Service difficulty report · Turbine · Aerosp ATR72201

Difficulty date
October 16, 2008
Submitted
December 18, 2008
Operation
General aviation
Make and model
Aerosp ATR72201
Engine
Pwa PW124B
Part
Turbine
Condition
Seized
Location
Lt Engine
Stage of operation
TO
How discovered
O
Nature of condition
X, J
Precautionary procedure
C

As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.

What was found

(CAN) DURING TAKEOFF, THE PILOT REPORTED LT ENG TQ INCREASE TO 109 PERCENT. THE PLA WAS MOVED TO GI BUT THE ENG SHUTDOWN ITSELF. THE ACFT WAS DIVERTED TO THE GATE. DURING TROUBLESHOOTING, THE ENG PARAMETERS WERE DOWNLOADED AND ANALYZED. REVIEW SHOWED A DROP OF NH FROM 92 PERCENT TO 0, AND FUEL FLOW REDUCING FROM 550 TO 300, AND THEN TO ZERO. THE NL SENSOR AND THE TMM CHIP DETECTOR WERE INSPECTED AND FOUND CONTAMINATED. THE STARTER GEN WAS REMOVED IN ORDER TO ROTATE THE HP SHAFT BUT THE HP TURBINE WAS SEIZED. BORESCOPE INSP PERFORMED AND CONFIRMED THAT THE HP TURBINE WAS NOT ROTATING. SUSPECTING DISTRESS IN THE TOWERSHAFT AREA, THE COVER OF THE AGB DRIVE WAS REMOVED. INSP SHOWED A TOWERSHAFT WITH SIGNIFICANT RADIAL CLEARANCE AND DAMAGED GEAR TEETH . IT WAS DECIDED TO REMOVE THE ENGINE AND SEND IT FOR REPAIR. MFG WILL CONTINUE INVESTIGATING THE EVENT AND ADVISE OF ROOT CAUSE ONCE ESTABLISHED.

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