In this article, Gloucestershire, UK based freelance copywriter Al Hidden details some of the case-studies that show how, despite being among the safest aircraft in their class, light helicopters still present many hazards to the unwary or careless during boarding and disembarkation…
In 1996 I started a course in technical authorship, part of which involved the research and writing of a technical report on the safety aspects associated with light helicopters. One of the report's appendices was a fascinating 'rogues gallery' of case-studies that illustrated the many safety issues encountered during boarding and disembarkation. The story is both fascinating and alarming.
The big safety issues come down to rotor strikes, impact with aircraft components, objects near the helicopter, poor handling practices whilst loading or unloading and passenger interference with aircraft controls. Typically, it's a combination of human errors and complacency that creates the danger around operational helicopters.
Because jettisoned objects can easily enter the helicopter's main or tail-rotor discs it should be obvious that nothing should be discharged from the aircraft, either on the ground or in the air if there is any likelihood of contact with the rotors. This was overlooked when spent machine-gun cartridge cases were ejected from the open door and struck the rotors of a helicopter while filming a movie in British Columbia, Canada. Only the pilot's quick response and the helicopter's proximity to the ground avoided disaster. The aircraft was subsequently withdrawn from service while replacement rotor-blades were fitted. Though a particularly unusual episode, this example clearly demonstrates how carelessness can cause problems. While this particular incident occurred during flight, others highlight the consequences of carelessly handling loose items on the ground.
You don't need much imagination to contemplate the sort of incidents that can – and do – occur when externally stowed freight items come adrift or the helicopter's baggage compartment doors open in flight.
One particular Canadian report reveals how careless stowage of external cargo led to disaster. During heli-skiing operations, it is normal practice to carry skis outside the helicopter. Nowadays, this is done with sealed cargo pod. Not so long ago, however, it was usual for skis to be strapped into an open basket and restrained with heavy-duty shock cord. In this particular case it was significant that only two passengers accompanied the pilot of the Bell 214, significantly less than the aircraft's 14-person capacity.
Shortly after taking off from a mountain lodge, the pilot heard a loud bang and the helicopter yawed violently before crashing into a snowy mountainside, killing the two passengers and seriously injuring the pilot. Subsequent investigation revealed that the passengers had put their skis into the external basket and that the pilot had not checked that they were secure. The official investigation also concluded that the heavy-duty shock cord used to restrain the skis was suitable for restraining many more than two pairs of skis. When used for only two sets the cord failed to hold the skis securely, allowed them to come adrift, enter the helicopter's slipstream and strike the tail-rotor, causing loss of control and the subsequent crash.
In another incident – this time in the UK – a quilted jacket became trapped in the baggage-compartment door of a Bell 206 JetRanger during loading. The mistake was not noticed, probably because the colour of the jacket blended with that of the helicopter. The door appeared to be correctly secured when, subsequent investigations revealed, the fastening mechanism had not been fully engaged. Pressure variations during the subsequent flight caused flexing of the tail-boom and the opening of the baggage-compartment door in flight. The jacket blew out and struck the tail-rotor, leading to the helicopter crashing and seriously injuring three passengers.
In both cases, ultimate responsibility for the security of the aircraft lay with the pilot. However, particularly when operating in remote territory, it is common for passengers to enter the helicopter in circumstances that make it difficult, if not impossible, for the pilot to leave the controls and physically inspect the baggage stowage.
This emphasises the importance of thorough preliminary training for anyone who may be required to stow luggage under such conditions. The fact that, in the second example, the baggage-compartment door had supposedly been secured by an experienced pilot merely reinforces the difficult nature of the problem.
A helicopter's rotor mechanism is inherently vulnerable to interference if objects are sucked into the rotors or if the helicopter is moved so the blades strike nearby objects. The case-studies reveal numerous instances where rotor blades have struck objects – empty agricultural sacks, tarpaulins and even signs blown-off nearby structures during operation in confined areas were all amongst the items featured in such incidents.
Particularly during take-of, helicopters are also vulnerable to the phenomenon known as dynamic rollover. This can happen when, for a variety of reasons, one side of the helicopter's undercarriage is momentarily held onto the ground or touches a static object during takeoff. Even an object such as a fuel drum can cause this, leading – if not controlled quickly – to sudden rollover and the rapid destruction of the helicopter by its own rotors.
The accident investigation reports recount various tales of mishap during loading or unloading of freight or baggage from helicopters. From Canada, with its tradition of remote lumber camps, come numerous salutary examples.
In one incident, bulky foam mattresses were being unloaded from a Hughes 369 at a lumber camp in Ontario. The aircraft was standing on the landing area with its engine idling and the rotors turning when a member of the camp crew inadvertently raised a mattress overhead so it entered the rotor disc. At low rotational speeds, a helicopter's rotor-blades are particularly susceptible to deflection: in this case the blade was deflected downwards, severing the helicopter's tail-boom. One of the basic rules for approach to a helicopter – that one never raises anything above head height – had been overlooked. Significantly, the official report also concluded that the crew were rushing to unload the aircraft when the incident happened.
In another incident, passengers were helping to unload an MD500 helicopter when the pilot heard a loud bang. On shutting down the engine it was discovered that a section of a main rotor-blade was missing. It transpired that, during unloading, one of the passengers had removed a hatchet from the baggage compartment and thrown it away from the aircraft and into the main rotor disc….
