Duct Switch Maintenance; Heater Overhaul Instructions; Heater Disassembly - Piper Navajo Chieftain PA-31-350 Service Manual

NAVAJO CHIEFTAIN SERVICE MANUAL
13-36. DUCT SWITCH. (Refer to Figure 13-18.) There is a micro switch added to the duct switch on the
heater system. This switch is wired to the existing terminals on the face of the duct switch.
a. Removal.
1. Place the control lever arm in high position and loosen the allen-head set screw that secures
the arm to the temperature selector shaft. Slide the lever and arm off the shaft.
2. Disconnect the two electrical leads from the terminals on the exposed face of the switch.
3.
Remove the two wires from the duct switch to the micro switch. (Identify wires to facilitate
reinstallation.)
4. Remove the two attaching screws and washers from the duct.
5. Carefully lift out the switch and gasket (if gasket is used).
b. Cleaning and Inspection.
1.
Brush off any dust or lint from the switch operating mechanism (exposed inside the duct)
and wipe external surfaces with a clean cloth.
c. Installation.
1. Insert the switch carefully, with gasket (if used), into the ventilating duct opening and
install the two attaching screws and washers.
2.
Connect the two electrical leads to their respective terminals, as marked during removal.
Connect the two wires from the micro switch to the duct switch terminals.
3. Set the temperature selector shaft at the high stop. Then carefully place the control lever
arm on the shaft at the high position and lock the lever by tightening the allen-head set screw. (Do not over
tighten.) Rotate the lever arm to make sure it clears the electrical terminal screws and support bracket when
it is moved to the high position.
4. Set the micro switch to activate at the very last movement of the control lever arm in the
high heat position.
5. Operate the heater with the duct switch set above ambient temperature to check operation.
(Refer to paragraph 13-50 for additional switch tests and setting instructions.)
13-37. OVERHAUL INSTRUCTIONS.
The heater assembly shall be overhauled after 1000 hours or when the Pressure Decay Test requirements
cannot be met. The heater should be removed from the aircraft. disassembled. all parts thoroughly inspected
and necessary repairs and replacements made prior to reassembly. Detailed step-by-step instructions are
included for a complete heater o\erhaul.
In some instances. however. inspections may reveal that it is,
unnescessary to remove certain parts. If so. those portions of the overhaul procedures may be eliminated
NOTE
For disassembly and reassembly operations refer to the exploded
view drawings and the parts list.
13-38. DISASSEMBLY.
(Refer to Figure 13-17.)
a. Remove the screw and slide the elbow adapter (16) off the combustion air inlet tube.
b. 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 re-used.
Revised:
10/15/82
HEATING AND VENTILATING SYSTEM
4C6