Page:CAB Accident Report, Allegheny Airlines Flight 604.pdf/4

- 4 - 1.8 Aids to Navigation

All aids to navigation serving the airport, including the ILS localizer, glide slope, and marker beacons, and the VOR radio range, were operating properly.

1.9 Comunications

There were no reported problems with communications. The captain was making all transmissions.

1.10 Aerodrome and Ground Facilities

The Willimsport—Lycoming County Airport is located in the Susquehanna River valley which is approximately one mile wide at the airport. The elevation is 528 feet 3.3.1. The principal runway, Runway 9-27, is 5,050 feet long and 150 feet wide with a bituminous surface. This runway essentially parallels Bald Eagle Mountain which forms an east-west ridge 12 miles long and over 2,000 feet high} just south of the air- port. The mountain extends approximately six miles east of the airport at which point the valley Opens to the southeast. The terrain to the north and northeast of the airport is composed of numerous knolls and valleys which rise rapidly to an eleva- tion of 1,300 feet m.s.l. Approximately nine miles northeast of the airport is Allegheny Ridge, with rough, heavily wooded terrain over 2,000 feet m.s.l.

1.11 Flight Recorder

The aircraft was not required to have a flight recorder, and none was installed.

1.12 Wreckage

Initial impact Occurred in an open field on the upslope of a small hill, at an elevation of approximately 1,100 feet m.s,1. The aircraft skidded approximately 320 feet in a northeasterly direction over the top of the rise and down a steep slope on the opposite side, finally coming. to rest on a heading of 035 degrees. The outboard 23 feet of the right wing was separated from the aircraft when it struck and severed an electric line pole at the top of the hill. The outboard 38 feet of the left wing was separated and broken into three sections. The fuselage ruptured between the cock- pit and cabin area, leaving a large hole on either side, just forward of the passenger compartment. The aircraft was gutted by ground fire several minutes after impact.

The landing gear and flaps were up at impact. The rudder, aileron, and elevator trim box rod extensions as found in the wreckage, were set on a sister aircraft to determine the approximate tab positions. The rudder and aileron trim tabs were neutral and the elevator was 2-1/2 degrees noseup.

The left engine fron accessory section, with the propeller installed on the propeller shaft, was detached from, but adjacent-to, the power section which had also separated. The power section was severely damaged by impact and intense heat from ground fire. The propeller blade angles as indicated by impact markings on the blade shimn plates were 34-35 degrees. There were slash marks from the left propeller blades at successive distances of 2 feet 8 inches, 2 feet 8 inches, 4 feet 8 inches, and 7 feet. The position of the propeller governor electric head high RPM adjusting screw indicated an engine. RPM of 2750. Computations based on this RPM and the intial propeller slash marks revealed that the aircraft was traveling at an airspeed of 98 knots at impact.