Page:CAB Accident Report, TWA Flight 891.pdf/33

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breakdowns, failures, etc., and, consequently, might have been the direct cause, or a contributing cause, of the crash.

The condition in which several of the individual parts were found, the particular nature of certain Installations, the damage caused by the impact, by the fire, and by the recovery operations, the virtual destruction of many control panels, the fact that the force of the impact moved many levers and smtches to the "on" or "of" position, the changes caused by the breaking off in flight, of part of the aircraft-mall these things rendered the examination extremely laborious. Hence, in some cases the conclusions derived from the examination were not so much the result of concrete and specific physical evidence as they were of careful and logical interpretation and of indirect but interesting indications.

Whenever necessary and considered useful, in order to determine whether certain indiv1dual parts and accessories of the installations were in good working order, such parts were subjected to bench tests and partially or totally disassembled.

We wish to explain that the term "abnormality" employed below means erg failure or breakdown which, having Occurred before or at the time of the accident, might have been the direct or indirect cause of it. HaVing given that explanation, we can proceed to sum up hereunder the results of the various examina- tions.

conditioning system

Pressurization. No abnormality. It was not posSible to determine ether the plane was pressurized at the time of the impact. As to the automatic control of the pressurizing system, see par. 11.2.3.7.

Heating, refri oration and air circulation. No abnormality: specifically, e two—heaters bore no signs of explosmn. It was not poSSible to determine whether the system was in opera.- tion when the plane struck the ground.

Automatic pilot system

No abnormality. It was not possible to determine with certainty whether the automatic pilot was on at the time of the crash. Howev r, a concurrence of considerations leads to the belief that, in all probability, it was not.

A checking of the Air Date Sensor' s calibration, in the condition in which it was recovered, showed the following data:

Altitude: between 2,685 and 7,000 feet Speed: between 1115 and 195 MPH