TM 55-1510-221-MTF
TROUBLESHOOTING GUIDE B -
INSTRUMENTS
CONDITION
PROBABLE CAUSE
B1.
Airspeed indicator reading remains fixed.
a.
Pilot pressure line clogged with ice or debris.
b.
Defective indicator.
B2.
Vertical velocity indicator inaccurate or inoperative.
a.
Static line clogged
b.
Leak in line or Instrument case or loose fit-
tings
c.
Defective vertical velocity indicator.
B3.
Airspeed indicator reads incorrectly or fluctuates
excessively.
a.
Pilot tube or pressure line partially restrict-
ed or leaking.
b.
Static port or line clogged or static line leak-
ing.
c.
Faulty airspeed indicator.
B4.
Magnetic compass inaccurate, sluggish or erratic.
a. Insufficient liquid
b.
External magnetic interference
c. Defective compass
d.
Windshield heat on
B5.
Turn-and-slip indicator inoperative or erratic.
a. Tripped turn-and-slip circuit breaker.
b. Defective turn-and-slip instrument.
B6.
Fuel quantity indicator fluctuates or reads low.
a. Defective pins in connector on harness that
mates with gage.
3-4
