The United Kingdom Air Accidents Investigation Branch (AAIB) has found no technical malfunction that would account for the fatal crash of an AgustaWestland AW139 helicopter near Gillingham Hall, Norfolk on March 13.
All four people on board the helicopter were killed in the crash, including Northern Ireland peer Lord Ballyedmond; another passenger, Declan Small; command pilot Carl Dickerson; and co-pilot Lee Hoyle.
In a special bulletin published April 3, the AAIB outlines initial facts related to the accident. According to the bulletin, due to passenger delays, the helicopter lifted from Gillingham Hall for Coventry Airport around 7:20 p.m. local time on March 13 — around 50 minutes behind schedule, and after night had fallen and dense fog had developed in the vicinity. Witnesses reported that visibility at the time of the crash was on the order of tens of meters.
As determined by recorded flight data and a video recording of the helicopter’s departure, the helicopter climbed, initially with very little ground speed, and began transitioning to forward flight at a height of approximately 32 feet above ground level (AGL). The radio altitude peaked at 125 feet AGL as the ground speed increased through 60 knots.
The helicopter thereafter pitched progressively nose-down, entering a descent as it did so, and reached a pitch attitude of 35 degrees nose-down one second before the end of the data recording. The final complete frame of recorded data analyzed to date showed a pitch attitude of 25 degrees nose-down, a radio altitude of 82 feet AGL, and a ground speed of 90 knots. The recorded rate of descent was 2,400 feet per minute, and increasing.
The helicopter’s cockpit voice recorder revealed that the co-pilot made two verbal prompts regarding pitch attitude to the commander, who was the pilot flying, during the final few seconds of the flight. Simultaneously, the recorded data shows that full collective was applied.
The recorded data includes parameters relating to cautions, warnings and faults. According to the bulletin, none were active during the accident flight with the exception of the last data points, when full collective had been applied and a gearbox torque-related caution was triggered. The data showed that trim release switches on the cyclic and collective controls, on which force must be applied against springs to achieve manual flight, were active throughout the flight.
The helicopter struck the ground in a gently rising field approximately 420 meters from the takeoff point. There was no evidence that the helicopter had made contact with any other object prior to this point.
“AAIB investigation to date has not identified any technical malfunction which might account for the accident,” the bulletin states. “The investigation continues, with the aim of identifying any technical matters of relevance, as well as focusing on flight in degraded visual environments.”
To read the complete bulletin on the AAIB website, click here.
