Unfallbericht:EC-135N aircraft 61-0328, call sign AGAR 23, was scheduled for an Advanced Range Instrumented Aircraft (ARIA) training mission out of Wright-Patterson AFB. The mission was designed provide training for the navigator and primary mission electronic equipment (PMEE) operators. On board the aircraft were 17 crewmembers and four authorized passengers. AGAR 23 departed at 10:05 and climbed to FL290, which was reached at 10:30. The aircraft commander occupied the right pilot seat and a passenger, his wife, occupied the left pilot seat.
|Datum:||Mittwoch 6 Mai 1981|
|Fluggesellschaft:||United States Air Force - USAF|
|Baujahr:|| 1961-11-14 (19 years 6 months)|
|Triebwerk:|| 4 Pratt & Whitney TF33-PW-102|
|Besatzung:||Todesopfer: 17 / Insassen: 17|
|Fluggäste:||Todesopfer: 4 / Insassen: 4|
|Gesamt:||Todesopfer: 21 / Insassen: 21 |
|Konsequenzen:|| Written off (damaged beyond repair)|
|Unfallort:||3 km (1.9 Meilen) NNE of Walkersville, MD ( USA)
|Flugphase:|| Während des Fluges (ENR)|
|Flug von:||Dayton-Wright Patterson AFB, OH (FFO/KFFO), USA|
|Flug nach:||Dayton-Wright Patterson AFB, OH (FFO/KFFO), USA|
For undetermined reasons, the aircraft pitch trim moved to the full nose-down position. The autopilot can overcome the trim until near full nose-down. The aircraft then rapidly pitched over, most likely upon release of the autopilot, and induced sufficient negative g forces to cause the generators to trip off line and loss of all AC electrical power. The pitch trim could not then be moved electrically. This condition, while unusual, can be easily controlled if prompt corrective action is taken; however, if corrective action is delayed approximately 8 sec., the aircraft pitch angle will be greater than 30 deg. nose-down and the airspeed in excess of 350 KIAS. Under these conditions, the aircraft cannot be controlled until the pitch trim is moved toward neutral. While it is clear that recovery was delayed, the reason for the delay is unknown. The aircraft became uncontrollable and entered a steep descent. The aircraft emerged from the clouds at 2,000 ft. AGL. Airspeed was in excess of 400 KTAS and dive angle was 20 to 30 deg. Engine power was above 2.0 EPR. At approximately 1,500 ft. MSL an explosion occurred inside the pressurized compartment of the fuselage and weakened the aircraft structure to the extent that catastrophic failure of the aircraft followed immediately.
This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.