Cessna 150 Series Service Manual page 25

NOTE
NOTE
The filter assembly may be cleaned with com- Recommended tire pressures should be main-
pressed air a maximum of 30 times, or it may tained.
Especially in cold weather, remember
be washed a maximum of 20 times. A new
that any drop in temperature of the air inside
filter should be installed after using 500 hours a tire causes a corresponding drop in air pres-
of engine operating time or one year, which-
sure.
ever should occur first. Paper induction air
filters must be replaced at intervals not
2-26. NOSE GEAR SHOCK STRUT. The nose gear
exceeding 500 hours time-in-service on the
shock strut requires periodic checking to ascertain
filter. However, a new filter should be
that the strut is filled with hydraulic fluid and is in-
installed anytime it is damaged. A damaged
flated to the correct air pressure. To fill the nose
filter may have sharp or broken edges in the
gear strut with hydraulic fluid and inflate with air,
filtering panels which would allow unfiltered
proceed as follows:
air to enter the induction system. Any filter
a. Remove filler valve cap and depress valve core
that appears doubtful shall have a new filter to completely deflate nose strut.
installed in its place. b. Remove filler valve from strut.
d. After washing, rinse filter with clear water until
c. With nose gear strut compressed to its shortest
rinse water draining from filter is clear. Allow water
length, fill strut with hydraulic fluid to the bottom of
to drain from filter and dry with compressed air (not
the filler hole.
over 100 psi).
d. Raise nose of aircraft, extend and compress
strut several times to expel any entrapped air, then
NOTE
lower nose of aircraft and repeat step "c".
e. With strut compressed to its shortest length,
The filtering panels of the filter may become
install filler valve assembly.
distorted when wet, but they will return to
f. With nose wheel off ground, inflate strut. Shock
their original shape when dry. strut pressure is listed in figure 1-1.
e. Be sure air box is clean; inspect filter. If filter is NOTE
damaged, install a new filter.
f. Install filter at entrance to air box with gasket on
The nose landing gear shock strut will nor-
aft face of filter frame and with air flow arrow on filter
mally require only a minimum amount of
frame pointed in the correct direction.
service. Maintain the strut extension pres-
2-23. VACUUM SYSTEM FILTER. The vacuum
sure, as shown in figure 1-1. Lubricate
2-23. VACUUM SYSTEM FILTER. The vacuum
system central air filter keeps dust and dirt from
landing gear as shown in figure 2-5.Check
entering the vacuum operated instruments. Change
the landing gear daily for general cleanli-
central air filter element every 500 hours of operating
ness, security of mounting, and for hydrau-
time and whenever suction gage reading drops below
lic fluid leakage.
Keep machined surfaces
4.8 inches of mercury. Also, do not operate the
wiped free of dirt and dust, using a clean
vacuum system with the filter removed, or a vacuum
lint-free cloth saturated with MIL-H-5606
line disconnected as particles of dust or other foreign
hydraulic fluid or kerosene. All surfaces
matter may enter the system and damage the gyros.
should be wiped free of excessive hydraulic
fluid.
2-24. BATTERY. Battery servicing involves adding
distilled water to maintain the electrolyte level even
2-27. NOSE GEAR SHIMMY DAMPENER.
The
with the horizontal baffle plate or split ring at the bot-
shimmy dampener should be serviced at least every
tom of the filler holes, checking cable connections, and
50 hours.
The shimmy dampener must be filled
neutralizing and cleaning off any spilled electrolyte or
completely with fluid, free of entrapped air, to
corrosion. Use bicarbonate of soda (baking soda) and
serve its purpose.
To service the shimmy damp-
clean water to neutralize electrolyte or corrosion.
ener, proceed as follows:
Follow with a thorough flushing with clean water. Do
a. Remove shimmy dampener from aircraft.
not allow bicarbonate of soda to enter battery.
b. While holding the dampener in a vertical posi-
Brighten cable and terminal connections with a wire
tion with fitting end pointed downward, pull fitting
brush, then coat with petroleum jelly before
end of the dampener shaft to its limit of travel.
connecting cables. Check the battery every 50 hours
c. While holding dampener in this position, fill
(or at least every 30 days), more often in hot weather.
dampener through open end of cylinder.
Add only distilled water, not acid or "rejuvenators," to d.
Push the shaft upward slowly to seal off the fil-
maintain electrolyte level in the battery. Inspect the ler hole.
battery box and surrounding area and clean and
e.
Clean dampener with solvent. Be sure to keep
remove any evidence of corrosion. Refer to Section 16
the shaft protruding through the filler hole until
for detailed battery removal, installation, and testing.
dampener is installed on the aircraft.
f. Install dampener on aircraft.
2-25. TIRES. Maintain tire pressure at the air
pressure specified in figure 1-1. When checking tire
NOTE
pressure, examine tires for wear, cuts, bruises, and
slippage. Remove oil, grease and mud from tires with
Keep shimmy dampener, especially the ex-
soap and water.
posed portions of the dampener piston shaft,
2-12 Change 1