MAINTENANCE OF THE M88A1 - OD1672 - LESSON 3/TASK 1
If it is extremely cold (0 to -25 F), hold the PREHEAT switch down in the
ON position for no longer than 120 seconds, during which time the engine
should start.
(4) Turn the START switch (5) (figure 29, view A, on page 68) to the ON
position and hold it there until the engine starts. If ambient temperature
is above 0 F and the engine does not start within one minute, release the
START switch (5) and hold the PREHEAT switch (4) down in the ON position for
an additional 20 seconds, but for no longer than one additional minute. If
ambient temperature is from 0 to -25 and the engine does not start after
one minute, hold down the PREHEAT switch (4) for not more than one
additional minute.
Try to start the engine again, but do not crank the
engine for longer than one minute at a time. Do not crank the APU engine
for longer than a total of five minutes.
(5) When the engine starts, release the PREHEAT switch (4) and START
switch (5). If the HIGH AIR TEMPERATURE light (6) comes on during engine
operation, turn OFF the APU and let it cool off.
(6) Let the APU warm up for three minutes before turning ON the
auxiliary generator (APU GEN) switch or operating the auxiliary hydraulic
system.
Turn OFF the auxiliary generator or hydraulics system after one
hour of operation when operating the APU with the auxiliary generator or
hydraulics engaged in a heavy load condition.
The engine will cool by
letting it run at idling speed before reengaging the auxiliary generator or
hydraulic system.
(7) While the APU is operating, frequently check the indicators on the
auxiliary power unit control box for possible malfunctions.
c.
To Stop the APU.
(1) Turn the APU GEN and FUEL SHUTOFF switches (1 and 2) (figure 29) to
the OFF position.
(2) If the FUEL SHUTOFF switch (2) does not stop the APU, turn the
MASTER switch (1) (figure 28, view C, on page 67) to the OFF position.
(3) If the APU still continues to run, go outside to the APU compartment
and turn OFF the emergency fuel shutoff valve (figure 29, view B).
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