TM 55-1510-219-MTF
TROUBLESHOOTING GUIDE B - INSTRUMENTS
CONDITION
PROBABLE CAUSE
B1.
Airspeed indicator reading remains fixed.
a.
Pitot pressure line clogged with ice or debris.
b.
Defective airspeed indicator.
B2.
Vertical velocity indicator inaccurate or inoperative.
a.
Static line clogged.
b.
Leak in line or instrument case or loose fittings.
c.
Defective vertical velocity indicator.
B3.
Airspeed indicator reads incorrectly or fluctuates
excessively.
a.
Pitot tube or pressure line partially restricted or leaking.
b.
Static port or line clogged or static line leaking.
c.
Faulty airspeed indicator.
B4.
Magnetic compass inaccurate, sluggish or erratic.
a.
Windshield heat on.
b.
Insufficient liquid.
c.
External magnetic interference.
d.
Defective compass.
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
gauge.
3-4
