Landing Gear Breaker Trips Only In Flight

EdFred

EdFred

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White Chocolate
Comanche 250

Solenoid breaker only trips while in flight, but not on the stands in the shop.

What say you PoA?

More info:

Had new cables and teflon guides installed a few years back, and those are all in good condition, so it's not that. The motor breaker doesn't trip (which prior to the cable replacement - that one did trip) only the solenoid breaker. Made note of where the gear handle was when the breaker tripped. Not always in the same position when tripped. Tripped on retraction and extension - but again only in flight and not while static and in the shop.
 
EdFred said:
Comanche 250

Solenoid breaker only trips while in flight, but not on the stands in the shop.

What say you PoA?

More info:

Had new cables and teflon guides installed a few years back, and those are all in good condition, so it's not that. The motor breaker doesn't trip (which prior to the cable replacement - that one did trip) only the solenoid breaker. Made note of where the gear handle was when the breaker tripped. Not always in the same position when tripped. Tripped on retraction and extension - but again only in flight and not while static and in the shop.
Click to expand...

Post your question on the Adelphi airworthy Comanche forum and/or contact Matt Kurke at comanchegear.com

Common issues with this breed, and those are the best resources.

- ‘58 Comanche owner...


Sent from my iPhone using Tapatalk
 
Sounds like the solenoid may be bad. The contacts can arc due to pitting on them causing problems.
 
Voltages are higher when the engine is running than in the shop when it's not, unless the shop is using a power cart that supplies normal charging voltage. A higher voltage means more current in a system, and for a marginal breaker it might be just enough to trip it.
 
Got out to the shop at lunch. A&P had run an ammeter on the solenoid while the gear was in operation, and said it only showed 1.5A draw.

Swapped wires to an adjacent 5A breaker, took the plane up, cycled the gear 7-8 times and the breaker never tripped. New breaker on order.
 
EdFred said:
Got out to the shop at lunch. A&P had run an ammeter on the solenoid while the gear was in operation, and said it only showed 1.5A draw.

Swapped wires to an adjacent 5A breaker, took the plane up, cycled the gear 7-8 times and the breaker never tripped. New breaker on order.
Click to expand...

My God man. You used a MULTIMETER and Ohm’s Law on an AIRPLANE?!

What’s the world coming to? Normally this thread would need to go at least four weeks before anyone tried stuff like that. :)
 
One reason things work OK on jack stands and not in flight is that there is no wind load on it on the stands. I bet the motors draw more current pulling the gear against the wind.
 
Found this -

Several different causes have been described for landing gear retraction problems. Most of the problems manifest themselves by the gear motor breaker popping just as the gear reaches the fully retracted position. The more obvious ones are worn gears in the retraction mechanism, lack of or too heavy lubricant for cold weather operation, weak circuit breaker. These problems can usually be overcome by helping the gear motor by pushing down on the emergency gear extension handle as the gear comes up.


Another not so obvious trouble can cause the gear to fail to retract all the way thereby causing the motor to overload and blow the breaker. The hydraulic brake line is fitted through a loop on the landing gear fork. It usually has freedom of movement through this loop or is positioned so that as the gear retracts the brake line folds inside the wheel well. In cold weather, if the brake line gets stiff, it can sometimes become trapped between the gear door and the wing and not fold entirely into the wheel well. Since the gear door can not close entirely, the breaker pops.


And one more cause came to light just a few days ago. The wheel well lining screws came loose and let the wheel well lining fall partially out of the well. When the gear came up, the wheel smashed the lining back into the wheel well in a not too graceful manner. The irresistible force met the immovable object and pop went the breaker.


Take a tip from one who has had it happen. Manual extension of the gear does not always lock the gear in the down position. Upon landing, the manually extended gear can collapse. A good thing to do it you have a co-pilot is to have him put his left foot on the emergency gear handle and hold it firmly against the wheel well.


ED: If the gear is properly adjusted and the downlock springs are installed per specification, the gear should remain locked.
 
denverpilot said:
My God man. You used a MULTIMETER and Ohm’s Law on an AIRPLANE?! What’s the world coming to? Normally this thread would need to go at least four weeks before anyone tried stuff like that. :)
Click to expand...

I can think of at least 4 parts, all over $500 each that could have been replaced before resorting to a logical and basic approach such as this; sacrilege!
 
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