Investigators probing a fatal helicopter crash in Glasgow last year have released an update on their latest findings.
All three people on board the EC135 Eurocopter died when it crashed on to the roof of the Clutha Vaults, killing seven other people and seriously injuring a further 11 who were in the pub at the time.
The aircraft had been on police operations when it came down just after 10pm on November 29, in Stockwell Street near the city centre.
Specialists from the Air Accident Investigations Branch (AAIB) are carrying out an ongoing methodical investigation.
An interim report, issued by the AAIB, has revealed that both engines failed, although there was no evidence of fuel leaks or blockages.
The exact time of the engine failures, known as flameouts, is unknown.
The right engine stopped first, followed shortly by the left one. Both engines were dismantled and examined, finding no evidence of foreign object damage, or intake or exhaust blockage in either.
There was also 167lb of fuel in the supply tanks. Recorded data has now been analysed, although the majority of information gleaned so far has no form of time stamp.
Investigators found that low fuel warnings had been triggered by thermal sensors in the supply tanks, appearing intermittently at first, then permanently.
In the manufacturer’s flight manual for the helicopter, the pilot is instructed to “land within 10 minutes” on receipt of these warnings.
An alarm also sounded, followed by intermittent warnings relating to low rotor speed.
The penultimate warning recorded related to the battery discharging, which happens when there is insufficient engine-driven generator power, followed by the last warning, indicating an autopilot system failure.
Investigators have not yet identified causes for the individual warnings. The AAIB investigation will continue to examine all operational aspects of the accident. In addition to the cause of the engine failure, investigators will seek to determine why no emergency radio transmission was received from the pilot.
Specialists will also look at why the aircraft’s blades did not continue to rotate, as designed.