Fred Rhodes Posted October 30 Report Posted October 30 I am having trouble with my 1977 J model. When it is cold the gear does not want to fully retract. The motor is trying to finish it as the electric meter shows a strain on the battery. I can put it back down and it goes up all the way on the second try. It is electric gear. It gets greased regularly. We swing it on annual inspection and it always goes through the cycle flawlessly. But the hangar is warm. Quote
Ragsf15e Posted October 30 Report Posted October 30 17 minutes ago, Fred Rhodes said: I am having trouble with my 1977 J model. When it is cold the gear does not want to fully retract. The motor is trying to finish it as the electric meter shows a strain on the battery. I can put it back down and it goes up all the way on the second try. It is electric gear. It gets greased regularly. We swing it on annual inspection and it always goes through the cycle flawlessly. But the hangar is warm. Is the circuit breaker popping or the motor stops running without the circuit breaker popping? Quote
201Mooniac Posted October 30 Report Posted October 30 Do you know it is not all the way up? It is just that the motor doesn't stop running, if so it might be an issue where the up limit switch is sticking when cold and not turning off the motor. I would expect the circuit breaker to pop in that situation though. Quote
Fred Rhodes Posted October 30 Author Report Posted October 30 I have viewed it with a camera attached to the tail tie down. It goes almost all the way up, but not all the way. Quote
Fred Rhodes Posted October 30 Author Report Posted October 30 The circuit breatee does not pop. It shows a short duration discharge. Quote
Fred Rhodes Posted October 30 Author Report Posted October 30 The motor stops trying after the first attempt to take it all the way. It just shows the light saying that the gear is unsafe. Quote
EricJ Posted October 30 Report Posted October 30 12 minutes ago, Fred Rhodes said: The motor stops trying after the first attempt to take it all the way. It just shows the light saying that the gear is unsafe. Something isn't right (obviously). The motor is on if the unsafe lamp is on, and doesn't turn off until the gear is fully up. If the gear has jammed and prevented the motor from running the gear all the way up, one would expect the breaker to pop. If the breaker doesn't pop, I suspect the brushes in the motor may be getting tired and need to be replaced, or there is a potential wiring issue that is limiting the current. 2 Quote
Fred Rhodes Posted October 30 Author Report Posted October 30 That is something that I have not checked Quote
KSMooniac Posted October 30 Report Posted October 30 If the motor has never been rebuilt, I'd start with that. My '77 quit on me in 2008 and required a motor overhaul. Quote
Ragsf15e Posted October 30 Report Posted October 30 (edited) And we’ll all have to be careful comparing ours to this as the lights changed over the years… the “unsafe” light on my ‘68 means the gear is completely up, ie it’s unsafe for landing. This is a normal condition. Mine could do exactly as described, even not fully pull the gear in if I had some sloppy ball joints in the main gear area… but again, mine is older. You need to look at the wiring diagram for your specific year. Edited October 30 by Ragsf15e Quote
Fred Rhodes Posted October 30 Author Report Posted October 30 Do you know who does the motor rebuilding? Quote
EricJ Posted October 30 Report Posted October 30 10 minutes ago, Fred Rhodes said: Do you know who does the motor rebuilding? There's nothing special about the motor itself. Most electric motor shops should be able to work on it. Quote
1980Mooney Posted October 30 Report Posted October 30 7 minutes ago, Fred Rhodes said: Do you know who does the motor rebuilding? That is a Dukes actuator on the '77 M20J - right? If it is more than just the motor then Don Maxwell or Lasar AD 75-23-04: SB M20-190 | Mysite (donmaxwell.com) Quote
Fred Rhodes Posted October 30 Author Report Posted October 30 It is a Dukes actuator. We keep up with the maintenance on the gear part and just changed out the coupling at the last annual. 1 Quote
N201MKTurbo Posted October 30 Report Posted October 30 If the motor stops intermittently with the unsafe light on, it may be the contactor. Next time it doesn’t retract, move your seat back and stomp on the floor right in front of the seat and see if it starts back up. Quote
N201MKTurbo Posted October 30 Report Posted October 30 FWIW, the brushes they use on those motors are huge. I doubt they will ever ware out. I have had them unscrew, but if that happens the motor won’t move at all. There isn’t anything I can think of that would make the motor only fail in one direction. Quote
Fred Rhodes Posted October 30 Author Report Posted October 30 The motor doesn't seem to keep trying after it stops. Quote
KSMooniac Posted October 30 Report Posted October 30 I expect it is stopping on a worn spot and needs some service inside. Mine was sent to George's Electric or something close to that in CA all those years ago, but I believe they're long-gone now. If it happened to me today, I'd start with a local electric motor shop and cash to get my homemade fan motor repaired. 1 Quote
Hank Posted October 31 Report Posted October 31 When my C started doing that, it began in cold weather and got worse as the winter deepened. The floor indicator showed barberpole, indicating that the gear wasn't all the way up, and speed was down by ~10 knots. Drove me crazy! Replacing the donuts in the landing gear resolved it--there are eleven, four in each main and three on the nose. The new set was 1/2" taller than the old ones. Quote
Fred Rhodes Posted October 31 Author Report Posted October 31 My donuts were replaced about 8 years ago. I will check specs to see if they are needing replaced. Quote
ArtVandelay Posted October 31 Report Posted October 31 My donuts were replaced about 8 years ago. I will check specs to see if they are needing replaced.8 years?! I think they should last 20 years or more. 1 Quote
Fred Rhodes Posted October 31 Author Report Posted October 31 That is my thinking. Also, but i'm not sure it's worth a check Quote
PT20J Posted October 31 Report Posted October 31 The symptoms as described do not make sense. 1. Only happens when cold 2. Motor stops before the gear is fully retracted but continues to draw current. 3. Gear CB does not trip 4. Fully retracts if gear is cycled. If it were a mechanical problem stalling the motor it should pop the breaker. When the motor stops running, it’s generally because power has been removed by a limit switch, relay or safety switch (squat or airspeed). Early M20Js have a squat switch on the left main gear. If the shock disks are good, I’d check the switch adjustment. If your airplane has a red override button next to the gear switch, you can press and hold that and if that causes the gear to retract fully it will confirm that the squat switch is the problem. 3 Quote
Fred Rhodes Posted October 31 Author Report Posted October 31 Mine does not have the override switch. But checking the squat switch will be on my list of things to check. Thanks. Quote
EricJ Posted October 31 Report Posted October 31 20 minutes ago, Fred Rhodes said: Mine does not have the override switch. But checking the squat switch will be on my list of things to check. Thanks. If you don't have the override switch you likely still have the squat switch, which could be contributing to the problem. A common modification is to replace the squat swith with an airspeed switch that has the override button. Mooney used to supply a kit to do that, they may still be able to. 1 Quote
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