Page:CAB Accident Report, Pan Am Flight 4.pdf/4

- 4 - four stages of the turbine section. Ninety-five guide vanes, from the PAA serviceable vane pool, were installed in the third stage. The first and second stage turbine inner air seals were removed, inspected, the No. 2 seal reworked, and both seals were reinstalled in the engine. The third and fourth stage inner air turbine seals were removed, reworked, and the third stage seal replaced with a new part while the fourth stage seal was replaced with a reworked part. The front compressor drive turbine rotor shaft was replaced. All recorded measurements of clearances in the reassembled engine were within the manufacturer's prescribed limits. The engine was tested in an engine test stand, inspected, and approved for installation.

Following its installation on 761PA the engine operated for slightly over 39 hours with no reported discrepancies.

The center of gravity (c.g.) limits for this flight were 16-35 percent. The takeoff c.g. was computed to 30.2 percent MAC at a weight of 266,631 pounds. According to Boeing Company computations, after engine separation the gross weight was 258,159 pounds and the c.g. was 29.3 percent MAC. Following the loss of the outer wing section the weight was 255,154 pounds and the c.g. was 28.3. landing weight was 249,538 pounds with a c.g. of 28.2 percent MAC. The weight and c.g. were within limits throughout the flight.

The aircraft had been serviced with 88,000 pounds of Jet A turbine fuel before takeoff. Approximately 82,000 pounds of fuel was aboard after landing.

1.7 Meteorological Information

The weather was clear and sunny, visibility 8 miles, temperature 77°F., and the wind from 310° at 15 knots.

1.8 Aids to Navigation

Not applicable.

1.9 Communications

Air to ground communcation [sic] was continuous although it was necessary for other aircraft to relay messages during part of the flight.

1.10 Aerodrome and Ground Facilities

Not applicable.

1.11 Flight Recorder

The flight recorder installed in this aircraft was a Lockheed model 109. The flight recorder tape was examined and read out for the entire flight, approximately 24 minutes and 30 seconds. Approximately 39 seconds after the indicated lift-off time the heading trace shows a sharp yaw, with a 1 "g" excursion of the acceleration trace. About 63 seconds after lift-off momentary excursions of the acceleration trace from 0.2 to 1.75 "g" were noted with variations of the heading, aircraft speed, and altitude trace occurring at the same time. No other significant variations occurred. There was no mechanical damage to the recorder medium.