-21..
12. The No. l engine‘s first stage compressor blades rubbed the inSide of the air inlet houSing.
13. Examination of the structure for fatigue produced completely negative results.
In reference to the localisation of the left inboard wing fire, as mentioned, it seems proper to present the follow1ng: At no point can there be found a con- tinuous fire or heat pattern across the rear portion of the wing, particularly along the Spar, the back Side of which is white, and the upper trailing edge sur— face, the under side of which is white. This material was clean. Two of the flap beams, flap station No. 174 and flap station No. 106, Showed some sooting; however, the soot marks are not continuous across break lines. The inboard flap beam at wing station No. 72 was completely clean. This beam went into the main wreckage area with the center section. The flaps themselves had fire patterns on them; however, at any paint where there was a fire pattern it could be shown that it did not eXist prior to the breakup of the flap and.most of this fire occurred in the area where the flap was torn through as a result of wing failure. Inboard of the station No. 72 flap beam there was evidence of inflight fire, and such would be expected Since there was a ball of fire paSSing through this area at the time of wing failure. The only point at which fire or heat can get into the fillet area on the rear portion of the wing is through a small opening under the fillet and above the Junction point of the upper cap of the rear spar to the fusslage. This area was completely clean and showed no evidence of soot, fire, or heat. This area, incidentally, is white and would show soot very readily. The only other way to get heat into the fillet area from outboard would be through the leading edge and through a similar opening from the leading edge into the fillet area; however, this did not get sooted in any way. It was noted during the mockup period that the trailing portion of the wing fillet makes a SCOOP or funnel capable of holding several gallons of kerosene, and ahead of this area there is a place where addi- tional fuel could be trapped for a short period of tune. This could contribute to a more prolonged fire than might normally be conSidered possible.
Any comprehenSiVe analySis must conSider, along with.the positire evidence in the wreckage, the following negative points
1 In the 07 radio call to the company the only maintenance items reported were an inoperative No. 3 sump pump and the bonding of a terminal strip. This was only two minutes prior to the accident.
2. There was no turbulence along the route of this flight at operating altitudes.
3. There was no record of this aircraft being subgected to a hard landing or to any appreCiable turbulence during its lflO—plus hours Since manufacture. There could be found only one inCident of any poss1ble maltreatment of the air— frame. This occurred on September 22, 1959, during a training flight wherein the pilot entered a secondary stall following an improperly executed stall recovery Any likelihood of damage resulting from this maneurer has been evaluated and dis- missed under Investigation.
4 According to ARTE records there was no conflicting traffic of aircraft operating on flight plan. The U. S. Nagy adVised that there were no aircraft
