Engines for ETOPS

Good point. I stand corrected.
The 146 doesn’t use turbofans, it uses hair driers!!!! 😉

rgds Cking

Geared fans? High bypass turbojets are sometimes classed as ducted fans so a geared fan would be the same.

Not necessarily. A high-bypass turbojet has the ducted fan rigidly shafted to the LP compressor. A turboprop, or a geared turbofan, has gearbox between turbine and fan – providing another point of failure. Bae 146 uses geared turbofans – and Bae means Bring Another Engine…

ETOPS/EROPS is a very big subject. It is also very interesting as it involves just about all the departments involved with air transport. I have been involved with the engineering side of ETOPS for about ten years now and still keep finding things I didn’t know about the subject.

Tri and quad jets tend to operate under EROPS conditions. I can feel another twenty questions coming on!…
EROPS is ETOPS for aircraft operating over inhospitable terrain. As engine failiur is not the only reason to need to land there have to be plans for diversions over some of the longer poalr routes. For example a sudden fuel leak over Siberia would require you to land sharpish! It wouldn’t matter if you were a 747 or a A330 you would need to land on two miles of concrete quick!
There’s another part of the subject for you. It’s ok saying that you can get an airliner into an airfield, can that airfield support it? Is there enough hotel rooms in the area to cater for three hundred people? Could you get the aircraft out agian?!!! The subject is huge.
Wankel engines? Name me an airliner that uses them
Geared fans? High bypass turbojets are sometimes classed as ducted fans so a geared fan would be the same.
Ditching requirements? You don’t ditch a jet airliner, it breaks up on impact and the bits sink like a stone. If you are luck enough to survive this, your life jacket, if it inflates, will keep you afloat for several hours. You will be dead from cold within twenty minutes mind you!!! Ditching is a myth, just hope and pray it dosn’t happen to you!

Rgds Cking

Mate of mine used to do ETOPS out of Fiji in an HS748!!! Don’t know what country’s flag it was operating under.

Aircraft with more than 30 passenger seats that fail to meet the ditching standards of the certification requirements must not be more than 120 minutes cruise or 400nm from ‘land suitable for making an emergency landing’ (non ETOPS)

What are the ditching requirements like? How well do the modern jets with high approach speed and high-bypass underwing turbofans perform when forced to ditch? Or what about modern commercial turboprops?

The bigger of the two or the smaller of the two?

Whichever comes first, think about it, the regs work well here.

How do you serve an island which does not have space for a really long and hard runway?

You serve it with turbo or piston props obviously, but remember without ETOPS you have to be 60 minutes from a suitable aerodrome, and in still air conditions this gives you 120 minutes flying time at the one engine inop TAS, you have what is known as a critical point, or equal time point, it is the point that if you reach it you can get out and you can get back with an engine out, this position will vary with wind, if you haven’t reached CP and you have an engine failure you must turn back, and if you pass it then obviously you go to your destination.
120 minutes flying time, is still a rather long way in today’s turboprops, even with 1 engine inop, with a tail wind as well can give healthy groundspeeds, you do the sums.
Now obviously if you have an island that is further away than 2hrs flying time you would apply for ETOPS, but seriously are there any remote islands that are served more than 2hrs flight time away? I don’t know of any.

Does this also apply to trimotors?

What aircraft are you thinking of here? are there many trimotor aircraft on a public transport CofA? if so the regs still apply.

The regs are quite extensive but here are some snippets.

Aircraft with more than 30 passenger seats that fail to meet the ditching standards of the certification requirements must not be more than 120 minutes cruise or 400nm from ‘land suitable for making an emergency landing’ (non ETOPS)

The bigger of the two or the smaller of the two?

From my understanding yes, propeller driven aircraft can apply for ETOPS, but why would they want to? an operator would not buy a twin prop to fly extensive routes over water.

Well, one disadvantage of jets is that they generally have high stall speeds. Therefore, they cannot use short runways, either for diversion or service, and do poorly when ditched or landed off runways.

How do you serve an island which does not have space for a really long and hard runway?

For tri engined aircraft without ETOPS (obviously) the following applies

Aircraft with three or more engines are allowed to operate at longer ranges from airfields than twin engined aircraft without ETOPS.

Does this also apply to trimotors?

We have a whole folder on Ops Procs, “almost” as tedious as Air Law

Our notes must be worse than yours on this topic 🙁

It’s Ops Procs BR 😉

Should I be able to quote the above in such finite detail having done Ops Procs, or is it an Air Law thing?

The regs are quite extensive but here are some snippets.

If two-engined aeroplanes are used, adequate aerodromes are available within the specified time and distance limitations for Extended Twin Engined Operations (ETOPS)

An operator shall ensure that operations are conducted in accordance with any restriction on the routes or the areas of operation, imposed by the Authority.

Aircraft with more than 30 passenger seats that fail to meet the ditching standards of the certification requirements must not be more than 120 minutes cruise or 400nm from ‘land suitable for making an emergency landing’ (non ETOPS)

I think the ETOPS times are 60 mins, 90 mins, 120 mins, 138 minutes and 180 minutes
From my understanding yes, propeller driven aircraft can apply for ETOPS, but why would they want to? an operator would not buy a twin prop to fly extensive routes over water.

For tri engined aircraft without ETOPS (obviously) the following applies

Aircraft with three or more engines are allowed to operate at longer ranges from airfields than twin engined aircraft without ETOPS. Beyond a certain distance from a suitable aerodrome such an aircraft must be able to sustain a double engine failure, continue to an en-route alternate and land.
But remember there are 3 classes of aircraft, class a – b – c, the rules regarding flight times from suitable alternates vary with class.