Page:CAB Accident Report, Braniff Airways Flight 542.pdf/20

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This would not create a hazard or place the aircraft in an attitude from which recovery would be difficult.

The extremely brittle ash res1due of the left air compressor of the air start system flaked away readily when handled, indicating that the compressor had burned where found on the ground at the left wing impact eite. Examination of the 81'1ng fire extinguishing system showed that the selector valves were in their normal peeitions and that none of the fire bottles had been discharged by crew action.

The pertinent observations of the phySical eVidence can be summarized as follows:

1. Inflight fire Was confined to the extreme inboard portion of the left wing, cauSing heat damage to the left windows rear of the wing trailing edge and sooting of the left rear fuselage.

2. The No. 2 fuel tank showed no eVidence of internal pressure or explosion and the planking fragments were burned and sooted in a random pattern.

3. The left inboard leading edge, the lower planking and the rear spar show- ed that the left wing failed at the inboard one-third of the No. 2 tank in upward bending and noseup torSion. The relatively small fragments of the upper planking indicated a strong probability of failure resulting from a high peeitive load.

4. The wing station No. 83 closmg rib of the left leading edge showed metal—to—metal scratches. Microscopic examination disclosed three to four changes of direction in these predominantly vertical marks.

5. The fracture faces of lower wing plank No. 3 at Wing station No. 65, left, showed eVidence of haVing recontacted each other after the fracture occurred. Microscopic examination revealed at least three cycles of recontact.

6. The forward attach pomt of the No l QEC upper outboard longeron showed heavy compressmn loading prior to failure and further disclosed multiple direc- tions of local bending in the several longeron members.

7. The forward attach area of the No. l QEC upper inboard longeron revealed a tension failure followed by a recontact of the fracture faces in a would—be compressmn load.

8. The electrical connectors and their wiring at the No. l nacelle firewall were failed in multiple directions of bending.

9. At the No. l firewall, the fuel line was bent up/inboard and down/outboar; prior to ultimate failure which was up/outboard.

10. Found in the No. l nacelle shroud were indentations which were made by the antiswirl assembly clamp bosses. There were also multiple clamp marks around the shroud but less pronounced than those at the clamp splitline.

11. Both No 1 gear box Lord mounts showed eVidences of repeated yaw loads and some indication of rear load. The rear mount disclosed exceSSive relative motion of the mount with respect to the nacelle structure.