Service Difficulty Advisory
8 February 2006
Pratt & Whitney PW 100 Engine - Electrical System Care
The purpose of this publication is for Transport Canada Civil Aviation (TCCA) to emphasize the importance of proper engine electrical system maintenance on the PW100 series engine.
Field reports and product service history have clearly identified that contaminated, loose, wet and corroded engine electrical connectors have led to undesirable and numerous in-service events.
Oil and Dirt Ingress
Poor maintenance practices related to connectors have caused in-flight occurrences such as uncommanded propeller auto-feather, incorrect engine torque sensing, faulty full authority digital engine control (FADEC) events, propeller control occurrences, inadvertent reversion of the engine electrical control (EEC) to manual mode, quick engine change (QEC) harness connections, engine bleed air valve malfunctions, EEC logic and manual fuel control (MFC)/fuel pump interaction problems. Intermittent electrical signal snags, caused by faulty connectors, can be elusive and difficult to rectify. This can result in excessive aircraft unavailability and costly component changes.
Pin Fretting and Oxidation
Pratt & Whitney Canada (PWC) has issued numerous service bulletins (SBs) to improve the reliability of electrical connectors. TCCA recommends that operators, owners and maintainers comply with the following P&WC publications:
Safety Information Letter (SIL) PW100-095 “Engine Electrical Signal Interruptions”;
PW100 Workscope Planning Guide – Section 10;
P&WC Engine Maintenance Manual (EMM) Chapter 72-01-10.
TCCA also recommends incorporation of the following P&WC Service Bulletins:
SB21004 - Electrical Wiring Harness Insulating Tape, Introduction of;
SB21269 - Electrical Wiring Harness Sleeves, Installation of;
SB21456 - Torque Sensor Air Gap, Optimization of;
SB21461 - Electrical Wiring Harness Contact Enhancer (Stabilant 22), Application of;
SB21463 - Electrical Wiring Harness, Replacement of,(PW120A/121/123/123B/C/D/E,123AF/124B);
SB21488 Electrical Wiring Harness, Replacement of, (PW118/118A/118B/120/121);
SB21550 Electrical Wiring Harness, Replacement of, (PW121A); and
SB21553 Electrical Wiring Harness, Replacement of, (PW125).
TCCA recommends that each time an electrical connector is disturbed that a proper visual inspection be performed, paying particular attention to damaged pins, corrosion, cleanliness and security.
Any further defects or occurrences should be reported to Transport Canada, Continuing Airworthiness, Ottawa via the Service Difficulty Reporting program.
For further information, please contact a Transport Canada Centre, or contact Mr. Barry Caldwell, Continuing Airworthiness, Ottawa, telephone 613 952-4358, facsimile 613 996-9178 or e-mail firstname.lastname@example.org
For Director, Aircraft Certification
Chief, Continuing Airworthiness
Note: For the electronic version of this document, please consult the following Web address: www.tc.gc.ca/eng/civilaviation/certification/menu.htm
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