Piper Navajo PA-31 Service Manual page 922

PIPER NAVAJO SERVICE MANUAL
13-16. 100 HOUR INSPECTION. Perform the following inspections at the end of 100 hours of heater
operation:
a. Inspect the sensing tube between the pressure switch and heater exhaust for clogging. Disconnect
tube at pressure switch and blow air through the tube. If combustion product residue has collected in the
exhaust end of the tube, it may be necessary to clean the tube with a wire.
b.
Inspect air inlets and exhaust outlets for restrictions, damage of any kind, and security at the
aircraft skinline.
c.
Check for abnormal stains, discoloration, and excessive carbon formation that would indicate
poor heater operation.
d.
Check the full length of all lines to be sure all joints and shrouds are secure, and that there is no
evidence of leaks. Be sure the fuel lines are secure at the points of attachment to the aircraft and be sure the
fuel drainlines are undamaged and free of obstructions.
e.
Inspect all heater and control wiring for loose connections, condition of insulation and security
of attachment points.
f. Make sure the high voltage cable is tight at the spark plug. Inspect it for burning or discoloration
of sheath, which would indicate arcing.
g. Perform inspections as required and operational check to insure the mechanical and electrical
integrity of the heater and its accessories.
13-17. 500 HOUR INSPECTION. At the end of 500 hours of heater operation or after each heating
season, whichever comes first, remove the heater from the airplane for complete inspection of heater parts
and any necessary repairs and replacements made prior to reassembly.
13-18. MAINTENANCE SERVICE. Instructions contained in this section consists of periodic inspection,
adjustments, and minor corrections required at normal designated intervals for the purpose of maintaining
the heating system in peak operating condition. These inspections assume that a heating system includes
accessory components mentioned in preceding paragraphs.
13-19. REMOVAL OF HEATER.
a. Turn the heater control switches off.
b. Remove the access panel located on the right side of the nose section.
c.
Open the forward baggage door and remove the access panel located on the right rear side of the
baggage compartment floor.
d. Remove the shroud cover of the fuel inlet line fitting located on the forward left upper side of
the heater. Disconnect the fuel line.
e.
Disconnect the air inlet hose from the forward end of the heater.
f. Remove the screws that secure the forward end of the heater to the fuselage bulkhead.
g.
Note the hook-up of the electrical wires to facilitatereinstallation, and disconnect the leads from
the heater.
h.
Disconnect the combustion air blower inlet tube from the blower and the tube between the
blower and heater.
i.
Disconnect the fuel drain and allow it to drop down.
j.
Disconnect the duct switch and cabin heat control cables.
k.
Disconnect the defroster and heat ducts from the air-heat distribution box.
1.
Loosen the clamp that secures the heater to its mounting bracket and remove the heater from the
airplane.