Where does the UK/JAR "twin only" mentality come from?
Join Date: Jul 2000
Location: Nova
Posts: 1,242
Likes: 0
Received 0 Likes
on
0 Posts
Hi SAS
Have you managed to read that PDF, because I can only download the first couple of pages. As you say, it's written by someone at Bell helicopters around 24 years ago.
I am genuinely interested in this, and will try to keep an open mind. Intrigued to see if you turn up anything of interest.
Cheers.
Have you managed to read that PDF, because I can only download the first couple of pages. As you say, it's written by someone at Bell helicopters around 24 years ago.
I am genuinely interested in this, and will try to keep an open mind. Intrigued to see if you turn up anything of interest.
Cheers.
Join Date: Jan 2008
Location: United Kingdom
Posts: 13
Likes: 0
Received 0 Likes
on
0 Posts
The referenced Flight Safety Foundation Flight Safety Digest for August 1991 can be found in actual PDF format at their own website.
http://flightsafety.org/fsd/fsd_aug91.pdf
It's a usable alternative to the pdf aggregation site posted by SASLess, which posts rendered snapshots of the pdf rather than the original work.
http://flightsafety.org/fsd/fsd_aug91.pdf
It's a usable alternative to the pdf aggregation site posted by SASLess, which posts rendered snapshots of the pdf rather than the original work.
Join Date: Dec 2007
Location: uk
Posts: 419
Likes: 0
Received 0 Likes
on
0 Posts
Looks like a document written by a paid Bell employee to tell the industry how much safer they'd be flying in a (Bell)206 than anything else. Does have some pertinent bits though. The Tree incident on page 33 is worth a good read!
As another member has pointed out, the CAA/EASA etc performance criteria are based only on engine isolation performace. Many other criteria introduced by the operators requirements (payload and redundancy of generators and hydraulics etc) mean in reality the choice of modern cheaper single engine helicopters is very limited in many circumstances.
As another member has pointed out, the CAA/EASA etc performance criteria are based only on engine isolation performace. Many other criteria introduced by the operators requirements (payload and redundancy of generators and hydraulics etc) mean in reality the choice of modern cheaper single engine helicopters is very limited in many circumstances.
Join Date: Dec 2008
Location: N/A
Posts: 845
Likes: 0
Received 0 Likes
on
0 Posts
TC: "Two of anything has got to be better/safer than only the one - common sense." not necessarily Two of something that might fail (and cause a problem) is worse than One thing that does not fail - common sense!
Join Date: Dec 2008
Location: N/A
Posts: 845
Likes: 0
Received 0 Likes
on
0 Posts
... and i don't really have anything against twins. It's just not all its cracked up to be and we should be straight about it. They are really handy if you want to comply with rules requiring 2 engines.
Avoid imitations
Join Date: Nov 2000
Location: Wandering the FIR and cyberspace often at highly unsociable times
Posts: 14,573
Received 422 Likes
on
222 Posts
AnFI, please do enlighten us all, by sharing how much time flying twin engined helicopters you have actually achieved, by which you might add some credence to these statements. Thank you.
Join Date: Dec 1999
Location: UK
Posts: 2,584
Likes: 0
Received 0 Likes
on
0 Posts
Two of anything has got to be better/safer than only the one - common sense.
Confuscius he say, "Man with one clock always know time. Man with two clocks never certain."
Two of something that might fail (and cause a problem) is worse than One thing that does not fail
The one thing that "does not fail" wouldn't be an aircraft that only has one engine would it?
So if you lose an engine on a twin engined a/c, is it better or worse than losing an engine on a sinlge engined a/c?
Mmmmmm, give me a minute to think about this one, will you?
Purveyor of Egg Liqueur to Lucifer
AnFI;
were more lynx or more gazelle lost due engine problems?
were more lynx or more gazelle lost due engine problems?
Aerospatiale Gazelle - Helicopter Database
Westland Lynx - Helicopter Database
Join Date: Dec 2007
Location: uk
Posts: 419
Likes: 0
Received 0 Likes
on
0 Posts
Without looking at the data, I'd say very few of either were lost due to engine problems. They were both operated in very demanding roles which would up the ratio of CFIT to a level that made mechanical failure leading to loss a small portion. 850 hours gazelle and 3000 lynx without an engine failure, one incident due to tail rotor drive failure, that was maintenance error, walked away from that, lucky I guess.
Join Date: Jul 2000
Location: Nova
Posts: 1,242
Likes: 0
Received 0 Likes
on
0 Posts
Read up on acidents on both the S-58 with the 1820 or PT 6.
