United 328.....Holeeeeee Shit.

[seano732]

Someone in the Acronym Department needs to be fired.

Routed to the WTF division?

[dannynoonan]

Why isn't it e-sops, eh?

[ötzi]

Why isn't it e-sops, eh?

Would seem logical.

[Ted Striker]

Extended Twin OPerationS

and there are dozens more just like it

[Ottime]

And just so everyone know, airplanes that fly for extended periods over the ocean (like this one) are ETOPS rated. ETOPS stands for "extended twin engine operations." In other words they must be certified to fly for a long time on just a single engine. I believe these 777s are rated to fly 330 minutes on one engine. It's no big deal--just put your window shade down.

Sure. Until a goose goes into that second one.

[evasive_MT]

Some friends of mine live in that neighborhood, but didn't get hit.

Same. I know someone who was walking his dog and heard it.

[The AD]

Sure. Until a goose goes into that second one.

Then the pilot's announcement may have more of an edge to it.

Apprently ETOPS was originally just "extended operations," but effectively these days it's referring to two-engine aircraft.

By the way, we do analyses for what happens if a fan blade does impact primary structure and it's easiest to just assume it has infinite energy. If the engine cowling doesn't contain the thrown blade bad things can happen.

[Ted Striker]

I had no idea, but that makes sense. 747s ruled the world before any of the big twins, and the DC8 before that.

[The AD]

I had no idea, but that makes sense. 747s ruled the world before any of the big twins, and the DC8 before that.

Yeah, I didn't either. I'd always heard it was specifically for twins, but Wikipedia knows all.

[Mazderati]

Well, it did here. The requirement is for the lost blades to be contained.

Are uncontained rotor failures not a subset of uncontained failures?

"Most gas turbine engine failures are “contained” which means that although the components might separate inside the engine, they either remain within the engine case or exit it via the tail pipe. This is a standard design feature of all turbine engines and generally means that the failure of a single engine on a multi engine aircraft will not present an immediate risk to the safety of the flight. Sizeable pieces of ejected debris may, though, present a hazard to persons on the ground.

However, an “uncontained” engine failure is likely to be a violent one, and can be much more serious because engine debris exits it at high speeds in other directions, posing potential danger to the pressurised aircraft structure, adjacent engines, the integrity of the flight control system and, possibly, directly to the aircraft occupants."

https://www.skybrary.aero/index.php/...re#Description

[ötzi]

Extended Twin OPerationS

and there are dozens more just like it

The "twin" part is the hitch in the acronym my man. It has twin engines to start with. Lose one and it's single-engine operation. Hence the suggestion above for ESOPS.

[John_B]

It must operate under ETOPS at all times.

[The AD]

Are uncontained rotor failures not a subset of uncontained failures?

"Most gas turbine engine failures are “contained” which means that although the components might separate inside the engine, they either remain within the engine case or exit it via the tail pipe. This is a standard design feature of all turbine engines and generally means that the failure of a single engine on a multi engine aircraft will not present an immediate risk to the safety of the flight. Sizeable pieces of ejected debris may, though, present a hazard to persons on the ground.

However, an “uncontained” engine failure is likely to be a violent one, and can be much more serious because engine debris exits it at high speeds in other directions, posing potential danger to the pressurised aircraft structure, adjacent engines, the integrity of the flight control system and, possibly, directly to the aircraft occupants."

https://www.skybrary.aero/index.php/...re#Description

Yes, they are. This Denver incident seems to have been a contained failure--at least as far as we know now. The actual engine components like turbine and fan blades were contained as far as not entering other parts of the aircraft.

The videos from the engine containment tests are pretty dramatic. For example:

[The AD]

The "twin" part is the hitch in the acronym my man. It has twin engines to start with. Lose one and it's single-engine operation. Hence the suggestion above for ESOPS.

That's pretty funny. I never even thought about that.

[Mazderati]

Yes, they are. This Denver incident seems to have been a contained failure--at least as far as we know now. The actual engine components like turbine and fan blades were contained as far as not entering other parts of the aircraft.

