Impulse Coupling Removal; Impulse Coupling Inspection - Piper PA-44-180 SEMINOLE Maintenance Manual

19. Check capacitors for looseness in the magneto cover of the harness assembly and for any physical damage.
The capacitors should be checked for capacitance, series resistance and leakage. Capacitance should be 0.34
to 0.41 microfarads. The use of a Bendix condenser tester, part number 11-1767 -1, -2 or-3 or equivalent
will simplify this test. Replace defective capacitors and torque securing nut to 60-70 inch-pounds.
Spring in capacitor outlet may cause an indication of a short to ground if adapter lead
is not used. (Refer to Figure 744.)

IMPULSE COUPLING REMOVAL.

1. Using heavy gloves or shop cloth, grasp the coupling body firmly to prevent the internal spring from
unwinding suddenly. Pull outward on the coupling body only enough to release it from the cam assembly.
Keep the coupling body close against the cam and allow the body to turn as the spring unwinds. After one
or two turns, the spring coils will wedge against the projections on the body, restraining the spring from
further unwinding.
2. Look into the hole in body and note the location of the inner eye of spring where it engages with mating
recess in cam hub. Insert a screwdriver under spring end and pry spring eye out of recess. Remove the
body and spring together. Uncoil spring from body and pry spring eye from body recess to disengage
spring.
3. Thread protective cap of 11-702-1 puller securely on end of shaft. Engage puller over protective cap and
cam assembly with wide jaws of puller hooked under cam assembly as shown in Figure 74-10.
4. Tighten puller handle to remove coupling from shaft. If coupling does not release with maximum hand
torque at puller handle, apply penetrating thread release compound between coupling and shaft. Then while
puller is still fully tightened, hold tip of hot heavy duty soldering iron in contact with hub of coupling cam
assembly. Solder wetting of the tip at point of contact with the cam hub will assist in heat transfer to the
parts. Retighten puller after about a minute of heat application.
DO NOT STRIKE THE PULLER WITH A HAMRNER. IF PULLER IS
STRUCK WITH A HAMMER THE MAIN BEARINGS MUST BE
REPLACED.
5. Do not tighten puller handle further after coupling cam releases from the shaft. This could damage the
flyweight if the flyweight is caught under the woodruff key. Remove the puller from the shaft. Then while
holding both flyweight tips inward, lift cam from the shaft, and remove woodruff key from rotor shaft.
INSPECTION OF IMPULSE COUPLING.
1. Check clearance between each flyweight and each stop pin by the following method:
A. Bend the end of a stiff piece of wire into a right angle, 1/8 inch long maximum.
B. Hold the magneto as shown in Figure 7411. Pull the heel of the flyweight outward with the fabricated
hooked wire and make certain that a feeler gauge of 0.015 of an inch minimum thickness will pass
between the stop pin and the highest point of the flyweight.
PIPER AIRCRAFT
PA - 4 4 - 1 8 0 / 1 8 0 T
AIRPLANE MAINTENANCE MANUAL
— Note —
— CAUTION —
3G6
7 4 - 11 - 0 5
Page 74-13
Revised: May 15, 1989