1966 M20E Landing Gear Actuator Motor

[Beaker]

I have a bad motor on the Dukes electric landing gear system and am looking either for just the motor or a place that can rebuild the motor. The actuator and gears are all fine. The last time I flew it took over a minute and a half for the gear to come down. Any suggestions? Part number 4196-00-10

[MikeOH]

How did you confirm that the motor is, in fact, at fault/bad?

Have you put the plane on jacks and tried manual extension to see if there is binding or excessive resistance?

[Beaker]

The 100 Hr ADs were both competed and the gear swung 7 times. They were slow 4 flights prior to that work being done(20-30) seconds. That is when I had the work done. All good, no binding. The next flight was 17 seconds to extend, then 7 seconds, the last flight was 1.5min. It seems like the brushes or the windings in the electric motor is what I am thinking.

[EricJ]

It could be the motor is not getting full voltage, which could be due to a corroded or loose external wire or dirty relay or a worn brush or a number of reasons. 

 

[MikeOH]

I think @EricJ is on to something.  This just doesn't seem like a motor going bad.

I have fixed more things than I can count by just looking very carefully at the wiring and connections; most electrical problems end up being a poor connection. You'd be surprised at what you can find by wiggling stuff, checking for loose screws, bad grounds, and chafing.

If that's not fruitful, I'd put a voltmeter right at the motor and troubleshoot back from there if the voltage is low.

Only then would I suspect the motor itself.

[Beaker]

Thanks for the ideas. I will give those a shot. If not I will still be looking for rebuild or purchase options. It seems like this part is difficult to source.

[Beaker]

Thanks for the ideas. I will give those a shot. If not I will still be looking for rebuild or purchase options. It seems like this part is difficult to source. 

The thought behind the bad motor is also because retraction only takes 3-5 seconds, it is only extension that takes a while.

[EricJ]

4 minutes ago, Beaker said:

Thanks for the ideas. I will give those a shot. If not I will still be looking for rebuild or purchase options. It seems like this part is difficult to source. 

The thought behind the bad motor is also because retraction only takes 3-5 seconds, it is only extension that takes a while.

The current path is different between the two, since the relays switch around to swap the polarity of the motor between extension and retraction.    One of the relay contacts or terminal connections in the extension path may be dirty or corroded or something.    Retraction takes more effort since the aero forces try to pull the gear down, so if it is working okay in that direction the motor itself is probably fine.

[Andy95W]

9 hours ago, Beaker said:

 

The thought behind the bad motor is also because retraction only takes 3-5 seconds, it is only extension that takes a while.

That sounds a lot like an old extension relay, or dirty contacts on that side of the system.  As the solenoid/relay actuates, it degrades the contactor and sparking adds carbon it.  Over enough decades, the increasing carbon buildup cuts the voltage to the electric motor which slows the rpm.

The retract motor uses the same brushes and armature for both directions, it swaps the +/- current to run different directions.  It sounds like your motor is fine, although finding options for eventual overhaul is a good idea.

[Yetti]

10 hours ago, Beaker said:

Thanks for the ideas. I will give those a shot. If not I will still be looking for rebuild or purchase options. It seems like this part is difficult to source. 

The thought behind the bad motor is also because retraction only takes 3-5 seconds, it is only extension that takes a while.

The part by the Mooney Part number is difficult to source.   Ebay will return many Cessna Flap Motors.    A good motor shop would be able to rebuild.    But check your wiring first. 

[N201MKTurbo]

You should put a volt meter on your motor leads and do an extension and retraction. It will tell the tale. Also look at the ammeter and see what the current draw is.

[Ragsf15e]

12 hours ago, Beaker said:

Thanks for the ideas. I will give those a shot. If not I will still be looking for rebuild or purchase options. It seems like this part is difficult to source. 

The thought behind the bad motor is also because retraction only takes 3-5 seconds, it is only extension that takes a while.

You need a little quality time with the electrical schematics to see exactly what might be happening.  The gear switch, limit switches and the solenoids all play a part.  It seems like you should start at the gear motor and check the voltage going up vs going down and see if they are different.  In my limited electrical experience, you need to do it with everything still connected (even the motor) as you need the amp draw to reduce the voltage at the point where the problem exists.  If you were to try testing without the motor connected, it might look fine because you have no amp draw. V=i R and all.