ANA 787 Engines shutdown during landing

[Leonakua]

Excellent

Your writing is quite accomplished, both in substance and style. It makes (this) reader feel less thick.

1. Why is the AC "Stuck in idle". Clearly thrust is used on the decel with reverse in the video?
2. Aren't the blocker doors contributing the bulk of decel by blocking 100 percent bypass?
3. My Assumption is that it is the loss of all bypass thrust that does the slowing?
4. My takeaway from the cascading process is that the engine's hot thrust counters the cascade vanes?
5. What is stopping performance with cut engines after touchdown?
6. Concerning this TCMA dual cut, is there a synopsis of windmilling decel?

You should write more often. Your style is welcoming, quite non arrogant.

Leo Nakua

[Leonakua]

Originally Posted by D Bru

“Over-engineering” or a “solution for one issue that constitutes another potential issue which could be of more grave consequences” comes to mind in the (Boeing) TCMA case. I got really concerned to learn that by design TCMA at least on Boeing 787 is armed and actively monitoring parameters below FL150 and 200kts. Of course it’s only supposed to actually deploy with WOW. One wonders if and if so, how this was addressed in Boeing’s 787 electrical power systems safety analysis in terms of hazard/risk assessment and probability of failure

My outrage at TCMA Included my ignorance of this procedural decision....It also came on the heels of Boeing's reluctance to ground the 787 after (Emergency) Battery fires in 2012...mostly apologies to tdracer and moderators....

[Someone Somewhere]

Originally Posted by Leonakua

Your writing is quite accomplished, both in substance and style. It makes (this) reader feel less thick.

1. Why is the AC "Stuck in idle". Clearly thrust is used on the decel with reverse in the video?
2. Aren't the blocker doors contributing the bulk of decel by blocking 100 percent bypass?
3. My Assumption is that it is the loss of all bypass thrust that does the slowing?
4. My takeaway from the cascading process is that the engine's hot thrust counters the cascade vanes?
5. What is stopping performance with cut engines after touchdown?
6. Concerning this TCMA dual cut, is there a synopsis of windmilling decel?

You should write more often. Your style is welcoming, quite non arrogant.

Leo Nakua

1) If the bypass door position does not match the thrust lever position, the FADEC will hold the engine at idle to prevent generating thrust in the wrong direction, or possible engine damage if full thrust is applied while the bypass doors are in transit (half-open).
2) There's enough actual reverse thrust that powerback is possible, but strongly not recommended due to FOD risk.
3) See above.
4) Modern engines have bypass ratios of 5-10. Even if the thrust redirected forwards is less than half as effective, that's still more thrust than the core exhaust provides.
5) Don't understand the question.
6) If you mean the original ANA event, the engines would have slowed down quite quickly due to low airspeed on landing.

[Leonakua]

#5... ANA (THREAD premise). Once cut, there is no hot or cold action.
So Dead Stick. My assumption is engines were CUT, to zero... Idle is not sufficient to rescue from a nose plant, eh? Thus the source of my worry.... (Narita)...wouldn't you rather try to stow cowls and doors, wait two seconds then add thrust?? Rather than have the option foreclosed?? Thanks for responding...
Leo

[Someone Somewhere]

Originally Posted by Leonakua

#5... ANA (THREAD premise). Once cut, there is no hot or cold action.
So Dead Stick. My assumption is engines were CUT, to zero... Idle is not sufficient to rescue from a nose plant, eh? Thus the source of my worry.... (Narita)...wouldn't you rather try to stow cowls and doors, wait two seconds then add thrust?? Rather than have the option foreclosed?? Thanks for responding...
Leo

The engine controllers believed that the engine was stuck at high thrust. TCMA should only activate if the engine thrust controls have failed and the engine is stuck at high thrust.

One engine at full forward thrust and one at full reverse will send any aircraft spinning off the runway with no hope of recovery (see that 747 in Hong Kong?). Trying to move the thrust reversers while at full thrust is likely to destroy them.

With the belief that the engine was uncontrollable and the crew don't want high thrust (as the thrust levers were at idle), shutting down the faulty engine was the right choice.

