Page:CAB Accident Report, Allegheny Airlines Flight 604.pdf/7

- 7 - the engine has a dry takeoff rating of 2,050 HP at 2700 RPM, and a wet rating of 2,000 HP at 2800 RPM, it is believed that the engine was producing takeoff power at the time of impact.

The weather is not considered to have-appreciably affected the operation of the flight, if at all. The haze restriction to visibility may have eliminated a clearly defined horizon, but the crew was very familiar with the topography, and the higher elevations to the northeast ware within four miles of the runway. In addition, the haze would not affect vertical visibility and the estimation of altitude above the terrain, nor would it preclude visual reference to the river valley to avoid high terrain. Likewise, the temperature would only reduce performonce about ten percent below standard day values. Neither of these circumstances represents causal involvement. The pilot-trainee stated that the air was smooth, and therefore turbulence did not aggravate the situation.

Despite the lack of information from the pilots, and the lack of a flight recorder on the aircraft, a certain meaningful sequence of events has been established. The testimony of the pilot-trainee revealed that the liftoff and gear retraction were normal. While he did not observe the flaps being retracted, he did recall that the propeller was manually feathered by the captain. Since the autofeather switch is not turned off until the flaps are raised, it is believed that they were retracted prior to the engine difficulty, and after acceleration to 126 knots. If the flaps had been raised prematurely, and then the engine failed, the crew would have lost control of the aircraft prior to climbing over 500 feet and traversing in excess of five miles to the crash site. However, a correlation of the estimated time at which the flaps would normally be retracted, 1:15 to 1:30 minutes after takeoff, and the-transmission that the right propeller was feathered, 2:30 minutes.after takeoff, indicates that the engine failure occurred very shortly after the flaps were retracted. During the next 1:30 minutes the right engine failed, the propeller was feathered, and the aircraft crashed 45 degrees left of the takeoff heading, approximately two miles north of the extended runway centerline.

The investigation established that the aircraft has the capability to accomplish a straight-ahead, single-engine climb to an altitude of 1,500 feet m.s.l. in approximately three minutes, even when the temperature is 78 degrees and the engine failure occurs at V$1$. Further, that the diameter of turn.under these conditions would be just over one mile using a nominal bank angle of 20 degrees. This should have enabled the-flight to avoid surrounding high terrain and negotiate a successful single-engine landing at the airport. Since Allegheny requires the pilots to practice single-engine turns in either direction, using 30 degrees of bank, on proficiency checks the captain should have performed such maneuvers within the preceding 30-day period.

Based upon the evidence it is apparent that subsequent to the engine failure the crew did not follow prescribed operating procedures for a straight-ahead single-engine climb. Because of the lack of information from the crewmembers, who testified that they could not recall any of the events surrounding the-flight, the Board will not undertake to speculate as to the reasons why the crew deviated from the runway heading, except to state that if the proper emergency procedures for single-engine operation had been followed the accident might not have occurred.