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SQ-368 (engine & wing on fire) final report out

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SQ-368 (engine & wing on fire) final report out

Old 15th Mar 2017, 16:49
  #841 (permalink)  
 
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Originally Posted by rcsa View Post
Andy - why?
Perhaps because they had a Captain onboard who appears incapable of making any decision.
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Old 15th Mar 2017, 17:12
  #842 (permalink)  
 
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I read it differently. All the combined brains of the technical department failed to spot symptoms of a problem that had been known about for a couple of years. So, if they didn't spot it, what chance did the pilot have with his limited resources (while managing an ailing aircraft at the same time)?
The bloke in charge of the fire service was accurate and up to date with his updates and was obviously very sensitive to the possibility that an evacuation via slides may not have been the safest option for the passengers. Presumably, he was aware of the potential danger of pooled, unburned fuel on the ground below the aircraft.
At no stage were the cabin crew calling like mad, telling the pilot there was heat. The pilot was busy attending to all the other things going on so the CC told their boss who told the IFS who can't remember if he passed that on to the flight deck. I would take that to mean "No, I didn't pass it on".
As for "shutting down an unhealthy engine"; that is discussed in the report and the answer seems to be that there was only 1 indication that was anything wrong, a low oil quantity alert. Other indicators showed it may be a defective indication as temperatures and oil pressures were OK.
The bottom line is not some sort of failure on the part of either the crew, the fire service or anyone else. The real culprit is the engine manufacturer who continued using the same fuel cooling system that had been shown to have failed more than once in the past. They had acknowledged this and issued a bulletin saying it should be checked the next time the engine is for maintenance and this was issued after the engine's last maintenance was done..
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Old 15th Mar 2017, 21:14
  #843 (permalink)  
 
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KelvinD.
The cabin crew were trying to contact the flight deck:
During the initial stages of the fire, several cabin crew members tried to contact the flight crew through the cabin interphone. However, only one call was answered by a flight crew member and he informed the cabin crew that they were aware of the situation and were handling it.
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Old 15th Mar 2017, 21:40
  #844 (permalink)  
 
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Touchdown was at 0649. The fire was observed approx 20 seconds later. The fire service arrived 57 seconds after the aircraft stopped. ( a very quick and fortuitous time). The fire was put out at 0653 some 4 minutes after initiation.
Some may say a very quick time however to put that in perspective during the Manchester fire the hull was breached betwean 5 and 20 seconds after stopping and the windows gave within a minute of stopping.
Approx 5 Passengers had died from the effect of the flames and heat (the rest from the effects of the toxic smoke) by, at the latest 1:30 minutes after stopping.
Compare this to the timeline of the Singapore incident and work out what they were chatting about at that point.
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Old 15th Mar 2017, 21:54
  #845 (permalink)  
 
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The Captain knows he has a fire despite not having any fire indications in the cockpit, because the tower has told him so.
Apart from giving a "cabin crew at stations" call ( or the Singapore equivalent) what does the crew do?
Contact is established with the FC at 0651:50 around 2 minutes after being told of a fire. No attempt to contact the cabin and establish what they could see. No attempt to turn on the video. No reported attempt to ask the tower.
Instead wait for the FC who inspite of saying the fire is a big one recomends disembarkation not evacuation. The FC was confident he would get the fire under control, however fire is unpredictable. Just look at what happened to that poor firefighter who lost his life in Dubai.
The Captain who is initially evacuation minded, defers to the FC and effectively absolves himself of responsibility and allows the FC to become the decision maker. Perhaps he woild like to donate his salary to the FC as well.
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Old 16th Mar 2017, 07:37
  #846 (permalink)  
 
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As for "shutting down an unhealthy engine"; that is discussed in the report and the answer seems to be that there was only 1 indication that was anything wrong, a low oil quantity alert. Other indicators showed it may be a defective indication as temperatures and oil pressures were OK.
I beg to differ with your alternative reading. Per the report, the first indication was a low oil quantity, with fluctuations in oil pressure and a higher oil temperature (in normal range, but when taken together with low oil quantity tell a story).

And it's not true that the crew offloaded all their decisions to the ground:
At 0328 hrs, the engineer sent a message via the Aircraft Communication and Reporting System (ACARS) to the flight crew informing them about the recommendation by the technical services personnel for the aircraft to return to Singapore and requesting them to contact the engineering
control centre.
The crew then spent 20 minutes arguing to continue to Milan. After that, they got engine vibrations and made another phone call, presumably to convince their colleagues that they could still make it to Milan with the #2 engine at idle. In the middle of the debate, they get a call from the back that the cabin is filling with smoke. So then they agree to return, at #2 idle and bleed off, but leaving the pack on.
Only on a second call do they switch the pack off.

They repeatedly told ATC that they had no problem, the FUEL DISAGREE message they disagreed with, and, when the FC told them to disembark from the left side of their burning aircraft, they wanted to make absolutely sure that they weren't supposed to evacuate. Heck, they didn't even use the bottles until ARFF asked them about it. Probably didn't think they were necessary.

