TDK-M

Operating principle of the TDK-M

The assembly combines two principal sections in one unit: a capsule temperature sensor and a pressure stabilizer. The temperature receiver contains a sealed gas charge, and its pressure changes with absolute temperature according to the gas-thermometer principle. A capsule and nozzle convert this response into the command pressure. A compensating bimetal package reduces the influence of fuel temperature on the sensor characteristic, while the stabilizer maintains the reference absolute pressure independently of return-line pressure. The resulting differential is proportional to the current temperature at the receiver.

Role in engine fuel-control equipment

Published technical training material places the TDK-M in the engine fuel-system group with the RRT-31VT1 fuel distributor and the RSF-31VT1 nozzle-and-afterburner regulator. The regulator receives a temperature-dependent hydraulic signal used in its control schedules. These units interact inside one fuel-control system but are not interchangeable. The related TDK sensor is provided for catalogue navigation only; replacement between TDK and TDK-M must be authorised by the documentation for the exact engine modification.

Published operating and environmental data

The published working fluid is engine fuel. The listed inlet pressure is 22 ±0.2 kgf/cm², the absolute drain pressure is 0.4–3.5 kgf/cm², and the pressure stabilizer produces an absolute pressure of 6.6 kgf/cm². Nominal inlet filtration is 16 µm or better. The listed fuel-temperature range is −50 to +120 °C; ambient temperature is −60 to +120 °C continuously and up to +220 °C for short periods. Published mass is not more than 1.2 kg. These values are useful for identification and preliminary procurement, but the individual passport remains controlling.

Identification, inspection and ordering

Before ordering, verify the TDK-M / ТДК-М nameplate, drawing and manufacturing numbers, three protected pressure ports, mounting base, safety wire and preservation condition. The unit should be installed and bench-tested only to approved engine and product documentation. For a quotation, state the required quantity, engine or system reference, acceptable condition and required passport or acceptance records. Application in the Su-27 / AL-31 family context must be confirmed for the exact aircraft and engine series rather than inferred from external appearance.