Yak 18T Flight Operations Manual
Page 72 of 82
Disclaimer: This manual is to be used as a reference only, it is based on translated Yak 18T Flight Operations
Manuals and has not been approved by the Yakovlev Design Bureau or any other authority.
unit
lights up on the console
indicating the magnetic
heading and a compass to
determine the aircraft course
2. Failure of the flux-gate
sensor and the erecting
mechanism
Readings of the magnetic
heading on the erecting
mechanism and gyro
magnetic heading in the
straight line flight are
incorrect and unstable
Use readings of the indicator
when the compass system is
operating in the gyro
direction indicator regime,
indications of the magnetic
compass and indications of
the instrument are employed
12.2.3.4
Magnetic Compass
The magnetic compass is used as a standby instrument for determination of the aircraft
magnetic heading. When using the magnetic compass it should be borne in mind that a
value of residual deviation on individual courses can constitute 10°.
12.2.3.5
Gyro-horizon
1.
The gyro-horizon is designed to inform the pilot about the aircraft pitch and bank angles
relative to the true horizon and also about slipping direction of the aircraft
2.
The gyro-horizon is switched on after the engine has been started and the converter
turned on. In order to switch the gyro-horizon on, cut-in the circuit breakers on the
switchboard. The gyro-horizon caging is automatic after turning the power on. The
correct gyro-horizon start is provided at pitch and bank angles at rest of ±4°
3.
On the line-up take-off position prior to take-off, the crew must check whether the gyro-
horizon is proper and make sure that:
•
the aircraft symbol on gyro-horizon indicator occupies the horizontal position and
coincides with the horizon line
•
while rotating the pitch angle set knob, the scale is deviating, on having checked the
indicator serviceability, set the pitching scale to zero
•
a red no-power warning light on the gyro-horizon is out
If one of the above mentioned requirements are not met, the take-off is
PROHIBITED
. The
take-off is allowed only after the gyro-horizon will get ready for operation (not earlier than in
3 minutes after its connection).
CAUTION
It is not permitted to use the caging button when the gyro-horizon is started and also during
its normal operation on the ground and in flight.
4.
The gyro-horizon bank and pitch angles are
360°
with the exception of pitch-up and dive
angles of 85-95°. Allowable errors in the gyro-horizon readings -
•
after take-off error not more than ±3°
•
errors in the bank angles indications after
360°
degree turns not over ±3° (separate
overshoots up to 5-6° are possible)
•
errors in bank and pitch angles readings after aerobatics manoeuvring -not more
than ±5°
5.
If in flight, the gyro-horizon provides wrong indications, it is necessary to make a
transition to levelling out and push the button CAGING ONLY OF LEVEL FLIGHT placed at
the horizon indicator front panel. In this case, a caging light on the indicator illuminates
and goes out when the caging is over. Make sure that the gyro-horizon operates
properly. Further flight must be performed with special attention paid to the gyro-horizon
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