From "This Is Wiltshire", the online version of the Amesbury Journal:
Inquest hears of crash helicopter's fatal flaw
A HELICOPTER crash which killed a Durrington pilot and two of his colleagues was caused by the wrong coating on a crucial part of the gearbox, an inquest heard this week.
Captain Ian Shoobridge and engineers Neville Moger and James Gordon-Stables died when their Twin Squirrel helicopter came down during a test flight at Hurstbourne Tarrant, near Andover, on December 2, 2003.
Eyewitnesses described how the aircraft made a "grinding and screaming sound" before it hit the ground and burst into flames.
Resident David Pykett told the inquest: "The tail boom had fractured but folded around the fuselage and it spun into some trees."
The emergency services were at the scene within minutes, but married father-of-one Mr Shoobridge (51), Mr Moger (45), from Romsey, and Mr Gordon-Stables (37), from Ludgershall, had been killed by the force of the impact.
The jury at the inquest in the Hampshire Centre Court Hotel, Basingstoke, heard that Mr Shoobridge had flown helicopters for more than 25 years and received the Air Force Medal after serving in Germany, the Falklands and Ireland.
He was on a test flight from Thruxton airfield after the helicopter's gearbox had been sent away to French engineering company Eurocopter for maintenance.
Mr Moger and Mr Gordon-Stables had put the aircraft back together and were described as "fastidious and methodical" in their work.
An initial test flight earlier in the afternoon went smoothly, apart from a slight mismatch in the engine power, but the second flight ended in tragedy.
The Air Accident Investigation Branch immediately launched an inquiry.
Six days after the accident, Eurocopter issued an emergency telex after five incidents, including a heavy landing and the Hurstbourne Tarrant crash.
The AAIB discovered that Eurocopter had changed its production techniques and instructed German company FAG, which produced the rollers used in the gearboxes, to add the coating which was designed to prevent slippage.
However, instead of using the required zinc phosphate, the company applied a manganese phosphate coating, which the AAIB say caused the freewheel in the gearbox to slip more easily and put additional pressure on the engines.
"Manganese has the opposite effect to zinc and increased the slippage," said Steve Moss from the AAIB.
"It appears, on this flight, the engine suddenly re-engaged.
"This re-engagement lead to the break up of the helicopter - it twisted, the tail boom fractured causing it to pitch and tear out the gearbox.
"Such an event is non-survivable."
The jury was told that lab tests had shown no difference in the performance of the two coatings but AAIB operations investigator Nicholas Dann said the accident was not caused by an operational error.
"No evidence has been found of operational failure or pilot mishandling," he said.
As the Journal went to press, the inquest was ongoing and coroner Andrew Bradley said it was expected to last three or four days.
Available online at
http://www.thisiswiltshire.co.uk/wil...MES_NEWS0.html