DOC AIRBUS | AMM A320FSTANDBY DATA : ATTITUDE AND HEADING - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
A. Standby Heading
The standby heading is performed by a magnetic compass that is an independent instrument which provides the flight crew with the A/C magnetic heading.
It is installed on the top of the windshield center post and allows a check of the heading provided by the main sources of the heading system. It acts in standby when these systems are inoperative.
The standby heading is performed by a magnetic compass that is an independent instrument which provides the flight crew with the A/C magnetic heading.
It is installed on the top of the windshield center post and allows a check of the heading provided by the main sources of the heading system. It acts in standby when these systems are inoperative.
B. Standby Attitude
The standby attitude is performed by a gyroscopic horizon that is an independent instrument which provides the flight crew, with a constant indication of the aircraft attitude. It is contained in a 3 ATIs case and installed on the center instrument panel. It allows a check of the attitude provided by the main sources of attitude system. It acts in standby when these systems are inoperative.
The standby attitude is performed by a gyroscopic horizon that is an independent instrument which provides the flight crew, with a constant indication of the aircraft attitude. It is contained in a 3 ATIs case and installed on the center instrument panel. It allows a check of the attitude provided by the main sources of attitude system. It acts in standby when these systems are inoperative.
2. Component Location
** ON A/C NOT FOR ALL 
Standby Data - Attitude and Heading - Component Location| FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
| ** ON A/C NOT FOR ALL | |||||
| 2FN | COMPASS-STANDBY | 210 | 34-22-23 | ||
| 7FN | IND-STANDBY HORIZON | 401VU | 211 | 34-22-24 | |
3. System Description
A. Standby Compass
The standby compass consists of a magnetic element rotating inside a compass bowl, immersed in a damping liquid. The magnetic element (1) is linked to a graduated compass card which moves against a lubber line (2) and gives the magnetic heading.
Above the viewing window are two apertures (4) marked B (E.W) and C (N.S) , allowing to achieve compensation by positioning the two small magnetized bars (compensator).
Below the viewing window is a non-magnetic lamp (3) assembly which provides illumination of the compass card.
The standby compass consists of a magnetic element rotating inside a compass bowl, immersed in a damping liquid. The magnetic element (1) is linked to a graduated compass card which moves against a lubber line (2) and gives the magnetic heading.
Above the viewing window are two apertures (4) marked B (E.W) and C (N.S) , allowing to achieve compensation by positioning the two small magnetized bars (compensator).
Below the viewing window is a non-magnetic lamp (3) assembly which provides illumination of the compass card.
B. Standby Horizon Indicator
The standby horizon indicator is supplied with 28VDC from essential bus 401PP.
A static inverter in the instrument converts this 28VDC into three phase alternate current to supply the gyroscopic motor. The gyro rotor rotates at high speed (> 23,000 RPM) around its vertical axis and provides the vertical reference.
The gimbal assy comprises two orthogonal axes (pitch and roll).
The internal gimbal which includes the stator controls the rotation of the drum in the pitch axis by means of gear. The pitch gimbal is restricted to approximately plus or minus 85 degrees around the pitch axis (mechanical stop).
The external gimbal controls the roll rotation. The roll gimbal has unrestricted 360 degrees rotation around the roll axis.
The gyro pin axis is maintained in the vertical position by the erection system (unstable pendulum erector) which is removed when the rotor axis deviates more than 9 degrees plus or minus 2 degrees. The accuracy of the vertical position in clean configuration is less than 0.5 degree. The fast resetting of the gyroscopic horizon can be activated by pulling the knob (8) located in the lower R corner of the indicator.
The indicator provides the following information :
The standby horizon indicator is supplied with 28VDC from essential bus 401PP.
A static inverter in the instrument converts this 28VDC into three phase alternate current to supply the gyroscopic motor. The gyro rotor rotates at high speed (> 23,000 RPM) around its vertical axis and provides the vertical reference.
The gimbal assy comprises two orthogonal axes (pitch and roll).
The internal gimbal which includes the stator controls the rotation of the drum in the pitch axis by means of gear. The pitch gimbal is restricted to approximately plus or minus 85 degrees around the pitch axis (mechanical stop).
The external gimbal controls the roll rotation. The roll gimbal has unrestricted 360 degrees rotation around the roll axis.
The gyro pin axis is maintained in the vertical position by the erection system (unstable pendulum erector) which is removed when the rotor axis deviates more than 9 degrees plus or minus 2 degrees. The accuracy of the vertical position in clean configuration is less than 0.5 degree. The fast resetting of the gyroscopic horizon can be activated by pulling the knob (8) located in the lower R corner of the indicator.
The indicator provides the following information :
- roll angle,
- pitch angle,
- instrument failure (RED flag).
(1) Pitch information
The aircraft symbol (black and yellow) (7) is fixed.
The pitch drum (9), in the center of the instrument is divided into two zones separated by the reference horizon (white) :
the upper part is blue, the lower part is brown.
The pitch indications are displayed by means of a drum which is graduated between -80 and +80 degrees.
The aircraft symbol (black and yellow) (7) is fixed.
The pitch drum (9), in the center of the instrument is divided into two zones separated by the reference horizon (white) :
the upper part is blue, the lower part is brown.
The pitch indications are displayed by means of a drum which is graduated between -80 and +80 degrees.
(2) Roll information
The roll information is given by a pointer (10) which moves in front of a dial (5) graduated in 10 degrees increments between -30 and +30 degrees.
The roll information is given by a pointer (10) which moves in front of a dial (5) graduated in 10 degrees increments between -30 and +30 degrees.
(3) Failure warning
The flag (6) comes into view if a failure is detected in the electrical power supply or if the gyro rotor speed drops below 18,000 RPM.
The flag (6) comes into view if a failure is detected in the electrical power supply or if the gyro rotor speed drops below 18,000 RPM.