Page:CAB Accident Report, Pacific Air Lines Flight 773.pdf/4

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At O'Z20, the Oakland ARTCC watch supervisor received information that the wreckage of Flight 773 had been located.

Witnesses along the path of flight and near the impact area describe a generally westward flight path prior to impact. They describe extreme and abrupt changes in attitude of Flight 773 coupled with erratic powerplant sounds and a large ball of fire following the final impact. Weather conditions at the time were described as overcast sky with good visibility.

The aircraft struck the up—slope of a 25.2 degree hill at a relative angle of 90.2 degrees. The wreckage was confined to the east slope of the 800 foot hill and strewn 1,050 feet up the slope along a 500 foot width from the main crater on approximately a 270 degree magnetic heading. The aircraft heading at impact was 216 degrees magnetic. The main crater was at the 6130 foot elevationéf

Allmf the aircraft's flight control surfaces were found around the main impact crater. The elevator and rudder trim actuators were found in the 3 degree nose-down and 1-2/3 degrees nose-left positions, respectively. Impact damage was so extensive that aileron trim could not be determined.

The landing gear cockpit indicator was found with the "up" position in all three windows. ihe gimbal nuts on the flap jackscrews indicated flaps were in a retracted position. Examination revealed no evidence of any failure or mal- function of the aircraft or any of its components prior to impact. There was no in—flight fire nor evidence of operational causal factors.

Both engines were severely damaged by impact. Examination of*rotating parts damage indicatedethat the right engine was at a high rotational speed but that the left engine had little or no rotation at time of impact. Contrasting left and rights propeller blade damage tended to confim that the right“ engineuwas developing power at impact while the left engine was not. Howeverrthere was no evidence to indicate that either powerplant had not been capable of normal operation.

Ekamination of the propeller blade bottom bearing races and of the pro- peller dome piston positions indicated that blade angles at impact had been ap- proximately 55 degrees and 145 degrees for the left and right propellers, respec- tively. Propeller performance data indicate that at the high impact airspeed evidenced by the flight recorder, hS degrees would have been an appropriate blade angle at an engine speed of approxmately 13,000 r.p.m. However, the 55 degrees left propeller blade angle is not consistent with normally powered operation of the propeller.

The cockpit area was so completely destroyed by impact that onlyr four small pieces of the instrument panel were retrieved. No single portion of more than eight square inches was recovered. Portions of the seat frame tubing from the captain's seat were recovered. chmSCopic examination of the tubing at

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6 The coordinates of the main crater were 3701;5'311" north latitude, 121° '21:“ west longitude.