Gear down warning problem

[nightmoves]

Hi everybody.

My F started having issues recently where my gear down siren will sound sporadically even when the gear is down - sometimes when taxing around even. The light on the dash will go off when the siren sounds, then back on when it stops. This can be quite alarming when about to flare and you are 99.9% you checked the gear 5 times but the siren goes off anyway. My mechanic mentioned a switch or relay of some sort near the nose gear that might be getting stuck in the 'up' position or having a short of some kind. Does anyone know where that is and what to look for? I am really hoping this is a simple fix.

 

Thanks to all.

[carusoam]

When the light goes off... is it emitting light?  (Some issues I have come across when writing about these things...)

There is another current thread describing water getting into the gear position proximity switch after a flight in rain...

Do you have the wiring diagram for your plane?  It’s in the POH...

Use caution...

The big reason this happens with Jbar Mooneys... the gear handle isn’t firmly locked in place.

The gear up alarm for the manual gear Mooneys requires two latches...

• Throttle out switch being sensed.
• Gear down, not being sensed.  Do you get a green light when the alarm is sounding?

Are you familiar with where the switch for the gear handle is?  It may need a simple adjustment for location.

If you are getting a gear up alarm with the gear safe green light on, this would be a different problem directly related to the piezo noise maker getting grounded from somewhere else...

There are a couple of threads related  piezo alarm devices...  (memory help for these things...?) Sonalerts! -Vance

PP thoughts only,

Best regards,

-a-

[TTaylor]

9 minutes ago, nightmoves said:

Hi everybody.

My F started having issues recently where my gear down siren will sound sporadically even when the gear is down - sometimes when taxing around even. The light on the dash will go off when the siren sounds, then back on when it stops. This can be quite alarming when about to flare and you are 99.9% you checked the gear 5 times but the siren goes off anyway. My mechanic mentioned a switch or relay of some sort near the nose gear that might be getting stuck in the 'up' position or having a short of some kind. Does anyone know where that is and what to look for? I am really hoping this is a simple fix.

 

Thanks to all.

Welcome to MooneySpace.  It would be helpful to provide the year and gear type of your F model.  The manual versus electric system are different.  

[nightmoves]

Sorry, some clarification.

'69 with Electric gear.

The light will sometimes flicker and each time its "off" when flickering I will hear a blip from the horn. Sometimes it will just go off and its a full siren, just like the gear is still up. The indicator in the floor shows gear down the whole time. Its so random that it seems like either a loose wire somewhere or literally the mechanism that indicates the gear is up/down is stuck or loose. I can be on the ground taxing, hit some bumps and it will go off/on 5 or 6 times and then shut off. I've also been on the ground and the gear down just sounded for 10 minutes until I took off. Very annoying.

Mechanic said something about on an Arrow there is some sort of switch that depresses, indicating gear is up, that he has seen get "stuck" and need some attention so it calls down when the gear comes down. He is thinking the Mooney may share that technology.

 

[carusoam]

So...

Do you need a POH for the wiring diagram...?

Do you need help finding the gear up switch... for the electric gear in the M20F?

Sounds like you know exactly what the problem is.  

Are you looking for the answer to where the problem is?

How can MSers help you more?

Best regards,

-a-

[nightmoves]

I think what I'm asking is, where is this switch and what does it look like? I'm not super excited about digging into wiring so if its a wiring issue I will have to defer to the mechanic. If its a "check this switch to see if its freely moving" issue, that's more my speed. So if someone can tell me where it is that would be awesome. Sorry for not being clear. I wasn't sure this mystical switch existed, my A&P has just suggested looking for one since he's seen that issue with Arrows before.

Thanks.

[carusoam]

You are now looking for the proximity switch for the landing gear.

It isn’t very magical.  All retract airplanes have one. Some have three.

a brief search will probably even show you pictures.

Unfortunately, mid-day Saturday is a popular time for flying.  Otherwise I bet @Marauder has an M20F picture or two in his gallery.

Do you know enough about what you are looking for?

You might be better off working with your mechanic to find this switch.  It probably is going to require removing some belly panels to get there...

 

 

FYI, departing with an alarm sounding, without at least knowing why, doesn’t sound like a very good idea.

