NTSB Identification: DEN06LA044.
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Accident occurred Saturday, February 25, 2006 in Parker, CO
Probable Cause Approval Date: 08/29/2006
Aircraft: Piper PA-28RT-201T, registration: N2939V
Injuries: 2 Uninjured.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The pilot stated that during cruise flight the engine rpm increased to an "over speed condition." When he increased power, he could not keep the rpm under redline and he elected to perform a forced landing. During the landing, the landing gear collapsed resulting in substantial damage. The pilot stated they had been having difficulty obtaining full rpm from the engine. He stated that the propeller governor had been adjusted several times, but full rpm was never obtained. On November 16, 2005, at an engine tachometer time of 1,959.37, the oil and filter were removed and replaced, and an oil sample was sent for analysis. The results from that analysis indicated "excessive wear." Removal of the oil suction screen revealed metal contamination inside and outside the screen. Examination of the propeller governor revealed the adjustment screw had been adjusted beyond its maximum stop. The propeller governor was removed and the screen between the governor and the engine was entirely obstructed with metal contamination. Removal and examination of the oil filter revealed metal contamination. Broken portions of the number two main bearing were found within the oil sump. Breakaway torque values revealed that the number two and number three cylinder throughbolt nuts, at the cylinder flange, were loose at 500 inch/pounds. Further examination revealed metal contamination throughout the engine, including the oil pump and the oil cooler. No other anomalies were noted with the airframe, propeller, or engine.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: the improper maintenance procedures resulting in the unseating of the number two main bearing. Contributing factors include the mechanic's improper troubleshooting procedures, and the pilot's improper decision to continue operating the airplane with known internal excessive engine wear, and engine rpm issues. Full narrative available
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