You will see the twin pack being more deadly.
You will see the twin pack being more deadly.
Really?
AnFI, please do enlighten us all, by sharing how much time flying twin engined helicopters you have actually achieved, by which you might add some credence to these statements. Thank you.
Just last night we were hovering in the cloudbase on Dartmoor in a rescue situation where one engine failing would have been exciting but very survivable - but we were in a twin - had we been in a single, the engine failure would have been pretty terminal.
You need a twin do do high-risk stuff in a helo if you want to minimise the likelihood of a flame-out/surge/mechanical failure etc on one power unit cancelling your booked late lunches.
Join Date: Mar 2005
Location: Holly Beach, Louisiana
Posts: 916
Likes: 0
Received 0 Likes
on
0 Posts
TR,
The same Twin-Pac still flies today in the Bell 212/412 products as well as in the S-76B, and the remaining S-58T's that are still flogging it today.
The concept is the same, the probability of an engine failure still exists for EACH engine and having two of them adds to the probability of one of the engines failing. Thus, I would wager that Twin's have more engine failures than do singles.
That the impact of a single engine failure on a single engine machine is rather more dramatic than the same single engine failure in a twin also goes without saying.
The variables of OEI performance and ability to maintain flight in all regimes of flight is also something that has to be considered.
I just love the smart ass replies some people make as if they hold the only valid perspective on all things aviation.
When it comes to posting your credentials on line here, how do we know you are who you say you are unless you post your real name and occupation?
Some of you British Chaps seem to think a lot of yourselves.
Crab, a quick question.
However did the RAF and RN ever survive much less actually rescue people using the Whirlwind?
The same Twin-Pac still flies today in the Bell 212/412 products as well as in the S-76B, and the remaining S-58T's that are still flogging it today.
The concept is the same, the probability of an engine failure still exists for EACH engine and having two of them adds to the probability of one of the engines failing. Thus, I would wager that Twin's have more engine failures than do singles.
That the impact of a single engine failure on a single engine machine is rather more dramatic than the same single engine failure in a twin also goes without saying.
The variables of OEI performance and ability to maintain flight in all regimes of flight is also something that has to be considered.
I just love the smart ass replies some people make as if they hold the only valid perspective on all things aviation.
When it comes to posting your credentials on line here, how do we know you are who you say you are unless you post your real name and occupation?
Some of you British Chaps seem to think a lot of yourselves.
Crab, a quick question.
However did the RAF and RN ever survive much less actually rescue people using the Whirlwind?
Join Date: Dec 2008
Location: N/A
Posts: 845
Likes: 0
Received 0 Likes
on
0 Posts
BB "the impact of a single engine failure on a single engine machine is rather more dramatic than the same single engine failure in a twin also goes without saying."
and to simplifiy the discussion: the impact of a gearbox failure (more probable in a twin) in a twin is pretty dramatic too!! That's why it wrong to only look at the downside of the engine failure without accounting for the consequential other risks. Yes there should be less forced landings in twins due to engines, but more for other reasons, making them overall unjustified (in general).
Crab - don't start getting rude again (and wrong) - and can't you just respect that I don't want the pressure on the identity?
and to simplifiy the discussion: the impact of a gearbox failure (more probable in a twin) in a twin is pretty dramatic too!! That's why it wrong to only look at the downside of the engine failure without accounting for the consequential other risks. Yes there should be less forced landings in twins due to engines, but more for other reasons, making them overall unjustified (in general).
Crab - don't start getting rude again (and wrong) - and can't you just respect that I don't want the pressure on the identity?
Join Date: Feb 2014
Location: between sun and sand
Posts: 106
Likes: 0
Received 0 Likes
on
0 Posts
quote: Two of anything has got to be better/safer than only the one - common sense.
hmmm, wasn't there a discussion about 2 pilots a while ago but with a bit different thinking from some usual suspects....
hmmm, wasn't there a discussion about 2 pilots a while ago but with a bit different thinking from some usual suspects....
Join Date: Feb 2004
Location: Langley, B.C. Canada
Posts: 162
Likes: 0
Received 0 Likes
on
0 Posts
In my 39 years and 23,000+ hours of flying rotary wing! I've had 9 engine failures....4 in singles, 5 in twins...ask me what my preference is....
Anyone trying to convince me that single engine aircraft is just as safe, needs a wee bit more education, or a full frontal lobotomy.....
Anyone trying to convince me that single engine aircraft is just as safe, needs a wee bit more education, or a full frontal lobotomy.....