Page:CAB Aviation Accident Report - TWA Flight 35.pdf/2

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it was backfiring end fire was coming from the nacelle. The left engine was therefore shut off again. Captain Polizzi realized that he would not be able to reach the Greensburg Airport because of the drag induced by the expanded engine cowling and the severe vibration set up in the failed engine with its propeller still windmilling. He contemplated landing upon a highway but abandoned the idea, when he observed heavy traffic thereon. Heading west, he released a landing flare and began a spiraling descent. As he approached an open field he pulled the aircraft up sharply to avoid a house, but immediately afterwards the left nacelle struck an electric line pole breaking it off about 2-1/2 feet from its top. Captain Polizzi cut the master ignition switch ad landed the aircraft in a tail-low attitude, with wheels and flaps up, on the side of a ridge. It skidded along about 100 yards on the bottom of the fuselage until the tail wheel locking mechanism failed, whereupon it made an abrupt ground loop of about 90 degrees to the right, up the slope of the hill.

An inspection of the terrain revealed that contact with the ground had been made on an open ridge-side with a slope of about 12 degrees, in such, a direct tan that the skidding had been parallel to the crest of the ridge and was neither up nor down grade. Examination of the left engine revealed that the No. 3 cylinder had core off during the flight, forcing the cowling off of its stops and causing it to open up and flare back, resulting in vibration and drag sufficient to prevent continuation of flight to cylinder, its piston, and wrist pin were missing, and all of the cylinder hold-down studs were broken off at the cylinder pad. The crank case was cracked between No. 2 and 3 cylinders. It was not determined whether the failure was initiated in the cylinder hold-down studs or in the adjacent portion of the crankcase. Further investigation disclosed that there had been no malfunctioning of the control system, or of the structure prior to impact, and that there had been ample fuel. The aircraft was not equipped with full-feathering propellers.

The total time on the left engine was 7996:03 hours. The time since last overhaul was 573:15 hours and the total time since last cylinder base stud check was 79:17 hours, both of which were within the prescribed overhaul and inspection periods required by the Civil Aeronautics Administration, Moreover, all phases of the flight were in accordance with the Civil Air Regulations and with the company's procedure.

As a result of similar accidents involving engine failure on multi-engine aircraft, the Civil Air Regulations were amended, effective August 1, 1941, to require that such aircraft when operated as scheduled air carriers be equipped with full-feathering propellers or other means of stopping propeller rotation.

PROBABLE CAUSE:

Structural failure of left engine resulting in a forced landing on unsuitable terrain.