Clothing from cabin brought down helicopter near Wanaka
Thursday, 20 December 2018
A pair of over-trousers flew from the cabin of a helicopter and became tangled in the tail rotor, causing it to crash near Wanaka Airport, investigators say.
The Transport Accident Investigation Commission (TAIC) has published an interim report into the October 18 crash, which killed pilot Nick Wallis and Department of Conservation workers Paul Hondelink and Scott Theobald.
It found paint marks on the over-trousers matched the colour and profile of the tail rotor blades, and marks on a tail rotor blade matched a zip and dome connector on the over-trousers.
TAIC chief commissioner Jane Meares also said there were three incidents in the month prior, in which doors on the same Hughes 500 helicopter opened in flight.
**READ MORE:
* Widow of late DOC biodiversity ranger accepts award
* DOC worker Paul Hondelink's legacy to continue
* Wanaka helicopter pilot Nick Wallis's zest for life and large heart remembered
* Brothers share heartbreaking tribute video of pilot Nick Wallis
* Brother of Wanaka helicopter crash victim says it 'could have been any of us'
* Helicopter plummeted 300m, creating a metre-deep hole in the ground
* Missing helicopter pilot's brother tells of desperate search
* Missing Wanaka pilot presumed dead as search enters recovery phase**
Jonathan Wallis, the older brother of Nick Wallis and managing director of the family company The Alpine Group, said the unexplained door separation was concerning.
'Since that accident in October we have been made aware of numerous incidents of doors opening in-flight on the same aircraft make and model.'
He was also concerned about the apparent characteristics of an inflight breakup of the Robinson R44II, which claimed the life of brother, Matt Wallis, also a pilot, on July 21.
The commission also released an interim report into that fatal crash over Lake Wanaka and said the wreckage showed evidence of mast bumping.
Mast bumping is contact between an inner part of a main rotor mechanism and the main rotor drive shaft; it usually results in the helicopter breaking up in flight.
It has been a concern relating to Robinson helicopters for some years, causing at least 20 previous deaths. Yet Robinsons continue to be widely used in NZ.
'Although we have not come to a conclusion about what caused this accident, evidence of mast bumping is always a concern for the commission,' the report said.
'There is also evidence that a main rotor blade has struck and entered the cabin in flight. There are score marks on the blade that match screws on the canopy bow; there is scoured paint on the screws. The same rotor blade has marks matching damage to the flight instruments panel.'
In the October 18 crash, the helicopter plummeted about 300 metres to the ground shortly after take off from Wanaka Airport.
The helicopter had been leased from aviation company Airwork by the Wallis family's company and had been heading to the first day of the Department of Conservation's controversial tahr cull.
The report said that less than a minute after leaving the airport several witnesses saw the helicopter descending near vertically, with items trailing behind it, and the helicopter rotating at various angles.
Two experienced instructors flying a Robinson helicopter nearby saw items coming out of the helicopter towards the tail rotor.
One of the witnesses saw what appeared to be a chilly bin falling.
'They saw the helicopter rotating in an upright attitude until it struck the ground.'
It caught fire after impact, which consumed most of the wreckage.
However, aircraft parts and items that had been in the cabin were scattered over a distance of about 500m from the main wreckage, including the pair of black, padded, bib over-trousers and the pair of red, padded overalls that had been inside of the cabin.
They were found close to the separated tail section, along with two pieces of the tail rotor blades and the tip of one of the main rotor blades.
Matt Wallis had been flying to Mt Aspiring National Park on a Saturday afternoon in his Robinson R44 when satellite stopped tracking his helicopter's position.
Jonathan Wallis heard the flight-following desk trying to contact his brother, immediately jumped into his helicopter and began searching.
About 25 minutes after contact was lost, Jonathan Wallis found an oil slick in Stephensons Arm in Lake Wanaka.
'I anticipated that he would be swimming in the lake because I found the oil, but it very quickly changed from that … and as I started to find debris, I realised this was quite serious,' Jonathan Wallis said.
It took three days for the Police National Dive Squad and the Navy to locate the wreckage and Wallis's body inside the helicopter, at a depth of about 47m on the flat bottom of the lake.
The Wallis brothers were the youngest of four brothers in Wanaka's well-known Wallis family and were both helicopter pilots in the family's aviation and tourism businesses.
Meares said the October crash report highlighted the risk posed by loose items in the cabins of helicopters.
The Civil Aviation Authority (CAA) had taken action to remind aviation participants of the risk of loose items in the cabins of helicopters.
With regards to the previous occasions where the helicopter door had opened, the commission recommended urgent action by the CAA director to remind aviation participants of the importance of reporting incidents in accordance with Civil Aviation rules.
'Effective safety management depends on such incidents being reported and investigated, but none of these occurrences was recorded in the operator's incident reporting system,' Meares said.
The report issued on Thursday are interim reports, so include no formal findings.
Jonathan Wallis said The Alpine Group unreservedly supported the safety message pertaining to the stowage of loose items, as well as the recommendation to aviation participants to be reminded of occurrence notification.
As TAIC and the CAA were still investigating, the company would not make further comment.