Wednesday, July 25, 2007
Experts have recreated the final, fateful moments leading up to last year's Black Hawk helicopter crash off Fiji.
Defence department experts have recreated the final, fateful moments leading up to last year's Black Hawk helicopter crash off Fiji.
It emerged at the Sydney military board of inquiry into the crash that given the conditions of the helicopter's approach to land on HMAS Kanimbla, there was insufficient power to slow its descent and lessen its impact with the warship.
Through a combination of 3D computer modelling, helicopter simulator trials and the analysis of the Black Hawk's flight data recorder (FDR), experts also were able to rule out engine failure as a cause of the crash.
The expert witnesses from the Defence Science and Technology Organisation (DSTO) gave evidence as part of the inquiry into how the helicopter failed to negotiate a landing on the deck of the Kanimbla and plunged into the sea last November.
The pilot, Captain Mark Bingley, and SAS Trooper Joshua Porter were killed when the aircraft crashed during practice for evacuations from coup-stricken Fiji.
Helicopter simulation expert Sylvain Manso talked the board through footage of two of the army's top pilots undertaking simulator runs recreating the ill-fated manoeuvre attempted by Capt Bingley.
Those that most closely followed Capt Bingley's route found it had resulted in "unrecoverable descent rate", Mr Manso told the board.
"There was insufficient available power to recover from the flight conditions from the defined ingress," Mr Manso said.
Video footage from a security camera aboard the Kanimbla allowed experts in photogrammetry, which is the science of measuring object position using images, to plot much of the Black Hawk's approach.
Another DSTO expert, Thuan Truong, brought to life an analysis of data from the FDR, retrieved from the helicopter wreckage.
Through a series of graphs depicting flight data recorded as frequently as eight times per second, Mr Truong was able to show how Capt Bingley desperately pulled hard on the control stick in a bid to raise the nose in the last two seconds before the crash.
The graphs also revealed how Capt Bingley frantically pumped the helicopter's right pedal as he tried to correct its course.
The FDR data also gave further weight to the role of "rotor droop", where the main rotor loses power, in causing the crash.
Although no data was recorded for the main rotor, Mr Truong said data showing how power to the tail rotor plummeted to 75 per cent could be applied with reasonable accuracy to the main rotor.
"There was a tremendous reduction of aircraft lift, at 75 per cent rpm (rotor speed) the aircraft lift is approximately half its weight," Mr Truong said.
Helicopter structure engineer Dominigo Lombardo said he had inspected the salvaged wreckage of the Black Hawk and found no evidence of engine failure.
"There was nothing that stood out as being unusual," he said.
The evidence from the FDR and simulator runs also ruled out engine failure.
The inquiry continues on Tuesday.