Piper Comanche PA-24 Service Manual page 774

PIPER COMANCHE SERVICE MANUAL
TABLE IX·VII. TROUBLESHOOTING
(COIIt)
Troubl.
Cau ••
Motor fails to operate.
(cont)
Dirty commutator.
Shorted, grounded, Or
open armature.
3
F3
Remedy
A new brush should be
run in until at least SO
percent seated; hoYiever.
if facilities are not avail-
able for running in brushes,
then the brush should be
properly seated
by
insert-
ing a strip of number 0000
sandpaper between the
brush and commutator.
with the sanded side next
to the brush. Pull sand·
paper in the direction of
rotation, being careful to
keep it in the same contou
as the commutator.
CAUTION
Do not use coarse
sandpaper or emery
cloth. After seating,
clean thoroughly to
remove all sand Bnd
metal particles to
prevent excessive
wear. Keep motor
bearing free from
sand or metal par-
ticles.
If commutator is rough or
dirty. smooth and polish
with
number
0000 sand-
paper.
If
too rough and
pitted, remove and turn
down: Blowout all par-
ticles.
Remove and replace with an
armature known to be in
good condition.
ELECTRICAL SYSTEM
ISSUED: 8/18172