OVERHAUL INSTRUCTIONS.
The heater assembly shall be overhauled after 1000 hours or whenever the pressure decay test requirement
cannot be met. The heater should be removed from the aircraft disassembled, all parts thoroughly inspected and
necessary repairs and/or replacements made prior to reassembly. Detailed step-by-step instructions are included
for a complete heater overhaul. In some instances, however, inspection may reveal that it is unnecessary to
remove certain parts. If so, those portions of the overhaul procedures may be eliminated.
DISASSEMBLY OF HEATER. (Refer to Figure 21-18)
1. Remove the screw and slide the elbow adapter off the combustion air inlet tube.
2. Disconnect and remove electrical wiring and individual wires from the various components on the heater.
If wires appear to be in good condition, it may be desirable to remove wire harness assembly intact. First
disconnect wires at terminal strip and components.
— Note —
It is advisable to label all wires, prior to removal, to insure correct connections during
reassembly. Cable straps and clips must be replaced if removed, as they cannot be
reused.
3. Carefully disconnect the high voltage ignition lead at the spark plug. Handle the spring connector on the
end of this lead with care to prevent fouling or damage.
4. Remove the four screws and cable straps to free the ignition assembly from the heater jacket and remove
the ignition assembly. The vibrator may be removed by releasing the clamp and exerting a firm pull
straightaway from the ignition assembly case.
5. Remove the grommet from the jacket and remove the spark plug with a 7/8 inch deep socket. Make sure
the spark plug gasket is removed.
6. Remove the two screws and lift out the overheat (limit) switch and spacer gaskets.
7. Remove the two screws and lift out the cycling switch.
8. Remove the four screws to release the terminal strip and insulator from the jacket.
9. Disconnect the tube fitting at the cover of the combustion air pressure switch. Take precaution when
bending tube. Unscrew and remove the combustion air pressure switch from the combustion air inlet
tube.
10. Remove vent air inlet adapter from the blower housing by removing the three screws.
11. Loosen the four screws and rotate the blower and motor housing to disengage the notched end from the
four screws in the end of the heater jacket. Disconnect the motor wiring quick-disconnect.
12. Remove the upper fuel shroud box cover by removing the screws.
13. Remove the grommet from the fuel shroud and carefully pull the fuel solenoid wires through the hole in
the shroud.
14. With an open end wrench, remove the fuel solenoid assembly being careful not to damage the wires on
the solenoid.
PA - 4 4 - 1 8 0 / 1 8 0 T
AIRPLANE MAINTENANCE MANUAL
2 1 - 4 4 - 0 1
Page 21-32
Revised: May 15, 1989
1F23
PIPER AIRCRAFT
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