Cessna 150M - Page 195

15-26. TROUBLE SHOOTING--VACUUM SYSTEM
TROUBLE PROBABLE CAUSE
REMEDY
HIGH
SUCTION GAGE READINGS. Gyros function normally-relief
Check screen, than valve. Com-
valve screen clogged, relief
pare gage readings with new gage.
valve malfunction.
Clean screen, reset valve.
Re-
place gage.
NORMAL SUCTION GAGE
Instrument air filters clogged.
Check operation with filters re-
READING, SLUGGISH OR moved.
Replace filters.
ERRATIC GYRO RESPONSE.
LOW SUCTION
GAGE
Leaks or restriction between
Check lines for leaks, disconnect
READINGS. instruments and relief valve,
and test pump.
Repair or replace
relief valve out of adjustment,
lines, adjust or replace relief
defective pump.
valve, repair or replace pump.
Central air filter dirty.
Check operation with filter re-
moved.
Clean or replace filter.
SUCTION GAGE FLUCTUATES. Defective gage or sticking relief
Check suction with test gage.
valve.
Replace gage.
Clean sticking
valve with Stoddard solvent.
Blow dry and test. If valve
sticks after cleaning, replace
valve.
15-27. TROUBLE SHOOTING--GYROS.
TROUBLE
PROBABLE CAUSE
REMEDY
HORIZON BAR FAILS TO
Central filter dirty.
Check filter.
Clean or replace
RESPOND.
filter.
Suction relief valve improperly
Adjust or replace relief valve.
adjusted.
Faulty suction gage.
Substitute known-good suction
gage and check gyro response.
Replace suction gage.
Vacuum pump failure.
Check pump.
Replace pump.
Vacuum line kinked or leaking.
Check lines for damage and leaks.
Repair or replace damaged lines,
tighten connections.
HORIZON BAR DOES NOT
Defective mechanism.
Substitute known-good gyro and
SETTLE.
check indication.
Replace in-
strument.
Insufficient vacuum.
Adjust or replace relief valve.
Excessive vibration.
Check panel shock-mounts.
Replace defective shock-mounts.
15-11