Heat Exchanger; Inspection, Cleaning And Repair; Blower Assemblies - Piper TWIN COMANCHE PA-30 Service Manual

PIPER TWIN COMANCHE SERVICE MANUAL
13-56.
INSPECTION, CLEANING AND REPAIR.
13-57. HEAT EXCHANGER.
a.
Inspect the heat exchanger for possible damage or leaks.
Small cracks in
the header plate or seams may be repaired by welding, provided the work is done
by a welder who is thoroughly experienced in the welding of stainless
steel. If
the heat exchangerhas large cracks, is excessivelywarped,
or hasburned through
at any point, it must be replaced.
When welding cracks,
Type 347 weld rod is
preferred,
although 321 or 310 may be used.
NOTE
Before welding, it is very important to clean all com-
bustion deposits away from the area to be welded, since
the lead compounds in the heat exchanger can contam -
inate the weld to such an extent that a tight weld is al-
mostimpossible.
Keepallweld beads as small as pos-
sible, preferably not over 1/8".
b. Clean combustion residue from inside walls of igniter housing with igniter
housing scraper tool.
c.
Remove combustion residue from inside heat exchanger by soaking this as-
sembly in a 20% byweightsolutionof
ammoniumacetateat
atemperatureof 180F
for a period of 5 to 10 hours. Flush out exchanger with water after cleaning, and
dry as well as possible with compressed air. This is the preferred
method of
cleaning.
An alternate is to tap the heat exchanger lightly with a rawhide mallet
to loosen carbon from the walls. This will loosen most of the residue, which may
then be blown out with compressed air.
d. Pressure test heat exchanger by plugging openings and applying 10 psi air
pressure to the flame detector switch or standpipe bushing while the unit is sub-
merged in water. Leakage will be indicated by bubbles. No leakage is permitted.
13-58.
FUEL CONTROL VALVE. Replace valve if found defective.
13-59.
BLOWER ASSEMBLIES.
a.
Clean both blower wheels, housings, and the ventilating air blower motor
mounting bracket with dry cleaning solvent, and blow dry.
Wipe off outside of
motors with a cloth dampened in solvent, but do not immerse motors.
b. Inspect blower wheels for bent blades and cracks. Pay special attention to
HEATING AND VENTILATING
Issued: 12/29/72
4 B16