No Joy on Landing Gear Extension - J Model

[Brent]

At the end of the second leg of a cross-country yesterday I moved the landing gear switch to "Down" and nothing happened. I toggled the switch a couple times and got nothing. No motor motion, no circuit breakers popped, the low RPMs gear alarm continued (along with airspeed...), the "Gear Unsafe" annunciator light was lit, and the floor window showed red-stripe gear up. I lowered the gear using the manual extension and landed safely. Luckily, the issue happened at my home airport, so there's that.  

Ahead of the troubleshooting on jacks with my mechanic tomorrow, I thought I would solicit info from anyone with prior experience on this issue. Areas I assume we'll look at: actuator motor, breakers, relays (one for up, one for down), any loose wiring. (I did have some rain and turbulence on that leg.)

(Side note for others: when you lower the gear via manual extension, be careful NOT to over-pull that ripcord cable. Lower the gear until the Gear Unsafe light goes off and you have normal green in the floor window, and that's it. If you force-pull the cable after you have a gear-safe condition, you will bend the long linkage rod in the belly. I almost learned that the hard way in a hangar with the plane on jacks a couple years ago.)  

[PT20J]

If there was no motion of the motor and no circuit breakers popped, then the problem is most likely the down limit microswitch or the down relay. When mine did this (but on retraction rather than extension) I isolated it to the relay by jacking the plane, removing the belly panel and tapping the relay with a screwdriver handle which caused the gear to operate. 

[EricJ]

+1 that it is most likely one of the relays or a loose wire to a relay or something like that.   

It should be reasonably easy to diagnose on jacks.

[Brent]

16 minutes ago, PT20J said:

If there was no motion of the motor and no circuit breakers popped, then the problem is most likely the down limit microswitch or the down relay. When mine did this (but on retraction rather than extension) I isolated it to the relay by jacking the plane, removing the belly panel and tapping the relay with a screwdriver handle which caused the gear to operate. 

No breakers popped. I clarified the original entry. Is the down-limit micro-switch that button with a little paddle clamped to the linkage rod? Thanks for the info. 

[EricJ]

3 minutes ago, Brent said:

No breakers popped. I clarified the original entry. Is the down-limit micro-switch that button with a little paddle clamped to the linkage rod? Thanks for the info. 

Yes, and they're very easy to test.    If one is sticky, contact cleaner will sometimes rehab it, but it is also telling you that it will need to be replaced eventually.

[Ragsf15e]

57 minutes ago, Brent said:

No breakers popped. I clarified the original entry. Is the down-limit micro-switch that button with a little paddle clamped to the linkage rod? Thanks for the info. 

There are the limit switches and the relays (which are near the actuator i think).  Limit switches are exactly as you described- paddles on the rod.

[PT20J]

The relays are bolted to the floorboard ahead of the left rear seat. 

[N201MKTurbo]

I’ve told this a few times. I think people think it is silly, but it is not. In your situation, if it is a contactor, they are mounted to the floor under the pilots seat. If the gear does nothing, stomping on the floor or bouncing on the seat may knock it loose and get the gear going. 
 

I also had this happen once and found one of the motor brushes fell out.

[Brent]

Tapping on the relay restored downward movement. The other parts of the system (motor, actuator gear, limit switches, down/up panel switch, breakers test ok.

So now I’m going on the hunt for the relays. PN 940050-501 is the applicable PN I see in the IPC. I’ll search today. If anyone has a sourcing idea, I’ll appreciate the advice.

[Brent]

UPDATE: I found two used relays from BAS Parts, PN 940084-501, which are the Mooney retrofit parts for the original but now obsolete/unavailable 6041H53 and 70-311221  parts. I couldn't find new anywhere. LASAR had history from several years ago showing $3000 and 18 weeks lead-time. Worst case, even though used, these retrofit parts must be decades newer than my originals. We'll see.

Thanks for the advice above. 

[Fritz1]

If the limit switches are same vintage as relays, might as well replace them while you are at it if you can find new switches and are planning to keep the plane for a while, food for thought...

[Will.iam]

Would not this relay since not available new anywhere be a prime candidate for owner produced part? How specialized can that relay be? Where is radio shack when you need one?

[N201MKTurbo]

55 minutes ago, Will.iam said:

Would not this relay since not available new anywhere be a prime candidate for owner produced part? How specialized can that relay be? Where is radio shack when you need one?

