Multi engined Airliners

[Wally Mk2]

I just happened to come across the Airliners.net site & saw a thread discussing the merits good or bad about having 4 eng planes still being built.
So thought why not have a 'chat' about it here where it can get interesting & amusing:)
Okay basic stuff. 4 engines good for ETOPS/EDOPS/EROPS etc, smaller size per engine for better installation slung under wing/s. Better redundancies etc.
The 3 Eng concept seems to have died off


Let the games begin.:)


Wmk2

[Capt Fathom]

4 engines vs 2 engines....

Double the chance of an engine failure! :uhoh:

[Capn Bloggs]

4 engines also better for 2nd segment performance (3/4 of power left after a failure, instead of only 1/2), so can be smaller.

Problem is whether 4 smaller donks cost the same or less than 2 bigger ones, relatively more powerful ones. I very much doubt it.

[Wally Mk2]

That's true 'bloggsy' everything is predicated on the 2nd segment (the worst case) but it's interesting to watch the A380 takeoff at heavy weights they seem to stagger into the air & climb the same as a C150 on a hot day! Optical illusion obviously but I'd hate to see one of the ugly beasts lose a donk out of Melb on a 40 deg day...eeeekkk!

I guess it comes down to just how 'safe' are 2 eng's compared to 4 (or 3 for Eg)

'Safe' is subjective, safest is to stay in bed & never get up!:-)


Wmk2

[LeadSled]

Wally et al,

Let's drop the word "safe" and use the word "risk", safe is an emotive word without definition, risk can be measured.

Going right back to the early days of EROPS/ETOPS now EDTO, have we all forgotten that the original risk analysis showed that in-flight fire was a greater risk than engine failure, hence the significantly different hold certification standards now applied.

The risk of an engine failure, when an aircraft is in cruise and in the EDTO phase of flight is, as I think we all know, very low, almost vanishingly low. It has been clearly demonstrated in practice, not just theory.

I would have thought that the last 30+ years of long range twin operation had put the question beyond argument.

(1) Right now, how many 4 engine large civil aircraft are in production?
(2) In each case, how are their sales going, what is the order backlog?
(3) How many of the above were delivered last year and how many deliveries have been deferred?
(4) Will the A380 production ever reach break even levels, let alone make a profit?
(5) Will Boeing ever make a buck out of the B747-8?
(6) How many EDTO certified or certifiable twins were delivered last year, and how many are on order?

The answers to the numbers questions, of course, is tens versus thousands --- I would say the market has spoken, wouldn't you.

Much of the Qantas long haul commercial malaise right now is attributable to not having ordered B777 almost 20 years ago, because the company was not, in my opinion, being run in the best interests of the shareholder and the company.

If Qantas has had fuel competitive aircraft for the last 10-15 years, instead of increasingly tired B744, the bottom line would be very different right now.

Tootle pip!!

[apache]

You are assuming of course, leadsled, that the reduction in fuel costs would have stayed in the company's coffers instead of ending up in bank accounts of managers, consultants, lawyers and politicians.

[404 Titan]

Pro’s Twins

We run twice daily flights from Asia to SFO. One is with a B777-300ER the other with a B747-400. Over a four day period the B777-300ER burnt 26.7% less fuel than the B747-400 for almost the same payload. Add in the significantly lower maintenance costs of the Tripler the 74 isn’t even in the race.

Con’s Twins

We operate a daily flight from Asia to JNB which has an elevation of about 5500ft. While the B777-300ER isn’t currently being used on this sector, when it is, it’s generally only used during the southern hemisphere winter as the OEI second segment is too restrictive to make it consistently viable without a tech stop in say BKK. As an example, on a 30°C day there is about a 50 Tonne payload restriction without a tech stop.

[Capn Rex Havoc]

Optical illusion obviously but I'd hate to see one of the ugly beasts lose a donk out of Melb on a 40 deg day...eeeekkk!


I would rather be in a 380 out of Melb on a 40 deg and lose a donk than on any twin.

The 340-300- well that is a different story altogether.

Even with one engine out on a 380, your driftdown will be above the mountain goats in the Himalayas. Not as comfy on a twin across there.

[neville_nobody]

Maybe we should ask the United 777 crew who had a shutdown just past the PNR in the middle of the Pacific and then flew on one engine for over 3 hours in the middle of the night on their thoughts!

Personally for the transpacific/antarctic routes 4 engines is probably safer. 3 hour EDTO is probably pushing the limits.

[TwoFiftyBelowTen]

Perhaps we could get some input from someone from CX perhaps who crew the twins and the quads? I do know they are getting more and more A330s and phasing out the A340. I don't think there is much in it as far as fuel burn goes, I gather it is about the maintenance costs of 4 vs 2 per unit?

[404 Titan]

neville_nobody

As someone who has flown both the 330 and 340, I'm more concerned about a cargo fire then an engine shutdown. One is extremely time critical, the other isn’t. To some it may sound frightening only being on one engine over the pond or arctic, but the reality is having a cargo fire in such a region is by far your worst nightmare situation, irrespective of the number of engines you have.

TwoFiftyBelowTen

I can’t give you exact figures but numbers I've heard are that the 340’s maintenance costs are about 25% higher than the 330's.

