Final report on CX780 accident published
 

English isn't perfect, but makes for interesting reading nevertheless.

Link to page:

Civil Aviation Department - Reports

Link to report .pdf:

http://www.cad.gov.hk/reports/2%20Fi...0compliant.pdf

As usual an excellent investigation and report.

I sense three areas that might elicit discussion on this board since no design changes are anticipated to eliminate this type of failure.

The continued possibility that fuel contamination may occur in the future if the fueling recommendations are not adhered to.

The minimal actions that the crew may employ in some phases of flight if the contamination should cause a sudden onset of engine control problems.

The mechanism on how this type of contamination affects engine control systems.

The last item is probably only suitable in a tech forum.

Ground & Other Ops Forums-Questions.
 

Refer to "B737 Smoking Brakes Scenario."

Then think of the casualties after this evacuation.

Fire dept attacking hot brakes with water, I think not! Classic formula for exploding tyres/wheels is NOT the environment in which to deposit the passengers.

Can we PLEASE think again on the criteria for chucking the pax down the slides and into hospital?!?! :ugh:

I don't wish to get drawn into a wider discussion on when/when not to evacuate, but I think it's worth pointing out that while on paper 62 pax and crew were injured during the evacuation, only one of those required hospital treatment for a broken ankle.

Wow that was a good outcome from a tricky situation.
Thanks for posting it.

Yep, our boys did well. I could only hope to perform as well in the future and fingers crossed I won't have to. :ok:

I'm curious as to the lack of any consideration or discussion in the report of the decision (however right or wrong) to have continued the flight to destination with faults showing on engines and one engine ineffective relatively early in the flight.

I'm curious about your lack of reading skills. Obviously you did not read the report, as those questions are addressed several times in the report.

Troll much? :hmm:

Phew! Reckon my pulse went up a bit as I read the History of the Flight.
I'd like to hear from the pilots themselves on the QT if, after years of hindsight, there's anything (or nothing) they'd have changed in the way they handled a not at all straightforward situation.
Well done - but, of course, that's what we expect from CX crew :ok:

Well handled by the crew from reading the report.
One surprising factor was the relatively high percentage of injuries to the crew from the disembarkation, who you would think would be more practised in this exercise. The report does not go into detail of the way the injuries were sustained but I suspect they were collision injuries due to a failure of the passengers to move away from the base of the slide after evacuating the aircraft, something that rarely occurs in training and currency checks.

I know I'm swimming upstream but I really hope we can avoid the typical PPRuNe second guessing of the crew's actions that usually accompany such reports. Those boys did a whale of a job in a situation none of us has ever even contemplated, never mind being trained for it. :ok:

Tell me again about the coming wave of remotely-piloted airliners.....

Why didn't he shut down that one stuck at hi power?
Seems like a no brainer, duh!

Great flying, job well done!

Superb bit of technical writing, even I understood it.

Killaroo,
The earlier publication “Accident Bulletin 1/2011 (An update Bulletin to Accident Bulletins 1/2010 and 3/2010)”
includes a paragraph 5, copied below (my bold):
“5. At 0530 hr, the ECAM caution message “ENG 1 STALL” was annunciated. The commander moved the No. 1 thrust lever to idle position. He then tested the engines by gently advancing and retarding the thrust levers. However, only No. 1 engine responded with stepped increase in N1 and did not reduce when the thrust lever was retarded. No. 2 engine remained at idle during the test. In an attempt to recover No. 2 engine control, the crew carried out a shutdown and restart on No. 2 engine in accordance with the Flight Crew Operating Manual (FCOM) procedures. However, the engine could only operate at sub-idle condition for the remainder of the flight. The No. 1 engine was stuck at approximately 74% N1 during the approach and reduced to about 70% N1 at touchdown. The No. 2 engine remained stuck at about 17% N1 throughout the approach and landing.”


One can only speculate as to the engine delivered and aircraft required thrust behaviour and consequences that would occur if Engine 1 had also been shutdown.


J.O. said it rather well

When reading it one has to remember that if you were in that situation, you don't know what will happen next and No. 1 engine may have decreased down to 17% or lower at any point.

You've no idea why what's happened has happened, and you don't know how much worse it may get. Hand flying under that pressure is hard work, when you're so focused on the why and what next.

- not much to 'speculate' on, really - it would probably have crashed.

A great piece of flying in circumstances that must have been very difficult to determine.

