FTW96LA050

While cruising at 9,500 feet MSL, the pilot noticed 'vibrations' accompanied by a 'slight' loss of power. He then 'heard a loud noise,' observed smoke, and the engine lost 'all power.' Subsequently, the airplane collided with trees during a forced landing on wooded/mountainous terrain. Engine examination revealed the following: A hole, 3 inches in diameter, was found adjacent to the #1 cylinder's attachment point on the right side of the crankcase. Debris from the #1 and #2 pistons and the #1 and #2 connecting rods was found throughout the interior of the crankcase. According to an FAA inspector's report, 'Cylinders 1 and 2 evidenced a catastrophic failure similar to that caused by detonation from uneven fuel distribution.' The rear crankcase journals were dry and displayed thermal damage. The interior of the crankcase and rear section of the crankshaft displayed impact damage associated with internal engine component failures. Part of an air intake bypass door from the throttle body air intake was found lodged in the intake port of the #6 cylinder. Examination of the throttle body revealed that a replacement air intake door had been installed, but maintenance records did not reveal service performed on (or a replacement of) the bypass door.

On November 21, 1995, approximately 0756 mountain standard time, a Beech BE-35, N9886R, registered to, and operated by the pilot, as a Title 14 CFR Part 91 flight was destroyed during a forced landing near Estancia, New Mexico. Visual meteorological conditions prevailed and no flight plan was filed. The private pilot and one passenger received minor injuries. The business flight was en route to Carlsbad, New Mexico, and originated from Albuquerque International Airport, Albuquerque, New Mexico, approximately 30 minutes prior to the accident.

The pilot reported that, while cruising at 9,500 feet MSL, he noticed "vibrations", accompanied by a "slight" loss of power. He then elected to return to Albuquerque. He further reported that, during the return flight, the "engine continued to lose power." Subsequently, the pilot "heard a loud noise", observed "white smoke", and the engine lost "all power." During the ensuing forced landing, the airplane descended into a mountainous area covered in mature forest growth, and came to rest upright, in a nose down attitude.

A detailed examination of the engine by a FAA airworthiness inspector revealed the following: A hole, 3-inches in diameter, was found adjacent to the number 1 cylinder's attachment point on the right side of the crankcase. The #1 and #2 cylinders could not be removed from the crankcase. Cylinders #3 through #6 displayed scoring in the barrels. Debris from the #1 and #2 pistons (which were destroyed) was found throughout the interior of the crankcase when the crankcase was opened. Additionally, debris from the #1 and #2 connecting rods (which were destroyed) was found inside the crankcase. The remainder of the connecting rods were intact and were free to rotate on the crankshaft. The rear crankshaft journals were dry and displayed thermal damage. The interior of both crankcase halves, and the rear section of the crankshaft, displayed impact damage associated with numerous internal engine component failures.

Part of an air intake bypass door from the throttle body air intake was found lodged in the intake port of the #6 cylinder. Further examination of this door, revealed that, the rivet holes on the door corresponded to the rivet holes in the throttle body hinge. Examination of the throttle body revealed that a replacement air intake bypass door had been installed. A review of the maintenance records did not reveal service performed or a replacement of the bypass door.