A helicopter's tail-rotor is the most obvious danger to people on the ground. This is due to its position in relation to the ground and its high speed which makes it difficult to see – particularly at night or in poor light. Although put out-of-bounds for passengers in every safety brochure and passenger briefing, people still walk into tail-rotor discs, often with fatal consequences.
In an incident documented by the British Air Accident Investigation Branch – and despite the presence of the pilot and another passenger – an elderly man with poor eyesight reportedly walked directly to the rear of a Bell JetRanger, 'ducked under' the tail boom and was struck by the rotating tail-rotor. This incident, like another tragedy described below, highlights the importance of special supervision for the elderly, young and infirm around helicopters.
In another Canadian incident, a helicopter had landed at a mountaintop site. With the rotors still turning, two passengers got out and unloaded freight while a third videoed the activity taking place at the front of the helicopter. While still filming, he is then reported to have been seen moving towards the tail of the helicopter before walking into the tail-rotor and receiving fatal head injuries.
To eliminate the risk of a rotor strike, passengers must wait until the rotor-blades are stationary before leaving or approaching the helicopter. In practice, and providing that approach or departure never takes place during rotor run-up or shutdown, it is often reasonable for passengers to board safely while the rotors are turning. Indeed, in many situations this is the only practical way to get passengers onboard and is achieved safely even with small helicopters having low rotor discs.
That said, the accident reports bear witness to situations where main-rotor blades have struck people on the ground. Sometimes this has occurred during emergency evacuation after a crash-landing. In other cases the evidence points more clearly to carelessness.
In one example, the pilot of an MD500 helicopter climbed up onto the aircraft to clean the 'bubble' canopy. The rotors were still turning and he was fatally injured when the blades struck him. In another incident a passenger, who had been given a 'joyride' in a Hughes 269 helicopter at a lakeside picnic, was allowed to jump from the helicopter while it hovered just above the surface of the water. As the passenger exited the aircraft the main-rotor blade struck a carelessly extended arm, severing three fingers. On a similar note, there have been several instances of 'helicopter delivered Santa Clauses' being injured as they waved to their audience too soon after disembarkation.
Finally, numerous lessons can be learned from an incident reported in the British press some years ago. Arriving back at a rural location after a flight in a small Robinson helicopter, the pilot had shut the aircraft down and exited the aircraft while the rotors ran down. According to reports, his four-year-old daughter approached him and was fatally injured when he lifted her onto his shoulders – and into the still moving main-rotor disc…
The diverse protuberances and relatively delicate fabric of a helicopter are vulnerable to impact damage. As well as causing injury, items such as antennae, pitot-tubes and cockpit glazing are easily damaged while loading freight or tools or just working near a helicopter. The Plexiglas 'chin-bubbles' on aircraft such as the Bell 206 or 212 are particularly susceptible to impact damage from rugged footwear such as ski boots during embarkation of a front-seat passenger. Moreover, on cold days, contact with heated pitot-tubes can cause nasty burns if touched with an unprotected hand…
What are the lessons?
Helicopters are misunderstood, with the popular perception of regular catastrophic rotor failures and aircraft plummeting to earth. In reality, properly maintained and flown helicopters are actually very safe with certain types comparing favourably with small fixed-wing aircraft and being rated amongst the safest aircraft in their category.
Most of the incidents encountered appear to have involved human factors, sometimes involving more than one person and in several cases being compounded by pilot errors.
From many case-studies (and aided by the gift of 20:20 hindsight) it is clear that complacency, probably borne of over-familiarity due to frequent exposure to helicopters, also played its part. Having spent considerable time around working helicopters and their operators in the UK, Switzerland and Canada and researched the subject comprehensively, it is the author's view that human error will never be totally eliminated from helicopter operation.
The application of a few key principles can, however, help reduce the occurrence of incidents such as those described above:
Regardless of any pre-flight briefing, passengers should know, and apply, the simple common-sense safety procedures that apply to boarding of light helicopters. Above all, they must concentrate on what they are doing whenever they are working near the helicopter.
Passengers should consider carefully and learn from the harsh lessons highlighted by available case-study material.
Regardless of any legal requirement, passengers must insist on a thorough pre-flight briefing covering general as well as aircraft-specific helicopter safety.
For maximum safety, passengers should ideally avoid boarding or disembarking from any helicopter whilst the rotors are turning. Where this is unavoidable, passengers must ensure that they understand and follow all appropriate safety procedures and must never approach the aircraft without the knowledge of the pilot and other authorised personnel.
It is essential to avoid complacency when boarding helicopters, even when frequency of travel may encourage this. Safety around helicopters is most certainly not for wimps: 'real men', at least those who want to avoid the deadly retribution of 'the angry palm tree', do take care!
Al Hidden, Gloucestershire Copywriter, specialises in website, SEO, newsletter, brochure and case study copywriting. As well as considerable experience in marketing, technical writing, copywriting and PR, Al has spent time working in and writing about the aerospace sector and has useful experience around helicopters in the UK, Switzerland and Western Canada.
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DISCLAIMER: None of the images included in this article is associated with any of the incidents described in the text.
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