NTSB Identification: MIA03IA062.
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Incident occurred Thursday, February 13, 2003 in Fort Lauderdale, FL
Probable Cause Approval Date: 06/08/2005
Aircraft: Cessna 500, registration: N891CA
Injuries: 2 Uninjured.
NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.
The airplane experienced an uncontained rupture of the high-pressure compressor (HPC) impeller in the No. 2 engine during takeoff. The flight crew stated that at about 40 knots during the take off roll/run, there was a loud bang, followed by the engine fan passing by the right side cockpit window, and the captain aborted the takeoff, secured the engine, and exited the runway. There were no injuries to either of the flight crew who were the only persons onboard the airplane during the positioning flight, and the airplane incurred minor damage. Initial on-scene examination of the No. 2 engine revealed it had experienced a penetration of the engine case in the plane of the HPC impeller. There was a large hole in the top of the engine cowling at approximately 1:00 aft looking forward, just forward of the thrust reverser clamshell. The missing segment of the HPC impeller was not located. The examination revealed the HPC impeller had separated from the HPC and HPT (high-pressure turbine). A metallurgical examination of the impeller revealed that the fracture was consistent with there having been a low-cycle fatigue crack that initiated along the circumferential machining feature on the aft face of the impeller. River lines were observed to be emanating from the aft face, consistent with the crack having initiated in the area of the groove and ultimately separating the HPC impeller from the engine. According to maintenance records, the impeller had a total of 7311.5 hours/6116 cycles when installed at the last overhaul of the engine on December 13, 1996. The engine had since accrued 1,582.1 hours /1,760 cycles, for a total of 7,876 cycles since new. The cyclic life limit on the impeller is 8,400 cycles.
The National Transportation Safety Board determines the probable cause(s) of this incident to be: Inadequate quality control following overhaul of the high-pressure compressor (HPC) impeller by other maintenance personnel that resulted in a machining groove on the aft face of the HPC impeller being undetected, which resulted in a fatigue fracture and an uncontained separation of the HPC impeller from the engine during the takeoff roll/run, and the pilot rejecting the takeoff.
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