NTSB Factual Report

On February 25, 2006, approximately 0845 mountain standard time, a Piper PA-28RT-201T, N2939V, piloted by commercial pilot, was substantially damaged during a forced landing 17 nautical miles south of Front Range Airport (FTG), near Parker, Colorado. Visual meteorological conditions prevailed at the time of the accident. The personal flight was being conducted under the provisions of Title 14 CFR Part 91 without a flight plan. The pilot and private pilot rated passenger on board reported no injuries. The cross-country flight departed FTG approximately 0830, and was en route to Buena Vista, Colorado.

According to the pilot, during cruise flight the engine rpm increased to an "over speed condition." The pilot stated that he reduced power but was unable to maintain altitude. 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 and folded aft. Both flap assemblies were bent up and aft. The aft spars in both wings and the false spars within the gear well area were bent.

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 March 3, 2006, the airframe and engine were examined under the auspices of the NTSB Investigator-in-Charge (IIC) and airworthiness inspectors from the Federal Aviation Administration (FAA). 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.

On March 15, 2006, the engine was further examined by the NTSB IIC. A representative from Teledyne Continental Motors (TCM) and two FAA airworthiness inspectors were present during the examination. 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. According to TCM Service Bulletin (SB) 96-7C, the cylinder through bolt nuts should be torqued to a value of 600 inch/pounds.

Disassembly of the engine revealed fretting between the crankcase halves at the number two and number three cylinder throughbolt positions. The remaining portions of number two main bearing were found around the crankshaft and fused to the number two crankshaft main bearing saddle. 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 engine, airframe, and propeller logbooks were made available to the NTSB IIC for review. On November 23, 2004, at an engine tachometer time of 1,809.17, the number 4 cylinder was removed, overhauled, and replaced by Precision Aircraft & Engine Services, Inc. The logbook entry states that "all work [was] done in accordance with TCM TSIO-360 overhaul manual." 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." No propeller governor entry was noted in any of the maintenance logbooks. At the time of the accident, the engine tachometer time was 1,988.28.

NTSB Probable Cause

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.