BSGO-400A

Limit monitoring through BSGO-400A

In operation, the BSGO-400A monitors both low and high main rotor speed conditions. A low-speed warning is used when rotor RPM drops below the permitted level, which can happen during abnormal engine power conditions or incorrect rotor loading. A high-speed warning is used when the rotor exceeds the allowed upper limit. The unit itself does not correct rotor speed and does not act on the engines. It only processes the incoming signal and sends the corresponding warning command to the aircraft indication circuits.

Main rotor RPM signal processing in BSGO-400A

The input signal normally comes from the main rotor speed sensor or from the related RPM measuring circuit. The signal frequency is proportional to rotor speed, and the electronic section of the unit compares it with internal reference thresholds. In older descriptions, this logic may be explained through monostable circuits or a dedicated calculating section. For maintenance, the whole chain matters: sensor condition, wiring, connectors, the BSGO unit, cockpit lamps, and power supply. A missing warning is not always caused by the warning unit itself.

Helicopter application of unit BSGO-400A

The BSGO-400A is used on helicopter types where main rotor RPM limit warning is required. Typical applications include Mi-8 / Mi-17 / Mi-171 family helicopters and Ka-32-type installations, depending on the onboard equipment set and modification standard. Installation location can differ by helicopter version. In some configurations the unit may be placed near electrical panels, in the radio compartment, or in another equipment bay defined by the aircraft documentation. Before replacement, the installed part should be checked against the aircraft parts catalog and wiring diagram.

Identification and ordering checks for BSGO-400A

Before ordering, the marking on the installed unit should be compared with the helicopter maintenance documentation, parts catalog, or overhaul records. Helicopters of the same family may have different warning system layouts after repair or modernization. It is useful to provide the unit designation, helicopter type, installation location, and a photo of the data plate. The product is also known under alternative designation БСГО-400А.