Disassembly Of Combustion Air Blower Assembly; Air Blower Cleaning; Cleaning And Inspecting The Combustion Tube Assembly - Piper Navajo Chieftain PA-31-350 Service Manual

NAVAJO CHIEFTAIN SERVICE MANUAL
13-39. DISASSEMBLY OF COMBUSTION AIR BLOWER ASSEMBLY. (Refer to Figure 13-18.)
a. Remove the combustion air blower inlet adapter (18) by removing three screws, lock washers,
cover plate and gasket.
b. Remove the housing outer half (16) by removing the four screws (17).
c. Loosen the set screw in the blower wheel and slide it off the motor shaft.
d. Remove the two hex nuts (14), lock washers (12) and flat washers (13), and slide the housing
inner half (10) off the motor through bolts. The spacer (9) will drop off.
e. Install new motor brushes as described in Paragraph 13-25, b. If the motor commutator is badly worn
or if the motor is defective in any respect, it must be replaced.
13-40. CLEANING. (Refer to Figure 13-17.)
a. Clean individual metal parts (except those parts containing switches and electrical wiring) and the
combustion tube assembly, by immersing them in dry-cleaning solvent, such as Stoddard solvent (Federal
Specification
P-D-680). A bristle brush should be used to assist the cleaning process if foreign
accumulations are stubborn to remove.
CAUTION
Do not attempt to burr or scrape off any deposits on face of spray
nozzle. The face of the nozle is very susceptible to damage from
mishandling. Carefully repeat cleaning process using only a bristle
brush and repeated applications of solvent to loosen any stubborn
deposits.
b. Use compressed air or lintless cloth to dry the parts, unless sufficient time is available for them to
air dry.
c. Wipe electrical components with a clean, dry cloth. If foreign material is difficult to remove,
moisten the cloth in carbon tetrachloride or electrical contact cleaner and clean all exterior surfaces
thoroughly.
13-41. CLEANING AND INSPECTING
THE COMBUSTION TUBE ASSEMBLY. (Refer to Figure
13-17.)
a.
Slight scaling and discoloration of the combustion tube assembly (20) is a normal condition for
units that have been in service up to 500 hours. The slight scaling condition will appear to be mottled and
a small accumulation of blue-gray powder may be present on the surface in certain areas. This condition does
not require replacement of combustion tube assembly. unless severe overheating has produced soft spots in
the metal.
NOTE
This assembly should be inspected prior to cleaning in order to
prevent the removal of visible evidences of damage.
b. Look inside the exhaust outlet to determine if the combustion tube appears to be heavily scaled
or mottled. Deformation is more difficult to detect visually but can usually be observed by looking straight
Revised: 10/15/82
HEATING AND VENTILATING SYSTEM
4C9