MAINTENANCE OF THE M88A1 - OD1672 - LESSON 3/TASK 1
Step 3. Install the new fuel filters hand tight. Then, use the fuel filter
wrench to further tighten the filters making sure the seals on top of the
filters are compressed between the top rim of the fuel filter and the
underneath of the filter cover to prevent leakage of fuel while the engine
is in operation.
Step 4. If still serviceable, install and tighten the screw and lockwasher
on the top cover of both air filters, and proceed to bleed the fuel system,
as described in the following subparagraph.
Whenever any type of maintenance or
repairs are performed on the fuel system, which permits air to enter the
system, such as replacing the filters, the air must be bled from the fuel
The following steps provide the procedures for bleeding the APU
Step 1. Ensure that the FUEL SHUTOFF switch (2) (refer back to figure 29,
view A, on page 68) is in the OFF position before attempting to bleed and
prime the APU fuel system. Disconnect the fuel return line (1) and return
line fitting (2) (figure 33 on the following page).
Gently try to actuate the priming lever (3) to determine if the
pump lobe on the engine camshaft is in the up position.
If the priming
lever fails to move, the pump lobe is in the up position, thereby preventing
the movement of the priming lever (3) to bleed and prime the APU fuel
system. Crank the engine one revolution to move the pump lobe away from the
up position and to permit hand priming of the fuel system. If the priming
lever moves freely, do not crank the engine; but, prime the fuel system as
described in the next step.
Step 3. Hand operate the priming lever (3) (figure 33) on the fuel transfer
pump (4) until no air bubbles appear in the fuel flowing from the return
line fitting (2).
Step 4. Return the priming lever (3) (figure 33) to the disengaged position
to permit normal operation of the fuel transfer pump (4).