EXCLUSIVE

An Australian CH-47D Chinook medium lift helicopter MLH prepares to touchdown at Kandahar Airfield in southern Afghanistan following a mission.

As they hammered north at 200km/h over the baking deserts of southern Afghanistan, the crew of Brahman 12 were not expecting trouble.

Their tandem rotor Chinook CH-47D was  cruising comfortably at 1500m on a benign mission to recover a broken-down United States aircraft.

On the ageing helicopter were two pilots, three aircrew and a 6th Aviation Regiment pilot, Lieutenant Marcus Case, 27, who was on a familiarisation flight for his work as a drone pilot.

Members of the Australian Defence Force and coalition partners from the International Security Assistance Force bid farewell to Australian Army Aviator Lieutenant Marcus Case at a memorial and ramp ceremony at Kandahar Airfield.

Around midday, as they approached an area punctuated with ridges and valleys, and prepared to hover, a wind gust hit the Chinook. Ten tonnes of helicopter went out of control, tilting nose up.

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In the rear of the 15m aircraft Lt Case and the gunner who had been sitting on the ramp scurried back into the cabin.

They paused near the ramp  and grabbed at each other's hands for safety, but the chopper abruptly seesawed, sending both men flying.

The mountainous terrain of Afghanistan dwarfs a CH-47D Chinook helicopter during a combat resupply mission in southern Afghanistan.

The crewman grabbed onto the fuselage but Lt Case went flying out the back. The extreme forces caused his safety strap to extend, leaving him dangling 4m outside the aircraft.

He swung like a pendulum under the rotors and the fuselage. The descending helicopter pointed up one last time before pitching back down to the point where it seemed to stand on its nose. At the controls, the horrified pilots' first response to this was to follow procedure and do nothing.

When they moved to take control it was too late.

Australia's Chinook fleet were initially deployed to Kandahar.

The aircraft crash-landed on top of Lt Case, rolled and caught fire. When the injured crew emerged they found Lt Case slumped near the ramp with blood in his ears. He'd been killed instantly. The 2011 crash immediately sent a shockwave through Defence Force circles.

Melbourne-born Lt Case had been a uniquely qualified soldier, having served as a commando in East Timor before retraining as a pilot and been posted to Afghanistan to fly Australia's fleet of Heron drones. 

And the Chinook was one of the force's main heavy lift troop-carrying aircraft, conducting thousands of missions, sometimes carrying dozens of troops at a time.

Lieutenant Marcus Sean Case died in a Chinook helicopter crash in Afghanistan.

Defence Force chief David Hurley ordered a Commission of Inquiry - the only one of its kind into a war zone death in Afghanistan. Against the wishes of Lt Case's family, it was held in public.

Days of technical evidence and examination of dozens of witnesses including crewmen, pilots, engineering experts and officers  accompanied the 2012 public hearings, which produced a 245-page report that should have explained all aspects of the incident.

But despite the report having been completed a year ago, it is still to be released. The Defence Department has also refused to release the transcripts from the inquiry despite it being held in public. Fairfax Media has learned that the completed report struggles to explain why the Defence Force was never told about the CH-47D helicopter's propensity to go out of control under certain conditions.

This is despite evidence at the inquiry that raised serious questions about what the helicopter's manufacturer Boeing knew about the problem given the aircraft had been in service since the 1970s. Buried deep in the report are worrying hints that many knew about the aircraft's history of "porpoising", yet no one appeared to raise any major warning flags..

Instead the report  focused mainly on how and why Lt Case was authorised to be on the flight, where he was allowed to sit, the type of restraint strap he was wearing and the advice given to pilots.This emphasis has deeply disappointed some members of Lt Case's family.

They believe it deflects from deeper issues and seeks to blame low-level soldiers and raise queries about routine familiarisation flights for drone pilots.

"The report fails to explain coherently what caused Marcus' death," said a statement from Lt Case's sisters, Jackie and Elizabeth, and brother Chris. "It practically takes the helicopter out of a helicopter crash.

