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How Close Was The Qantas A-380 To Crashing?  
User currently offlinewashingtonian From , joined Dec 1969, posts, RR:
Posted (3 years 2 months 2 weeks 3 days 16 hours ago) and read 28615 times:

I don't mean to start a sensationalist thread, but how close was the Qantas A-380 with the engine explosion out of SIN close to crashing?

53 replies: All unread, showing first 25:
 
User currently offlineblackwidow From United Kingdom, joined Feb 2008, 95 posts, RR: 0
Reply 1, posted (3 years 2 months 2 weeks 3 days 16 hours ago) and read 28488 times:

Which leads me to ask - when's she gonna fly again?? Must be soon....

User currently offlineSEPilot From United States of America, joined Dec 2006, 7117 posts, RR: 46
Reply 2, posted (3 years 2 months 2 weeks 3 days 16 hours ago) and read 28401 times:

I will put it in perspective. I just had a chance to see the Collings Foundation B-17 & B-24, and I recall pictures of B-17's that had limped back to England with incredible damage, including a couple that landed with only one operating engine, IIRC. Compared to those, the A380 was in good shape. But this was a very different situation, and from what I have read the crew had their hands full and did a magnificent job of getting the plane down safely. The only way to really tell how well they did is to put the same situation in the simulator and see how different crews cope with it (which I'm sure Airbus has done.) I have not heard any results of such an experiment, however. Just for another perspective, they did that after UA232, and none of the crews were able to get the plane anywhere near the airport, let alone make anything close to a controlled landing.


The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
User currently offlineplanespotting From United States of America, joined Apr 2004, 3539 posts, RR: 5
Reply 3, posted (3 years 2 months 2 weeks 3 days 16 hours ago) and read 28197 times:

Here is Patrick Smith's bullet point list (from his Nov. 18 "Ask the Pilot" article in Salon which cannot be linked to from this site for reasons that cannot be elaborated upon) of crap the flight crew had to deal with all at once:

- Complete, uncontained failure of No. 2 engine.
- Shrapnel hole on one of the left wing-flap fairings
- Large shrapnel puncture clear through the forward section of the left wing.
- Failure of the automatic bus transfer between the failed No. 2 engine and the still operating No. 1 engine, among other electrical problems
- Total loss of all fluid in one of the plane, two main hydraulic systems
-Substantial leaks in two of the plane, left wing fuel tanks
- lectronic and/or mechanical failure of important fuel transfer functions (leading to a fuel imbalance).
- Malfunction of the fuel jettison system.
- Partial failure of leading edge slats.
- Partial failure of speed brakes and ground spoilers (once on the ground)
- Loss of brake anti-skid system
- Inability to shut down the adjacent, No. 1 engine using normal or emergency ("fire switch") methods (meaning if the No. 1 engine had also failed or started on fire, there would have been no way to shut it down)

As you can see, it's quite the laundry list of failures and problems that probably had never been demonstrated in the simulator before (at least in aggregate).

[Edited 2011-10-04 13:52:00]


Do you like movies about gladiators?
User currently offlineSPREE34 From United States of America, joined Jun 2004, 2264 posts, RR: 9
Reply 4, posted (3 years 2 months 2 weeks 3 days 14 hours ago) and read 27602 times:

Quoting washingtonian (Thread starter):
close to crashing?

Not at all. Rudundancy worked.



I don't understand everything I don't know about this.
User currently offlinegdg9 From United States of America, joined Jun 2005, 672 posts, RR: 0
Reply 5, posted (3 years 2 months 2 weeks 3 days 14 hours ago) and read 27513 times:

Great job by the professionals at QF in landing the aircraft.

User currently offlineRoseFlyer From United States of America, joined Feb 2004, 9813 posts, RR: 52
Reply 6, posted (3 years 2 months 2 weeks 3 days 14 hours ago) and read 27414 times:

Quoting SPREE34 (Reply 4):
Quoting washingtonian (Thread starter):
close to crashing?

Not at all. Rudundancy worked.

