Attention offshore passengers. Engine failures !
Thread Starter
Attention offshore passengers. Engine failures !
Please would those of you who still believe that when any helicopter loses all engine power to the rotors, it will fall straight down like a brick, help me to quash this fallacy. Even after more than 30 years of offshore helicopter flying, I still occasionally hear this nonsense.
Most recently I shut down offshore for a minor engine problem which necessitated an engineer being flown out to investigate. As usual and understandably, there were the usual questions about "what if both engines were to fail?" Even the oil company's safety representative had difficulty accepting the concept of autorotation.
In the extremely unlikely event that this should happen on a large twin-engined helicopter, or a little more frequently on a small single-engined helicopter, the aircraft descends under the law of gravity. The descent angle is something less than 45 degrees and the relative airflow "rushes up" from below and forward.
This airflow passes through the main rotor and causes it to "windmill" (autorotate) resulting in the rotors maintaining approximately their normal rpm. Although the rate of descent is about 4 times greater than that of an aeroplane, in the last couple of hundred feet the pilot flares (raises the nose) of the helicopter which reduces the rate of descent to near zero and reduces the forward speed to something like 20 mph.
The flaring manoeuvre causes the rotor to increase rpm, which gives extra inertia (stored energy) in the rotor for a few seconds, allowing the pilot to cushion the touchdown to a very gentle bump, possibly as gentle as a normal landing.
Which would you prefer; a gentle bump with very low forward speed, or being in an aeroplane in a similar situation and arriving on the surface with forward speed in the region of 100 mph?
I'm no hero and I wouldn't dream of flying anything which just falls vertically as soon as all power is lost. My flying experience spans 45 years and I've flown single-engined military aeroplanes and helicopters, as well as single- and twin-engined helicopters for my civilian career.
Please, please use whatever channels you have to pass this on to offshore workers. Perhaps it will help to reduce some of the apprehension which they might feel and let them understand that if one of the two engines in offshore helicopters should fail, then they aren't suddenly in serious danger.
Here's a link to a good Youtube video of what I'm talking about
.
Perhaps offshore workers don't realise that when considering offshore helicopter accidents in the UKCS only (no single-engined, no onshore, no private flights) then the accident statistics are closer to large airliners than to helicopters in general.
Most recently I shut down offshore for a minor engine problem which necessitated an engineer being flown out to investigate. As usual and understandably, there were the usual questions about "what if both engines were to fail?" Even the oil company's safety representative had difficulty accepting the concept of autorotation.
In the extremely unlikely event that this should happen on a large twin-engined helicopter, or a little more frequently on a small single-engined helicopter, the aircraft descends under the law of gravity. The descent angle is something less than 45 degrees and the relative airflow "rushes up" from below and forward.
This airflow passes through the main rotor and causes it to "windmill" (autorotate) resulting in the rotors maintaining approximately their normal rpm. Although the rate of descent is about 4 times greater than that of an aeroplane, in the last couple of hundred feet the pilot flares (raises the nose) of the helicopter which reduces the rate of descent to near zero and reduces the forward speed to something like 20 mph.
The flaring manoeuvre causes the rotor to increase rpm, which gives extra inertia (stored energy) in the rotor for a few seconds, allowing the pilot to cushion the touchdown to a very gentle bump, possibly as gentle as a normal landing.
Which would you prefer; a gentle bump with very low forward speed, or being in an aeroplane in a similar situation and arriving on the surface with forward speed in the region of 100 mph?
I'm no hero and I wouldn't dream of flying anything which just falls vertically as soon as all power is lost. My flying experience spans 45 years and I've flown single-engined military aeroplanes and helicopters, as well as single- and twin-engined helicopters for my civilian career.
Please, please use whatever channels you have to pass this on to offshore workers. Perhaps it will help to reduce some of the apprehension which they might feel and let them understand that if one of the two engines in offshore helicopters should fail, then they aren't suddenly in serious danger.
Here's a link to a good Youtube video of what I'm talking about
Perhaps offshore workers don't realise that when considering offshore helicopter accidents in the UKCS only (no single-engined, no onshore, no private flights) then the accident statistics are closer to large airliners than to helicopters in general.
Last edited by Colibri49; 29th Apr 2012 at 12:02.
For further encouraging evidence, look at the outcome of G-TIGK's lightning strike: lost the tail rotor and then landed/ditched with both engines shutdown (required response to TR failure)!
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A more telling argument - can you imagine a civil servant risking the pension to rubber stamp a helicopter as safe to fly if it wasn't? 
Phil
Phil
I wouldn't dream of flying anything which just falls vertically as soon as all power is lost.
The answer to your dilemma is for helicopter operators to issue pilots and mechanics with small sachets containing sycamore seeds.
When an enquirer poses the standard question "what happens when the engine stops" the crew member should hold the enquirer in a steady gaze while reaching into his sycamore pouch and then proceed to thrust generous handfuls of the seeds skywards allowing them to flutter to the ground wherafter he (or even she) should state .. "that's what happens."
Ahh nature .. a marvellous thing!
You could also throw in simple physics.
Kinetic Energy: Airspeed, RRPM
Potential Energy: Altitude (transformed into kinetic energy during descent)
This stored energy is used in order to keep the rotors turning down to a safe landing.
Kinetic Energy: Airspeed, RRPM
Potential Energy: Altitude (transformed into kinetic energy during descent)
This stored energy is used in order to keep the rotors turning down to a safe landing.
