and then a mass of wires that leads to a connector. Disconnect that one? What if it that works and it narrows it down to the box itself, then what? Thanks! 
-Rhea


I would be curious what box you are looking at. Any pictures?


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Just now, Marauder said:

 


If the plane has not had a wire clean up like mine, it will be a rat’s nest under there. I would check the breaker panel really carefully. They probably added a breaker for the DME so they were in that area.


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There is indeed a breaker for the DME. I had the breaker box out as far as I was comfortable with, leaning against some wires and such, very difficult to see clearly but it appeared free of obstructions. Worth another look I suppose.

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Just now, Flyingfisher said:

Oh I think I read your thread, I'm glad you chimed in. When I remove the glareshield pilot side I see right behind the annunciator lights for the gear and the gear lever itself a glob of what looks like silicone and then a mass of wires that leads to a connector. Disconnect that one? What if it that works and it narrows it down to the box itself, then what? Thanks! 

-Rhea

Your 1975 may be different than my 1970...the control box in my plane is at the very TOP of the panel; right under the glare shield, and the connector is just to the right, not quite in the center.  I can try and help with troubleshooting the box, IF that is it.  As Marauder suggested, it could well be near the CB since they were messing around there.

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Just now, Marauder said:

 


I would be curious what box you are looking at. Any pictures?


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I wish but I wasn't planning on posting at the time. I'll take one when I get back to it. Sadly I work for the airlines and will be gone for several days but I'll take pics and post them Tuesday if I can't figure it out on Tuesday haha 

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Just now, MikeOH said:

Your 1975 may be different than my 1970...the control box in my plane is at the very TOP of the panel; right under the glare shield, and the connector is just to the right, not quite in the center.  I can try and help with troubleshooting the box, IF that is it.  As Marauder suggested, it could well be near the CB since they were messing around there.

Hmm okay there's something there I remember fiddling with but ad I said to another poster I won't be back for a few days. I'll take pics on tuesday. :)

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Here are the pictures of my control box when I had it on the bench.  You can just see the black rectangular connector on the wire bundle.  Sorry, I don't have any showing how it mounts in the plane.  The shaft on the lower left is the dimmer control, the smaller control is the 'push to test' button for the warning lights.  In the next to last image you can just see the Adel clamp if you look real close!

IMG_0044.JPG

IMG_0045.JPG

IMG_0046.JPG

IMG_0047.JPG

IMG_0048.JPG

Edited by MikeOH
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I would be curious what box you are looking at. Any pictures?


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Here is a picture of my gear switch and indicators looking from above. The one labeled “up” is the gear safety bypass button.

621d25feb07b99ab76ce286ca6d7bba6.jpg


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Also slightly off topic but how reliable is the gear window in the floor? If I have to fly the A/C to a MSC or something is it safe to fly? I don't know how accurate the floor indicator is haha


The indicator on the floor is physically attached to the gear system. Unless the plastic piece breaks, it is very reliable to indicate gear position.




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Here are the pictures of my control box when I had it on the bench.  You can just see the black rectangular connector on the wire bundle.  Sorry, I don't have any showing how it mounts in the plane.  The shaft on the lower left is the dimmer control, the smaller control is the 'push to test' button for the warning lights.  In the next to last image you can just see the Adel clamp if you look real close!
IMG_0044.thumb.JPG.c7b025a5edf1993111c0d27314033263.JPG
IMG_0045.thumb.JPG.354fd0a58eca39180faf9c74aed15e6f.JPG
IMG_0046.thumb.JPG.b620a02db85d921f1522c6b2134f7c3c.JPG
IMG_0047.thumb.JPG.a8804012037989e73a2c297bb6482059.JPG
IMG_0048.thumb.JPG.8a4964727edc634a7a1e84380523f442.JPG


Unfortunately the 75 models were redesigned and we don’t have that box.


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