Thank you for your concern. Well my reading skills aren't what they used to be when I worked on the design of the RB211 forty odd years ago, and I'm not trolling.

It's a long report, I've not read every word. I see the first maintenance engineer gave advice and based on that the crew made the decision to continue. By the time ME2 was involved VHHH was clearly the only possibility. I still haven't found any discussion - just a one liner "reasonable". Maybe no more needs to be said.

Much trust in one engine flying. Pleased to have been involved in the early stages of design of such a reliable power plant. However, for right or for wrong I would have been very tempted to head straight for Singapore. In hindsight the decision to continue to destination proved to be problematic. Maybe I'm being oversensitive living just a stone's throw from Kegworth.

I think in hindsight, they would have landed ASPAP (Red!). However, they didn't know what was going on or how serious it was at the time, and I'm not sure I would have handled it any differently.



But, it was very well handled. Good show chaps! :ok:

Killaroo. No - it wasn't a no brainer - duh.....

Barking mad. On the ground in an emergency situation, I would far rather risk a few injuries down the slide than having my passengers trapped on a burning or smoke filled aircraft. Just look at the video of the 737 at Naha some time ago. If they had rethought that for just a minute longer, there may have been a very different outcome. The downside risk of SERIOUS injuries during an evacuation is very small. So, no - I will not rethink my thinking on this matter.

I wonder why other aircraft were not affected by the contaminated fuel.

Well the same flight the day before, was! Nowhere near as badly, obviously. They do seem to have discontinued use of that fuelling equipment as soon as the problem was suspected, limiting further possible problems. Maybe the vibration that happened while refuelling dislodged a lot of the spheres - many more than smooth flow would have. I remember years ago testing air filters, and just tapping them lets a lot of the trapped particles loose into the air, and having pulsed air flow really made them fly. Rather like the difference between placing a hammer on a nail, and hitting it repeatedly. It seems this is a very rare occurrance, and maybe the design of the affected parts makes them susceptible, while other engines may not have been affected as badly, or at all.

It could also be that also be that there is something about the A330 and/or the Trent 700 that makes it susceptible to that particular type of contamination. I doubt they get a lot of A330 traffic in/out of Surabaya

I know that the Rolls RB211-524G/H controls on the 767 and 747-400 were very sensitive to fine particle contamination.

I thought the crew did an outstanding job. Some small details that showed some excellent skills:

1. When it became obvious that they had both engines indicating 'stall', the commander traded excess airspeed for altitude. A small detail, but an action that shows excellent situational awareness.

2. Turned off the flight director and hand flew the aircraft when appropriate.

3. Managed excess energy using 'S turns' on final.

4. Whilst hand flying under unusual circumstances, realized that he'd called for the incorrect bearing intercept for the ILS and corrected it.

A 35 year old Commander and a 37 year old F.O. that showed they weren't children of the magenta line. Nicely played.

and so are most of the new FADEC controlled engines on all model types.

It's the fuel metering concept that requires close clearances, not-too-tight and not-too-loose, just like a musical valve instrument.

Please don't open one up when not in a clean room.

Screens are fine, except when the contamination is created from a dissolved substances into a particle after it passes through the screen.

Nothing left but trust in the fuel as well as the crew.

ALL fuel controls - FADEC and pure Hydromechanical - are sensitive to contamination - lots of moving parts with tight clearances. The RB211-524G/H was much worse due to even tighter clearances than is typical for most controls. Lucas (now part of Goodrich) liked to use much tighter clearances for their valves than the other guys, and it caused problems the others didn't see.

OTOH I know very little about the Trent 700 - I don't even know who supplies their Fuel Metering Unit (i.e. is it the company formerly known as Lucas, or is it someone else).

I was interested to read that Airbus revised the QRH to provide a suspected fuel contamination and a fuel contamination checklist for the the 330.

I operate the 320/321 IAEs and I wondered why said aircraft was not included in this style of checklist, upon looking at ENG 1(2) FUEL CTL FAULT I think I [I]may[I] have found the reason, I shall leave it for others to determine.

Worth a look in your Abnormal checklist.

I think it may have crossed the minds of the crew to divert based on the report. So they were making these considerations.

"During the climb, the flight crew noticed some abnormal Engine Pressure Ratio (EPR) fluctuations on No. 2 engine, with a range of approximately ± 0.015 around EPR target. No. 1 engine also had abnormal EPR fluctuations but within a narrower range."