I'm just sayin'. That's not offloading decision-making.

My favorite recommendation:
The aircraft manufacturer evaluate the need for providing guidance on
how to perform fuel leak check with the engines operated at unequal
thrust. [TSIB Recommendation RA-2017-023]
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Old 16th Mar 2017, 21:27
  #847 (permalink)  
 
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My favorite recommendation:

Quote:
The aircraft manufacturer evaluate the need for providing guidance on
how to perform fuel leak check with the engines operated at unequal
thrust. [TSIB Recommendation RA-2017-023]
Dinger, there already is a system along that line (not sure if it's been fully implemented through the Boeing fleet yet but it was an FAA mandate). Basically, it compares fuel used (according to the engine fuel flow indications) with fuel remaining (according to FQIS). If it differs significantly it sets an EICAS message. Although it wouldn't catch a leak downstream of the fuel flow meter, it would help indicate a fuel leak of this type (fuel/oil heat exchanger). However the problem is neither the FQIS or the fuel flow meter systems are super accurate, so the limits are set rather loose to avoid nuisance alerts.
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Old 17th Mar 2017, 13:58
  #848 (permalink)  
 
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For me the big question is:

If you have operated an engine in idle for a long time before landing due to suspected damage, why would you use the reverser on that engine?

If they hadn't used the reverser this thread would never happened.
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Old 17th Mar 2017, 14:26
  #849 (permalink)  
 
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tdracer, maybe I'm misunderstanding something, since it sounds like what you are describing is the Calculated fuel that, in fact, did catch the leak and did send an EICAS message, but was ignored.

I find it interesting to work through the logic. Here's what the report says:

At 0521 hrs, the flight crew received a FUEL DISAGREE message on the EICAS. The flight crew performed the FUEL DISAGREE checklist. The FUEL DISAGREE checklist suggested four scenarios in which a fuel leak should be suspected and when the flight crew should perform the FUEL LEAK checklist. One such scenario is when the TOTALIZER fuel quantity is less than the CALCULATED.
And the footnote:
The CALCULATED fuel quantity is determined by the flight management computer by subtracting the fuel used (calculated basing on fuel flow figures as measured by sensors in the engines) from the total fuel quantity at the start of the flight fuel quantity.
So, as I understand it, the totalizer and the calculated (via FQIS) numbers disagreed, and it kicked a message. The flight crew disregarded the message, because they assumed that the Calculated quantity was the FMS' version of the planned fuel remaining quantity, based on predicted performance according to what planned engine settings were and the aircraft's route. (Does the FMC use Calculated fuel as the basis for its Arrival Fuel Prediction?)

Since the FMS did not have an option for calculating performance based on one engine running at idle, they ran the numbers with one engine INOP.

So they figured that since

A) earlier, they found themselves with 600 kg more fuel than planned
B) the FMS was calculating performance for a route they were not taking, and
C) the right engine was consuming fuel at idle, rather than being shut down, as the FMS thought

that the FUEL DISAGREE message was spurious. They did some back-of-the-envelope calculations and decided they didn't need to do a fuel leak check, presumably because that would involve having to shut their engine down.


In other words, when they got the message, they made up a definition of "CALCULATED" fuel where the calculations were based on the FMS instead of the EQIS. In their imaginary world, there wasn't a problem.

And that's why I'm amused by the recommendation. Someone no doubt who is not as ignorant as I will gladly explain to me:

1. Outside of ETOPS certification, why on a twin with one good engine and near several suitable airports, would it make more sense to reduce a malfunctioning engine to idle than to shut it down?
2. What the benefit is of a fuel leak test with both engines operating, but asymmetrically? How often does a FUEL DISAGREE EICAS message pop up on an already-malfunctioning engine without there being a fuel leak?


In the report's defense, it does make the comment:
During the initial training to operate this aircraft, the operator provides training to all its pilots to understand the requirements of the FUEL
DISAGREE checklist. However, in this case, the flight crew appeared to have misinterpreted certain requirements of this checklist even though they have undergone the training.
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Old 17th Mar 2017, 14:39
  #850 (permalink)  
 
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Presumably if they had shut down the engine they would have needed to follow the checklist and land at the nearest suitable airport which would not have been Singapore. The recommendations from base were no doubt influenced by the same desire to get the aircraft back to base.
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Old 17th Mar 2017, 14:46
  #851 (permalink)  
 
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Originally Posted by DingerX View Post
1. Outside of ETOPS certification, why on a twin with one good engine and near several suitable airports, would it make more sense to reduce a malfunctioning engine to idle than to shut it down?
Engine failure lesson 1: An engine at idle still produces some electricy, hydraulics, bleed air and less drag. It is always better to have it at idle than to shut it down. You only shut it down if you really, really have to.
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Old 18th Mar 2017, 00:31
  #852 (permalink)  
 
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Didn't fly big machinery, but a tale of small twin turbine. In cruise and oil pressure dropped into the yellow and temp reduction of 10. Reduced power to idle and pressure was in the bottom of allowable. No APU, kept engine running so as to have auxiliaries available, and should our "good" engine decide to take a holiday. Upon landing and shutting down ramp advised of a puddle of oil on the tarmac. Checking the dipstick no oil was evident. Cause, a split in the reservoir to pump line. So while the engine was running it was sucking in air and aerating the oil, explaining the drop in both pressure and temp. The instant of shutting down all the oil drained out of the split.

