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Latent M20C Gear Down Indication


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Has anyone ever seen their gear down green light be delayed when you extend the gear during flight?  Mine works 100% on jacks, but in the air 90% of the time it is delayed and sometimes does not come on until you are on the ground.  The floor indication is fine, just the light.

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There is a nice diagram of the electrical gear system in the mm.  You can probably use that to figure out what’s required to turn that light on.  I have had some “delayed reaction” issues with my gear, but it didn’t move at all, until it did.  Those were apparently caused by the up/down limit switches sticking.  They are wired into many parts of the system.  They are under a panel in the belly and pretty easy to find/lube which seems to have solved my problem for now (k.o.w.).  So sorry I can’t be of more help.

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5 hours ago, 1352cc said:

Has anyone ever seen their gear down green light be delayed when you extend the gear during flight?  Mine works 100% on jacks, but in the air 90% of the time it is delayed and sometimes does not come on until you are on the ground.  The floor indication is fine, just the light.

Welcome aboard 1352 

  1. What model Mooney do you have?
  2. Do you have manual or electric gear?
  3. Do you have the manuals with the wiring diagrams?  These can be real handy troubleshooting.
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On my 67F (I don't no for the C), the gear down switch is mounted into an pushing rod box with return spring. With the time, it necessary to lubricate the pushing rod. Otherwise, the return spring is not strong enough and the switch does not immediately deliver the information.

20150124_054.jpg

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The Mooney in question is a 1970 M20C with electric gear.  I have the manuals and have pulled apart the wiring to the limit switch and cleaned up the connections.  After doing that, it worked flawlessly twice and then back to the delayed illumination.    

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2 hours ago, 1352cc said:

The Mooney in question is a 1970 M20C with electric gear.  I have the manuals and have pulled apart the wiring to the limit switch and cleaned up the connections.  After doing that, it worked flawlessly twice and then back to the delayed illumination.    

 

5 hours ago, Raymond J said:

On my 67F (I don't no for the C), the gear down switch is mounted into an pushing rod box with return spring. With the time, it necessary to lubricate the pushing rod. Otherwise, the return spring is not strong enough and the switch does not immediately deliver the information.

20150124_054.jpg

Check the manual aspect of the switch - in the above picture the micro switch is attached to the bracket with a plunger.  If that plunger is stuck or sticky it won't let the microswitch return to its non active state.  You may want to check that plunger to make sure its free.

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If it’s the limit switch, definitely clean/lubricate the plunger and make sure you’re getting full compression of the switch by the gear.  And full extension.

That being said, I called Dmax about mine and he said cleaning it will probably work for a while but the switches do fail.  They aren’t terribly hard to replace (Dmax told me that though...).

Edited by Ragsf15e
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There isn’t anything else that can cause a delay other than the switch...

If you cleaned it and it worked a few times... you now know the culprit...

It is probably something related to the spring in the switch is no longer working as designed...

Contact your favorite MSC to get a new one...  or see if the switch can be OH’d...

If you don’t have a favorite... Many people will call Dan at Lasar...

PP thoughts only, not a switch guy....

Best regards,

-a-

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2 hours ago, carusoam said:

There isn’t anything else that can cause a delay other than the switch...

If you cleaned it and it worked a few times... you now know the culprit...

It is probably something related to the spring in the switch is no longer working as designed...

Contact your favorite MSC to get a new one...  or see if the switch can be OH’d...

If you don’t have a favorite... Many people will call Dan at Lasar...

PP thoughts only, not a switch guy....

Best regards,

-a-

The longevity of the lubricant film the microswitch pusher depends on several factors :

- The nature of the lubricant ;

- The operating frequencies ;

- The temperatures - humidity levels encountered in the working environment ;

- The level of mechanical wear of this system ;

- The presence or absence of the protective bellows of the pusher.

 

In the case of moderate use of the aircraft, in "severe" environment (humidity - heat - great cold), it is advisable lubricants called "dry", that is to say containing little solvent and whose soap is not miscible or sensitive to water. Currently, on the market, "dielectric" lubricants based on teflon(R) are preferred. If you use your mooney every week, a "sewing machine" oil greasing every 50 hours is enough. Your local MSC can very well advise you for this.

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All, thank you for the input.  Yes I was going to reach out to Dan at Lasar and may try lubricating it and cleaning by the light bulb itself.  I was leaning towards it not being the mechanical aspect of the switch because it serves two purposes:  gear down limit and warning light.  The gear seems to stop without failure and its just the warning light which seems to be in question.  Thanks again!!

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