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qf789
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SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 4:18 pm

Just seen this on FR24, SQ836 operated on 23rd May 2015 SIN-PVG lost power to both engines and dropped 13,000 feet before power returned. Operated by A330-300, 9V-SSF. Well done to the pilots for getting the engines running again.

[Edited 2015-05-26 09:55:55]

[Edited 2015-05-26 09:56:13]
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 4:31 pm

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B8887
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 4:44 pm

http://avherald.com/h?article=486d5637&opt=0

WTF?!?...

13k feet?...

I am sure this will be thoroughly investigated, especially the decision to continue all the way to PVG...

Regards.

B8887
 
mham001
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 4:44 pm

Hope this is not a pattern.

[Edited 2015-05-26 10:02:05]
 
BoeingGuy
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 4:54 pm

Why in the world didn't they divert? If it were Ice Crystal Icing the had possible fan blade damage.
 
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jfklganyc
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 4:56 pm

If you lose both engines or even one engine up in the mid 30's you have to drift down at L/D Max or glide speed.

This is not a high speed roller coaster drop. It is a gradual descent. One engine can't sustain airspeed at cruise altitude and two engines gone...well you are a glider.

The idea is to preserve altitude vs time vs distance.

And dropping to the mid teens (even with one engine operating) is normal. Most aircraft near a full load can't sustain single engine ops above the mid teens.

Sounds like crew did a good job

[Edited 2015-05-26 09:58:01]
 
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 5:10 pm

Quoting B8887 (Reply 2):
I am sure this will be thoroughly investigated, especially the decision to continue all the way to PVG...

Agreed. At time of incident they were only about 140nm from HKG.

The aircraft involved 9V-SSF was delivered on the 30th March 2015.
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 5:33 pm

Quoting BoeingGuy (Reply 4):
Why in the world didn't they divert?

That's what I'm screaming.

We certainly haven't heard the end of this.
I myself, suspect a more prosaic motive... ~Thranduil
 
col
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 6:06 pm

There is no reason for the two engines stopping given as yet. Pilots re-lit both engines using normal procedures by 26K. They also discussed with engineers on the ground, who I am sure had data in coming, and decision to carry on was made. China has many airports between HKG and PVG where an A330 can land in emergency. Plane was on ground at PVG for 4 hours, including inspection then release for flight. It is a strange one, but I think we can wait for the hard fact report to be released before making judgements.

Quoting BoeingGuy (Reply 4):
Why in the world didn't they divert? If it were Ice Crystal Icing the had possible fan blade damage.

Fan blade damage comes with vibration, been on two PW aircraft that had power surges on take off (757) and also one bird strike (744). All required immediate returns and as a pax you can feel the vibration. Engines have sensors for reading this in the cockpit. I am sure that both crew and engineers ran through the procedures and decided to carry on based on factual information they had to hand.

Quoting mham001 (Reply 3):
Hope this is not a pattern.

Pattern based on one episode? 
 
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barney captain
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 6:12 pm

I am a huge fan of SQ and their pilots - but why they didn't immediately divert after a dual engine failure is inexcusable.
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BoeingGuy
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 6:57 pm

Quoting col (Reply 8):
Fan blade damage comes with vibration, been on two PW aircraft that had power surges on take off (757) and also one bird strike (744). All required immediate returns and as a pax you can feel the vibration. Engines have sensors for reading this in the cockpit. I am sure that both crew and engineers ran through the procedures and decided to carry on based on factual information they had to hand.

You are only partially correct. While there are vibration reading in the flight deck, there have been occurrences of fan blade damaged caused by ice crystal icing that were not detected in the flight deck.

I stand by my statement. Both engines failed for undetermined reasons. Get the hell on the ground now.
 
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 7:02 pm

Quoting BoeingGuy (Reply 10):
I stand by my statement. Both engines failed for undetermined reasons.

We don't know why they failed, but perhaps the flight crew and airline did? And determined that continuing to PVG was acceptable? After all, they released the plane for the return after an inspection so that strikes me as they were confirming that whatever they felt caused the dual-failure was in fact the cause and successful remediation had been performed.
 
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 7:12 pm

Quoting Stitch (Reply 11):
We don't know why they failed, but perhaps the flight crew and airline did? And determined that continuing to PVG was acceptable?

There is no way they could "know" anything until a complete inspection was done.

I'm with BoeingGuy on this one.
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catiii
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 7:17 pm

Quoting mham001 (Reply 3):
Hope this is not a pattern.
Quoting barney captain (Reply 9):
a dual engine failure
Quoting LAX772LR (Reply 7):
That's what I'm screaming.
Quoting qf789 (Reply 6):
Agreed. At time of incident they were only about 140nm from HKG.
Quoting BoeingGuy (Reply 4):
Why in the world didn't they divert?

