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Glasgow helicopter crash investigation finds both engines 'flamed out' Glasgow helicopter crash investigation finds both engines 'flamed out' Glasgow helicopter crash investigation finds both engines 'flamed out'
(1 day later)
The investigation into last November's fatal helicopter crash in Glasgow has found that both the aircraft's engines "flamed out" suddenly, causing it to lose power and fall "at a high rate of descent".The investigation into last November's fatal helicopter crash in Glasgow has found that both the aircraft's engines "flamed out" suddenly, causing it to lose power and fall "at a high rate of descent".
The Air Accident Investigation Board (AAIB) said it was still unclear why both the engines had cut out, or flamed out, in quick succession, despite weeks of exhaustive examination of the Eurocopter EC135 T2 wreckage at the board's Farnborough headquarters.The Air Accident Investigation Board (AAIB) said it was still unclear why both the engines had cut out, or flamed out, in quick succession, despite weeks of exhaustive examination of the Eurocopter EC135 T2 wreckage at the board's Farnborough headquarters.
Ten people were killed when the Eurocopter hit the Clutha bar in central Glasgow, when the well-known pub was packed with people watching a local ska band perform. The dead included both the pilot, the experienced RAF combat veteran Captain David Traill, and two police officers, Kirsty Nelis and Tony Collins.Ten people were killed when the Eurocopter hit the Clutha bar in central Glasgow, when the well-known pub was packed with people watching a local ska band perform. The dead included both the pilot, the experienced RAF combat veteran Captain David Traill, and two police officers, Kirsty Nelis and Tony Collins.
The cause of the accident has until now mystified investigators, hampered partly by the lack of black box flight recorders on that type of aircraft.The cause of the accident has until now mystified investigators, hampered partly by the lack of black box flight recorders on that type of aircraft.
But the AAIB said it had now discovered that the combustion in both engines suddenly cut out, according to information found in the engine's FADEC digital controllers after a series of warnings about low fuel and an "alarm gong" going off to warn of engine problems.But the AAIB said it had now discovered that the combustion in both engines suddenly cut out, according to information found in the engine's FADEC digital controllers after a series of warnings about low fuel and an "alarm gong" going off to warn of engine problems.
Even so, there was no distress signal from the pilot.Even so, there was no distress signal from the pilot.
It said there was first a temporary warning and then a permanent warning for low fuel in the left supply tanks and also a permanent warning for low fuel for the right-hand tank.It said there was first a temporary warning and then a permanent warning for low fuel in the left supply tanks and also a permanent warning for low fuel for the right-hand tank.
"Recorded data indicates that, in the latter stages of the flight, the right engine flamed out, and shortly after the left engine flamed out," a new special report said."Recorded data indicates that, in the latter stages of the flight, the right engine flamed out, and shortly after the left engine flamed out," a new special report said.
"The helicopter descended and struck the roof of the Clutha Vaults bar at a high rate of descent, in an upright attitude. Evidence indicates that the rotor blades and Fenestron tail rotor were not rotating at the moment of impact. The force of the impact caused the roof to collapse and the helicopter entered the building.""The helicopter descended and struck the roof of the Clutha Vaults bar at a high rate of descent, in an upright attitude. Evidence indicates that the rotor blades and Fenestron tail rotor were not rotating at the moment of impact. The force of the impact caused the roof to collapse and the helicopter entered the building."
It continued: "An alarm gong was also recorded followed by intermittent warnings relating to low rotor rpm. The penultimate warning recorded related to the battery discharging, which occurs when there is insufficient engine-driven generator power. The last warning related to an autopilot system failure.It continued: "An alarm gong was also recorded followed by intermittent warnings relating to low rotor rpm. The penultimate warning recorded related to the battery discharging, which occurs when there is insufficient engine-driven generator power. The last warning related to an autopilot system failure.
"Investigation into the possible causes for the individual warnings is continuing.""Investigation into the possible causes for the individual warnings is continuing."
The AAIB said the manufacturer's flight manual instructed a pilot to land within 10 minutes of fuel warnings, but they could not be certain when the warning lights came on. The helicopter was only a few miles from its base near the Glasgow Transport museum, and investigators found roughly 76kg of fuel left in the main tank.The AAIB said the manufacturer's flight manual instructed a pilot to land within 10 minutes of fuel warnings, but they could not be certain when the warning lights came on. The helicopter was only a few miles from its base near the Glasgow Transport museum, and investigators found roughly 76kg of fuel left in the main tank.
It added there was no evidence of any damage or malfunction of the fuel supply and transfer pumps, nor was there any evidence of foreign bodies or blockages, while the engine fuel control units were "found to be serviceable in all respects".It added there was no evidence of any damage or malfunction of the fuel supply and transfer pumps, nor was there any evidence of foreign bodies or blockages, while the engine fuel control units were "found to be serviceable in all respects".
It reported: "Examination of all internal pipe work and transfer passages has not revealed any pre- or post-impact failure and all paths still permit uninterrupted fuel flow.It reported: "Examination of all internal pipe work and transfer passages has not revealed any pre- or post-impact failure and all paths still permit uninterrupted fuel flow.
"It has been established that unrestricted flow was also available from each supply tank to the corresponding engine fuel control unit, through the relevant fuel shut-off valves which were found set to the open position.""It has been established that unrestricted flow was also available from each supply tank to the corresponding engine fuel control unit, through the relevant fuel shut-off valves which were found set to the open position."
It continued: "There was no evidence of foreign object damage or intake or exhaust blockage in either engine. Also, there were no signs of bearing or lubrication system failure, and the oil system chip detectors were clean and free from metallic particles."It continued: "There was no evidence of foreign object damage or intake or exhaust blockage in either engine. Also, there were no signs of bearing or lubrication system failure, and the oil system chip detectors were clean and free from metallic particles."
After testing and examining the aircraft's main and rear rotors, the AAIB found "all of the damage to the main rotor and Fenestron blades was attributable to impact with the building and supports the evidence that they were not rotating just before or at the point of impact.After testing and examining the aircraft's main and rear rotors, the AAIB found "all of the damage to the main rotor and Fenestron blades was attributable to impact with the building and supports the evidence that they were not rotating just before or at the point of impact.
"From the overall examination and assessment of the system no faults have been found with the transmission or rotor system.""From the overall examination and assessment of the system no faults have been found with the transmission or rotor system."
The report said investigations were continuing: "In particular, the investigation will seek to determine why a situation arose that led to both the helicopter's engines flaming out when 76kg of fuel remained in the fuel tank group, why no emergency radio transmission was received from the pilot and why, following the double engine failure, an autorotative descent and flare recovery was not achieved."The report said investigations were continuing: "In particular, the investigation will seek to determine why a situation arose that led to both the helicopter's engines flaming out when 76kg of fuel remained in the fuel tank group, why no emergency radio transmission was received from the pilot and why, following the double engine failure, an autorotative descent and flare recovery was not achieved."
A spokesman for the British Airline Pilots Association said the report was a useful step in trying to find out what caused the crash.A spokesman for the British Airline Pilots Association said the report was a useful step in trying to find out what caused the crash.
"We now know that the engines were not running at the time of the crash and it appears this was to do with the fuel system," he said."We now know that the engines were not running at the time of the crash and it appears this was to do with the fuel system," he said.
"However, pilots, like the AAIB, will not be satisfied until this is explored further and the exact reason for that failure is identified. The AAIB have our continued support in their work.""However, pilots, like the AAIB, will not be satisfied until this is explored further and the exact reason for that failure is identified. The AAIB have our continued support in their work."