Piper Malibu Meridian PA-46-500TP Airplane Maintenance Manual page 1399

WARNING: FAILURE TO CONSULT APPLICABLE VENDOR PUBLICATION(S), WHEN SERVICING
OR INSPECTING VENDOR EQUIPMENT INSTALLED IN PIPER AIRCRAFT, MAY
RENDER THE AIRCRAFT UNAIRWORTHY. (SEE INTRODUCTION - SUPPLEMENTARY
PUBLICATIONS.)
This chapter supplements Pratt & Whitney Canada's Maintenance Manual - Turboprop Gas Turbine
Engine Model(s) PT6A-38/-40/-41/-42/-42A - Part No. (P/N) 3021442 and consists of removal and
installation of external components and engine accessories. Repairs beyond this level should be
accomplished by an approved Pratt & Whitney Canada overhaul facility.
In the interest of maintaining efficient engine performance, an Engine Condition Trend Monitoring
System has been established by Pratt & Whitney Canada. This is not a mandatory procedure, but is
highly recommended by Pratt & Whitney Canada and Piper. Introduction of the monitoring system when
engines are new or newly overhauled enables the establishment of a performance baseline before any
deterioration of components takes place within the engine. Engine condition can then be observed
without actual teardown of components. The complete procedure can be found in the Engine Condition
Trend Monitoring Analytical Guide (EAG) Manual P/N 3043607, latest revision, available from Pratt &
Whitney Canada.
1. Description and Operation
The PA-46-500TP is powered by a lightweight, reverse-flow free turbine, Pratt & Whitney Canada PT6A-42A
gas turbine engine rated at 500 shaft horsepower at 2000 propeller RPM for takeoff and flat-rated at 400
SHP at 2000 propeller RPM for maximum continous power. The PT6A-42A uses two independent
turbine sections: one drives the compressor in the gas generator section and the second drives the
propeller shaft through a reduction gearbox. Accessories include a starter/generator and a belt driven
alternator and air conditioning compressor.
Engine intake air is provided through dual, symmetric air inlets located on the forward portion of the
cowling at the four and eight o'clock positions. The inlets are of fixed geometry such that no moving ice
vanes or doors are utilized. The inlets are designed such that the dynamics of icing conditions do not
allow the inlet to ice closed. Both inlets supply air to an inertial separator, which in turn supplies a
common engine inlet plenum and intake screen.
The inertial separator functions by preventing foreign objects from making an abrupt turn into the plenum
and instead exit through the bypass outlet. As air enters through the intake screen, it is ducted into a
three-stage axial and single-stage centrifugal compressor driven by a single-stage reaction turbine. A
dual turbine, counter-rotating with the first, drives the propeller through a two-stage reduction gear box.
Exhaust is provided through dual exhaust ports located on either side of the engine just behind the
propeller.
A single annular combustion chamber, containing 14 removable fuel nozzles and two igniter plugs,
comprises the combustion system. Only seven of the fuel nozzles are used for starting; the remaining
nozzles activate as the engine accelerates. A hydropneumatic fuel control unit schedules fuel flow to
maintain the power set by the gas generator power lever.
The ignition system consists of one exciter box, two ignition leads and two spark igniters. Both igniters
are engaged simultaneously. DC power is delivered to the exciter box from the essential bus through an
ignition mode selector switch in the engine control switch panel and a torque pressure switch. While in
the Automatic ignition mode, the ignition system will activate when the torque is less than or equal to
approximately 275 ft. lbs., and deactivate when the torque is greater than or equal to approximately 375
ft. lbs. Continuous ignition, at any torque setting, is provided in the Manual ignition mode.
7D15
PIPER AIRCRAFT, INC.
PA-46-500TP, MALIBU MERIDIAN
MAINTENANCE MANUAL
GENERAL
71-00-00
Apr 15/07
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