Fourteen oil workers and two crew died when the Bond-operated Super Puma plunged into the water off the Aberdeenshire coast while returning from the BP Miller platform on April 1, 2009.
Verner Hill, an engineer and deputy shift supervisor with Bond at the time, said he was “unhappy” and “uneasy” after a problem was detected in the aircraft days before the tragedy.
Mr Hill, 54, who now works as a fleet support specialist with Bristow Helicopters, was giving evidence at a fatal accident inquiry at Aberdeen’s Town House.
He was on duty on March 25, 2009 when a colleague flagged up a problem with the helicopter’s health and usage monitoring systems (Hums) during a turnaround inspection after the aircraft’s first flight rotation that day.
The helicopter had flown from Aberdeen to the Unity platform in the North Sea, returning at 8.20am.
Mr Hill said data downloaded from the Hums showed a purple flashing warning light on the main gearbox indicator that appeared to indicate its chip detector had picked up a particle of metal.
The issue was only discovered after the helicopter had taken off on another flight at 9.25am, the inquiry heard. Mr Hill said that at the time there was no requirement for Hums data to be fully downloaded and examined before a helicopter took off again, but that was now standard procedure.
He said he spoke to his line manager about the problem after further checks were carried out and no more anomalies were found. “I was asking whether we needed to recall the aircraft from flight, if I remember correctly,” he said. “I wasn’t told to recall it.”
He was shown a report prepared after the fatal crash which, he told the inquiry, appeared to indicate that the particle had been detected 94 times.
When the helicopter returned at 11.40am, Mr Hill and another colleague carried out an inspection on the main gearbox and no particles were found, the inquiry heard. But an examination of the Hums after the helicopter’s second flight still showed the warning.
An investigation into the crash has found that the aircraft suffered a “catastrophic failure” of its main rotor gearbox.
The inquiry before Sheriff Principal Derek Pyle is expected to last about six weeks and will examine the circumstances of the crash in order to prevent any future tragedy.