Since no one knows WHY the engines shut down (maybe they were inadvertantly shut down by the flight crew), how about we all take a deep breath, relax, and wait for the official report before second guessing if they should have diverted?
 
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 7:34 pm

Scary stuff but as we all know SQ have some of the best pilots in the business and this crew appears to have handled things well. I recall a QR A330 going through a similar incident a few years back and if I recall correctly that crew continued on too and did not divert either.

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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 7:35 pm

From my amateurish understanding, the air conditioning system doesn't work without the engines. So wouldn't the aircraft depressurize? Or would the SOP dictate immediate activation of the APU to feed the packs? Would a depressurization mean intimidate diversion even if the issue was rectified in-flight?

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Stitch
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 7:51 pm

Quoting krisyyz (Reply 15):
From my amateurish understanding, the air conditioning system doesn't work without the engines. So wouldn't the aircraft depressurize?

The pressure vessel of the fuselage would maintain the existing cabin pressure for some time.
 
ukoverlander
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 8:07 pm

Ah....so this is today's "guilty until proven innocent" thread!!!
 
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 8:07 pm

Quoting Stitch (Reply 16):
Quoting krisyyz (Reply 15):
From my amateurish understanding, the air conditioning system doesn't work without the engines. So wouldn't the aircraft depressurize?

The pressure vessel of the fuselage would maintain the existing cabin pressure for some time.

The APU can provide bleed air for the packs. Unless they were out of fuel it's not an issue.
 
Curiousflyer
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 8:23 pm

Even in case the APU was not working, does the 330 have a RAT? Is it sufficient for the packs?

Also, was there any power available for passenger comfort (e.g. IFE and bathrooms) or was it diverted to re-start the engines? I am wondering whether it was scary moment for passengers or they had no idea of what happened. I know that as a passenger I could have thought that we are just starting our descent early and that the engines are making less noise because less power is needed when a plane goes down, as long as there are no other telltale signs accumulating, such as lighting/IFE/bathroom issues.

In any case, very interesting, and great the pilots made it to PVG.
 
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 8:36 pm

Quoting catiii (Reply 13):
(maybe they were inadvertantly shut down by the flight crew),

This is what I was thinking...
 
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 8:41 pm

Quoting Stitch (Reply 16):
The pressure vessel of the fuselage would maintain the existing cabin pressure for some time.

Even a brand new a/c will slowly begin to depressurize with both engines (or packs) off.
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 8:42 pm

Quoting barney captain (Reply 9):
I am a huge fan of SQ and their pilots - but why they didn't immediately divert after a dual engine failure is inexcusable.

Perhaps as simple as Aviate, Navigate, Communicate.

So... you lose power to both engines and first thing you want to do is call a May Day w/o attempting to restart them? This is showing little trust to technology!

If they restart (and they did here), the next most logical thing to do in my (mostly uneducated) opinion would be to try to reach back cruise altitude, or at least stabilize the descent, as a jet does not belong at 27,000 ft or under.

Then, and only then, once this is under control, a radio call comes. Also the pilots probably investigated what happened right away with the means available on board, and determined that the engines were back performing as normal.

It is worth noting that they were approaching the coastline of China and diversion airports probably are plenty if they had to do a controlled descent with no power before PVG. If they would have continued as they were about to cross an ocean, that might have been a different situation.
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aviatorcraig
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 8:43 pm

The fact that the aircraft flew on to destination without diverting and then 4 hours later flew the return leg (seemingly on a revenue service) means the crew and airline MUST have known and fully understood what caused not one but both engines to lose power. Anything else and the crew and airline are grossly neglegent (which I doubt).

My guess would be fuel mismanagement (based on absolutely no evidence at all!)
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Part147
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 8:44 pm

Well to look at it another way, plane lands safely after double engine in-flight shut down.

Or else it was the side-stick controlling, computer-operated, pitot-tube icing death scarebus machine!  
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col
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 8:52 pm

Place your bets folks:

1) Ice
2) Fuel
3) Pilot error
4) Lack of engines
5) Compressor stall (I will throw that one in)

The plane is on ground in Singapore being inspected, so bet now before results become available.
 
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 8:52 pm

Quoting YULWinterSkies (Reply 25):
It is worth noting that they were approaching the coastline of China and diversion airports probably are plenty if they had to do a controlled descent with no power before PVG. If they would have continued as they were about to cross an ocean, that might have been a different situation.

