Page:CAB Accident Report, TWA Flight 891.pdf/44

 11.h.16

11.11.17

11.h.18

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Inspection of the vent outlets of the wrecked plane

The inspection was made in order to ascertain whether the vents showed traces of lightning strikes or of static electric discharges (streamer corona) such as might cause gasoline vapors to ignite.

The examination diSclosed that the vents showed no ev1dence of electric discharges; however, it was deCided that this did not exclude the possibilityT that static discharges had occurred in the vents that could have ignited the gasoline vapors issuing from them.

Microspectrographic examination of the metallic mesh filter

This examination was made in order to ascertain whether the filter might have been, in some way, the starting paint of the explosmn in that tank and whether it showed anything abnormal.

The result of the examination was negative. Tests on the ignition of gasoline vapors issuing from the vent outlets of Super Constellation plane L-1649-K, by means of static electrical discharges (streamer corona) These tests, made in a specialized laboratory, disclosed that: [1] On an L—16h9—A plane static discharges should occur at the vent outlets if the aircraft is struck anywhere by lightning, or, if it is not struck, when it flies through clouds that are charged with electricity;

[2] Static discharges, generated at the vent outlets, can and do ignite the gasoline vapors issuing from the outlets;

[3] Static discharges can, and generally should, develop tau-.11.

out leaving on typical aircraft metals, and therefore on the vent outlets, any normally ViSible endence.

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CHAPTER XII GROUND INSTALLATION S

The)r are not pertinent to the purposes of this inquiry.