Earlier in life had been given the advice, "never shut down an engine capable of providing power".
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Old 18th Mar 2017, 07:17
  #853 (permalink)  
 
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This video from inside the cabin shows a remarkably calm environment. (Certainly less panicky than some posters on here)
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Old 18th Mar 2017, 07:46
  #854 (permalink)  
 
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Dinger

The flight crew disregarded the message, because they assumed that the Calculated quantity was the FMS' version of the planned fuel remaining quantity, based on predicted performance according to what planned engine settings were and the aircraft's route.)

The fuel disagree/leak checklists for the 777 are quite explicit that "calculated" for fault finding/QRH purposes is the instantaneous calculated on board fuel ( i.e. initial onload minus the integrated flow), and that is the number to be compared with the FQIS tanks totaliser figure; both are displayed for easy comparison, right next to each other, on FMS page Progress 2 (in our case). Since they are instantaneous, not predicted figures, there's no need for any future performance input/knowledge of route, etc.

On most flights the two figures will be well within a within a tonne of each other. Now from the report it seems the SIN crew had a 4 tonne mismatch (!!!!) so unfortunately it looks like they well and truely managed to over analyse things and talked themselves out of actioning the Fuel Leak checklist...however...

Don't want to offend tdracer or Boeing but you mention the comment in the report about the training of the fuel disagree/fuel leak checklist, and I'd say that could well be a fair cop.......FWIW for the 777 this has been a very "hot" item for trainers for a while at at least one outfit I know of. The checklists are somewhat protracted (for good reason), convoluted, but there are one or two interestingly worded questions and as a result using the electronic checklist it is quite easy to end up ticking the wrong box and going up a blind or misleading alley, or not going up an alley at all (such as going into the Fuel imbalance Checklist but then not going on to action the Fuel Leak Checklist....when in fact taking a step back it might be obvious it is the sensible thing to do).....

Does the FMC use Calculated fuel as the basis for its Arrival Fuel Prediction?)
FWIW Arrival fuel prediction (FMS progress page 1) does use the calculated fuel minus predicted burn, winds, temps etc etc. There is an option, rarely used to switch to using the FQIS quantity..but in any event you shouldn't be using that predicted figure arrival as a decider for Fuel leak analysis, it's the instantaneous calculated fuel vs. gauged fuel tanks that matters..

Last edited by wiggy; 18th Mar 2017 at 12:26.
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Old 18th Mar 2017, 09:24
  #855 (permalink)  
 
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Originally Posted by YRP View Post
It is interesting how the report dances around the decision to evacuate or not but avoids reaching a conclusion on that.
Anyone familiar with the work culture in Singapore, knows the answer to that question. I wonder what the status of the crew is at the moment.
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Old 18th Mar 2017, 10:18
  #856 (permalink)  
 
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Concur 100%. I would extend the question to the status of the FC as well...
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Old 19th Mar 2017, 00:49
  #857 (permalink)  
 
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@RCSA - it is simple. The risks of fire are so unpredictable and great, and the rapidity at which toxic effects can spread, is that the decision not to evacuate even with this 'safe' outcome is far worse than evacuating immediately before the option is taken away. BA in Vegas is a sterling example of how to do it properly. Singapore were lucky. Aviation does not need lucky.
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Old 19th Mar 2017, 00:54
  #858 (permalink)  
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Absolutely no similarities between the BA incident in Las Vegas and the SQ incident at Changi - the evacuation in Las Vegas wasn't so hot either, pax walking away with their carry on luggage, imagine the congestion in the aisles that must have caused.
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Old 19th Mar 2017, 04:46
  #859 (permalink)  
 
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You would think that after the Sewol capsize, where pax were instructed to remain their cabins and were later found drowned, that captains would be more inclined to evacuate before it's too late.

The lesson has not been learned in Singapore.

Next time the luck might not hold.

Last edited by RatherBeFlying; 19th Mar 2017 at 05:01.
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Old 21st Mar 2017, 03:44
  #860 (permalink)  
 
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Would a windmilling engine at cruise (i.e. shut down) still produce some degree of hydraulic pressure and electrical generation? What sort of speed would the engine be rotating at compared to idle? Or does a complete shutdown isolate everything? Just trying to understand what is to be gained by leaving a sick engine running at idle for hours. Apologies if it's a daft question...
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