Ever wonder what magic those motor shops
perform on the electric motors in your Beechcraft? Well wonder no more, here is
an array of equipment and methods used by a Beechcraft owner to keep his
electric motors operating at top form. Email him
HERE for info on how he can help you with your electric motors.
Here is his narrative (and yes, of course he
is A&P supervised)
1st picture is of as removed armature. Remove Bearings
Clean it in a ultrasonic ammomia bath for 20 minutes
check segments of armature for shorts or breaks using a
As Removed Armature
After Clean Up
Dry it in lab oven for 1 hour at 180 degrees
segments of armature for shorts or breaks using a armature growler
Then take the armature and true it in the armature lathe and also cut the
mica to the correct depth--after that he checks it to make sure it is still within
spec ( greater than 1.00" diameter)
Then it gets checked on the growler again
The armature then gets new bearings--the housing is cleaned
and any worn wires are replaced the motor is then reassembled its run in one
direction at 3 volts for 15 min--then the other direction for 15 minutes--it is
then brought up to speed at 14 volts and run each way for 1 min. The dynamic
brake is also checked both ways--if everything checks out--the motor is taken
apart and cleaned again and reassembled--its run up again to check for vibration
Some of his refurbished/repaired motors
Left one is a flap motor, center one a gear motor, right one
is a flap motor from a 47 bonanza.
This was just a brief show of what he does--- He has a check
list of over 20 items that are checked.
A landing gear motor is then taken to the blue fixture
pictured below -- attached to a gear transmission--run up and down to make sure
its producing the right torque and the dynamic brake is working under a load.
Note the weights on the fixture equal the weight of both gear
and have the same arch as the gear does (swing).
Here is what one Beechcraft owner who has opened up a lot of these motors,
thinks about Beech gear motor brands:
"had several to play with today--3/4 of them would run , but no dynamic
brake----started switching parts around with the few good electomech motors I
have---turns out that the armatures on the bad motors were the problem---they
tested fine on the growler ( no shorts)--but had higher resistance than the good
armatures----my thought--when the electromech have a problem (due to bad brushes
or contamination of the armature) they would lose dynamic brake--this causes the
gear to go too far and hitting the stops in the trans---it then takes a higher
current to get it to move off the stops--this higher current causes the armature
to heat up--screwing it up someway.
The lamb armatures are a more robust unit--even though some are 50 years
old--you can tell someone took pride in what they were doing--I almost never
find a bad Lamb armature--they just get worn down below service limits--this
usually happens after 4 or 5 OHs."
This is a picture of a data plate from an early Bonanza (circa 1947) gear
motor---its a lamb motor made by Black & Decker!
Happy Electric Motor Skies!
Why Continuing to Replace Gear Motor
Brushes is not Such a Good Idea!
This is what the motor refurber with the above
equipment found when he opened up a 12V landing gear motor and NO, that's not a
fire ant dirt mound
This is a classic case of several
motor brush replacements without a complete open up and cleaning and servicing
of the motor.
The motor's owner reported that
it would not work every once in a while, it was slow on RPM, had little to no
dynamic braking, and was low on torque.
After cleaning the armature three
times to get all the gunk out of it, installing new bearings, new brushes and
running them in, this refurber returned the motor to smooth "sewing machine"
Don't let your gear motor get
this bad before giving it the service it deserves.