PT20J Posted February 2 Report Posted February 2 After landing I put the flap switch in up position and the flaps did not move and the circuit breaker popped. Thereafter, I noted that the breaker would pop when the master was turned on with the flap switch in up, takeoff, or down position (the airplane is a later model with the three position flap switch). I tried wiggling the flaps because some have said that got them working again, but to no avail. I'm not saying others are wrong, but the up/down limit switches ride on the acme screw barrel of the actuator which cannot be back driven due to the wheel and worm gearing of the actuator so I have a hard time seeing how wiggling the flaps can move the switches. Be that as it may, it did nothing for my problem. Removing the belly skin and inspecting things, I noticed that the actuator had overrun past the down limit and jammed the barrel. I disconnected the barrel and manually freed it and rotated it to the up position. But the breaker still popped. I disconnected the connector that feeds the motor and the breaker still popped indicating that the problem was not the motor. I disconnected the connector that goes to the up and down relays and the breaker didn't pop, so the wiring is good. Next I removed the down relay and reconnected the connectors and the breaker did not trip indicating that the short was in the relay. I took the down relay apart and found that the armature had become dislodged and that all three contacts (C, NO, NC) were stuck together creating a short circuit. The Magnacraft relay looks like a pretty flimsy mechanical design to me. I found some new/old stock online and ordered two. Hopefully this helps someone with a similar problem. 9 8 Quote
Fly Boomer Posted February 2 Report Posted February 2 16 hours ago, PT20J said: After landing I put the flap switch in up position and the flaps did not move and the circuit breaker popped. Thereafter, I noted that the breaker would pop when the master was turned on with the flap switch in up, takeoff, or down position (the airplane is a later model with the three position flap switch). I tried wiggling the flaps because some have said that got them working again, but to no avail. I'm not saying others are wrong, but the up/down limit switches ride on the acme screw barrel of the actuator which cannot be back driven due to the wheel and worm gearing of the actuator so I have a hard time seeing how wiggling the flaps can move the switches. Be that as it may, it did nothing for my problem. Removing the belly skin and inspecting things, I noticed that the actuator had overrun past the down limit and jammed the barrel. I disconnected the barrel and manually freed it and rotated it to the up position. But the breaker still popped. I disconnected the connector that feeds the motor and the breaker still popped indicating that the problem was not the motor. I disconnected the connector that goes to the up and down relays and the breaker didn't pop, so the wiring is good. Next I removed the down relay and reconnected the connectors and the breaker did not trip indicating that the short was in the relay. I took the down relay apart and found that the armature had become dislodged and that all three contacts (C, NO, NC) were stuck together creating a short circuit. The Magnacraft relay looks like a pretty flimsy mechanical design to me. I found some new/old stock online and ordered two. Hopefully this helps someone with a similar problem. I love reading about this kind of troubleshooting -- way easier reading about it than actually having to do it. 1 3 Quote
Yetti Posted February 5 Report Posted February 5 On the F there are two relays and only half the relay is used. So you can move the wires to the other side of the relay and that should still work. I do have a spare flap relay that I found online. Quote
PT20J Posted February 5 Author Report Posted February 5 1 hour ago, Yetti said: On the F there are two relays and only half the relay is used. So you can move the wires to the other side of the relay and that should still work. I do have a spare flap relay that I found online. The J is the same way, but if the armature jams it affects both sets and it's a pain to solder on the socket contacts upside down under the airplane. The new relays were only $35 each (which is pretty cheap for an airplane part which is probably why they fail as they look pretty cheap when you take them apart). 3 Quote
Yetti Posted February 6 Report Posted February 6 21 hours ago, PT20J said: The J is the same way, but if the armature jams it affects both sets and it's a pain to solder on the socket contacts upside down under the airplane. The new relays were only $35 each (which is pretty cheap for an airplane part which is probably why they fail as they look pretty cheap when you take them apart). solder is a cruel factory trick. Nothing hurts quite like when it drops on your skin. The F are ring terminals. I think I calculated the much failed comms relay up under the panel is undersized for the King suite of Avionics. and most of them failed. My gear solenoid is similar to a 4 post solenoid off a N Model Ford tractor. 1 Quote
PT20J Posted February 7 Author Report Posted February 7 12 hours ago, Yetti said: I think I calculated the much failed comms relay up under the panel is undersized for the King suite of Avionics. and most of them failed. My M20J Kissling 26.64.01 rated for 100A continuous current. I think I’m good. Quote
Yetti Posted February 7 Report Posted February 7 10 hours ago, PT20J said: My M20J Kissling 26.64.01 rated for 100A continuous current. I think I’m good. The 75 F had a Cuttler Hammer or Potter Brumfield from the factor so I guess Mooney got wise and upgraded the amperage. Quote
A64Pilot Posted February 12 Report Posted February 12 On 2/6/2025 at 12:07 PM, Yetti said: My gear solenoid is similar to a 4 post solenoid off a N Model Ford tractor. On my 81J running the part number comes up as a Golf Cart solenoid, which I believe is the same, but widely available and cheap. The difference between the two maybe is the golf cart solenoid is continuous duty, where the starter solenoid likely isn’t. The pic Mooney part on left, golf cart one on right, remember by part number they are the same. The landing gear switch thankfully is available by part number and cheap too. 1 Quote
PT20J Posted February 12 Author Report Posted February 12 How did we go from troubleshooting a failed flap relay to avionics power relays to starter relays to golf cart parts? 1 1 Quote
Yetti Posted February 12 Report Posted February 12 2 hours ago, A64Pilot said: On my 81J running the part number comes up as a Golf Cart solenoid, which I believe is the same, but widely available and cheap. The difference between the two maybe is the golf cart solenoid is continuous duty, where the starter solenoid likely isn’t. The pic Mooney part on left, golf cart one on right, remember by part number they are the same. The landing gear switch thankfully is available by part number and cheap too. Nope. The Ford 8N starter solenoid is only 4 post. The main post run the gear motor. The 4th post is Positive and turns the brake off in the back of the motor. The brake is there to keep the gear from chattering down. Interesting enough some of the F models run two solenoids for the gear. One up and one down. Quote
Hank Posted February 13 Report Posted February 13 22 hours ago, PT20J said: How did we go from troubleshooting a failed flap relay to avionics power relays to starter relays to golf cart parts? Because isn't it amazing where some of our Mooney parts came from? Quote
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