It was extremely close to not being able to land safely because the airplane had so many concurrent failures that affected the ability to land. So many parts of the airplane were damaged that the landing distance could not even be effectively calculated. No pilots train for that many failures at once. Redundancy worked, but it was on the ragged edge of being able to safely land the plane. Redundancy is based on statistics and no one would have predicted that a fan blade loss would result in that many failures.

With the leading edge damaged, a higher approach speed was necessary.
With the spoilers damaged, the airplane would not get sufficient weight on wheels to allow full effectiveness of the brakes.
With the loss of a hydraulic system, anti-skid was disabled.
With a fuel imbalance due to loss of fuel pumps and associated leak, the CG was off.
With loss of engine 1 controls, the engine could not be operated as usual or even shut down.
With fuel leaking on overheated brakes/tires, fire was possible.
With inabiliity to jettison fuel, airplane was overweight
With loss of electrical system, communications were partially limited.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineprebennorholm From Denmark, joined Mar 2000, 6537 posts, RR: 54
Reply 7, posted (3 years 2 months 2 weeks 3 days 12 hours ago) and read 27016 times:

With the long list of malfunctioning subsystems they had better find a good long runway, preferably dry, and no adverse weather. That's also what they did.

The combination of fuel leak in one wing and non-functioning fuel dump was, however, a potentially dangerous thing. Had the leak been a lot more massive, then it could have produced a dangerous lateral imbalance.

Apart from that, redundancy worked. And thank God the flight crew staid cool and did what they were trained to do.

But I am pretty sure that the non-functioning fuel dump has provided a few sleepless nights in Toulouse. I could imagine that Airbus has investigated very carefully what exactly caused the fuel dump malfunction, and that they are (or have been) looking into ways to eliminate that, or build in an additional layer of redundancy there.

Quoting RoseFlyer (Reply 6):
...no one would have predicted that a fan blade loss would result in that many failures.

There was nothing wrong with the fan, it was the IP turbine disk which disintegrated.

Quoting RoseFlyer (Reply 6):
Redundancy is based on statistics...

What???? Redundancy is based on failure tolerant design.



Always keep your number of landings equal to your number of take-offs, Preben Norholm
User currently offlineRoseFlyer From United States of America, joined Feb 2004, 9813 posts, RR: 52
Reply 8, posted (3 years 2 months 2 weeks 3 days 12 hours ago) and read 26904 times:

Quoting prebennorholm (Reply 7):
Quoting RoseFlyer (Reply 6):
Redundancy is based on statistics...

What???? Redundancy is based on failure tolerant design.

I'll expand a bit. Redundancy is based on tolerating a failure, but what type of redundancy is about the probability of a specific failure and the effects that it has. For example, the probability of landing gear deploying in flight causing excess drag on an overwater flight and leading to fuel starvation is so low that a redundant method for gear retraction is not required. However the probability of landing gear not being able to be deployed and causing a gear up landing is high enough that a secondary landing gear extension system is required on almost all airplanes.

What I am getting at is that the probability of a single engine failure mode taking out enough systems to result in a condition preventing a safe landing has to be low enough to be considered so improbable that it will not happen. My point is that the single event came very close to preventing the airplane from safely landing. The condition was so unlikely that not all parameters on the airplane could be used to calculate a safe landing distance since it was never thought that such an event could happen. In the end the airplane was able to make a safe landing, but I would not say that the airplane was not at all close to having an unsafe landing (going off runway, fire, etc). It took some exceptional skill by the crew to execute a safe landing.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlinethegeek From Australia, joined Nov 2007, 2638 posts, RR: 0
Reply 9, posted (3 years 2 months 2 weeks 3 days 12 hours ago) and read 26671 times:

Quoting RoseFlyer (Reply 8):
My point is that the single event came very close to preventing the airplane from safely landing.

That would be your opinion though. Other posters have disagreed, in this thread and others.

I don't know if anyone has an objective answer to this question. If they do, I for one would love to see it.

Quoting prebennorholm (Reply 7):
The combination of fuel leak in one wing and non-functioning fuel dump was, however, a potentially dangerous thing. Had the leak been a lot more massive, then it could have produced a dangerous lateral imbalance.