"shortly after levelling off at FL390 (i.e. 39,000 ft AMSL at standard atmosphere conditions), Electronic Centralised Aircraft Monitoring (ECAM) message “ENG 2 CTL SYS FAULT” was annunciated. ECAM information “ENG 2 SLOW RESPONSE” was shown for crew awareness."

"The maintenance engineer (ME1) at the IOC asked the flight crew to check the responses of the engines to thrust lever movements. The flight crew advised that the EPR was fluctuating around an EPR target."

"As all engine parameters were considered normal other than the EPR fluctuations, the flight crew elected to continue the flight to Hong Kong."

"At 0316 hrs, ECAM message “ENG 2 CTL SYS FAULT” reappeared when the aircraft was levelling off at FL380. This time ECAM information “AVOID RAPID THR CHANGES” was also displayed in addition to the “ENG 2 SLOW RESPONSE”."

"The flight crew called MC again via SATCOM for further discussions. Another maintenance engineer (ME2) responded to the call and confirmed that he was aware of the earlier situation as they had been monitoring the engine parameters during the flight. The flight crew, with more concern this time, reported the ECAM message and the observed increase in EPR fluctuation (± 0.1 for No. 2 engine and ± 0.03 for No. 1 engine). The flight crew queried whether it was safe to continue the flight."

"Significant windshear was forecasted for both runways 07L and 07R."

Might be long, but this statement makes some pretty large assumptions:

Your questions are answered in the report. The engines where not "ineffective". They were both producing cruise thrust and the crew carried out several tests to ensure they were functioning normally. When they carried out the step descent, the engines responded normally as well. Being a fuel contamination problem, I think this sort of issue grew in severity as the flight progressed, and became a real problem only upon arrival at their TOD.

And the decision to continue was talked about in several parts of the report, and deemed completely safe and appropriate. That is what led me to question your insinuation that it was not.

You an I can sit here with the knowledge of "fuel contamination blockage caused by SAP spheres", but they did not have that knowledge at the time. All they had where some ECAM messages for which they followed their QRH and discussed with engineering for further insight.

Ignore the "significant Windshear forecast,......" etc etc as that appears on most days in VHHH :eek:

Apologies - that was a misread of the timing of events on skimming through.

I believe that we're missing the essence of the event when we start discussing should-ofs, could-ofs regarding crew actions.

The threat from the contamination is not steady state cruise but any throttle dithering that exercises the valving in the fuel control to either stick up or down or in some cases advance on its own to max thrust without response to the throttle position.

A/P on at 1144'. Daytime departure. :{

Fascinating reading.

All be it, I don't understand a lot of the technical stuff, but still very interesting to read.

An interesting thread for sure but among all the comments made I'm surprised that there is almost no mention of the root cause of the incident and what can be done to prevent re-occurrence, i.e. fuel contamination.

Ha :p

Yeah. I noticed that. Perhaps the FO had been hand flying the aircraft so much he decided that some automation familiarization was in order ....

The point of the Magenta Line syndrome isn't the fact that familiarity with automation is inherently dangerous. It's the danger of a degradation of other abilities as a result of it. In this case, I think the Commander showed that there was no degradation of his ability to aviate. When 'push came to shove', he still knew what he was doing.

Widebody captain at 35? That's a fairy tale over here....

Child of the Magenta Line?
 

The F/O was previously an F18 driver then Learjet/Westwind target tow pilot prior to joining Cathay, so I don't doubt his ability to hand fly an Airbus.

There is if you read the report. From what I understood, as in most accidents, it was a chain of events. Contamination of salt water from some relief ponds in the airport managed to get into the airport's refueling system when it was being worked on during a parking ramp extension.

The contaminants blocked the filters, and the fueling company just pumped up the pressure instead of investigating the reason for reduced flow. This pressure exceeded the inner metal structure design limits of the filtering cartridge, causing it to collapse and bulge slightly, creating more restriction.

The saltwater in the system affected the integrity of the filtering material, which then released the globules into the fuel flow. These spheres where small enough to not be detected during visual inspections, and caused FCU malfunctions after prolonged operation which allowed excessive buildups to block moving components.

There were plenty of recommendations to all parties, and the filter manufacturer improved the design of their system. Overall, I think the fault lies on the airport operator for sloppy construction practices followed by sloppy inspection and flushing of the system. The fueling operator also suffered from a bit of sloppiness in not investigating the blockage causing the pressure drop.