PP thoughts only, not a mechanic.  Just trying to help an MSer out...

Best regards,

-a-

 

 

[ArtVandelay]

2 minutes ago, nightmoves said:

I think what I'm asking is, where is this switch and what does it look like? I'm not super excited about digging into wiring so if its a wiring issue I will have to defer to the mechanic. If its a "check this switch to see if its freely moving" issue, that's more my speed. So if someone can tell me where it is that would be awesome. Sorry for not being clear. I wasn't sure this mystical switch existed, my A&P has just suggested looking for one since he's seen that issue with Arrows before

On the early Js, there are two different types of switches (down and up limits) are  different, why I don’t know. You won’t be able to tell from looking at them unless they have come loose. They can be hard to find.

[carusoam]

Nightmoves...

Go to this thread...

How,does that sound?

Vance may have your solution right there.  Of course, you might have to hand this to your mechanic to help him get there...

Best regards,

-a-

[Vance Harral]

Seems like a rash of these gear indicator/warning problems lately.  Speaking only for M20F serial numbers 22-1246 and later, If both the gear warning sonalert sounds and the gear down indicator light in the panel turns off, it does suggest the side of the DPDT limit-down switch that powers the Gear Down light and inhibits the gear warning horn is malfunctioning, or the wire that connects to it is loose.

The up and down limit switches are in the belly, and you'll have to remove the belly panels to get to them.  Because of the way the panels overlap, you'll have to remove two panels: the one just aft of the exhaust tunnels, and the one aft of that one.

Below is a screen grab of a pretty nice video showing electric gear operation with the belly panels off.  It's not my video, and I'm not sure which make/model of Mooney this is, but yours is likely to be very similar.  I've drawn a green circle around the down-limit switch (which is hard to see because the gear is down and the tab that actuates the switch is mostly covering the switch itself) and a red circle around the up-limit switch (which is easier to see).

 

If you watch the actual video, you'll see how the tabs that are connected to the rods which move the gear hit the switches to open/close them:

Hope that helps.

[ArtVandelay]

Here is pix of a 78J versions:

 

[carusoam]

Good news for @nightmoves if he is checking in...

Best regards,

-a-

[nightmoves]

You guys and gals are great! I will probably hand this over to my mechanic but at the very least it should save him some time trying to hunt it down, which saves me money. Thanks to everyone for their input!

[Yetti]

You might want to look at the switch that is near the throttle cable under the panel.   That is what actuates the gear warning horn. Check for loose wires and lose switch that may be bouncing around. Search for threads on adjusting it for proper MP for the warning to sound.

[Stephen]

On 4/29/2018 at 2:46 PM, nightmoves said:

You guys and gals are great! I will probably hand this over to my mechanic but at the very least it should save him some time trying to hunt it down, which saves me money. Thanks to everyone for their input!

I have a ‘69 F. My alert was going off in cruise when anthing less than full throttle was selected, it turned out to be an avionics nut that had fallen into the throttle position switch located under the throttle quadrant cover. Does not sound kike your issue but will throw it in for posterity. 

[RobertGary1]

Make sure during annual you put the gear in the 1/2 down position and lube and exercise both the up and down buttons that interface between the pads and the microswitch behind it (don't get triflow on the micro switch, just on the button). 

You also need the gear in the 1/2 way position to do the Don Maxwell approve trunnion lubrication (gear must be unlocked).

Its also a good time to lube the gear jackscrew.

 

-Robert

[lithium366]

To clean gear limit switches with electrical cleaner do I try to spray inside from the button end or I have to somehow disassemble switch? 

[PT20J]

13 hours ago, lithium366 said:

To clean gear limit switches with electrical cleaner do I try to spray inside from the button end or I have to somehow disassemble switch? 

The switches are sealed so there is no way to clean the contacts if that's the problem. If the plunger is sticking, you can spray it with solvent and work it back and forth manually before the solvent dries.

[lithium366]

On 12/10/2024 at 12:59 PM, PT20J said:

The switches are sealed so there is no way to clean the contacts if that's the problem. If the plunger is sticking, you can spray it with solvent and work it back and forth manually before the solvent dries.

Thanks, this fixed my problem, switch was sticking