PT6A - 114 and 114A compressor turbine blades - Service Difficulty Advisory

No. AV-2007-06
19 September 2007

There have been a number of inflight shutdowns (IFSDs) and Service Difficulty Reports (SDRs) related to CT blade failures. Transport Canada Civil Aviation (TCCA) has determined it necessary to advise operators, owners, maintainers and overhaul shops of the importance of proper engine maintenance and engine power management.

Liberation of CT blade(s) or portions thereof, resulted in significant downstream hot section damage. Other negative consequences have been increased maintenance and operating costs and a reduced margin of safety.

One of the primary reasons for CT blade fractures and resultant engine power loss is operating the engine beyond the power settings specified in the respective Aircraft Flight Manual (AFM). Not following the specified AFM requirements has largely contributed to incidents of blade creep and reduced blade life.

In order to reduce CT blade distress, it is essential to detect and control hot section sulfidation, oxidation and blade erosion. An important preventive practice such as regular fuel nozzle maintenance will minimize or prevent hot section distress. Regular borescope inspections, Engine Conditioning Trend Monitoring (ECTM) and turbine washes are fundamental tools in detection and subsequent prevention of CT blade failures.

In an effort to reduce CT blade events, the engine OEM has conducted maintenance and engine operating training seminars in several continents and published numerous recommendations. Many of these IFSDs could have been prevented if OEM instructions had been complied with.

In the past years, P&WC have published several Service Information Letters (SIL) to address PT6A 114/114A in-service problems, as follows:

SIL PT6A-53 EPL usage

SIL PT6A-116R1 Borescope Inspection

SIL PT6A-125 Inadvertent Cut-off/Relight

SIL PT6A-146 CT Blade Cut-Up at HSI

P&WC have recently issued SIL PT6-146 titled “Compressor Turbine Blade Maintenance” advising all operator, owners and maintainers of the upcoming revisions to PT6A-114/114A Instructions for Continuing Airworthiness (ICA).

TCCA strongly advise all responsible persons and agencies to comply with the aforementioned SILs.

Malfunctions, defects and failures occurring on aeronautical products should be reported to TCCA, Continuing Airworthiness via the CAR 591 reporting requirements. For further information, please contact a local Transport Canada Centre (TCC) or Mr. Barry Caldwell at (613) 952-4356 or Facsimile (613) 996-9178.

For Director, Aircraft Certification

B. Goyaniuk Chief,
Continuing Airworthiness

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