TDK

Temperature-to-pressure operating principle

The capsule sensing assembly reacts to the temperature surrounding its receiver. The internal mechanism forms a pressure differential whose value changes with inlet-air temperature. This pressure signal is used by compatible engine fuel-control equipment to introduce temperature correction into the governing schedule. The exact port assignment, calibration curve and test limits are determined by the TDK passport and the engine maintenance documentation. The yellow protective caps, sealed fittings, safety wires and hydraulic connections visible in the photographs are important identification and preservation features and must not be treated as electrical connectors.

Role in the RD-33 control system

In the RD-33 control system, the TDK signal participates in correcting the high-pressure rotor speed regulator and the compressor control schedule for inlet temperature. Published descriptions place TDK in the main engine fuel-control circuit together with the NR-59A pump-regulator and the BPR-88 Series 4 limiting-regulator unit. These links describe interaction inside the system; they do not mean that any of the units can replace another. A modified TDK-M execution is documented for later engine configurations, but substitution for TDK must be approved by the applicable engine documentation.

Aircraft and engine application

Public technical records associate TDK with the RD-33 installed on the MiG-29 and with the AL-31F installed on the Su-27. The exact engine series, aircraft modification and installation position must be checked before supply because control-system configurations changed during production and modernization. The published designation 2706.000 is associated with the TDK family, but the complete marking, serial number and drawing reference on the offered unit remain the controlling identifiers.

Identification, inspection and ordering

Before ordering, compare the designation TDK / ТДК, nameplate, pressure-port layout, mounting base, safety locking and any engraved manufacturing reference with the engine illustrated parts catalogue. The supplied photographs show the complete unit from the front, three-quarter, side and port-side views. For a quotation, state the required quantity, engine type, acceptable condition and required documentation. Installation and bench testing must follow the approved passport limits; open-source dimensions and operating data below are useful for identification but do not replace the individual product passport.