A controlled decent with no power in a 300 seat airliner is not something any pilot will consider anytime any other options exist. Therefore when they regained power they must have been pretty damned sure they fully understood what had happened otherwise it would have been get on the ground quick time.
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barney captain
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 8:54 pm

Quoting YULWinterSkies (Reply 25):
So... you lose power to both engines and first thing you want to do is call a May Day w/o attempting to restart them? This is showing little trust to technology!

Ah, no.

Obviously the first issue was running the QRH and getting one or both re-lit.

Quoting YULWinterSkies (Reply 25):
If they restart (and they did here), the next most logical thing to do in my (mostly uneducated) opinion would be to try to reach back cruise altitude, or at least stabilize the descent, as a jet does not belong at 27,000 ft or under.

Again, no. A dual engine flame-out (even a single engine flame out) requires a diversion to the nearest suitable airport - regardless whether or not you get one or both re-lit. This applies even if they inadvertently shut them down. Flying another 4 hours isn't appropriate with HKG so close. FL270 is absolutely an acceptable altitude - for any number of reasons. But not after you lost thrust in both engines.
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32andBelow
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 8:59 pm

Quoting aviatorcraig (Reply 29):
Therefore when they regained power they must have been pretty damned sure they fully understood what had happened otherwise it would have been get on the ground quick time

Yes, they probably knew they turned off the engines.  
 
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 9:24 pm

Quoting catiii (Reply 13):
Quoting qf789 (Reply 6):Agreed. At time of incident they were only about 140nm from HKG. Quoting BoeingGuy (Reply 4):Why in the world didn't they divert?
Since no one knows WHY the engines shut down (maybe they were inadvertantly shut down by the flight crew), how about we all take a deep breath, relax, and wait for the official report before second guessing if they should have diverted?

Assuming you are correct and there is some logical reason for not diverting (can't imagine what that would be), what would be the proper action if they'd been on an, e.g., ETOPS 240 flight 200 minutes from nearest suitable? Also continue?
"You're sitting. In a chair. In the SKY!!" ~ Louis C.K.
 
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 9:32 pm

Quoting hivue (Reply 32):
Assuming you are correct and there is some logical reason for not diverting (can't imagine what that would be), what would be the proper action if they'd been on an, e.g., ETOPS 240 flight 200 minutes from nearest suitable? Also continue?

You're kind of answering your own question. They would continue 200 mins to the nearest suitable.
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 9:33 pm

Quoting Curiousflyer (Reply 19):
Even in case the APU was not working, does the 330 have a RAT?

Yes it does have a RAT. It deploys automatically if both engines fail.

Quoting Curiousflyer (Reply 19):
Is it sufficient for the packs?

The RAT has no role in maintaining pressurisation.

Quoting krisyyz (Reply 15):
So wouldn't the aircraft depressurize?

Gradually yes.

Quoting krisyyz (Reply 15):
Or would the SOP dictate immediate activation of the APU to feed the packs?

The priority would be to get an engine relight. The crew would begin a descent with an optimum relight speed which is probably 300-320 knots or .80-.83M on the A330.

If that fails, you start the APU, get the bleed going and continue your attempts to restart an engine.

Failing that, your next job is to slow to green dot and prepare for a landing or ditching.
 
roseflyer
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 9:36 pm

A dual engine failure is very serious. On ETOPS flights, this can be considered catastrophic. This regulatory authorities should be all over this. Weather alone causing a dual engine failure in airspace with good radar coverage and the airplane equipped with weather radar is also going to provoke some questions.

I also think the regulators are going to look in to how this happened to an airplane that is only two months old. The airplane being so new raises some questions.
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aklrno
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 9:46 pm

I read the AV Herald article a couple of times and it wasn't to clear to me that the engines shut down completely. It said loss of power, but does that mean loss of all power or possibly a reduction of power? If it was just a reduction, and they figured out that a control setting might have caused that, then just fixing the improper setting and continuing on may be just fine.

Was there any reliable info telling us the engines shut down completely?
 
trex8
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 9:57 pm

This is a Roller powered plane but IIRC a QR A330 with Ge engines flamed out both engines in heavy rain. IIRC happened to another airline too with GE ? CI.
http://www.pprune.org/rumours-news/2...ays-a330-dual-engine-flameout.html
 
BoeingGuy
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 10:00 pm

Quoting barney captain (Reply 30):
Obviously the first issue was running the QRH and getting one or both re-lit.

On Boeing airplanes, the first several steps on the Dual Engine Failure checklist are memory items. The crews are required to have them memorize and perform them immediately without needing to look them up. Then they would have pulled the QRH.
 
