CHART 3404. TROUBLESHOOTING (MAGNETIC COMPASS) (cont.)
Liquid leakage. Loose bezel screws. Replace instrument.
Broken cover glass. Replace instrument.
Defective sealing gaskets. Replace instrument.
Discolored markings. Age. Replace instrument.
Defective light. Burned out lamp or broken Check lamp or continuity
circuit. of wiring.
Card sticks. Altitude compensating Replace instrument.
diaphragm collapsed.
Card does not move when The gears that turn compen- Replace instrument.
compensating screws arc sating magnets are stripped.
turned.
Compass swings erratically Normal.
when radio transmitter is
keyed.
TURN AND BANK/PICTORIAL RATE INSTRUMENTS
GENERAL
Unlike the free gyro rotors found in directional and attitude gyros both the turn and bank, and pictorial rate
indicator have captive gyro rotors. The axis of these are attached to the instrument housings. Since the
spinning gyro rotors are forced to follow airframe movement, the gyros resists changing position by exerting
precession forces. The greater rate of change, the greater the precession forces. The turn and bank and the
pictorial rate indicator only measure movement - not position or displacement. The gyro rotor is mounted at a
60° angle to detect both yaw and roll motion. The ball portion of both instruments is free to roll within the
inclined glass tube display. The glass tube is filled with non-freezing liquid to dampen movements of the ball
within the tube. The ball portion of both instruments only indicates side forces. The turn and bank rotor is
driven either electrically or by air, while the pictorial rate instrument is electric.
TROUBLESHOOTING
An obvious malfunction of either instrument requires repair by an FAA approved instrument repair facility,
or replacement. Service is restricted to instrument installation and air/electric power requirements.
—END—
34 - 17 - 00
Page 34 - 12
Reissued: August 1, 1986
2D20
PIPER AIRCRAFT
PA-28-236
MAINTENANCE MANUAL
Trouble Cause Remedy
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