If uncontained rotor failures are a subset of uncontained failures, that means there are other possible causes of uncontained failures; i.e., shit flying off the outside of the engine would also be an uncontained failure by definition since the failure is not contained within the engine or exhaust. No?

[The AD]

If uncontained rotor failures are a subset of uncontained failures, that means there are other possible causes of uncontained failures; i.e., shit flying off the outside of the engine would also be an uncontained failure by definition since the failure is not contained within the engine or exhaust. No?

I don't think so. I think the regulatory agencies are really most concerned about engine components, i.e. things with lots of kinetic energy that could cut through aircraft systems.

[ötzi]

Yes.

[rideit]

“Shoulda gone to Jared’s”



(Ps: it’s a screenshot, don’t click it)

[Ted Striker]

The "twin" part is the hitch in the acronym my man. It has twin engines to start with. Lose one and it's single-engine operation. Hence the suggestion above for ESOPS.

Oh, now I get where you're coming from. Pilots use the word twin as a type, i.e. if one engine fails the airplane is still a twin.

When I was a young(ish) lad in ground school, I was told that the word twin was in there because back in the day it was considered to be crazy to fly a twin over open ocean.

I'm kinda laughing that the word twin isn't even in there, but most pilots I know think it is. Just like most think they're Maverick when they're actually Murdock.

[seano732]

Oh, now I get where you're coming from. Pilots use the word twin as a type, i.e. if one engine fails the airplane is still a twin.

When I was a young(ish) lad in ground school, I was told that the word twin was in there because back in the day it was considered to be crazy to fly a twin over open ocean.

I'm kinda laughing that the word twin isn't even in there, but most pilots I know think it is. Just like most think they're Maverick when they're actually Murdock.

Well that’s comforting....

[DJSapp]

And just so everyone know, airplanes that fly for extended periods over the ocean (like this one) are ETOPS rated. ETOPS stands for "extended twin engine operations." In other words they must be certified to fly for a long time on just a single engine. I believe these 777s are rated to fly 330 minutes on one engine. It's no big deal--just put your window shade down.

Totally get that. I'd just think it's a bigger deal to be on the initial acceleration and climb and lose an engine vs. at cruise altitude and lower power. Do twin engine craft basically need to be able to do everything as a single, from roll out and takeoff or make certification?

And the old school way to get around ETOPS was the DC-10 and L1011 Tri Star. 3 engines means no need for ETOPS certs, but didn't come with 747 size.

[Ted Striker]

Do twin engine craft basically need to be able to do everything as a single, from roll out and takeoff or make certification?

Short answer, yes.

There's a calculation for "balanced field" which in its simplest form means that the aircraft can accelerate to the speed it needs to get airborne (which is weight dependent) and then if something goes wrong is capable of stopping within the remaining runway using only the brakes.

Speeds in an airplane are denoted by the letter V, for instance the speed at takeoff is Vr (speed at rotation).

Now let's say there isn't enough runway for the aircraft to accelerate to Vr then pull the power, slam the brakes, and stop before sliding off the end. So you're going to need a new speed to set as your decision point between stopping or going flying.

That speed is called V1, and in the case of this shorter runway it's obviously going to be slower than Vr.

In order to be certified, a twin engine passenger jet must be able to lose one engine at V1, continue the takeoff roll, and climb to a safe altitude above the airport.

[Gepeto]

Having trouble wrapping up how v1 could be greater than vr?

[splat]

When an engine goes out on a twin engine jet, the first th thought is the other is going to go out, ie, bad fuel.

Also, DJ - density altitude.

Sent from my SM-S767VL using TGR Forums mobile app

[Ted Striker]

Having trouble wrapping up how v1 could be greater than vr?

You're correct, it can't be. When the runway is longer than the length required for a balanced field V1 and Vr are the same.

I used that example because it shows that one engine has enough power to continue accelerating on the runway, take off, and climb out.