"You can't trust someone who is writing their own investigation. Imagine writing your own performance review, or a student marking their own exam. The attempt is worse than meaningless. 

"The employer duty of care obligation to Marcus is a different issue altogether."

Fairfax Media understands the completed inquiry report states that in "broad compass", the cause of the crash lay with the pilots who did not respond correctly and had been given the wrong advice as to how respond to the aircraft's flaw.

It notes that commanders who let Lt Case on the aircraft failed to comply with official directives and states that Lt Case should have been treated as a passenger and not as crew even though he was a qualified helicopter and  drone pilot.

The report recommendations included that policies of reporting of aviation incidents be reinforced, that directives or instructions to do with carrying passengers be reviewed and redrafted and that the restraint straps be investigated by the airworthiness authority.

These are only some of the issues that the crash raises.

On page 76 of the report there is a disturbing table that records 12 previous occasions when Australian chinooks started "porpoising", as the phenomena was locally described by pilots. The first occurred in 2005 at Cape Cleveland in Queensland when a chopper went to minus 25 degrees in angle. Others then followed over the years – one in Papua New Guinea and another at Shoalwater Bay in Queensland.

But it was in 2011 in the hot gusty conditions in Afghanistan and in the months before Lt Case died that incidences seemed to skyrocket. On four occasions in 2011, prior to Lt Case's death in Afghanistan, pilots reported Chinooks "porpoising". The most serious was on February 11, when one aircraft went to some 40 degrees from the vertical. Even after the crash, three more cases occurred in Afghanistan prompting the aircraft to be briefly grounded.

The report found that the problem was caused by the Advanced Flight Control System (AFCS), a type of auto-pilot that was getting saturated. It stated the appropriate corrective action was not taught or understood in the wider chinook community but was only known to a very small test pilot community in Australia and three other countries – the names of which were redacted. The report noted that back as far as 1995, a paper party authored by Boeing was given at the American Helicopter Society conference discussing the chinook's handling, and mentioning that the AFCS could become saturated during the approach to hover, and standard "abort hover" manoeuvres.

But this was dismissed by the Commission of Inquiry as being irrelevant as the circumstances were different to the those experienced by Australian pilots at cruise flight.

The report said that the test pilot community knew about the propensity to "porpoise" but this was not passed on to general aviators. , And in 2008, Australian junior pilots were even told to let the aircraft AFCS correct itself, the report noted.

This was wrong as the pilot needed to react immediately to the pitching of the nose and try to manually counteract it by taking control of the aircraft.

After the fatal crash the army arranged for a Defence Science Technology Organisation expert Rhys Lehmann to investigate what was causing the "porpoising". He managed to recreate the porpoising affect in one of Boeing's own simulators by applying the same conditions experienced by Australian pilots. 

Despite the phenomena being able to be recreated in their own simulator Boeing had never issued an official warning about the issue. It was only after Lehmann's work in the simulator that Boeing released a service note relating to the issue.  

The note specifically advised that the pitching needed to be actively arrested by the pilots. While Boeing claimed not to know about this specific issue, it had however upgraded or changed the AFCS from an analogue model to digital one in later model chinooks like the F class.

This upgrade reduced the chances of the AFCS being saturated and meant the aircraft was far less likely to "porpoise".During the inquiry hearings this issue was discussed in some depth – but little of the evidence was detailed in the final report.

Mr Lehmann  was asked by Lieutenant Commander Peter Billings representing Lt Case's family if Boeing had ever offered to explain what exactly they took into account when developing the later F model with the digital AFCS or if he had asked about this.

"They were quite unwilling to discuss the F model at that time as I understood it … Because of export constraints," he said.

Queried whether the fact the F model had an upgrade in parts that addressed the issue was some indication that Boeing was "well aware" of the issue, the engineer agreed.

However when he was asked if Boeing had knowledge of the saturation issue prior to his research, the Inquiry president Andrew Kirkham QC stated that such a response would be "speculation" and not helpful to the commission. As a result the question went unanswered. 

