Piper SEMINOLE PA-44-180, Maintenance Manual

Page: 135 / 881

Method III.
A. Fabricate or purchase from Piper the special tool from dimensions given in Figure 21-22.
B. Install the threaded end of the tool into the spark plug hole.
C. Slide the rod of the tool into the combustion head until it contacts the ground electrode.
D. Check that the indicator ring on the rod lines up with the end of the tool. The ground electrode may be
bent to obtain the required gap.
— Note —
Inspect the ground electrode for erosion. If it is eroded to approximately has of its
original 1/8 inch diameter, it should be replaced. This can be done as follows:
(1) Grind off the head of the rivet where it projects through the combustion head and
remove the electrode.
(2) Install a new CRES rivet AN125452 which is 1.500 inches in length.
(3) Heliarc tack weld the rivet head to hold it in place.
(4) Check spark gap as noted in Methods I or II.
4. Installation: (Refer to Figure 21-12)
A. If a new spark plug is being installed, be sure to adjust the spark gap. Do not bend the electrode on
the spark plug.
B. Place a new spark plug gasket on the threads. If the gasket does not hold on the threads and would
be likely to fall off during installation, place a small drop of Aviation Permatex or similar material
on the gasket to stick it temporarily to the plug shell.
C. Screw the spark plug into the heater with a deep socket wrench. Tighten to a torque of 28 foot-
pounds.
D. Install the grommet (39, Figure 21-18) in the heater jacket opening.
E. Carefully insert the spring connector on the high voltage lead into the spark plug shell, press down
gently and start the nut on the threads. Tighten the nut to 20 foot-pounds.
F. Operate the heater to check dependability and close all access openings.
IGNITION UNIT.
This unit converts 14 volt DC to high voltage, oscillating current capable of producing a continuous spark in
the combustion chamber of the heater. This unit remains energized and produces a continuous spark during
heater operation. It contains a condenser, resistor, radio noise filter and vibrator socket. It also has an externally
mounted vibrator and ignition coil.
IGNITION UNIT REMOVAL AND INSTALLATION.
1. Removal: (Refer to Figure 21-18)
— Note —
Make sure heater electrical circuits are de-energized.
PA - 4 4 - 1 8 0 / 1 8 0 T
AIRPLANE MAINTENANCE MANUAL
2 1 - 4 3 - 1 4
Page 21-24
Revised: May 15, 1989
1F15
PIPER AIRCRAFT