Last edited by eivissa; 23rd Apr 2012 at 08:54. Reason: Typo
When this question shows up, I always pinpoint to the sycamore seeds. Even pre-school-kids are satisfied with this answer and the solution,what mother nature "invented" millions of years ago...
skadi
skadi
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Yeah thats right, tell them half the story.
Dont mention low speed/high GW profiles in non Cat-A machines where the surviving engine takes you to the scene of the crash.
Also dont show them H/V curves where the autorotation landing becomes brick-like.
There are plenty of profiles where the helicopter behaves more like a brick than a sycamore seed.
But dont tell them!
Dont mention low speed/high GW profiles in non Cat-A machines where the surviving engine takes you to the scene of the crash.
Also dont show them H/V curves where the autorotation landing becomes brick-like.
There are plenty of profiles where the helicopter behaves more like a brick than a sycamore seed.
But dont tell them!
TukTukBoomBoom. We are talking about Group A helicopters in offshore Europe, not GOM kiddycars.
The Bristol Sycamore was the most aptly named helicopter of all time because that what it was doing most of the time.
The Bristol Sycamore was the most aptly named helicopter of all time because that what it was doing most of the time.
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Oh you mean those cat-A S-92s and 332s that never have issues.
Except the gearboxes, flying apart or running dry.
Did someone say kiddy cars?
Believe me engines are the LEAST of your problems!
Except the gearboxes, flying apart or running dry.
Did someone say kiddy cars?
Believe me engines are the LEAST of your problems!
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As a PAX myself I would much prefer the AR manouvere to be explained to all during our various offshore survival training courses, as well as what could also potentially go wrong preventing such a manouvere to be completed effectively e.g. seized/dragging MRGB causing Nr to drop below AR minimum requirement etc.
The only fact that we are told is that the AC will more than likely flip over upon ditching, however this is incorrect as it depends on many factors, flotation devices effectiveness, sea state, speed/angle of descent etc but the trainers err on the side of caution and instruct all to be prepared for a capsize evac.
In light of the recent increase in media coverage and PAX questions in various threads on this forum there is clearly a need for better communication to PAX. This IMHO should originate from the oil companies in conjunction with the operators.
Over here in Canada this communication path vastly improved after Cougar 491, at least now all involved in the industry over here have the opportunity to know more on the facts.
Safe flying
Max
The only fact that we are told is that the AC will more than likely flip over upon ditching, however this is incorrect as it depends on many factors, flotation devices effectiveness, sea state, speed/angle of descent etc but the trainers err on the side of caution and instruct all to be prepared for a capsize evac.
In light of the recent increase in media coverage and PAX questions in various threads on this forum there is clearly a need for better communication to PAX. This IMHO should originate from the oil companies in conjunction with the operators.
Over here in Canada this communication path vastly improved after Cougar 491, at least now all involved in the industry over here have the opportunity to know more on the facts.
Safe flying
Max
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Max:
I agree, certainly with your opening point. Last year a colleague of mine, and I found ourselves doing the BOSIET course at an offshore training facility in Aberdeen with a class full of offshore workers (some were new, some were old salty types returning offshore). As it is a rare thing for aircrew to go through a BOSIET course we quickly found ourselves being cornered by cohorts and instructors alike. We were each asked by instructors to take to the stage in their class for some Q&A when covering the "helicopter transport", topic and it was worthwhile having us around at a few other stages throughout the three day course as questions popped up arbitrarily.
We both thoroughly enjoyed it as we were able to spend time with those who were ultimately going to be our customers - dispelling myths and and clarifying truths. Afterwards we were puzzled that it wasn't common practice when we considered how simple it had been to disseminate so much information, and stop so much misinformation so quickly.
But then it occurred to us how much a "consultant/expert", would cost to do just that...
Tuk Tuk:
You raise valid points. However this thread is about engine failures... it's all in the name.
I agree, certainly with your opening point. Last year a colleague of mine, and I found ourselves doing the BOSIET course at an offshore training facility in Aberdeen with a class full of offshore workers (some were new, some were old salty types returning offshore). As it is a rare thing for aircrew to go through a BOSIET course we quickly found ourselves being cornered by cohorts and instructors alike. We were each asked by instructors to take to the stage in their class for some Q&A when covering the "helicopter transport", topic and it was worthwhile having us around at a few other stages throughout the three day course as questions popped up arbitrarily.
We both thoroughly enjoyed it as we were able to spend time with those who were ultimately going to be our customers - dispelling myths and and clarifying truths. Afterwards we were puzzled that it wasn't common practice when we considered how simple it had been to disseminate so much information, and stop so much misinformation so quickly.
But then it occurred to us how much a "consultant/expert", would cost to do just that...
Tuk Tuk:
You raise valid points. However this thread is about engine failures... it's all in the name.
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A good informative video for PAX and their families/friends
One of the recommendations from our safety inquiry post-Cougar 491 was to share more non-technical knowledge on helicopter transportation and safety. A video has just been released primarily aimed at the offshore workers over here and the attached link is being distributed within the oil and gas operators this side of the pond.
http://web6c3.mmpros.net/6c3web1014/...P-FullShow.mp4
I've watched some of this today and it looks pretty good, certainly provides a nice insight to operations over here, so I thought I'd put it on this thread seeing as it was started on the basis of knowledge sharing.
Safe flying
Max
http://web6c3.mmpros.net/6c3web1014/...P-FullShow.mp4
I've watched some of this today and it looks pretty good, certainly provides a nice insight to operations over here, so I thought I'd put it on this thread seeing as it was started on the basis of knowledge sharing.
Safe flying
Max