How severe might this issue have been? Could you have run out of aileron authority to compensate for the imbalance? I'd be very surprised.

I suppose if all the fuel leaked out of the port wing, the #1 engine would also have (presumably) stopped, which with the still heavy weight from the full starboard wing tanks would have impacted your climb ability pretty severely. I'd still be very surprised if this effect was enough to cause you to hit the water.


User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 10, posted (3 years 2 months 2 weeks 3 days 12 hours ago) and read 26182 times:

Quoting washingtonian (Thread starter):
how close was the Qantas A-380 with the engine explosion out of SIN close to crashing?

The biggest thread, as RoseFlyer stated, was a runway overrun. There was no immediate threat of a crash because they had positive control of the airplane in all three axis and positive speed control. They had a ton of issues to deal with, but essentially none of them were threats to continued safe flight or landing. It's often very easy to forget that the gulf between normal airliner capability and inability to actually fly is very very very wide.

Quoting planespotting (Reply 3):
- Complete, uncontained failure of No. 2 engine.
- Shrapnel hole on one of the left wing-flap fairings
- Large shrapnel puncture clear through the forward section of the left wing.
- Failure of the automatic bus transfer between the failed No. 2 engine and the still operating No. 1 engine, among other electrical problems
- Total loss of all fluid in one of the plane, two main hydraulic systems
-Substantial leaks in two of the plane, left wing fuel tanks
- lectronic and/or mechanical failure of important fuel transfer functions (leading to a fuel imbalance).
- Malfunction of the fuel jettison system.
- Loss of brake anti-skid system
- Inability to shut down the adjacent, No. 1 engine using normal or emergency ("fire switch") methods (meaning if the No. 1 engine had also failed or started on fire, there would have been no way to shut it down)

None of these are threats to continued safe flight and landing because they're all covered by existing redundancy. You've lost levels of protection (many levels in this case) but you haven't lost any flight critical function.

Quoting planespotting (Reply 3):
- Partial failure of leading edge slats.
- Partial failure of speed brakes and ground spoilers (once on the ground)

This combination was probably the closest to being a threat to continued safe flight, as the combination isn't tested as far as I know. Either failure individually is tested but that doesn't guarantee the combination is also safe.

Quoting RoseFlyer (Reply 6):
It was extremely close to not being able to land safely because the airplane had so many concurrent failures that affected the ability to land.

None of them affected the ability to reach touchdown safely...a bunch affected the ability to stop. Hence the risk was much more of a runway overrun.

Quoting prebennorholm (Reply 7):
The combination of fuel leak in one wing and non-functioning fuel dump was, however, a potentially dangerous thing. Had the leak been a lot more massive, then it could have produced a dangerous lateral imbalance.

Full fuel tank drain due to rotor burst is a design condition and should be part of the aileron sizing criteria. It should be impossible to get a dangerous lateral imbalance due to a punctured fuel tank. Now, if they punctured two tanks, it probably depends on which two.

I am NOT trying to minimize the severity of this event, just trying to answer the OP's question. They weren't in any danger of crashing given the failures they had...given how many levels of protection they lost, however, they might have been a single failure away from certain fatalities.

Tom.


User currently offlinekanban From United States of America, joined Jan 2008, 3856 posts, RR: 27
Reply 11, posted (3 years 2 months 2 weeks 3 days 12 hours ago) and read 26180 times:
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Quoting blackwidow (Reply 1):
Which leads me to ask - when's she gonna fly again?? Must be soon....

I saw somewhere a Feb 2012 date..


User currently offlinethegeek From Australia, joined Nov 2007, 2638 posts, RR: 0
Reply 12, posted (3 years 2 months 2 weeks 3 days 11 hours ago) and read 25559 times:

I think the answer to "how close was this flight to crashing" (other than a runway overrun) was how close they came to losing the remaining hydraulic system. Is that a known? Although it has happened that an A300 has landed after even this extreme loss of control.