Rara
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 10:05 pm

That is definitely worrisome. Let's keep in mind that we don't know yet whether the engines actually failed entirely, or "only" lost most of their power. There's a number of possible fail indications that will cause pilots to reduce an engine's thrust setting rather than switching off the engine entirely.


As to why the aircraft didn't divert to HKG: Keep in mind that a diversion only makes sense if it improves safety over the alternative. In this case, diverting to Xiamen would have been as safe as diverting to Hong Kong. Diverting to Taipei likewise, Wenzhou likewise, and so on all the way to PVG. In other words, as long as the aircraft is stable and flying, there's no real added safety benefit to landing as soon as possible.

Quoting YULWinterSkies (Reply 25):
If they restart (and they did here), the next most logical thing to do in my (mostly uneducated) opinion would be to try to reach back cruise altitude, or at least stabilize the descent, as a jet does not belong at 27,000 ft or under.

Then, and only then, once this is under control, a radio call comes.

I disagree. In controlled airspace, if you aren't able to hold your assigned altitude, you need to notify ATC as soon as possible. They really need to know, as there may be other aircraft below you which they need to re-route. You can discuss the situation with them later, but a distress call should come much earlier than you suggest.
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barney captain
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 10:17 pm

Quoting BoeingGuy (Reply 38):
On Boeing airplanes, the first several steps on the Dual Engine Failure checklist are memory items. The crews are required to have them memorize and perform them immediately without needing to look them up. Then they would have pulled the QRH.

Now we're getting into the weeds a bit but technically yes - Memory Items, QRH, Performance, Notifications and ton of other items. It's a busy time.
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Kaiarahi
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 10:23 pm

Quoting barney captain (Reply 30):
A dual engine flame-out (even a single engine flame out) requires a diversion to the nearest suitable airport - regardless whether or not you get one or both re-lit.

It's not clear to me from reading the avherald report that there was a flameout and relight.

The title reads: "temporary loss of power on both engines"

The body of the report reads: "... both engines (Trent 772) of the aircraft lost power. While descending the aircraft the crew worked the related checklists and managed to restore normal operation of both engines."

Nothing there about a flameout and relight - we may be jumping to conclusions. It may have been something as "benign" as an A/T malfunction that required them to complete the flight with manual throttle control.

[Edited 2015-05-26 15:31:54]
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 10:42 pm

Quoting aklrno (Reply 36):
I read the AV Herald article a couple of times and it wasn't to clear to me that the engines shut down completely. It said loss of power, but does that mean loss of all power or possibly a reduction of power?

I was thinking the same. There is obviously something which we don't know (yet). The few "facts" we see:

- dual engine failure
- unknown reason, investigation started
- dual relight 13kft lower, but no divertion
- plane takes off again for passenger flight after 4 hours on the ground including inspection.

It simply doesn't add up. Somewhere there is A LOT less drama involved in this incident than some posters seem to assume. And with the data available it is impossible to know what is reality.

We can make wild guesses only. My first guess would involve some nasty icing condition, which the crew handled according to what they had learned in training.
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SwissCanuck
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 11:23 pm

Quoting aklrno (Reply 36):
I read the AV Herald article a couple of times and it wasn't to clear to me that the engines shut down completely. It said loss of power, but does that mean loss of all power or possibly a reduction of power?

Simon chooses his words carefully. He creates some awkward phrasing here and there (as does any non-native speaker) but otherwise he's very careful. Given the facts as presented, I think we know absolutely nothing and I'm certainly not reaching for my pitchfork.
 
hivue
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Tue May 26, 2015 11:59 pm

Quoting barney captain (Reply 33):
You're kind of answering your own question. They would continue 200 mins to the nearest suitable.

I think you missed my point. Would they continue to destination (as this airplane did) or divert to the nearest suitable airport 200 min away? The poster I quoted was trying to make an argument that there could have been a good reason they didn't divert. I was simply wondering if that hypothetical reason might still be a good one if they were way out over the water on an ETOPS 240 flight with, say, 300 minutes left to destination.
"You're sitting. In a chair. In the SKY!!" ~ Louis C.K.
 
solarflyer22
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Wed May 27, 2015 1:11 am

Quoting catiii (Reply 13):
Since no one knows WHY the engines shut down (maybe they were inadvertantly shut down by the flight crew),

Yeah, this was my thinking as well. The article does state that they were at 39,000 FT and inclement weather. Certainly sets up as a icing event but perhaps the crew and ground staff didn't realize there could be fan blade damage due to icing.

Quoting aviatorcraig (Reply 26):
My guess would be fuel mismanagement (based on absolutely no evidence at all!)

