ST-115B

ST-115B electric starter

ST-115B is an enclosed series-wound DC electric motor used to crank the rotor of the GTDE-117 or GTDE-117-1 gas-turbine starter unit. It supplies mechanical drive only during the starting sequence and is not an aircraft electrical generator. The suffix B is part of the exact product identity and must be retained in the enquiry, purchase documents and inspection records. The designation on the offered unit should be compared with its passport and the approved equipment documentation.

Documented installation with the GTDE-117

Technical training material for the MiG-29 and T-10 aircraft systems identifies the ST-115B as the electric starter of the GTDE-117 family. The starter is mounted on the accessory gearbox of the gas-turbine unit and is connected to the turbocompressor rotor through a freewheel clutch. Once the GTDE reaches the required self-sustaining condition, the clutch separates the electric motor from the running rotor. This documented arrangement explains why ST-115B selection depends on the exact GTDE execution, drive interface and aircraft installation.

Starting-system operation and associated equipment

In the documented T-10 starting system, operation is coordinated by the APD-99 starting automatic unit together with the DTA-10 turbocompressor-speed sensor. The GTDE-117 fuel-control mechanism issues the starter-disconnection command according to the starting programme. Other installations may use their own approved control designation, so APD-99 or DTA-10 must not be assumed solely from the starter name. The ST-115B works within a system that also includes the freewheel clutch, accessory gearbox, starting-fuel equipment and ignition equipment.

Electrical data and construction

The retained product data for this exact catalogue position specifies a 16–29.4 V DC supply range, steady current not exceeding 180 A and a steady rotational speed of 9,000 rpm. The recorded maximum accompaniment speed is 24,000 rpm and maximum shaft load torque is 0.15 kgf·m. The B execution is recorded without an integral centrifugal switch; disconnection is provided by the associated starting system and freewheel drive. Retained dimensional data is approximately Ø150 × 205 mm, operating temperature −60 to +100 °C and mass not more than 4.1 kg. Because public secondary listings contain conflicting figures, the passport of the offered unit remains controlling.

Identification, inspection and ordering

Before installation, check the ST-115B marking, housing, mounting interface, drive end, free rotation, electrical terminal assembly, insulation and preservation condition. ST-115A and other related starters are not interchangeable merely because they share a family name or similar ratings. For comparison and catalogue navigation, see ST-115A, STV-3TPB, SGS-30B and STG-12TM. State the required condition, quantity, passport and inspection documents when requesting a quotation.

Product Type: Electric starter
Designation: ST-115B / СТ-115Б
Alternative Designations: ST-115B; ST 115B; ST115B; СТ-115Б; СТ 115Б; СТ115Б
Function: Cranking the turbocompressor rotor during the GTDE starting cycle
Documented Starter Unit: GTDE-117 / GTDE-117-1
Documented Aircraft Context: MiG-29 and T-10 technical training documentation
Electrical Machine: Series-wound DC motor
Execution: Enclosed construction
Drive Connection: Freewheel clutch between the electric starter and the GTDE turbocompressor rotor
Installation Location: GTDE accessory gearbox
Supply Voltage: 16–29.4 V DC
Steady Current Consumption: Not more than 180 A
Steady Rotational Speed: 9,000 rpm
Maximum Accompaniment Speed: 24,000 rpm
Maximum Shaft Load Torque: 0.15 kgf·m
Integral Centrifugal Switch: Not fitted in the retained data for the B execution
Documented Control Context: APD-99 starting automatic unit and DTA-10 speed sensor in the T-10 installation
Disconnection Principle: Command from the associated starting system and mechanical separation by the freewheel clutch
Operating Temperature Range: −60 to +100 °C
Overall Dimensions: Approximately Ø150 × 205 mm; verify by product passport
Mass: Not more than 4.1 kg; verify by product passport
Compatibility Check: Confirm exact designation, GTDE execution, mounting, drive and electrical circuit
Documentation: Product passport and approved aircraft/GTDE starting-system documentation

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