Inspect for leaking APU fuel lines and fittings.
replace the defective lines or fittings IAW procedures shown in
cleaner filter element as outlined in TM 9-2350-267-10.
operations normally contribute to engine start-up difficulties. During cold
weather operations, it is very important that the APU preheating system is
operating properly. Should you encounter difficulty in starting the engine
during cold weather, the following troubleshooting steps are to be applied
to determine the cause:
Set the MASTER switch to the OFF position. Disconnect lead R to
the glow plugs and the preheaters (Figure 22).
continuity from the preheat relay terminal to the glow plugs and
The meter reading should indicate 0 ohms.
meter reading is not 0 ohms, repair or replacement of lead R from
the relay terminal to the glow plugs and preheaters is necessary.
If circuit R shows continuity, disconnect lead R from the glow
plug and measure resistance from each glow plug terminal to
The meter reading should indicate 4.75 1.5 ohms for
each glow plug.
If not, the applicable glow plug is defective
and Support Maintenance is to be notified.
If, during the previous test, the meter reading is within the
established reading, measure the resistance from the preheater
plug terminal to the preheat terminal. The meter reading should
indicate a reading of 0.6 0.05 ohms. If this reading is not in
accordance with the specified ohms, replace the appropriate
defective heater plug.
Troubleshooting the APU Engine when Engine Misfires.
The problems that normally contribute to the engine misfiring is an improper
This condition is
normally caused by contaminated or clogged fuel system or a dirty or clogged
air cleaner system.
Apply the following troubleshooting procedures to
Inspect the condition of the air cleaner filter element. Clean