Yak 18T - Compass System; Pre-Flight Compass Switching-On

Yak 18T Flight Operations Manual
Page 70 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.
• set the operation mode switches on the control panel and the switch on the
intercommunication subscriber's apparatus to the OFF position
• switch the circuit breakers for the APK to off
12.2.3.1 Compass System
Designation
The heading system serves to determine and to indicate the heading and turn angles of the
aircraft and to provide magnetic (or true) bearings, it is fitted with the complete set given
below –
• Flux-gate sensor 1 pos
• Erecting mechanism 1 pos
• Console 1 pos
• Gyroscopic unit 1 pos
• Indicator 1 pos
• Slaving unit 1 pos
Depending on the flight conditions and the tasks to be executed, the system can operate in
one of two regimes –
• magnetic slaving or
• gyro direction indicator
The main mode of operation is the gyro direction indication regime.
12.2.3.2 Pre-Flight Compass Switching-on
To switch the compass system on prior to flight, proceed as follows –
• set the console switch NORTH-SOUTH to the NORTH position when flying in the
northern hemisphere and to the SOUTH when flying in the southern hemisphere;
• set the take-off airfield latitude on the respective potentiometer on the console
• set the magnetic declination, equal to zero on the erecting mechanism
• switch the compass system power on
The readiness time of this compass system for operation in the magnetic slaving regime 5
minutes. In 3 minutes after the power has been supplied, carry out the pre-flight checking of
the compass system serviceability.
Pre-flight Compass System Checking
To check the compass system before the flight, perform the following procedures –
• set the MONITORING switch to the positions 0 and 300 respectively, make sure, that
the compass indicator shows the indications within 0±10° and 300±10°
• set the gyro direction indicator regime and deflect the heading set switch, make sure
that the movable scale is rotating
• set the slaving regime and by using the heading set switch on slave the system
In-flight Usage of Compass System
1. Flight in the magnetic slaving operation mode
To perform flights in the magnetic slaving regime, proceed as follows –
• set zero on the erecting mechanism
• set the magnetic slaving regime