Piper SEMINOLE PA-44-180, Maintenance Manual

Page: 155 / 881

TEST PROCEDURE.
GENERAL INFORMATION.
A test of all components should have been made after overhaul to insure proper operation. Some shops may
not have complete testing facilities for measuring airflows, pressure drops, and other factors which would be
accomplished in a laboratory-type test. If such a test cannot be made, install the heater and check operation on
the ground and in the air to determine if operation is normal. In shops where complete test equipment is available
and a complete functional test can be performed, the test routine described in subsequent paragraphs should be
made.
EQUIPMENT REQUIRED. (Refer to Figure 21-20.)
1. An improvised stand to hold the heater during test. The heater should be located far enough away from
any combustible material or atmosphere to avoid hazard. A location should be chosen where exhaust can
be dispelled. Do not add an excessive extension to the heater exhaust.
2. A source of fuel capable of being regulated at seven psi.
3. The combustion air blower to be used with the heater should be used for the test.
4. A 12 volt current supply which may be a DC generator with a rheostat, ammeter, and voltmeter in the line
to control and indicate the current draw and voltage output.
5. Two water manometers (zero to 5.0 inch water column) for measuring the pressure in the ventilating air
duct and in the combustion air stream.
6. A piece of duct to be attached to the downstream end of the heater. It should have a minimum length of
24 inches and the same diameter as the heater being tested. A 2.25 inch diameter orifice should be
centrally located at the outlet end. An aperture should be provided for the thermometer and duct switch
and a static tap should be attached as shown in Figure 21-20.
7. A thermometer with 500° F scale.
8. A fuel-pressure gauge.
9. A controlled source of compressed air for final leakage test.
OPERATIONAL TEST (ON TEST BENCH). (Refer to Figures 21-20 and 21-21)
1. Connect the heater to the test setup as shown in Figure 21-20. Make sure the combustion air blower is
mounted securely and that the heater is clamped to its supporting stand.
2. Insert the duct switch in the sheet metal extension tube at the location shown in Figure 21-20.
3. Connect components and heater as outlined in the wiring connection diagram, Figure 21-21. The power
supply switch should be open.
4. Connect the power source to the heater.
5. Disconnect wire lead from terminal No. 3 on the heater side of heater terminal strip to prevent the heater
from lighting and close the power source switch to check operation of blowers. The combustion air
blower and ventilating air blower should operate at full speed with no blower wheel interference. If
either blower fails to run, locate and correct the trouble before proceeding with the test.
6. Connect a voltmeter from open side of combustion air pressure switch terminal to ground to determine if
the switch is closed, which would be indicated by a full voltage reading on the meter. If a full voltage
reading is not obtained, the combustion air supply is either inadequate or the switch is defective or
improperly adjusted. Make necessary corrections.
PA - 4 4 - 1 8 0 / 1 8 0 T
AIRPLANE MAINTENANCE MANUAL
2 1 - 4 5 - 0 3
Page 21-44
Revised: May 15, 1989
1G11
PIPER AIRCRAFT