User currently offlineXT6Wagon From United States of America, joined Feb 2007, 3432 posts, RR: 4
Reply 13, posted (3 years 2 months 2 weeks 3 days 11 hours ago) and read 25331 times:

Quoting thegeek (Reply 12):
I think the answer to "how close was this flight to crashing" (other than a runway overrun) was how close they came to losing the remaining hydraulic system. Is that a known? Although it has happened that an A300 has landed after even this extreme loss of control.

Many other ways they could have lost the lotto on where the pieces of the rotor disk went. I think someone here said that the A380 has a limited "manual reversion" capiblity for all hydraulics lost, but clearly more damage to the ability to control the plane would have been... dangerous.

The one that IMO they were most lucky to avoid was taking a major chunk of the compressor in the other engine. 2 engine out on the same wing... not likely to allow a return to the airport even if it was still controlable.


User currently offlineNWAROOSTER From United States of America, joined Feb 2005, 1150 posts, RR: 3
Reply 14, posted (3 years 2 months 2 weeks 3 days 11 hours ago) and read 24814 times:
Support Airliners.net - become a First Class Member!

The main thing taught pilots, when an aircraft is trouble. "Fly the Airplane."
This is what the pilots did and they did it well.   



Procrastination Is The Theft Of Time.......
User currently offlinethegeek From Australia, joined Nov 2007, 2638 posts, RR: 0
Reply 15, posted (3 years 2 months 2 weeks 3 days 11 hours ago) and read 24754 times:

Quoting XT6Wagon (Reply 13):
I think someone here said that the A380 has a limited "manual reversion" capiblity for all hydraulics lost

I think there is something for some of the tail surfaces, maybe pitch trim? But they did lose the EHA systems so I am pretty sure that the ailerons, for example, were not controllable had they lost the other hyd system in addition to the other damage.

Quoting XT6Wagon (Reply 13):
The one that IMO they were most lucky to avoid was taking a major chunk of the compressor in the other engine. 2 engine out on the same wing... not likely to allow a return to the airport even if it was still controlable.

I can only imagine that this would only be a problem at either low level (not enough time to fuel dump) or without the fuel dump capability. Of course the fuel dump capability was damaged, but even so, I expect the glide angle on the remaining two engines would have been shallow enough to return to SIN and risk a runway overrun in the worst case.

Or am I missing what you are saying?


User currently offlineXT6Wagon From United States of America, joined Feb 2007, 3432 posts, RR: 4
Reply 16, posted (3 years 2 months 2 weeks 3 days 10 hours ago) and read 24510 times:

Quoting thegeek (Reply 15):
Or am I missing what you are saying?

severe control issues in addition to a lack of thrust for this weight. I hope Airbus took the history of 747's that lost both engines on a wing into account since the 747 atleast is shooting a big gooseegg in suviving that. Yet, I doubt the A380 would retain full control with the two engines out even if no other damage occured. Thats just too many systems suddenly lacking hydraulic power, bleed air, and electricity. Nor would I expect them to design for it since independant failures of both engines on one wing should be as likely as winning the lotto on the same day as you win the indy 500. Also RR was supposed to insure that the chance of uncontained failure was 0.


User currently offlinethegeek From Australia, joined Nov 2007, 2638 posts, RR: 0
Reply 17, posted (3 years 2 months 2 weeks 3 days 10 hours ago) and read 23837 times:

Quoting XT6Wagon (Reply 16):
I hope Airbus took the history of 747's that lost both engines on a wing into account since the 747 atleast is shooting a big gooseegg in suviving that

That El Al freighter also had damage to the wing and/or its high lift devices, which was the main reason it crashed AIUI. It was also at a much lower altitude than QF32, so less options and also more weight due to more full fuel tanks.

Looking it up, I have to wonder if the pilots in that case were aware that the leading edge flaps were deployed on one wing but not the other. You would think they would notice the high aileron input required though.

Quoting XT6Wagon (Reply 16):
Also RR was supposed to insure that the chance of uncontained failure was 0.

Surely negligible, not 0.


