Baron B58 owner Larry O., had a mysterious
gear problem where his gear would retract partially then come to a
complete stop. This problem could crop up in B55 and Bonanza aircraft with a
squat switch mounted on one or both gear legs.
Conventional troubleshooting of the gear motor
and switches came up with nothing unusual.
Here is what Larry found:
I had a gear wire break in the wheel well, pix attached. I'm
posting because this is the second time this has happened (once on each gear)...
so it could be common.
This is where the wire bundle comes from the down safety
switch and goes back to a connector at the rear of the wheel well. (This is a
mid 70s B58, but could be similar in other planes).
This is just a heads up. Perhaps hard to troubleshoot, to find
out if a wire is "going to break", but if the wrapping is in poor shape, there's
a though to take it off and examine the wires. Much easier to deal with on jacks
The wire that broke in my case was the wire that goes from the
safety switch to the gear motor. When the gear switch is put up, the safety
switch closes and this wire provides power to raise the gear. There's two parts
to the safety switch, and the other side opens when the plane lifts off and
disconnects the gear up warning horn when the plane is on the ground.
Well, I had a well respected mechanic (actually two of them),
mis- diagnose this issue by identifying the switch as being defective after
crossing power from the horn circuit to the gear motor, thinking it was the gear
circuit..... After I replaced the switch and it still didn't work, I dug into
the wiring diagram and with some help from Stuart S. (another Baron
owner/operator/IA), got to the right place.
Food for thought......
Here is the bend area that takes the most
stress over the years. Bonanza and B55 Barons are similar in that the wiring
must make a bend to go up into the wing from the squat switch. This bend takes
all the flexing over the years of gear cycles.
B55 Baron owner, Lance F., offers some
Note that the squat switch can only prevent the gear from
retracting, if the switch fails or the wire breaks it will still go down. Also,
if the switch is in the "weight on wheels" position with the gear selector in
the UP position, the gear horn will sound but if a wire break stops the gear mid
cycle the horn won't sound. It's also possible for a break in the same bundle to
prevent the horn from working when the plane's on the ground with the gear
selector in the UP position.
From time to time it might be a good idea to
give this area of your wiring a close inspection for cracked insulation or wire
Check your specific wiring diagram for your SN
airframe for the exact details of your squat switch wiring system.
The little rubber bootie protector on top of
the switch actuator can deteriorate (left picture) and allow moisture and crud
into the mechanism. Guess what happens next, yup, you've got a switch that no
Check yours at annual to be sure it remains intact and functional. The picture
on the right is the same bootie repaired with a rubber epoxy/sealant.
Check RAPID for this little gem. The OLD squat
switch bootie is reported to be 35-361148 @ $22.95 on 6/17/2011. BUT,
remember to check YOUR parts catalog for the PN for YOUR airplane.
Great find and pictures Larry!