I have heard that it was the CAA who had the restriction, and also that it was probably the reason that Alan Bristow got the 212's when he did. I heard too that he was granted permission to fly singles over built up areas (Whirlwinds??) during some floods just before he got the 212's.
This info is second hand at best so it may well be wrong, don't quote me.
Simple answers:- 1/.CAA reckon safer with two engines rather than one! 2/. Keeps the less well qualified from flying these missions. 3/. they can make more money from people doing twin ratings etc than single ratings.
There is no twin-only mentality; the restriction on flights over a hostile environment (and specifically a congested hostile environment) arises from compliance with the ICAO Annexes - you know, the Chicago Convention to which all States agree to comply:
ICAO Annex 2 - Rules of the Air; and Annex 6 - Operation of Aircraft.
Respectively, the need to 'land clear' (protection of third parties) and the requirement for a 'safe-forced-landing' (protection of crew and passengers).
There is also linkage to the the certification principle that no hazardous outcome should be permitted with an event which has a classification of 'Reasonably Probable' (which is based upon a probability on the order of between 1:1,000 and 1:100,000). Because engines tend to fail within that probability spectrum, ICAO SARPs attempt to keep the helicopter away from an area where the effect of the failure could be hazardous.
Before anyone is tempted to point out that there are other failures (including Human Factors) that have a similar, or worse, spectrum, the answer was as specific as the question.
I think you will find that many insurance companies will not insure 'high profile' individuals (so called celebs etc) to fly in singles any more. They want twin engine, two crew machines. I know of one particular instance, quite a few years ago, when Sly Stallone arrived at Battersea and walked up to 'his' B222 with only one pilot, then promptly about-turned and refused to get in. His comment: his insurance company would only allow him to fly twin crew in a twin engined helicopter! He's not the only one, either.
Interesting. But how come news/medevac/police use singles in the USA. They come under ICAO too don't they?
Re EMS providers. I suggest that you compare the recent accident record for EMS providers in the USA and the UK. Even anecdotally (or by doing a PPRuNe search), the results should provide you with the answers that you are looking for.
But for me, it seems to come down to a difference in attitude from the respective regulatory bodies. The CAA (and JAA as a whole) seem to want to reduce the level of risk to as close to zero by any viable and realistic means. If this means insisting on 2 engines for certain operations or environments (ie EMS, Police or NS), then so be it. The FAA, on the other hand, seem to accept that there might be a few casualties along the way, but on the whole, operations are pretty safe. The comparable recent safety records for the 2 main offshore areas (ie the GOM and the NS) would appear to support this.
This is, of course, just IMHO so please take it that way.
manfromuncle asked, "Where does the UK/JAR "twin only" mentality come from?"
The answer is simple, look in the mirror. Whenever I post a thread that attempts to discuss the idea that a twin need not hover on one engine, the vast majority of ppruners (esp those from the correct side of the pond) are aghast that the current crop of twins cannot hover on one engine. Imagine if we were to try and discuss a single engine commercial machine!
Clearly the answer to your astute question is - UK pilots, who think engines are the source of safety, in spite of the statistics, reason or common sense.
I'm sure that the statement about to be quoted has been heard before and will cause an outcry and it goes something like this, "In the case of twin engined helicopters - or aircraft for that matter - in the event of one engine failing the second one takes you to the scene of the accident." I speak with first hand experience. But rules are made and helicopters sold because of this and at the end of the day I think it all has to do with that age old thing called the bottom line. Cases for and against will be argued till the end of time and safety will touted as the main reason, but lurking in the background will be all the companies/individuals who floated the idea making potloads of cash.
Where does the ‘mentality’ come from? I reckon it comes from the manufacturers and the salesmen active between 1960 and 1990; and I was one of them.
We would tell any potential buyer that would listen that two engines were safer than one; and I think that we were correct in presenting that argument. Of course it also helped to increase the value of our order book.
The argument stemmed from the statistics of the previous 20 to 30 years that supported the argument. In piston engine times big engines were less reliable, hence it was safer to propose two smaller engines than one big one. Whether this argument should have been translated across to turbine helicopters is of course another topic.
It is only in living memory that bigger engines have established the reliability figures that gave travelers and operators the confidence to accept a fleet of twin engine aircraft flying across the Atlantic and the Pacific.
How long will it take the modern helicopter engines to establish an improved failure rate giving a probability of better than 1:100,000 and get us out of the ‘reasonably probable’ definition? Probably never!
When it comes to being a passenger I will choose a multi over a single every time because you have to factor in the pilot. I have been taken on some horrendous rides by pilots of single engine helicopters who would almost certainly have killed everyone on board if the only engine on their light helicopter was to stop. Those of you who have been on a scenic flight in Rio or the high mountains of Nepal or India will know what I mean.
Talking of twin-engined airliners flying over the Atlantic and Pacific (Hidden Agenda) I find it a little strange that certification authorities seem perfectly happy (under ETOPS-180) to allow hundreds of passenger to be flown for up to three hours on one engine over hostile terrain or oceans, yet have the screaming heebie-jeebies over flying a fare-paying passenger in a single-engine helicopter into a field in a 'congested area'.
A lot of the 'blame' can be given to the UK CAA regulations. However, wealthy owners like twins because the helicopter maker's salesmen tell them that they are a lot safer than singles. As an aside, most CEO's of large USA companies and wealthy American individuals have written into their life insurance policy 'two engines and two pilots' as a minimum for flying as a passenger.
Frankly we could use some effective regulation in the U.S. U.S. helicopter EMS is the wild, wild west, and the FAA won't do anything about it.
The FAA's idea of "safety" is to put things like CVRs & FDRs into aircraft. Brilliant. Those will let you know the rate of descent when the single engine aircraft with power failure slams into the rock-covered hillside, and will record the pilot's last words for posterity.
Instead, the FAA should mandate twins, that would give us an option to immediate, unpowered landing in the event of an engine failure.
It would also drive a lot of the marginal operators (and there are plenty) out of business, and reduce the current approximately 50% ("gut" number) oversaturation of aircraft working in a lot of market areas.
In many areas I routinely fly at night, if my aircraft's single engine quit, there is zero probability of an autorotational landing without destroying the airframe and injuring the occupants.
Be honest with yourselves, if you were a commercial operator and the CAA said single eng ops were OK you'd rip the a*se out of it. Night, IFR, hostile terrain, over water, no probs, after all the CAA says it is OK... But you are the pilot who'd have to fly this beast knowing that when the engine stops gravity will prevail. Statistically you may be lucky, but as your hours build your chances will get slimmer. Flight safety is paramount, fly twins.