Page:CAB Accident Report, United Airlines Flight 21.pdf/42

 the fire took place after impact. Lack of fuel could not have contributed to the accident because the fuel tanks were found unbroken and contained about 335 gallons of gasoline.

Examination of the wings, tail surfaces and control surfaces disclosed only damage occasioned by the crash. No structural failure in the air was indicated and the flight controls were intact to the point where they obviously had been broken by the impact. The right wing was intact except for slight damage to the tip and at the trailing edge. The left wing was curled upward from the wing tip to a point about 5 feet outboard of the landing light. The wing flaps were extended to the three-quarter "down" position normal for landing. The tail surfaces were practically undamaged and all trip tabs were intact and in good working condition. The de-icing boots on all surfaces were in good condition except for a few cuts due to the impact.

Inspection of the airplane for ice accumulation showed that ice remained on the nose of the de-icer boot on the right wing about ⅜ of an inch thick, forming a cap extending backward on each side for a distance of 2 inches from the leading edge. This ice was of a rough granular nature. A clear, glaze ice formation of from 1/32 to 1/16 of an inch in thickness extended back of this cap to within one inch of the attachment strip of the de-icer boot. No ice was observed on either the de-icer attachment strip or on the wings back of the strip.

No ice was found on the left wing, probably because it had been