[Ozgrade3]

Does anyone one know the BSFC of the engine off the 748 v the 777's GE 90

[Angle of Attack]

Ozgrade3 if your talking about an engine to engine comparison I would say the 777 GE has a higher, but thats just my guess, ot sure of the figures, but surely a 747-8 wouldnt have 4 engines burning the same as a 777 GE engine? Anyway well find out in course I guess..

[Exaviator]

The only reason I flew four engine aircraft was that there were few eight engine ones available :)

[neville_nobody]

but the reality is having a cargo fire in such a region is by far your worst nightmare situation, irrespective of the number of engines you have.

Yeah I agree, but my example actually happened for real rather than a theoretical cargo fire that maybe might happen.

On saying that the UPS accident in DXB puts cold shivers through any pilot.

[NG_Kaptain]

"Multi Engine Airliners". Aren't they all. Last non multi engine airliners I flew were Cessna !82's and 206's doing air taxi work. I fly a twin now.

[drpixie]

Exaviator - so that wouldn't be you I heard fighting your way through the dreaded 7 engine approach!

[Seabreeze]

It was the dreaded 9 engine approach on the B36 that did my head in: (hang on, surely a B36 is just a developmental derivative of that sweet handling A36!)

http://www.nmusafvirtualtour.com/media/062/B-36J%20Engineer.html

SB

[Tankengine]

A crusty old Captain was asked his opinion on the subject:

"I like the Flight Engineer to tell me when engine #8 is running a bit hot, I then ask him which wing!":E

[Slippery_Pete]

All these useless comparisons about second segment, redundancy safety, hot & high performance, drift down over high terrain, blah blah blah...

Airline management around the world (and particularly in Australia) don't give a flying :mad: about which one might be safest.

All these aircraft are certified to a minimum required standard, and therein ends their thoughts on it.

They choose the cheapest one. Period.

If you could build a six engine airliner with the same payload as a 777 which was 1% cheaper overall (considering purchase price, maintenance, fuel efficiency, staff costs etc. etc.) the 777 would go the way of the dodo faster than you could say "Here comes another management bonus".

[Bevan666]

There is a Beech B36 - it's a turbocharged and has a slightly longer wing for better high altitude performance over the A36

Bevan

[airspace alpha]

Then again, there is the (possibly apocryphal) comment from Sir Henry Royce who, when asked why he would only fly on 4-engined aircraft, replied "Because young man, nobody has yet built a five engined aircraft"

[VH-Cheer Up]

When I gained my PPL in the UK I offered my uncle, a retired Halifax pilot with many, many missions experience, if he would care to go for a flight.

He asked me: "What aircraft?"

"It's Piper Cherokee 140".

"Huh. Don't know it. How many chances does it have?"

"I don't take chances, what do you mean?"

"Chances. How many chances"?

"Thinking something had been missed from my training, I confessed I really didn't know how to answer.

"Laddie, I like aircraft with four chances of getting home. Two on each wing."

I suppose he had every reason to be cautious, having had to bale out of a burning bomber twice, once over the Channel, and once over Yugoslavia, where the resistance smuggled him back to England.

You take away alternates, friendly ATC vectoring, radar, FADEC and EFIS, add a lot of molten metal exploding all around you, and the fuel burn and cost savings associated with two engines seems immaterial.

The more engines, the more likely to get home. May he rest in peace.

[LeadSled]

You are assuming of course, leadsled, that the reduction in fuel costs would have stayed in the company's coffers instead of ending up in bank accounts of managers, consultants, lawyers and politicians.
Apache,
Quite so!

The apparent fiddling that has gone of for years, particularly to make JetStar look good, in my opinion, contravenes some well understood sections of the Corporation Act 2001, re. duties of directors and officers of a company.

Back to twins versus the rest, all the old jokes have been exhumed, everybody has had a bit of fun, about the only thing missing is somebody saying we should bring back flight engineers.

The facts are simple , the statistics are clear, and the winner is the long range twin.

Tootle pip!!

[fl610]

about the only thing missing is somebody saying we should bring back flight engineers.

We should bring back Flight Engineers! :E

[Andy_RR]

We should bring back Flight Engineers! :E

...and nubile trolley dollies.

[Pinky the pilot]

Second the post of Andy_RR.:D

Apache; Long time no hear. How are ya? Miss the Boulia pub much?:E

[apache]

Pinky old mate!
Believe it or not..... No. Whilst I have fond memories, (and some blurred ones too!), I have moved on from the boulia pub.

What I have found is that it doesn't matter how many engines it has,it can NEVER get you to the pub fast enough.

[aroa]

VH Cheer up...did yr uncle ever write a book.? Sounds like it it would be a ripper read.
His spirit would surely be pleased to know that a Halifax is under resto in Canada

4 up sounds good. First ride ever in a DC 4 and the Song of the Round Ones is with me yet.

RIP Uncle.

[kellykelpie]

Agree with LeadSled. I think 4 engines are a thing of the past - now, what about one pilot...

[Arnold E]

now, what about one pilot...

Hmmm, or indeed NO ( human) pilot.:eek:

[kellykelpie]

Can only do one pilot if you can do no pilot - know what I mean?.