Page:CAB Accident Report, United Air Lines Flight 823.pdf/9

 also run through this compartment. A degree of isolation of the hydraulic lines from the electrical components was attained in the design by physical separation and barriers. Fire damage in the electrical bay area was extensive, particularly on the left side. The majority of the components were destroyed or not recovered. Examination of the recovered electrical components did not reveal any evidence of a heat generating fault. One battery terminal did show an arc produced mark. No evidence of a hydraulic line leak was found. There was no consistent pattern of inflight fire discernible in this area. Smoke patterns on the main spar cap as well as soot and discoloration patterns on seat track pieces that were installed between FS-335 and FS-414 were given detailed attention. Clean fracture and scrape marks next to sooted or discolored areas and discoloration of seat track pieces on the underside, which is exposed in the electric bay, contrasted with clean upper surfaces which are in the passenger cabin but not exposed.

An inflight fire existed in the passenger-occupied portion of the cabin. The only flammable liquid carried as a part of the airplane above the fuselage floor is hydraulic fluid in a reservoir located in a compartment between the carry-on luggage rack and the lavatory. The reservoir was damaged by impact and fire and was empty. The fire damage pattern in and about the reservoir compartment did not support hydraulic fluid as a contributing factor to the fire. Another source of flammable fluid known to have been aboard the aircraft was a one-gallon can containing a commercial paint modifier. This can was recovered in the wreckage area,crushed with no evidence of fire damage to either the can or its paper wrapping.

Fire damage and smoke patterns were found in three general areas of the passenger cabin. These were (1) Beneath No. 4 window on the left side from approximately FS-388 to FS-395; (2) On the cabin side of the forward bulkhead, FS-198, on its left side; (3) On the exterior wall of the forward lavatory, right side at FS-232. There were other isolated areas of fire or soot damage throughout the cabin including the lower half of the No. 9 window, on several public address system speakers, and on some passenger seats.

Under the No. 4 window there was heavy sooting of the shear cleats of the stringer which were tightly compressed against the fuselage skin during breakup. Clean (unsooted) breaks were noted in the sooted areas under the window as well as clean areas where flush rivets had been pulled from the structure.

Two large sections of the left forward bulkhead, FS-198, had received fire damage. The vinyl material that covers the top half was missing but the backing material was not damaged while the bottom half was heavily matted with a deep soot pattern. Another piece of decorative wall material was heavily sooted and matted but the splintered edges of the plywood backing were comparatively clean. The front wall attachment bracket for the blanket rack was moderately sooted but was clean under the rotated reinforcement plate. Most of the fuselage former sections from FS-399 aft to FS-618 displayed distinct unsooted areas that were covered by blanket rack support brackets before breakup. A portion of a soundproof window was