Glasgow Helicopter Crash – Press Clueless

[Update at end of post]

The creative ability of the Fourth Estate, it seems, now extends to reinterpreting Special Bulletins published by the Air Accidents Investigation Branch (AAIB) to reach conclusions that have not actually been made. This can be seen in the reaction to Bulletin S9/2013 giving preliminary findings from examination of the helicopter that crashed into the Clutha Bar in Glasgow eleven days ago.

A Eurocopter in service in the West Midlands

“Engine failure was NOT to blame for helicopter crash into pub which killed nine say accident investigators” thunders the Daily Mail – wrongly. The AAIB didn’t say that. Perhaps someone else would care to have a try? The deeply subversive Guardian tries “Glasgow helicopter crash investigation finds no evidence of engine failure” which is closer, but still not totally correct.

What does the BBC say? “Clutha helicopter crash: AAIB finds 'no evidence' of mechanical fault”. That’s closer still, and the Maily Telegraph concurs: “No mechanical faults found on Clutha crash helicopter”. Both these reports could have benefited from the addition of the word “yet”. Let’s go through the relevant part of the Bulletin to see just what the AAIB has said.

“Preliminary examination showed that all main rotor blades were attached at the time of the impact but that neither the main rotor nor the fenestron tail rotor were rotating”. So the earlier Mail speculation resulting from an earlier manufacturer’s advisory notice was wrong. The rotor blades were all present and correct, but when the aircraft crashed they were not functioning.

Fuel situation? “Approximately 95 litres of fuel were drained from the fuel tank system”. That doesn’t look low enough to make fuel starvation a cause. Now the main event: “Initial assessment provided no evidence of major mechanical disruption of either engine and indicated that the main rotor gearbox was capable of providing drive from the No 2 engine power turbine to the main rotor and to the fenestron drive shaft”. That has been interpreted as “no evidence of engine failure”.

However, and in these matters there is inevitably a however, “Clear impact distortion of the structure had caused a splined shaft on the drive train from the No 1 engine to disengage, preventing a similar continuity check”. The Eurocopter EC135 is a twin-engined machine. Drive from the No 1 engine has not yet been checked over.

What the AAIB has told is that, yes, the gearbox looks OK, as does the drive from the No 2 engine. But the rotors were not turning at the time of the crash. Therefore it appears that no power was being transmitted to them, which suggests that the engines ceased to provide power. What may have led to that situation will no doubt come clear as the investigation progresses.

In the meantime, expect more short-cut headlines. No change there, then.

[UPDATE 12 December 1820 hours: a number of Eurocopter EC135s operated by Bond Air Services for Police and Ambulance services across the UK have been voluntarily grounded following discovery of a fault indication with one aircraft.

What this might be is as yet unknown, but this comment from Chief Superintendent Ian Whitehouse, chief operating officer of the National Police Air Service, is telling: "In light of the technical issue identified by Bond Air Services, as a precautionary measure, we are increasing fuel levels on all NPAS EC135 aircraft and increasing the minimum level of fuel which pilots are allowed to operate on".

A sudden descent with rotor blades not functioning could well be the result of fuel starvation, although I'd ruled that out, given 95 litres was drained from the aircraft that crashed into the Clutha Bar. Perhaps that conclusion was wrong. More later, no doubt]