User currently offlineqf002 From Australia, joined Jul 2011, 3020 posts, RR: 2
Reply 18, posted (3 years 2 months 2 weeks 3 days 10 hours ago) and read 23559 times:

So in summary, she was very close to crashing, but it was a few strokes of luck that allowed the crew to maintain control and land the aircraft safely. If any one of the factors that contributed to the safe landing of that aircraft hadn't fallen into place then it's likely that the aircraft would have crashed, and I personally think that's pretty close to a crash, regardless of what others try to say about the aircraft being controllable etc -- that was pure luck IMO.

User currently offlinetype-rated From , joined Dec 1969, posts, RR:
Reply 19, posted (3 years 2 months 2 weeks 3 days 10 hours ago) and read 23557 times:

Quoting NWAROOSTER (Reply 14):
The main thing taught pilots, when an aircraft is trouble. "Fly the Airplane."

Fly the airplane FIRST.

Stabilize the aircraft, then attend to any problems that have come up. If you lose control of the aircraft what use is the rest of it?


User currently offlineprebennorholm From Denmark, joined Mar 2000, 6537 posts, RR: 54
Reply 20, posted (3 years 2 months 2 weeks 3 days 9 hours ago) and read 23332 times:

Quoting thegeek (Reply 9):
Could you have run out of aileron authority to compensate for the imbalance? I'd be very surprised.

Aileron authority increases with the square of speed. Meaning that at landing speed it is pretty low.

In case of, say, 100,000 lbs more fuel in the right wing than in the left wing, then it would have dictated a very high landing speed to maintain just a little roll control authority, and I could imagine 22 bust tires, therefore little breaking, and a very, very unpleasant runway overrun.

Quoting tdscanuck (Reply 10):
Full fuel tank drain due to rotor burst is a design condition and should be part of the aileron sizing criteria. It should be impossible to get a dangerous lateral imbalance due to a punctured fuel tank. Now, if they punctured two tanks, it probably depends on which two.

I agree with you, tdscanuck, and I am also pretty sure that in this case the lateral imbalance was only, or little more than, a trim problem.

But magnitude of catastrophic fuel tanks rupture is something which is difficult to design for. In addition it may happen at a more inconvenient place, say five hours flight away from nearest useful airport. It is more likely that it happens during climb, as it did, when the engines work harder. But in theory it may happen at any time from gate A to B.

It is the job of the airliner designers to learn from experience when incidents like this one happen. When things have a totally happy end like this time, then they shall imagine the same failures also with the worst thinkable magnitudes of the individual failures. And imagine whether the consequences would be any different.

I am pretty sure that the non-functional fuel dump and fuel transfer system is the single issue which have caused the most grey hairs in Toulouse. All the other failures, which developed on QF14, were designed for. But for sure they didn't install fuel dump and transfer abilities only for being inop in case of an uncontained engine failure.

Of course I have no idea what caused the inop dump and transfer, but if it was something as simple as a ruptured electric cable, then sure it can be improved with another layer of redundancy without much rocket science redesign.

Long range planes, where almost half of the take off mass is fuel, have the potential to develope uncontrolable imbalance, making fuel dump ability more than a convenience to avoid overweight landing, and also a primany safety issue.



Always keep your number of landings equal to your number of take-offs, Preben Norholm
User currently offlineJAAlbert From United States of America, joined Jan 2006, 1624 posts, RR: 1
Reply 21, posted (3 years 2 months 2 weeks 3 days 9 hours ago) and read 23127 times:

Why couldn't the crew shut down the engine? How did they eventually shut it down? Throw a hammer into it?

User currently offlineqf002 From Australia, joined Jul 2011, 3020 posts, RR: 2
Reply 22, posted (3 years 2 months 2 weeks 3 days 9 hours ago) and read 22853 times:

Quoting JAAlbert (Reply 21):
Why couldn't the crew shut down the engine? How did they eventually shut it down? Throw a hammer into it?

Access was cut off by the wing damage (IIRC) -- fire crews slaughtered it with water, then when that didn't work with foam... It took 30+ minutes to get it stopped I think...


