Field Cleaning Engine - Piper Cheyenne IIIA Airplane Maintenance Manual

PIPER AIRCRAFT
PA-42-720 (Advanced Trainer)
MAINTENANCE MANUAL
Servicing
A. General
This chapter covers all routine servicing of airplane, scheduled and non-scheduled, including
replenishment of fuel, oil, hydraulic fluid, oxygen, tire pressure, lubrication requirements, servicing of
oleo struts with air and oil, etc. Pay special attention to all WARNINGS or CAUTIONS.
B. Engine/Compressor Wash
Due to accumulated environmental airborne chlorides which cause deterioration of compressor blades
by a process known as sulphidation, Pratt & Whitney Aircraft recommends a compressor wash be
carried out weekly regardless of apparent atmospheric conditions. Pratt & Whitney Maintenance
Manual, P/N 3034342 for PT6A-61 engine, gives full, detailed instructions to wash of engine and
compressor. For specific Piper installations instructions, use following additional instructions:
CAUTION: BEFORE CLEANING, CABLES MUST BE PROPERLY SEALED TO PREVENT
WATER FROM ENTERING CABLE HOUSINGS. DO NOT DIRECT ANY WATER
PRESSURE AT THESE SEALS. WATER COULD FREEZE AND BIND CABLES
UNDER CERTAIN CONDITIONS.
CAUTION: DO NOT USE TAP WATER AS INHERENT CHEMICALS CAN CAUSE DEPOSITS
ON COMPRESSOR BLADES.
CAUTION: BE CAREFUL WHEN WASHING EXTERIOR OF FCU. DO NOT ALLOW WASH
SOLUTION TO ENTER VENT HOLES OF FCU, WHICH COULD GIVE FALSE
INDICATION OF FUEL PUMP LEAK.
CAUTION: OBSERVE STARTER OPERATING LIMITS OF 30 SECONDS ON, 60 SECONDS
OFF, 30 SECONDS ON, 60 SECONDS OFF, 30 SECONDS ON, AND 30 MINUTES
OFF.
CAUTION: RUN ENGINE WITH STARTER ONLY. ENSURE IGNITION IS OFF AND
APPROPRIATE FUEL FIREWALL SHUTOFF VALVE IS CLOSED.
1. Allow engine to cool for at least 30 minutes before performing compressor wash.
2. With top cowling removed, disconnect bleed air line at union below T-connection. Secure cap
lines.
3. Close bleed air shutoff valve and install ground run cowl. Disconnect and cap HI and LO stage
bleed lines. Do not wash engine with bleed mixing valve connected to bleed lines as valve control
passageways become plugged or fouled, rendering valve inoperative and uncontrollable.
4. Open access door on side of bottom cowl; clean mechanism attached to wash ring fitting and
clean according to Pratt & Whitney Maintenance Manual.
5. Soak for about 15 minutes after wash.
C. Field Cleaning Engine
Field cleaning consists of internal washing of engine compressor and external washing of engine.
Refer to Pratt & Whitney Maintenance Manual, P/N 3034342, Chapter 71, for approved procedures
and precautions.
EFFECTIVITY:
040-999
12-00-00 Jan
10 /90
12-00-00