Turn Coordinator; Trouble Shooting - Cessna 150 STANDARD Service Manual

15-55. TURN COORDINATOR.
15-56. DESCRIPTION. The turn coordinator is an
electrically operated, gyroscopic, roll-rate turn
indicator. Its gyro simultaneously senses rate of
motion roll and yaw axes which is projected on a
single indicator. The gyro is a non-tumbling type re-
quiring no caging mechanism and incorporates an
a. c. brushless spin motor with a solid state inver-
ter.
15- 57. TROUBLE SHOOTING.
TROUBLE PROBABLE CAUSE
REMEDY
INDICATOR DOES NOT Friction caused by contamination
Replace instrument.
RETURN TO CENTER.
in the indicator damping.
Friction in gimbal assembly. Replace instrument.
DOES NOT INDICATE A Low voltage.
Measure voltage at instrument.
STANDARD RATE TURN
Correct voltage.
(TOO SLOW).
Inverter frequency changed. Replace instrument.
NOISY MOTOR. Faulty bearings.
Replace instrument.
ROTOR DOES NOT START. Faulty electrical connection. Check continuity and voltage.
Correct voltage or replace
faulty wire.
Inverter malfunctioning.
Replace instrument.
Motor shorted.
Replace instrument.
Bearings frozen.
Replace instrument.
IN COLD TEMPERATURES, Oil in indicator becomes Replace instrument.
HAND FAILS TO RESPOND too thick.
OR IS SLUGGISH.
Insufficient bearing end play. Replace instrument.
Low voltage.
Check voltage at instrument.
Correct voltage.
NOISY GYRO. High voltage.
Check voltage to instrument.
Correct voltage.
Loose or defective rotor Replace instrument.
bearings.
15-20