User currently offlinezeke From Hong Kong, joined Dec 2006, 9229 posts, RR: 76
Reply 23, posted (3 years 2 months 2 weeks 3 days 9 hours ago) and read 22591 times:

Quoting washingtonian (Thread starter):
I don't mean to start a sensationalist thread, but how close was the Qantas A-380 with the engine explosion out of SIN close to crashing?

It was a rare combination of faults to deal with at once, however the crew that was flying the aircraft worked as a team and applied a conservative approach to resolving the situation. The actual flight on 3 engines and the approach back into SIN by all accounts was very smooth.

Quoting blackwidow (Reply 1):
Which leads me to ask - when's she gonna fly again?? Must be soon....

Repairs are well under way, looks like the deliberations in terms of dealing with the insurance aspects and compensation may have taken longer than the actual repair.

Quoting RoseFlyer (Reply 6):
It was extremely close to not being able to land safely because the airplane had so many concurrent failures that affected the ability to land.

I disagree, the pilot still had full control over the aircraft. In fact the crew used the autopilot down to about 1000 ft on final approach.

Quoting RoseFlyer (Reply 6):
So many parts of the airplane were damaged that the landing distance could not even be effectively calculated.

Calculating the landing distance is a red herring, the onboard landing distance performance application (LDPA) was actually able to calculate a landing distance after the crew changed the runway conditions from wet to dry. The LDPA calculated they had a 100 m buffer, they actually stopped sooner than LDPA calculated.

From the ATSB report

"The FO and the SCC input the affected aircraft systems into the landing distance performance application (LDPA) to determine the landing distance required for an overweight landing to runway 20C at Changi Airport of about 440 t, which was 50 t above the aircrafts maximum landing weight.

Based on the initial inputs to the LDPA by the flight crew, the LDPA did not calculate a landing distance. After discussion, and in the knowledge that the runway at Changi was dry, the crew elected to remove the inputs applicable to a landing on a wet runway and re-ran the calculation. This second calculation indicated that a landing on runway 20C was feasible, with 100 m of runway remaining. The crew elected to proceed on the basis of that calculation and advised ATC to that effect."

Quoting RoseFlyer (Reply 6):
No pilots train for that many failures at once.

I disagree, do a command course, they would throw a lot more than that at you in the command LOFTs.

Quoting RoseFlyer (Reply 6):
With the spoilers damaged, the airplane would not get sufficient weight on wheels to allow full effectiveness of the brakes.

According to the ATSB report, only spoiler #4 was inoperative, the aircraft has 8 spoilers per wing.

Quoting RoseFlyer (Reply 6):

With the loss of a hydraulic system, anti-skid was disabled.

According to the ATSB report, anti-skid braking was available on the body landing gear.

Quoting RoseFlyer (Reply 6):
With a fuel imbalance due to loss of fuel pumps and associated leak, the CG was off.

Nothing in the ATSB report to indicate that was the case. Aft or outer fuel transfer does not start at such low altitudes, and the aircraft would have been within CG limits on takeoff (which is also the landing CG limits). By default the CG will be 39.5% MAC, the forward limit is around 37% and aft limit 43% at their landing weight. The normal fuel burn sequence is inner tanks to feed tanks, mid tanks to feed tanks, and then the trim tanks to feed tanks, and finally outer tanks to feed tanks. The normal fuel sequence at this fuel level would have them burning from the inner tanks still. The messages regarding to CG would be relating to the aircraft being unable to do the after and inner fuel transfers that it normally does.

Quoting RoseFlyer (Reply 6):
With loss of engine 1 controls, the engine could not be operated as usual or even shut down.

According to the ATSB report, engine 1 was producing the commanded thrust in flight. The "degraded mode" refers to going from EPR as being the primary engine instrument to N1 control. i.e. instead of EPR limiting the maximum thrust in a go around, it would be a maximum N1.

“Consequently, the PIC set the thrust levers for Nos 1 and 4 engines to provide symmetric thrust, and controlled the aircraft’s speed with the thrust from No 3 engine.”

Quoting prebennorholm (Reply 7):
With the long list of malfunctioning subsystems they had better find a good long runway, preferably dry, and no adverse weather. That's also what they did.

