A CHINOOK helicopter that suffered a flight computer failure and crashed killing an Australian soldier was one of four ''remanufactured'' aircraft operated by Australia that used airframes of the C-class model, a type flown in the 1970s, the Herald has learnt.
Lieutenant Marcus Case died and five soldiers were injured after the Chinook Ch-47 D-class they were flying started violently tilting and rising to the point where the nose pointed down at 110 degrees, causing a crash on May 30 in Zabul province in Afghanistan.
An open military inquiry into the crash has heard evidence from a Defence Science and Technology Organisation aeronautical engineer, Rhys Lehmann, who found that the D-class's analog automatic flight control system (AFCS) could become overloaded at high altitude in turbulence and cause the violent tilting motion.
During his evidence, it was also revealed four of the Chinooks operated by the Defence Force, including the crash helicopter, had been upgraded using the C-class airframes.
Flight Lieutenant Richard Gration, who is representing one of the pilots from the crashed helicopter, suggested to Mr Lehmann that the aircraft involved in the fatal crash ''was in a previous life, a C-model Chinook'' which had been modified in the United States to become a D model with a new tail number.
Mr Lehmann replied: ''I wouldn't be able to tell you specifically, but I believe that may be the case.''
He said it was his understanding that the RAAF operated the earlier model CH-47C helicopter from 1973 to 1989.
A Defence spokesman confirmed yesterday that Australia was operating four ex-C model aircraft which had been ''re-manufactured'' by Boeing to the D-model standard. ''Whilst elements of the primary aircraft structure were reutilised in this process, the majority of the dynamic and avionics components were new or recapitalised [renewed to 'as new' condition],'' the spokesman said.
He said the other two Chinooks operated by Australia were new D models.
The overall accumulated age of the ADF fleet was extremely young compared with the remainder of the global fleet of D model aircraft, he said.
''The Australian Defence Force has no safety concerns with regard to the age of the ADF Chinook fleet,'' he said. ''The ADF maintains safety programs and engineering programs specifically targeted to identifying issues with ageing aircraft well in advance of any problems being realised.''