The Lycoming T53 L7 01 uses an electric torquemeter system
to monitor power output. The Avco Lycoming electric torquemeter is a
refined torque measuring system which measures torque imposed on the
engine power output shaft. The torque signal is a result of tension
and compression stresses changing the magnetic reluctance of the
shaft.
The torque system is comprised of five components and their
interconnecting wiring. Two of these, the power supply and the
indicator, are airframe mounted components and may be replaced at any
time without recalibration. The remaining three, the power output
shaft, the head assembly (transformer), and junction box, must be
replaced only as a precalibrated set.
The transformer consists of one primary and two secondary
windings. The primary generates a constant magnetic field which
penetrates the transformer core attached to the primary sun gear.
The voltage induced in the two secondaries varies with the tension
and compression stresses imposed on the shaft. This difference in
secondary voltage is transmitted through the junction box and is read
on the cockpit indicator as psi of torque. Figure 4.33 is a cross
section of the inlet housing to show relationship of power output
shaft, torquemeter head assembly, and torquemeter junction box.
4.22.
ELECTRICAL SYSTEM
The engine electrical system consists of the main wiring
harness and connectors for electrical components as shown in figure
4.34. The airframe and engine wiring diagram is shown in figure
4.35. The following subparagraphs briefly discuss the operation of
a. Ignition system. The highenergy, mediumvoltage,
capacitordischarge ignition system consists of an ignitionexciter
unit, output leads, sparksplitter coil, and four surfacegap igniter
plugs. The system is activated simultaneously with the start fuel
solenoid valve and starter by a switch in the cockpit. The ignition
system is used only for engine starting and not for sustaining
Power from the 28v dc electrical system is stepped up in
in the combustion chamber at a spark rate of two to eight per second.
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