Exactly.

Quoting prebennorholm (Reply 7):

The combination of fuel leak in one wing and non-functioning fuel dump was, however, a potentially dangerous thing. Had the leak been a lot more massive, then it could have produced a dangerous lateral imbalance.

The books actually say you can have in emergency situations 100% imbalance and still fly. The imbalance limits in the books are based upon structural limits for normal operations, they are not control related.

Quoting tdscanuck (Reply 10):
There was no immediate threat of a crash because they had positive control of the airplane in all three axis and positive speed control. They had a ton of issues to deal with, but essentially none of them were threats to continued safe flight or landing.

Correct, from the ATSB report

"Prior to leaving the holding pattern, the crew discussed the controllability of the aircraft and conducted a number of manual handling checks at the holding speed. The crew decided that the aircraft remained controllable"

"As the crew started to reconfigure the aircraft for the approach by lowering flaps, they conducted further controllability checks at the approach speed and decided that the aircraft remained controllable."

Quoting thegeek (Reply 12):
I think the answer to "how close was this flight to crashing" (other than a runway overrun) was how close they came to losing the remaining hydraulic system. Is that a known?

The A380 is the first large aircraft made that can continue to fly even with the loss of all hydraulic systems, this is due to having Electro-Hydrostatic Actuators (EHAs) and Electrical Backup Hydraulic Actuators (EBHAs) which continue to work even in event of a failure of the aircraft hydraulic systems.

The actuators are found symmetrically on on the inner and middle ailerons, spoilers 5&6, inboard and outboard elevators, as well as on the lower and upper rudder.

Quoting XT6Wagon (Reply 13):
I think someone here said that the A380 has a limited "manual reversion" capiblity for all hydraulics lost, but clearly more damage to the ability to control the plane would have been... dangerous.

With ailerons, elevator, rudder, and spoilers, I doubt anyone could say 'limited". It does not have the backup actuators on all roll control surfaces (it does on pitch an yaw), so only the roll rate would not be as fast as normal, however it is more than adequate.



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 24, posted (3 years 2 months 2 weeks 3 days 8 hours ago) and read 22175 times:

Quoting XT6Wagon (Reply 16):
Also RR was supposed to insure that the chance of uncontained failure was 0.

Not zero, just statistically very unlikely. I'm not sure how the exact fault tree runs for a rotor burst but if the chance was actually zero then you wouldn't have to design so much of the rest of the aircraft around it happening.

Quoting qf002 (Reply 18):
So in summary, she was very close to crashing, but it was a few strokes of luck that allowed the crew to maintain control and land the aircraft safely.

Fantastic design work by the Airbus engineers coupled with fantastic CRM by the flight crew is many things but it's not luck.

Quoting qf002 (Reply 18):
If any one of the factors that contributed to the safe landing of that aircraft hadn't fallen into place then it's likely that the aircraft would have crashed

I disagree; although they had lost many levels of protection they still had some left, especially on the things that really mattered. They had landing gear and brakes, they had flight controls, they had thrust. Airbus did a magnificent job.

Quoting prebennorholm (Reply 20):
But magnitude of catastrophic fuel tanks rupture is something which is difficult to design for. In addition it may happen at a more inconvenient place, say five hours flight away from nearest useful airport. It is more likely that it happens during climb, as it did, when the engines work harder. But in theory it may happen at any time from gate A to B.

That's why the requirement is to design for the worst possible case. Typically, that would be full tanks with total drainage of the most critical tank on the other side. Since, as prebennorholm noted, aileron control goes up with speed squared, the worst cases are at low speed (takeoff and landing).

Quoting prebennorholm (Reply 20):
Long range planes, where almost half of the take off mass is fuel, have the potential to develope uncontrolable imbalance

They shouldn't...the whole point of the design is that you can withstand the worst possible imbalance.

Quoting prebennorholm (Reply 20):
making fuel dump ability more than a convenience to avoid overweight landing, and also a primany safety issue.

Every airplane out there is fully capable of landing at MTOW. Fuel dump is a huge safety improvement but total loss of the fuel dump system should never result in loss of safe landing capability.

