BS-1

Signal routing through the BS-1 block

In the GMK-1 system, the BS-1 handles the electrical connection between units that generate, correct and display heading information. It helps route heading signals from the gyro unit to indicators such as UGR-4UK, and also to external users when the aircraft configuration requires it. These users may include autopilot channels or navigation equipment that need heading data for stabilization, course holding or related functions. The block is therefore part of the signal chain that keeps the heading system useful beyond the cockpit indicator alone.

BS-1 with GMK-1 system components

The BS-1 normally operates together with the main GMK-1 equipment group: the ID-3 induction detector, GA-6 gyro unit, KM-8 correction mechanism, AS-1 matching unit and PU-26 or PU-27 control panel. Each of these units has its own task, but they need stable electrical coordination to work as one system. The BS-1 supports that coordination by switching and matching the required circuits. When diagnosing heading system faults, this block should be considered together with the connected units, wiring and aircraft power supply, not as an isolated box.

Heading data transfer and autopilot signal

One of the functions associated with the BS-1 is transfer of angular heading information through synchro-type circuits. In the heading system, the block may also participate in forming the Δψ signal, which represents the difference between the selected course and the current aircraft heading. This signal can be used by the autopilot or stabilization equipment, depending on aircraft installation. Because the signal is related to course control, small transmission errors matter. The unit must maintain correct signal continuity and switching accuracy within the limits specified for the GMK-1 system.

Operating modes supported by BS-1

The BS-1 is involved in switching circuits used in different GMK-1 operating modes, including magnetic correction and gyro-compass operation. In magnetic correction mode, the system works with data from the induction detector and correction circuits. In gyro mode, the system relies on the gyro reference and related control logic. The exact switching behavior depends on the GMK-1 modification and aircraft wiring diagram. For replacement or troubleshooting, the unit should be checked against the specific system version installed on the aircraft.

Aircraft application of the BS-1 unit

The GMK-1 heading system was used on various Soviet and Russian aircraft and helicopters, including platforms such as Mi-8 and Yak-40, depending on modification and installed avionics package. The BS-1 unit belongs to this heading system and is usually required when maintaining, repairing or restoring the complete GMK-1 installation. Before supply, it is important to confirm the exact system version, drawing number, connector type and documentation. Similar-looking units from related heading systems may not be interchangeable without verification through the aircraft parts catalog and wiring documentation.