GS-24B Series 2

Documented An-24 and An-26 system context

Aircraft training and maintenance material lists GS-24B in the DC electrical systems of the An-24 and An-26 families. In the reviewed An-26 configuration it is the reserve or auxiliary DC source associated with the RU19A-300 auxiliary power unit, while two STG-18TMO units serve as the main engine-driven sources. Exact effectivity must be checked against the aircraft and APU modification.

Onboard bus and main-engine starting modes

For ordinary aircraft-bus supply, the reviewed technical description gives 28.5 V and up to 300 A, corresponding to 9 kW at 30 V and approximately 6,500 rpm. When supplying the main starter-generators during engine start, the output may rise to the documented starting-channel values of up to 55 V and 800 A for the limited starting cycle. These are different operating modes and must not be combined into one continuous rating.

Starter mode for the auxiliary engine

When GS-24B Series 2 starts its own auxiliary engine, the recorded supply is 24 V DC with current not exceeding approximately 780 A. The documented starter speed is at least about 1,580 rpm within the stated tolerance, while generator operation covers a wider speed range of approximately 4,000–7,400 rpm. The installation is controlled by the APU starting and aircraft power-distribution equipment.

Identification, inspection and ordering

Confirm the full GS-24B-2S marking, rotation, drive flange, red connector assembly and APU effectivity. Similar GS-24 family names do not establish interchangeability. Inspect the drive end, housing, ventilation areas, connectors and nameplate before testing. State the aircraft and APU modification in the enquiry. Related units are listed under Generators & Starter-Generators.