Yeah, I was thinking maybe they accidentally went too high and the engines flamed out. I don't think if there is a noticeable vibration they would do anything other than land immediately.

Correct me if I am wrong, but there was another dual engine failure on A330 some years ago in East Asia as well. Don't remember the airline. Wondering if they have a design flaw like the 777 ingesting frozen fuel or something.
 
benjjk
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Wed May 27, 2015 1:14 am

Quoting prebennorholm (Reply 43):
I was thinking the same. There is obviously something which we don't know (yet). The few "facts" we see:

- dual engine failure
- unknown reason, investigation started
- dual relight 13kft lower, but no divertion
- plane takes off again for passenger flight after 4 hours on the ground including inspection.

It simply doesn't add up. Somewhere there is A LOT less drama involved in this incident than some posters seem to assume. And with the data available it is impossible to know what is reality.

Adding to that, it took a few days for this to become public knowledge. If the passengers knew both engines quit it would have been all over social media before the wheels hit the ground.

We know that there was a temporary loss of power - how much power? For all we know the engines were still capable of producing 50% thrust.

Chill your boots, everyone.
 
KELPkid
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Wed May 27, 2015 1:21 am

Quoting Rara (Reply 39):






That is definitely worrisome. Let's keep in mind that we don't know yet whether the engines actually failed entirely, or "only" lost most of their power. There's a number of possible fail indications that will cause pilots to reduce an engine's thrust setting rather than switching off the engine entirely.

I wonder if we're dealing with another water in the fuel lines incident like the one that befell BA 38    Rolls-Royce engines in both, not sure how similar a Trent 700 and Trent 800 are to each other... I'm assuming that Rolls-Royce dealt with the BA38 issue by modifying things somewhat in the Trent 800.
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Wed May 27, 2015 1:32 am

Quoting benjjk (Reply 52):
Adding to that, it took a few days for this to become public knowledge. If the passengers knew both engines quit it would have been all over social media before the wheels hit the ground.


Not necessarily, the likes of facebook and twitter are banned in China so it would take a while for information to get out.
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Wed May 27, 2015 1:36 am

Think a diversion should have been done.

Way back in the 1990s, a Continental Airbus A-300 hit birds on takeoff out of EWR. Engines were still running, all parameters were normal, decision was made to continue to MCO. Upon arrival at MCO with a heads up from Houston MX Control, greeted the aircraft upon arrival at the gate. Immediate grounding and cancellation of the return EWR flight. 3 Fan Blades were mangled in number 1 engine, I mean, really mangled, bent and twisted. I couldn't believe the engine made power with normal readings. Ended up changing out 6 fan blades for balance.

Engine shuts down, divert.

Glad the flight ended okay.
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Wed May 27, 2015 2:07 am

Quoting catiii (Reply 13):
Since no one knows WHY the engines shut down (maybe they were inadvertantly shut down by the flight crew), how about we all take a deep breath, relax, and wait for the official report before second guessing if they should have diverted?

catiii, you make a great point, and I ask this purely out of ignorance: in a controlled, power-off glide, does it actually take 13,000 feet to re-light the engines and get them to speed, in the case of an unintentional shutdown by the crew?
 
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Wed May 27, 2015 2:48 am

Quoting qf789 (Reply 54):
Not necessarily, the likes of facebook and twitter are banned in China so it would take a while for information to get out.

But they still have things like Weibo with 500 million users. China isn't the isolated society it was even 20 years ago, I really don't think you can keep such a big incident hidden for so long (perhaps North Korea is the exception..).

No doubt something did happen here, and it should be of interest to us aviation-types. But I don't think it was nearly as catastrophic as an A330 gliding with no engines. I can't wait to read a report.
 
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RE: SQ836 Lost Power To Both Engines, Drops 13000 Feet

Wed May 27, 2015 3:06 am

Quoting nitepilot79 (Reply 57):
in a controlled, power-off glide, does it actually take 13,000 feet to re-light the engines and get them to speed, in the case of an unintentional shutdown by the crew?

Currently feeding my kid so you'll have to rely on my memory and not 'Abnormal Procedures'.

If you have a dual flame out at cruise, depending on aircraft type, windmilling is normally the first port of call when attempting to restart the engine. I don't think the A330 has auto APU start as some types (777) do.

Your best chance of success with the windmill procedure is at relatively high airspeed in the region of 300KIAS. From cruise, it should only take a small pitch down to about -2.5 degrees to maintain that airspeed with a gradual descent of about -2500fpm. If things are going your way, a relight can be achieved in less than 60s after selecting engine start selector.

If a windmilling start fails, you can try and use the APU to provide bleed for an assisted start.

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