I had one go bad. Found a new old stock of the OEM part number. There are plenty of Chinese knock offs.

[EricJ]

Also look for crosses to other part numbers, or a MS number or such that might expand the part search.   Also, if you can find a manufacturer name and PN on it, sometimes that can help.

 

[201Steve]

Food for thought, I had an intermittent issue with gear going UP. I tapped on the contactors and voila! It went up! I replaced both for good measure. And then, it still didn’t work right. 
 

Long story short, the light tap of a hammer in the general area created enough vibration to break loose the real problem, that turned out to be a limit switch actuator. YRMV. 

[PT20J]

I would buy a used electrical component only as a last resort - who knows how much life is left in it? The Safran catalog still lists the 6041H53 (p 26). I might contact them. I replaced my 28v 6041H220 relays with Safran parts.

SE&P_Relay_Catalog.pdf

[Ragsf15e]

I agree with the guys above.  Instead of looking for the Mooney part number (unless it’s actually available, which in this case it’s not), pull the original manufacturer and part number off the part. If it’s been superseded, you’ll need that part number. Search by that manufacturer and part.  It’s amazing what you’ll find.  Make sure your mechanic is ok with using parts that are from the original manufacturer instead of being blessed by Mooney (even though they are the correct part).

[Brent]

12 hours ago, PT20J said:

I would buy a used electrical component only as a last resort - who knows how much life is left in it? The Safran catalog still lists the 6041H53 (p 26). I might contact them. I replaced my 28v 6041H220 relays with Safran parts.

SE&P_Relay_Catalog.pdf 2.19 MB · 3 downloads

Yes, I wasn't keen on used since that's what I have now, but I wasn't having any luck on any of the part numbers new.  

So thanks for the OEM catalog. I didn't know that. I did contact Safran's distributor. They had no stock go the 6041H53 (14v) but will check with the OEM. We'll see. 

 

[Ragsf15e]

43 minutes ago, Brent said:

Yes, I wasn't keen on used since that's what I have now, but I wasn't having any luck on any of the part numbers new.  

So thanks for the OEM catalog. I didn't know that. I did contact Safran's distributor. They had no stock go the 6041H53 (14v) but will check with the OEM. We'll see. 

 

I have had good luck with “electronic warehouses” that stock all kinds of old-new parts.  Found a microswitch that had been superseded, but the newer one had a slightly different actuator that wouldn’t work.  I would possibly expand out past the distributors if needed…

[Ragsf15e]

43 minutes ago, Brent said:

Yes, I wasn't keen on used since that's what I have now, but I wasn't having any luck on any of the part numbers new.  

So thanks for the OEM catalog. I didn't know that. I did contact Safran's distributor. They had no stock go the 6041H53 (14v) but will check with the OEM. We'll see. 

 

I have had good luck with “electronic warehouses” that stock all kinds of old-new parts.  Found a microswitch that had been superseded, but the newer one had a slightly different actuator that wouldn’t work.  I would possibly expand out past the distributors if needed…

[Fly Boomer]

13 hours ago, PT20J said:

I would buy a used electrical component only as a last resort - who knows how much life is left in it? The Safran catalog still lists the 6041H53 (p 26). I might contact them. I replaced my 28v 6041H220 relays with Safran parts.

SE&P_Relay_Catalog.pdf 2.19 MB · 4 downloads

Were you able to buy directly from Safran?  If not, who?

[PT20J]

24 minutes ago, Fly Boomer said:

Were you able to buy directly from Safran?  If not, who?

I got mine from peerlesselectronics.com

 

[Brent]

2 hours ago, PT20J said:

I got mine from peerlesselectronics.com

 

That's who I called. They have my RFQ. We'll see.

[blaine beaven]

On 9/3/2025 at 11:06 AM, PT20J said:

The relays are bolted to the floorboard ahead of the left rear seat. 

I am amazed at how shiny your floorboards are. 

[Yetti]

On 9/5/2025 at 1:51 PM, Brent said:

That's who I called. They have my RFQ. We'll see.

A quick google search on 6041H53    shows it to be a Cutler Hammer    which was bought by Eaton.

This looks like a pretty good fact sheet.    http://www.aeroelectric.com/Reference_Docs/Misc_Pdf/6041SeriesPowerRelays.pdf

28V   2PDT         Has an MS number   MS25031-D1B 

I found the F model flap relay NOS at like Relays.com or something.     I should probably sell it.