CHAPTER 71
POWERPLANT
71-00 Description
One Rolls-Royce model 250-C300/A1 (commercial designation RR300) free-turbine turboshaft
engine powers the helicopter. The engine is equipped with an ignition exciter, igniter, starter-
generator, two tachometer senders, and additional powerplant instrument senders.
A direct drive, squirrel cage style cooling fan is mounted to the intermediate shaft and supplies
cooling air to the engine and gearbox oil coolers.
Induction air enters through multiple openings in the upper fuselage cowlings and ows into
a plenum forward of the rewall. The plenum contains a radial-ow air lter at the engine
compressor inlet.
If the air lter becomes blocked, spring-loaded doors at the front of the lter housing open
allowing unltered air to the engine. The AIR FILTER annunciator illuminates when lter
bypass is occurring.
Periodically performing power assurance checks may provide indication of engine deterioration
or air lter blockage. Maintenance actions such as air lter cleaning and compressor wash
should be performed if aircraft fails power assurance check.
A temperature switch is mounted to the rewall above the engine to detect a re in the
engine compartment. Abnormally high temperature causes the ENGINE FIRE annunciator to
illuminate.
SEP 2012 R66 Maintenance Manual Chapter 71 Powerplant Page 71.1
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