The issues have gravely concerned the Case siblings, who had previously called for the transcripts of the inquiry to be released publicly - a request rejected by Defence.

"Any attention on the helicopter itself was cursory or quickly steered in other directions,"  said the Cases in their statement.

"The prime focus was on witnesses fighting in the warzone." Some of the witnesses were "witch-hunted with with highly leading and accusatorial questions to support a blame story that just wasn't corroborated by the evidence". "This is partly why the report falls apart under the weight of its own contradictions," the Cases said.

The Cases said that after enduring a few years of immense stress they eventually received a copy of the report which hand delivered and reinforced their thinking that the transcripts should be released.

"We were left thinking what commission was this?" they said. "What's the problem (with releasing the transcripts)?

"They (Defence chiefs) know the commission was public and at no time closed so there are no valid secrecy or operational excuses to deny such a joint release. If they don't release the transcripts then the conflict of interest is fatal and the whole public transparency claim is a sham. "

A defence spokesman said:  "The Commission of Inquiry was appointed to further inquire into certain aspects of the helicopter crash, following the completion of a technical investigation conducted by an Aviation Accident Investigation Team from the Directorate of Defence Aviation and Air Force Safety. The family of Lieutenant Case were briefed on the Aviation Accident Investigation Report in early 2012."

He added: "Army purchased a standard CH-47D helicopter training package from the US Army and this training package did not contain any mention of uncommanded pitch oscillations."

A spokesman for Boeing yesterday said Boeing had  fully supported the ADF's Commission of Inquiry but because Boeing has not received the inquiry report it could not make any comment.

Defence workhorses for two decades

The Ch-47D or Chinook helicopters have been Australia's top workhorses for troop transport and heavy lift cargo operations for decades.

The first four D models were obtained by Defence in 1993. Two more were bought  in 2001.

Another two were purchased in 2011-2012 to replace crashed aircraft in Afghanistan. 

In 2006, two of the Ch-47D Chinooks were deployed to Afghanistan and conducted thousands of missions carrying troops and cargo till they were returned to Australian in 2013.

Following the fatal crash that destroyed one of the aircraft and killed Lieutenant Marcus Case, and  other control issue incidents in 2011, the Chinooks were briefly grounded until the cause of the crash was determined.

They have a top speed of  315km/h and can carry 33 soldiers.

The first chinook models were introduced in 1962 seeing service in Vietnam. The first Ch47-d models were delivered in 1982 and were produced till 1994. 

In 2010, the Australiangovernment  ordered  seven Ch-47 F class Chinooks to replace the existing six D class aircraft based in Townsville. The aircraft are due to be operational by at least 201.

Kandahar posting became big mission

Australia's Chinook fleet were initially deployed to Kandahar airfield in southern Afghanistan supporting the International Security Assistance Force operations in 2006.

About 60 soldiers mostly from Australia's 5th Aviation Regiment from Townsville were based in Kandahar supporting the helicopters operations which involved 11 tours from 2006 to 2013.

During the course of their operations the helicopters, known colloquially as "Chooks", flew more than 6000 combat missions, carrying some 40,000 personnel and transported about 3600 tonnes of military cargo.

Flying in Southern Afghanistan, the helicopters encountered 50-degree  temperatures and often cruised at altitudes above the height of Mount Koscziusko as they transported soldiers and cargo across the country.

In 2011, one of the aircraft was destroyed when it crashed killing Lieutenant Marcus Case, 27, after the chopper's automatic flight control system became saturated from reacting to a wind gust. Another aircraft was damaged in a hard landing.

At the time of the fatal crash the Defence Force had Chinooks operating at Horn island at the tip of Cape York, in Townsville in North Queensland as well as the pair based in Kandahar.

Aircrew from the Chinook deployments have received  decorations for their service in Afghanistan including the Medal for Gallantry, Distinguished Service Medal, the Meritorious Unit Citation for the 5th Aviation Regiment, several US Bronze Stars and multiple US Air Medals.