A350 seeks 420 minute ETOPS
 

An article on the Wall Street Journal website states that Airbus has told customers and air-safety officials that the A350 design contemplates 420 minute approval some day.

A question for folks with engine knowledge: how does one assess the reliability of an engine operating at high power for prolonged time as required in single-engine diversions? As a former reliability guy (in semiconductors) I'm moderately uncomfortable with estimating reliability behavior in a regime far away from high-volume field experience, which we always found to be a useful backup and corrective to estimates made from accelerated testing and various forms of analysis.

A350 seeks 420 minute ETOPS
 

Not a specialist here but would there still be some routes not covered by a 420min ETOPS ?!

archae86:I don't have anything quantitative at hand, but worked a decade or two on an early "big" engine used in twins, trijets, and quads. No technical difference between, same engine really, but the environment and thrust used in cruise was substantially different.

In the final analysis, it was the number of flight cycles that accounted for the wear and tear on the machines. The twin generally flew the shortest legs, and thus accumulated the most flight cycles, thus generating the most shop visits.

420 minute ETOPS? Very long legs, few cycles accumulated, so I'd expect long life for the machine.

7 hours aloft after an engine failure in a twin? So when I have an engine failure right after departing Honolulu, I can just continue to Los Angeles. :ugh:

Why not just get rid of the whole ETOPS concept altogether then?

Would be nice if somebody could provide reliability figures for the CFM56 on the A319 and on the A340. On the A340 they run at higher power for much longer periods. I would bet the figures are better.

I guess that is exactly what would happen in the future, once all aircraft will be twins. And just like for nuclear power, everybody will be shaken up once the statistical figures proof to be right, and the unlikely but certain event will happen one day. Extremly reliable does not mean unfailable.

It is Boeing's intention to remove any time limits on EROPS and the new rules/planning requirements would then apply to all Aircraft. ( twin and quad )

The longest time on wing without any shop visit actually was a CFM56 on a 737, over 50.000 hours if i remember correctly. The previous record was also on a 737 with over 40.000 hours. The A340 CFMs apparently need to be taken off the wing much more often.

Let them go 420 minutes ETOPs. Its just the manufacturers selling point ! Just make the operators approval very exacting with stringent criterias. Nothing to do with ETOPs but most of us are a little shy of cargo fires, (2 or 4 engine), this far away from a suitable ETOPs alternate.

Fluke, I'm thinking if you have an uncontrolled cargo fire, if you're more than 15 minutes from a suitable airport you're chances of a happy outcome are not good. At that point 120 minutes vs. 330 minutes vs. 420 minutes isn't going to make much difference.

tdracer, I hear you !

In a controlled cargo fire ( ahhh). How about a cargo fire that has been extinguished with the first bottle. Then you need numerous other bottles to keep the fire suppressed while you return to your planned ETOPs alternate 420 minutes away. Of course you will have 2 engines working but ventilation shut off which may result in computers overheating. Perhaps the extra fuel planned for the 1 engine out depressurised scenario will cover you? or perhaps there is a nearer adequate airport that your ETOPs nominated one.
Either way its a boundary I wont be pushing unless the whole ETOPs/EROPs certification is updated to reflect reality rather than the theoretical.

Fluke


The new ETOPS rules (FAR Part 25 Appendix K in the FAA world) attempt to take all those things into account (healthy skepticism is probably justifiedhttp://images.ibsrv.net/ibsrv/res/sr...y_dog_eyes.gif ).

During my recurrent DER training a couple years back they went over the Appendix K rules in some detail including the 'why'. The basic admission was the engine reliability on modern engines was to the point that loosing multiple engines due to independent causes on the same flight was no longer the only, or even primary, ETOPS concern - it was now the rest of the airplane. Things like electrical systems, fire suppression, etc.

Hence the new ETOPS regulations apply regardless of the number of engines (never mind it pretty much trashes the original ETOPS definition). IIRC, the new regs are mandatory in 2015 for all Part 25 passenger airplanes (3 and 4 engine freighters are exempt - apparently their flight crews don't matter :ugh:). While engine reliability is still relevant for twins, 3 and 4 engine airplanes the regulations don't have much to do with the engines.

Right now the 777 has 330 minute ETOPS, I don't work the 777 but what I'm hearing is that extending that is not technically an issue - it's just time and money - and 330 covers everything that the operators have wanted. 420 covers some theoretical Antarctic polar routes, and could potentially give Airbus some bragging rights until Boeing responded.http://images.ibsrv.net/ibsrv/res/sr...y_dog_eyes.gif

My personal opinion is 420 minute ETOPS is just AIRBUS way of claiming their attachments are bigger http://images.ibsrv.net/ibsrv/res/sr...s/badteeth.gif

SR-22 - Check this article - 50,000h on wing CFM.

Volume - I don't think there is a competition - The thrust rating on the CFM's on 737 are low compared to the A340's (check the trust rating vs aircraft in wiki)

Back to the OP - My feelings are similar to fluke and tdracer... The engines are no longer the limiting factor...

ETOPS beyond 180
 

I think you will find that the limiting factor for any ETOPS beyond 180 minutes is cargo fire/smoke suppression. Engine performance is of course a consideration but the limits are established by more critical issues involving how long can I keep this darn thing airborne with a cargo fire.

What's the difference between a Tri or 4 engine aircraft cargo fire suppression system versus a twins? Are we not talking about system redundancy instead?

ETOPs doesn't mean that you'll have a happy ending with every incident, it's just a planning tool ( sic) .

ETOPS
 

I do believe that tri and quad freighter aircraft are exempt for ETOPS rules. See AC142-20B for more info

ETOPS = Extended-range Twin OPerations

Perhaps a clue in the name?

180 minutes set by fire suppression?
 

As has no doubt been discussed above:
Isn't 180 minutes about a factor of 10 times too long for that to be the case?

ETOPS = Extended-range Twin OPerations

DaveReid - As I noted in my previous post, effective next year all Part 25 passenger aircraft will be subject to ETOPS rules, regardless of the number of engines. To keep the acronym semi-meaningful, they are saying it stands for ExTended OPerations.:rolleyes:


The new ETOPS rules don't apply to Freighter aircraft with more than two engines, again noted in my previous post.

Or simply more evolution. They were the first manufacturer to have aircraft certified beyond 60 minutes (A300 before ETOPS existed), first to be certified beyond 180 minutes (A330), and maybe the first manufacturer to be certified to 420 minutes (A350).

Probably also were the first manufacturer to have quads meeting the ETOPS regs (A340).

That doesn't make any sense at all.
How does fire differentiate between a quad and a twin?
Why should a quad survive a fire a single minute longer than a twin?
And in any case of a fire either it is extinguished successfully or after twenty minutes it's game over anyway.