Tom.


25 Post contains links thegeek : My understanding is that these EHAs and EBHAs were non-functional for most surfaces in the case of QF32. Tried to dig up a link for that, and the bes
26 qf002 : Yet they were flying on a clear day, had a nice big and clear runway to return to and the engine shrapnel didn't puncture further systems or the fuse
27 zeke : The ailerons are powered symmetrically. • Outer ailerons are powered by green and yellow hydraulics, with conventional servocontrols • Mid ailero
28 thegeek : The way I remember the info is that the ESS bus was still working but not AC 1 nor AC 2, so even without the yellow hydraulics they should have had so
29 BeakerLTN : This is the bit that continues to confuse me. My understanding is that dual redundancy requires the redundant lines to not be co-located, thereby rem
30 UALWN : Yes, and, as we say around here, if my aunt had a penis, we would call her "uncle"...
31 Archer : What is the tail number/letters?
32 nicoeddf : Thank you very much - indeed my thinking!!!
33 777STL : VH-OQA - QF's first 380 delivered. (And the only one I've flown on!)
34 tdscanuck : Nothing was wrong with their navigation or flight control capability...how would weather have changed the outcome? Having a suitable diversion runway
35 frmrCapCadet : Somewhat analogous, by the end of WWII damage control and design was such that all of the five or so USS heavy carriers that sunk early in the war cou
36 flipdewaf : So you are saying that if something didn't work the way it was supposed to then something would have gone wrong? F/O: OH NO!!! That uncontained engin
37 qf002 : Your points are all true and valid. I think it ultimately depends on how you define close to crashing -- I'd say that if someone were to survive a ca
38 Baroque : So I need to check on the number of engines each time I get on an A380, good point there, otherwise my luck will run out. Should I ask the pilot if h
39 Post contains links n729pa : Rather than a load guess work and theory, why not have a read of the ATSB accident report. http://www.atsb.gov.au/publications/...reports/2010/aair/ao
40 francoflier : Does anybody know whether Airbus has implemented software and/or hardware mods to address the systmes faults which led to the fuel imbalance, inabilit
41 Post contains links faro : So long as flight control was maintained, the A380 was IMHO as far from crashing as this Tu-154 was far from landing safely: http://www.youtube.com/wa
42 Post contains links vgnatl747 : There is an investigative report from a show called Four Corners that was pretty good. It has interviews with the crews and everything: http://www.you
43 yellowtail : IIRC....there were also one or two extra senior captains on the flight doing training or something of the sort....and they helped with the CRM.
44 SLCPilot : The A-380 was clearly able to physically fly, and presumably without heroic control inputs from its crew. There is little doubt in my mind ANY airbus
45 prebennorholm : The Concorde at CDG was different. The tank leak fed fuel into the #1 and #2 engine intakes and put them on fire. And the primary reason for the disa
46 Baroque : Even with Avgas, a the climb speed of an A380, the speed of the flame front might not be enough to keep a fire going. Hence the tactic of bombers in
47 tdscanuck : I agree that it depends on how we define "close to crashing" but I think the airbag analogy is flawed...they had more than one system still left prot
48 XT6Wagon : Bad weather increases the risks to a huge degree. It adds to the crew workload/stress. It puts extra stress on the damaged components. It can require
49 zeke : As far as the flight control computers were concerned, it was not a big deal, they were still in normally pitch and yaw laws, and alternate roll. The
50 JerseyFlyer : I for one will be very happy flying A380s in future. If it can survive that, it can survuve anything!
51 Post contains links cedarjet : Extraordinary documentary by the ABC, Aussie version of the BBC - full interviews with capt, co, purser, SIN tower, dispatcher, punters, you name it.
52 ikramerica : We had a far less crude saying as a kid. "And if Grandma had wheels she'd be a trolly car." Is this similar to rubber "marbles" on banked car racing
53 flipdewaf : LOL, Less than one minute in and one of the pax says "it doesn't take alot of imagination to relise that one spark and we were cinder". I have thrown
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