GA-3

GA-3 directional gyro unit for aircraft heading systems

GA-3 is an aircraft gyro unit used as a sensitive heading reference element in precision aircraft heading systems. The unit is a three-degree directional gyroscope intended to measure, store and transmit aircraft heading data to onboard consumers. Depending on the installed system, GA-3 can provide orthodromic, magnetic or true heading information to autopilot systems, navigation computers and cockpit indicators.

Function of the GA-3 gyro unit

The main function of GA-3 is stable heading storage and heading signal output during flight. The gyro axis maintains its spatial direction, while aircraft turns are detected by angular sensing elements and converted into electrical heading signals. These signals are used by the aircraft heading system and related navigation equipment. GA-3 is especially important in operating modes where magnetic references are less reliable, including maneuvering flight, turbulence and operation in high-latitude areas.

GA-3 in TKS and GMK heading systems

GA-3 is used in aircraft heading complexes such as TKS-P, TKS-P2, GMK-1G and GMK-1AE, depending on aircraft type and avionics configuration. In these systems, the unit operates together with heading correction equipment, magnetic sensors, control panels and signal distribution circuits. For increased reliability, aircraft heading systems may include two or three GA-3 gyro units, typically arranged as main, control and reserve channels.

Operating modes of the GA-3 gyro aggregate

In DG mode, the GA-3 works as an autonomous directional gyro and stores the selected heading reference. This mode is used for accurate heading holding and stable navigation output. In magnetic correction mode, the gyro unit can be synchronized with a magnetic heading source, such as an induction magnetic sensor, for initial heading alignment or correction during stable straight flight. Latitude correction may also be used to compensate for Earth rotation according to the current flight latitude.

Construction features of GA-3

The GA-3 unit contains a high-speed aircraft gyro motor in a sealed metal housing. The source context indicates the IAV-824 gyro motor or an equivalent type. The rotor operates at high speed, creating the kinetic moment needed for stable directional reference. The unit includes a heating assembly with thermal elements and a bimetallic relay to maintain reliable operation at low temperatures. It may also include a gyro topple warning function when aircraft maneuvers exceed the operating limits of the gimbal suspension.

Installation and maintenance of GA-3

GA-3 is mounted on a special frame with shock absorbers to protect the gyro mechanism from vibration and impact loads. During installation, the base plane must be aligned with the aircraft construction axis according to maintenance documentation. The sealed metal casing may include an inspection window for visual monitoring of the internal gimbal frame. Before procurement or replacement, the required aircraft system, modification, condition, passport availability and test status should be confirmed.

Product Type: Aircraft directional gyro unit / heading reference gyro aggregate
Designation: GA-3
Alternative Designations: GA 3, GA-3 gyro unit, ГА-3, гироагрегат ГА-3
Function: Measurement, storage and output of aircraft heading data
Heading Data Types: Orthodromic, magnetic or true heading depending on system configuration
Gyro Type: Three-degree directional gyroscope
Parent Systems: TKS-P, TKS-P2, GMK-1G, GMK-1AE according to source context
Application / Where Used: Aircraft heading and navigation systems
Compatible Aircraft / Equipment: Tu-154, Il-76, Yak-42 and other aircraft depending on installed heading system documentation
Typical System Redundancy: Two or three GA-3 units in main, control and reserve channels, according to source context
Operating Modes: DG mode and magnetic correction mode
Correction Functions: Latitude correction and magnetic correction depending on system configuration
Associated Magnetic Sensor: ID-3 induction magnetic sensor, according to source context
Gyro Motor Type: IAV-824 three-phase asynchronous gyro motor or equivalent, according to source context
Rotor Speed: 22,000–22,500 rpm
Gyro Kinetic Moment: Approximately 1.96 N·m·s
AC Power Supply: Three-phase 36 V, 400 Hz
Electrical Connector: Specialized 30-pin plug connector, according to source context
Azimuth Drift in DG Mode: Not more than ±1° per 30 minutes
Normal Azimuth Correction Rate: Not less than 40 angular minutes per minute
Fast Azimuth Correction Rate: Not less than 2° per second
Maximum Dimensions: 390 × 272 × 252 mm, including shock-mounted frame
Weight: Not more than 13.2 kg
Vibration Resistance: Up to 0.5 mm amplitude at 15–20 Hz, according to source context
Shock Load Resistance: Up to 4g short-term shock loads, according to source context
High-Frequency Vibration Reference: Up to 2.3g at 80 Hz, according to source context
Heating: Internal thermal elements and bimetallic relay
Mounting: Special mounting frame with spring or rubber shock absorbers
Installation Alignment: Base plane aligned with aircraft construction axis within ±1°, according to source context
Inspection Feature: Inspection window on sealed metal casing, according to source context
Condition: New / As-Stored / Overhauled / Serviceable, depending on availability
Technical Documentation: Product passport, test report, storage records and aircraft heading system documentation if available

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Warranty
All products are covered by a standard 6-month warranty.
Extended warranty is available upon request and is agreed individually; it may affect the final product price.