T53 Series – Engine External Components Overview

N1 Accessory Gearbox
Located at the 6 o’clock position on the inlet housing.

N2 Accessory Gearbox
Driven by the powershaft and provides drive for the
overspeed governor, N2 tachometer and the torquemeter boost pump.

Main Electric Connector
Provides an interface between the engine electrical components and the aircraft electrical system.

Hot Air Solenoid Valve
Provides anti-icing air for the inlet housing.

Start Fuel Solenoid Valve
Electrically controlled two position (on-off) valve, spring loaded closed.

Ignition Unit
Converts low input voltage to high voltage output for ignitor plugs.

Starting Fuel Nozzle
Stainless steel tube directing start fuel to the 2 start fuel nozzles (left side).

Ignitor Plug
Receives high voltage from the ignition unit for engine start.

Exhaust Thermocouple
Flexible harness, 6 probes, each probe consists of 2 thermocouples, connected in parallel by an adapter plug.

Fuel Flow Divider
Directs fuel flow to the primary and secondary portion of the main fuel manifolds.

Lead And Coil Assembly
Directs the high voltage from the ignition unit to the four ignitor plugs.

Fuel Control
N1 driven, fuel regulator.

Emergency Fuel Transfer Solenoid
Repositions the changeover valve by servo fuel pressure.

Torquemeter Boost Pump
Duel element gerotor type eccentric pump, one pres- sure element and one scavenge.

Oil Filter
Filters all the oil passing to the engine.

Oil Pump
Dual sliding vane type pump, one element supplies oil pressure, the other element will scavenge the oil.

T1 Sensing Unit
Monitors inlet air temperature and programs fuel control to deliver fuel at a rate relative to ambient temperature.

Exhaust Thermocouple
Flexible harness, 6 probes, each probe consists of 2 thermocouples, connected in parallel by an adapter plug.

Main Fuel Manifold
Directs fuel flow to the 22 dual orifice atomizing nozzles during engine operation.

Purge Air Check Valve
Purges start fuel manifolds and start fuel nozzles after engine start.

Variable Inlet Guide Vane Actuator
Positions inlet guide vanes as a function of N1 speed.

Interstage Air-bleed Actuator
Facilitates compressor rotor acceleration and prevents engine surges.

Ignition Lead
Transmits high voltage from the ignition unit to the 2 ignitor plugs (right side).


MGT Lead
Provides measured gas temperature signal to the aircraft gauge

MGT Junction Box
Contains three circuits of four thermocouples each to provide the operator a more direct indication of engine temperature signal.

Impeller Housing
Replaces the magnesium housing with a stainless steel
housing, provides a greater strength and resistance to erosion and corrosion. A one piece customer air-bleed pad accommodates the new stainless steel upper impeller housing.


* Basic Understanding and Best Practices – All Information & Documentation within is for Training and Guiding Purposes Only.
Any information should be cross checked with applicable OEM aircraft & maintenance.
** Any and All Training Information contained in official publications shall govern.
*** This guide may suggest and advise — BUT NOT DICTATE — Contents herein and are subject to change without
prior notice Please refer to official publication and current revisions.