Gear Relay Fuse Tripping

[hafner152]

Hello,

To all you Mooniacs, I'm having an issue with my gear relay fuse tripping when raising and lowering the gear.  Two mechanics have looked at the issue with no fix.  Recently when raising the gear after takeoff, the gear relay fuse will "pop" and the gear will not retract fully.  The gear will then extend after the gear lever handle is lowered and the fuse pushed back in.  If the gear does not trip when retracting the gear, it has been tripping when extending the gear prior to landing.  The problem, so far, has been resolved with pushing the fuse back in and subsequent lowering of the gear lever.  The problem was intermittent at first, but now it seems to happen every flight. 

The two mechanics have put the plane on jacks and there is no issue lowering and raising the gear....they've stated they've applied force when extending and retracting with no issues.  We have also replaced the gear relay fuse with a new one....same issue upon flight.  One of the mechanics has stated he also applied airspeed to the pitot tube and extended and retracted the gear on jacks with no issues.  So, the problem seems to only happen during actual flight.  In addition, the mechanic has applied lubricant to all rotational points.  Does anyone have any suggestions or similar experiences?  The airplane is a 1998 Mooney J model Allegro.  Any insight would be helpful!  Thank you

[PT20J]

The gear relay circuit breaker (it's a circuit breaker, not a fuse ) supplies power from the main bus to the gear switch and then through the limit switches to the relays that operate the motor. There are up and down relays and up and down limit switches. Since the problem happens during both retraction and extension it must be something common to both circuits. I would put it on jacks, check the operation of the limit switches, and then look for a short in the wiring somewhere. Since it has become more or less continuous, it might be easier to troubleshoot now. And as it has been degrading, I would not fly it for concern that an intermittent short would become a continuous short rendering the electric system inoperative.

Skip

[GeeBee]

The two times this has happened in my Ovation, it has turned out to be a bad gear bypass switch.

[PT20J]

  On 5/14/2022 at 7:05 PM, GeeBee said:

The two times this has happened in my Ovation, it has turned out to be a bad gear bypass switch.

Expand  

Worth checking. Did it do it in both up and down directions? Looking at the schematic, the power goes to the gear switch first and the bypass switch appears out of the circuit in the down direction. 

[GeeBee]

Actually it would do it up, down and sometimes in level flight with the gear retracted

[PT20J]

Strange. Not doubting you, though. I don't have a R schematic handy -- wonder if it is different somehow than my J.

[GeeBee]

All I know is switch replaced problem solved

[larryb]

I have had a similar issue. In my case, the gear relay CB tripped when the gear was up. I found I could leave it tripped, move the gear switch to down, and then reset the CB and the gear would extend fine and no problems. But when the gear was all the way up, the CB would eventually trip. The problem is that there is very little clearance between one of the tabs on the gear system and the back of the gear limit switch. When the gear was up this tab was barely touching one of the screws on the back of one of the gear limit switches. I don't remember exactly which one at this point. But with the plane on jacks and the gear retracted, carefully check the terminals of both gear limit switches. The fix in my case was to simply remove the un-used terminal screw of the limit switch that the tab was shorting to.

 

This all started after the MSC replaced on of the gear limit switches because it was intermittent.

[flyboy0681]

The original gear relay's for the J are no longer available and require a retrofit kit which contains new relays. Lasar states that delivery time is 18 weeks. Anybody out there know how to get them quicker or somebody selling the kit?

[Airways]

I had exactly the same. Gear relay tripped when selecting gear up.  Mechanic found some chafed wiring and cleaned that up.  Problem solved. 

[Yetti]

  On 5/16/2022 at 2:35 PM, flyboy0681 said:

The original gear relay's for the J are no longer available and require a retrofit kit which contains new relays. Lasar states that delivery time is 18 weeks. Anybody out there know how to get them quicker or somebody selling the kit?

Expand  

If you put some pictures and parts numbers you may find that they are readily available.   Like the flap relay for a 75F   Part number W97CSX-1     Got one from https://www.relayspec.com/

[flyboy0681]

  On 5/17/2022 at 12:41 PM, Yetti said:

If you put some pictures and parts numbers you may find that they are readily available.   Like the flap relay for a 75F   Part number W97CSX-1     Got one from https://www.relayspec.com/

Expand  

There have been a lot of posts over the years here at MS about the relays, and the common theme that runs through them are that the originals are no longer available. While some have been able to adapt relays from everything from refrigerators to Ford F150's, my partners and I decided to wait for the factory certified solution. 

[GeeBee]

There is nothing wrong with purchasing the same make and model of relay from a non-factory source. The relays for the long bodies can be purchased from non-factory sources for 1/2 the cost. They are identical and as a matter of fact, the factory parts manual will often spec the make and model so you can source it directly.

[flyboy0681]

I was able to bag probably the last available relay retrofit kit in the United States (world?). When Lasar stated that there is a five to six month lead time, I started searching like hell and was unable to find one anywhere. Then I called Premier at FXE and they had one unit in stock. I drove down there like a bat out of hell to pick it up just in case someone else needed one as well.