The helicopter manufacturer Airbus took more than a decade to issue a worldwide alert about persistent water leaks in the fuel systems of the EC135 aircraft model that crashed into the Clutha pub, killing 10 people in 2013.
The Fatal Accident Inquiry (FAI) into the crash heard last week that Bond Air Services engineers had first raised the issue of water contamination in 2003. On 27 June of that year, Mr David Price, then Bond's head of engineering, wrote to Eurocopter Deutschland – part of Airbus – to raise concerns that a hydro-mechanical unit (HMU) could suck water into the engine. Mr Price believed that the problem had been caused by a previous change to how the aircraft were produced in the factory. His engineers solved the problem temporarily by disconnecting the unit and changing a pipe. When no water contamination had been found after five days of taking samples, they recommended the move to Airbus for approval.
Ten years later, on the very morning of the Clutha incident, fuel system changes were still being discussed by an internal committee at Airbus. A worldwide service bulletin outlining changes to be made to the fuel supply system was finally issued to aircraft operators in April 2014 – five months after the Clutha crash and another incident involving an air ambulance at Barton, near Manchester.
Mr Price, 56, now at Babcock Aviation Group, which took over Bond, detailed a series of incidents and complaints concerning inaccurate fuel readings, many of them caused by water contamination. This was traced either to occasions when refuelling had been carried out during heavy rain, but more commonly after scheduled washing of aircraft engines. When 770 fuel sensors were tested from EC135 aircraft worldwide in early 2014, just 698 were passed, with 72 others showing some form of 'indicator drift'.
Mr Price told the inquiry that, as far back as 2003, the possibility of water getting into the fuel system had been a primary concern. He wrote to Airbus contact Ralf Nicolai: 'The HMU has been sucking water into the engine during the starting cycle and some is returning to the tank. As the engine accelerates past 5%, some water passes into the engine fuel system'. He was told by Mr Nicolai that 'we are on the case now,' but complained two years later in 2005 that no action had been taken. Mr Nicolai blamed 'other priorities'.
At one stage, another Eurocopter representative, Kelly Brookes, had suggested to Mr Price that a proposed solution was not workable, and proposed a new approach. Mr Price and his colleagues felt that Airbus (Eurocopter's owners) were passing the buck back to Bond. 'There was a feeling of great frustration on a number of occasions over 10 years. What was basically conveyed was "you use your design department rather than us using ours to come up with a solution",' recalled Mr Price.
In June 2011, pilot Craig Trott complained to senior colleagues about 'fuel issues' concerning the Police Scotland aircraft, registration G-SPAO. On take-off from Islay, his fuel readings had differed significantly from the figures checked on landing. A red fuel warning lamp had lit up, even though the fuel readings were normal, and there was another disparity during the journey back to base in Glasgow.
Captain David Traill, the pilot who died at the controls of the police helicopter during the Clutha crash, had completed a 'very accomplished' proficiency test with the manager in charge of training at Bond Air Services a year before the tragedy. Alex Stobo, 44, director of operations at Babcock mission critical services supervised the pilot's annual test in 2012. He told the inquiry that the experienced pilot performed to a 'very high standard' throughout the test.
Mr Stobo told advocate depute Gordon Lamont that Babcock had tightened up its guidelines and practices since 2013, but denied that the changes had stemmed wholly from the Clutha incident. The minimum amount of fuel recommended for the EC135 model helicopter is now 90kg, rather than the previous 60kg. 'We now have an electronic flight monitoring system that has triggers that will alert us if fuel levels on the aircraft go below 90kg,' he added.
Previously, Mr Stobo and senior managers relied on pilots to report whether they had gone below minimum fuel levels. He told Donald Findlay QC, acting for the family of one victim, that Captain Traill should have issued at least a 'Pan' warning – whereby an aircraft would get priority to land because of low fuel – to air traffic control, and probably a full Mayday alert. Mr Findlay put it to him that pilots would have had little incentive to report that they had flown with less than the minimum recommended fuel levels, if they had made a safe landing. 'They should report it,' said Mr Stobo.
The inquiry heard that Captain Traill had passed an autorotation exercise carried out on a simulator, during the June 2012 test. On the night of the fatal crash 17 months later, he made several unsuccessful attempts at autorotation – an emergency procedure used when both engines have 'flamed out' or failed – during the seconds before hitting the pub roof.
Ms Shelagh McCall QC, representing Captain Traill's partner Dr Lucy Thomas, raised the possibility that the pilot may have been flying using 'visual contact' (VFR) rather than his night-time instruments, and therefore believed he would have enough fuel to land. 'If the pilot had thought he was operating on VFR and had 65kg in the tank, they would not have needed a Mayday,' she suggested. 'Correct,' said Mr Stobo.
Two weeks later, the air ambulance made an emergency landing at Barton after an erroneous fuel warning. Police in Saxony, Germany, had reported a similar incident at Dresden Airport. Thereafter, Airbus made a worldwide recall to check fuel systems on hundreds of EC135 aircraft.
The crash helicopter had been diagnosed with two faulty fuel sensors four months earlier. Engineer Bill Meredith told the inquiry that he had been unable to complete a full annual audit of the EC135 aircraft in April 2013, because a replacement helicopter had not been available at Glasgow heliport. Mr Meredith, 48, then the quality assurance manager for Bond Air Services said he had found five 'discrepancies' with the aircraft, all of which were repaired or had parts replaced. His check did not include the fuel system.
However, on 8 July, a sensor in the main tank was found to be responsible for 'inaccurate' fuel readings and replaced. Two days later, another fuel tank sensor was changed after further discrepancies were uncovered. Police air observer PC Alistair Rennie, who flew with Captain Traill regularly and had been onboard G-SPAO during an earlier shift on the day of the crash, described the pilot as 'a safe pair of hands' and a 'stickler' for procedure.
Captain Traill, 51, and police observers Tony Collins, 43, and Kirsty Nelis, 36, died in the cockpit, as the crash killed Clutha customers Gary Arthur, 48; Joe Cusker, 59; Colin Gibson, 33; Robert Jenkins, 61; John McGarrigle, 57; Samuel McGhee, 56; and Mark O'Prey, 44. Thirty-one others were injured.
The inquiry, before Sheriff Principal Craig Turnbull at Hampden Stadium, continues.
Maurice Smith will be attending and reporting on the Clutha FAI in SR