Figure 4-13.-Correct and incorrect installation of flexible
hose.
Figure 4-14.-Fuel line fittings. (A) bulkhead fitting;
(B) universal fitting; (C) universal fitting with O-ring seal
and seal ring.
Bulkhead Fitting. -- Bulkhead fittings must be
properly installed. To ensure proper installation
the seal ring should be coated sparingly with
of the fitting shown in figure 4-14, view A, the
petrolatum or hydraulic fluid. Work the seal ring,
mechanic must check to see that the bulkhead has
with the smooth (hair) side toward the O-ring seal,
the required thickness for which the fitting was
into the counterbores of the nut. You then turn
designed.
the nut down until the O-ring seal is pushed firmly
against the lower threaded section of the fitting.
Fitting With O-Ring Seal.-- The nut should be
Install the fitting into the boss. You then keep the
assembled on the fitting end until the washer face
nut turning with the fitting until the O-ring
of the nut lines up with the upper corner of the
contacts the boss. This point can be determined
seal groove. The O-ring seal should be lubricated
by a sudden increase in torque. With the fitting
sparingly with petrolatum and placed on the
in this position, put a wrench on the nut to
fitting groove so it contacts the nut. Then screw
prevent its turning; then turn the fitting in 1 1/2
the fitting (and nut simultaneously) into the boss
turns. Then position the fitting by turning in not
until the seal contacts the boss chamfer and the
more than one additional turn. Hold the fitting
nut contacts the boss. Before tightening the
and turn the nut down tight against the boss.
locknut, position the fitting direction by turning
Slight extrusion of the ring is not considered
it three-fourths turn or turning it out one-fourth
detrimental. See figure 4-14, view C.
turn. Assemble the fluid line to the fitting end.
Holding the fitting stationary in the selected
FUEL DRAINS.-- So the moisture content
position, tighten the locknut. See figure 4-14,
can be checked and moisture drained from
view B.
the fuel system, the drain valve(s) is/are in-
stalled in the low point (or points) in the system
Fitting With O-Ring Seal and Seal Ring.--
(or units).
The threads of the fitting, the O-ring seal, and
4-19