LAX04FA187 · Piper PA-28RT-201T

Following a loss of engine power in the takeoff initial climb, the airplane collided with vehicles during a forced landing on a freeway. During a cross-country flight the engine began to run rough and the pilot diverted to Concord. He phoned the FBO he rented the airplane from and advised them of the problem. The company contacted another maintenance facility at Concord who found a broken exhaust valve in the number 2 cylinder. The Concord maintenance facility estimated the repair job at 20 labor hours and the rental company declined to use them. The company dispatched a mechanic to Concord to make the repairs. The company mechanic replaced the number 2 cylinder and piston; however, he replaced the correct low compression piston with an incorrect high compression piston. He performed the work in just 3 hours. He failed to conduct a complete inspection of the engine for the missing pieces of the exhaust valve. After the mechanic verbally told the pilot the airplane was "good to go," the pilot fueled the airplane to capacity and completed the engine run up with no noted abnormalities. He departed using runway 19L, the shortest runway at CCR. When the airplane was about 150 to 200 feet above ground level, the pilot noted a loss of engine power. He decided he could not return to the airport and elected to land on the I-680 freeway. During the landing, the airplane collided with vehicles and came to rest in the center divider of the freeway. The airplane was largely consumed by the post impact fire. During the post accident engine examination, various determinations were made, including the following: Cylinders 2, 4, and 6 were mechanically damaged by a foreign object, most likely the number 2 exhaust valve head; the number 4 cylinder contained a foreign object that appeared to be a portion of the number 2 valve head; the spark plugs in cylinders 2, 4, and 6 were mechanically damaged with the electrode gaps closed or nearly so; cylinders number 1, 2, 4, 5, and 6 contained improper pistons that were certified to be installed into IO-360 series engines not into the accident engine a TSIO-360-FB; and the turbocharger turbine wheel exhibited foreign object damage. The number 2 main bearing was rotated 90 degrees. The bearing rotation and fretting damage to the number 2 and 3 upper main bearing support and the numbers 6 through 11 backbone bolt locations indicate that the through bolts were inadequately torqued during the installation of the number 2 cylinder.

Verbatim NTSB analysis and probable cause from the NTSB dataset