Electrical issues when raise and lower gear

[Mark Callender]

We are having difficulty finding an electrical issue.  When we raise or lower the gear hear a pop in the headset and the 430 shuts down briefly and the transponder goes off.  Will also do it in rough air or randomly but doesn't do it all the time.  We have changed out the battery relay and the battery but still doing it.  Sounds like a short somewhere but can't trace it.  Would appreciate any help if someone else has had this problem. Thanks!

[Don Lawrenz]

I would suggest you jack the plane and run through several cycles with the avionics power on. Check behind the pedestal to see if the cable that goes to your mechanical gear indicator (I think you have one of those) is not fouling a wire. It is surprising that a breaker has not blown somewhere.

I have not had this particular problem, but I can not think of where any of the power wiring that might cause this would be in proximity to the motion of the gear train other than behind the pedestal.

Good Luck!

[Steve Zeller]

Could the brushes in the gear motor be arcing? That might be the "pop" you hear. If the motor is worn out, it could also be pulling too much current and dragging your DC bus voltage way down. That should pop the gear motor breaker.  I'd inspect the brushes and commutator in both the gear motor and generator/alternator. Brush arcing tends to make that popping noise in the audio system.Steve Zeller2011-12-07 08:49:37

[Tom Pelz]

Mark,

Does the "pop" occur when the gear switch is selected up or down?  That is, does the "pop" occur immediately, or does the "pop" occur at the end of the cycle (Up or down)?

If you have the old style instrument panel with the key which includes the "master" switch in addition to the master switch behind the sub panel door on the right side, have you considered that the "key switch" may be the problem?   

Before I upgraded to a BDS panel, I had replaced my switch, which resolved many of my problems.

Tom

[Stuart Spindel]

He has the S model, which is the newer style panel.



I agree that the motor first be checked.



After that, it gets interesting...

[Tom Pelz]

Mark,



while you are sending out the motor for overhaul, take a good look at the limit switches.



These are easily found after you have removed the seats and access plates.  I have read that sometimes they give problems.  While you are there, look for loose wires, etc.



Please let us know what you find is the problem.



Tom