Page:CAB Aircaft Accident Report, Trans-Canada Air Lines Flight 304.pdf/5

 on which the bushing flange normally beds. Damage resulting from the bushing turning in its panel precluded a determination of why the bushing was initially allowed to spin. The bushing flange was cracked. Displacement of the bushing resulted in a partial disengagement of the driven and driving bevel gears and thus altered the stresses in these parts.

The teeth of the high-speed pinion of the propeller reduction gearing were stripped to the extent that the propeller had become uncoupled from the engine. Discoloration from overheat was evident on the high-speed pinion and thrust bearing, with some deterioration having occurred to this latter part also.

The forward edges of the teeth of the high-speed pinion were displaced forward as the pinion progressively failed. The propeller oil transfer housing, which is located just forward of the high-speed pinion, had a circular groove cut into its aft face. This groove mated with the deformed pinion teeth which, by measurement, interfered with the propeller oil transfer housing. The circular groove was of sufficient depth to intersect the internal oil passages. Three successive tests to determine the oil pressure available for feathering subsequent to the described damage resulted in 300 p. s. i., 250 p. s. i., and 215 p. s. i.

The hub, with the propeller shaft, and the four propeller blades fell in five separate units and were found separately but in relatively close proximity to each other where they had fallen from the aircraft. The blades had pulled radially out of the hub bores, as evidenced by the