TCMA in that case was poorly programmed, and avoiding that case is why the GE versions start monitoring engine performance long before you're on the ground. I imagine they have all been thoroughly reviewed which should prevent a re-occurrence.

[Musician]

Originally Posted by Someone Somewhere

5) Don't understand the question.

I understand the question to ask how a dual engine shutdown affects the stopping distance.

I think this needs to be weighed against uncommanded high thrust affecting the stopping distance (and the pilots probably need to shut down the engine then, too).

The ANA 787 stopped safely.

[Leonakua]

"I understand the question to ask how a dual engine shutdown affects the stopping distance."

More importantly, survivability..... GEnx takes two seconds to deploy (reverse) fully. Less than three to stow... The CF6-80 (Narita MD11) similar in design. Without power, the aircraft is stranded in Pitch oscillations, interrupted by un-mitigable nose gear collisions with the runway?? Elsewhere in this thread rotor burst is (described as) an emergency that takes longer to develop than the difference between pilot intervention CutOff and TCMA CutOff...?? If so, then??? Thanks.

[Musician]

Originally Posted by Leonakua

Without power, the aircraft is stranded in Pitch oscillations, interrupted by un-mitigable nose gear collisions with the runway??

I'm super sorry, but I give up.
I've asked you before to be more explicit, and to explain more, and instead you keep churning out these bangers that are impossible for me to follow.

[Someone Somewhere]

Originally Posted by Leonakua

"I understand the question to ask how a dual engine shutdown affects the stopping distance."

More importantly, survivability..... GEnx takes two seconds to deploy (reverse) fully. Less than three to stow... The CF6-80 (Narita MD11) similar in design. Without power, the aircraft is stranded in Pitch oscillations, interrupted by un-mitigable nose gear collisions with the runway?? Elsewhere in this thread rotor burst is (described as) an emergency that takes longer to develop than the difference between pilot intervention CutOff and TCMA CutOff...?? If so, then??? Thanks.

TCMA isn't designed to protect against rotor burst; that's a different protection system. Both are designed to act very quickly because uncommanded high thrust/speed (whether it could result in rotor burst or not) occurs very quickly, faster than crew can reasonably expect to react.

The time taken to deploy/retract reversers is irrelevant, because you cannot deploy/retract reversers when the engine is at high thrust, and TCMA is designed to deal with engines that are stuck at a high thrust setting.

Originally Posted by Musician

I understand the question to ask how a dual engine shutdown affects the stopping distance.

Makes sense; I over-thought that.
Aircraft are generally supposed to be able to land even without thrust reversers, especially on dry runways. A single-engine TCMA shutdown should be no worse than any other single engine failure. Uncontrolled thrust is really nasty especially on slippery runways, which is the situation where reverse thrust is actually useful for stopping distance.

Originally Posted by Musician

I'm super sorry, but I give up.
I've asked you before to be more explicit, and to explain more, and instead you keep churning out these bangers that are impossible for me to follow.

I think this is a reference to FedEx Flight 80, which was an MD-11 that bounced, porpoised, and crashed at Narita in 2009.

If a crew had a bounced landing that bad, they could/should have applied power and gone around. If TCMA had activated (on all three engines, which again, should not happen and only occurred because RR had a software bug/lack of imagination), the crew might have been forced to land what should have been a go-around.

[Leonakua]

"If a crew had a bounced landing that bad, they could/should have applied power and gone around."

If I am asked to write a pleading, I get paid by the word... Sorry.

Yes, what does a crew do with a wicked bounce, with out Power?

1. Is there some residual thrust with TR?
2. Does Thrust Reverse tend to provide NU?
I think both are true??

[Musician]

Originally Posted by Leonakua

Yes, what does a crew do with a wicked bounce, with out Power?

Pitch to 7.5⁰ and land.

[TURIN]

According to Leo's profile they are a retired CPL on 737s.
Joined Pprune in November 25.
Some of the questions being asked are not the sort you would expect from a professional aviator.
Either there is something lost in translation or Leo is having us on.
Be well.
Merry Christmas.