1981 M20k gear electrical issue

[Pierre07]

Hi all,

I need your help and knowledge here.

just went on a quick flight this pm after the annual just got done.

Everything went fine until I got back in the pattern and pulled the gear lever down and everything electrical seems like it tripped, my best hint was my GNS530 completely restarted.

Gear went down good, everything ended up being good but I couldn’t just let that go.

After we got it in the hangar, we jacked it up and tried the same thing, when I took the gear lever up, the beep and red light on the bypass button wouldn’t stay steady, it was flickering, I had to push harder on the master and it seemed like it helped.

I’m wondering if it’s the master switch, or the relay or…

Did that ever happen to someone before or does anyone have any hints on what it could be?

Thank you very much in advance!!!

 

[Z W]

Never seen that before. I would suspect something binding / shorting out in the gear motor, since that's the system you were turning on when the problem started.

[Ragsf15e]

13 hours ago, Pierre07 said:

Hi all,

I need your help and knowledge here.

just went on a quick flight this pm after the annual just got done.

Everything went fine until I got back in the pattern and pulled the gear lever down and everything electrical seems like it tripped, my best hint was my GNS530 completely restarted.

Gear went down good, everything ended up being good but I couldn’t just let that go.

After we got it in the hangar, we jacked it up and tried the same thing, when I took the gear lever up, the beep and red light on the bypass button wouldn’t stay steady, it was flickering, I had to push harder on the master and it seemed like it helped.

I’m wondering if it’s the master switch, or the relay or…

Did that ever happen to someone before or does anyone have any hints on what it could be?

Thank you very much in advance!!!

 

What did they work on during the annual?  That’s where I’d look if it was working before… adjust gear tension?  Take apart gear motor for lube? Etc

[EricJ]

The gear motor is one of the larger electrical loads in the system, especially during retraction, so it could be that the problem isn't directly with the gear, but it's just putting enough strain on the system to expose a fault somewhere else.    Or it could be that the gear is now binding somewhere or has a loose connection.

There's no obvious first place to look, but everything that got touched during the annual is suspect.   If this never happened before, it's likely due to something that got changed/adjusted/touched during the annual.

 

[1980Mooney]

As @EricJ says the gear motor is just a large load.  Remember that the gear motor is on its own circuit breaker.  If you had binding or overload in the landing gear system, it would trip that breaker first.  It is just a load that is within design limits.  

If the plane was in annual for a while the battery may have been down a bit and was still charging.  When you pulled the gear there may have been a drop in voltage momentarily.  As said maybe some adjustments made the motor work harder (still within limits) but pull a bigger load than you normally see.  This voltage drop can effect relays that are weak.

Did any other power cut out except the radios/nav?  If not I would look at your radio master relay.  It could be just from sitting the relay contacts had some resistance.  Cycling may resolve.

[231LV]

I was flying my bi-annual with my CFI when we practiced an engine out landing. I dropped the gear as I would in a simulated off-field landing and then executed a go around. The gear wouldn't retract...nothing. I used the emergency pull cord and got the gear down for a safe landing at my mechanic's field. He jacked it up, pulled the belly panels and found the problem...bad and corroded leads which he cleaned up and tightened....problem solved....check for loose connections and or a short due to corrosion....that is the low hanging fruit and relatively cheap to solve before moving to the more expensive stuff.

[A64Pilot]

I don’t believe the gear is much larger load than the heated pitot, try turning the heated pitot on and off and see if it causes a problem. Worth trying.

It could be many things even a master relay going bad, but having trouble shot electrical problems forever it’s usually a ground, don’t know why, but most often it’s the ground not power side.

Watch the Amp meter when retracting and extending the gear to see how many amps are drawn, it could even be a loose battery cable.

[N201MKTurbo]

Did your mechanic make any adjustments or any other work on the landing gear?

When I bought my plane it would often pop the gear breaker. It would seriously drag the buss down. It turns out that when the airplane was repaired after a gear up landing, the mounting bracket for the actuator was installed backwards. The previous owner said he took the plane to 3 different shops, including DM, and nobody could fix it. After I re-installed the bracket the right way around it worked fine and didn't pop the breaker any more. The point is, about the only thing that will do that is if the gear system is binding somewhere.

[Pierre07]

Thank you very much everyone one for your answers!!!
Sorry it took forever to reply, I had to jump on a "away from home" job and just got back.

I felt so stupid this weekend going through everything and it ended up being the master switch connection.

Screwed it back tight, jacked the planed, gear in/out test couple times and everything was good.

Took it out and everything was good.

Really happy it was only that!!!

Thanks again!

[carusoam]

On 4/3/2023 at 7:46 AM, Pierre07 said:

Thank you very much everyone one for your answers!!!
Sorry it took forever to reply, I had to jump on a "away from home" job and just got back.

I felt so stupid this weekend going through everything and it ended up being the master switch connection.

Screwed it back tight, jacked the planed, gear in/out test couple times and everything was good.

Took it out and everything was good.

Really happy it was only that!!!

Thanks again!

Great follow-up Pierre!

Thanks for sharing the details!

Go MS!

Best regards,

-a-