The disintegration of a rotor blade could have caused a Netcare 911 helicopter to spin out of control, killing all occupants probably before they hit the ground.
This was the view of African Pilot magazine editor Athol Franz, commenting on a preliminary report released on Tuesday by the SA Civil Aviation Authority (SACAA) into the crash of the Bell 430 helicopter last month.
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The aircraft took off from Ultimate Heli heliport in Midrand, Gauteng, for Hillcrest Hospital near Durban on January 21. The medical staff travelling in the aircraft were en route to save a Covid-19 patient in KwaZulu-Natal.
The report found that after about 1.5 hours in flight and cruising at 725ft (221m above ground level), the helicopter started to spin uncontrollably, breaking up in flight, while losing height rapidly.
“The helicopter impacted the ground and immediately post-impact fire erupted, which destroyed the helicopter. All five occupants on board were fatally injured,” the report read.
The crash claimed the lives of anaesthetist Dr Kgopotso Rudolph Mononyane, cardiothoracic surgeon Dr Curnick Siyabonga (Sia) Mahlangu, specialist theatre nurse Mpho Xaba, Netcare 911 advanced life-support paramedic Sinjin Joshua Farrance and pilot Mark Stoxreiter, from National Airways Corporation.
Objects flung from the helicopter included airframe parts severed by one or more of the helicopter’s main rotor blades while spinning out of control, as well as some airframe parts that broke off during the accident sequence.
The Bell 430 had been operating in Angola before being imported, in parts, and reassembled in SA.
The report said eyewitnesses travelling on the N3 highway and a farmer reported the helicopter “suddenly started to spin around while losing height rapidly. The witnesses then saw what looked like helicopter parts breaking off before it crashed and burst into flames.
The Bell 430 had been operating in Angola before being imported, in parts, and reassembled in SA.
Franz said it seemed that maintenance engineers only found three rotor blades. The fourth was missing.
“The most likely explanation is that one of the four blades disintegrated. It is most likely that if a blade disintegrates during a flight, that would have thrown the balance of the rotor completely out and it is quite likely that the occupants inside the helicopter would [have been subjected to what it is like inside a washing machine]. They might have died actually before they hit the ground,” he said.
“It was a terrible accident and also an unnecessary accident. It is one of the finest helicopters ever built for the purpose, but if the blade disintegrated, then serious questions need to be asked. Why did the blades disintegrate?”
The wreckage was scattered across a 500m radius in Winterton.
“It is very likely that the vibration that came as a result of that disintegrating blade broke the tail off because the bearing would have snapped because of the vibration.
“With that huge imbalance, the vibration would have been so bad that I doubt that the occupants, no matter how well they were strapped down, lived through it.”
But aviation expert Linden Birns cautioned that preliminary reports were just “a catalogue of prima facie evidence”, adding that there were no conclusions and no findings.
“It is just a catalogue of the evidence and it is basically saying here are all the things that the investigating officer needs to investigate.”
Birns said in terms of UN International Civil Aviation Organisation (ICAO) protocols on aircraft accident investigations, investigators are obliged to publish a preliminary report within 30 days of the occurrence.
“The investigators will, by process of elimination, scrutinise all of these and any acts or omissions by all parties, to determine the cause of the loss and any contributory causal factors.
“Typically this takes several months, sometimes more than a year. The investigators must publish an interim report on the first anniversary of the occurrence if their work is not complete by then. Only the final report will provide a determination on the cause and contributory factors.”
Unlike criminal investigations, an air accident investigation does not attempt to apportion blame, Birns said.
Our thoughts remain with the families and loved ones of our deceased colleagues at this difficult time.
— Dr Richard Friedland, Netcare CEO
“It is purely to establish what happened so the remedial measures can be implemented to prevent a recurrence. However, upon the release of the final report, civil claims could be filed in court.
“If the final report points to negligence, then criminal prosecutions might also follow, but at this stage it would be wrong to suggest or infer that this is a likely outcome of this particular investigation.”
Dr Richard Friedland, CEO of Netcare, said they hoped the investigation would answer “painful questions” surrounding the accident.
“Our thoughts remain with the families and loved ones of our deceased colleagues at this difficult time. We are all still reeling from the tragedy and are appreciative of the SACAA’s efforts to establish the cause and to make aviation safer.
“As this is only a preliminary report, we won’t comment further at this stage. However, we continue to offer our full support to the investigation,” Friedland said.
* This article has been corrected since its initial publication to remove a line saying Franz had visited the accident scene. We apologise for the error. - ed
