Cathay 780

[ExSp33db1rd]

Just seen a "Mayday" TV presentation of an incident involving a Cathay Pacific Airbus 330 from Jakarta to Hong Kong on April 13th 2010. Cathay 780.

In the cruise the Stbd. engine started to vibrate and give trouble so was reduced to idle power, not shut down. ATC advised single engine landing necessary. Subsequently Port engine experienced same problems and again was reduced to idle, not shut down. "Mayday" declared and ditching contemplated. On the now forced descent the Captain experimented with Port engine thrust lever and discovered that he could partially restore power, and so it would be possible to reach Hong Kong for original single engine landing plan.

On final approach he was unable to reduce speed sufficiently for a normal approach, as although reducing the partially serviceable engine thrust lever, it was not following thrust lever commands and the thrust remained around 74%, hence the inability to reduce speed and still maintain the required descent profile.

The aircraft eventually landed around 100 kts ( ? I think they said ? )anyway, much too fast, difficult to set down and stop, but eventually he succeeded before running off the end, then ordered an evacuation due to suspected brake and tyre fire.

My question ... once established on the descent profile, and landing guaranteed, why would they not then shut down the engine instead of trying to manage the excess speed ?

In view of the subsequent finding that degraded fuel control valves, due to salt contaminated fuel as a result of salt water getting into the fuel supplies pumped aboard, shutting down may also have been impossible, but it appeared that they didn’t even consider it ? Seems so obvious, so why not ?

Any answers ? Just curious.

[Ex-Ascot]

I presume you mean shut down the starboard which was giving idle thrust. I think that I would prefer both to be burning and turning if I had the choice. I once had to shut one (of 4) down just after take off, forget why, but relight it before landing.

Do not know aircraft type but did he have an option of playing with the spoilers?

[ExSp33db1rd]

Ex-A. No, he avoided a ditching by regaining some power on the Port engine, but when he attempted to reduce thrust to execute what was effectively a one engined approach, the Port engine remained at the higher power he had regained and couldn’t be reduced, therefore when in an acceptable approach profile, I.e. gear down, landing flaps set, he was going too fast, raising the nose, which was now his only means of reducing speed, would have had him overshoot the selected touchdown point, so he maintained the profile and crossed the threshold way too fast, so why not decide at what point in the final approach he would "have it made" with the now rogue engine stopped at that point, and achieve a more desirable approach speed. There was never any chance of executing a go around, so why not remove the then only reason for the excess speed ?

I have no knowledge of the speed brake, spoiler, systems on that type, Airbus 333 it was described as, and they were never mentioned by either pilot.

East to talk, we weren’t there, thankfully ! Both pilots were congratulated and given some award, but as I watched the enhanced drama created by the TV production, and the pilot wrestling with the too fast configuration because he couldn't reduce power on the one, half working, engine and subsequently having difficulty landing as a result, I couldn't help shouting " cut the fxxxing engine ! "

I also shut 1 of 4 in the cruise due loss of oil quantity, deciding to keep what oil it still had available to relight for a four engined landing, but when relit for the approach it promptly quickly dumped all of the remaining oil overboard and we had to shut it down again and make the three engine landing after all ! Murphy is always with us.

Cheers. ExS.

Not important, just curious as to why they didn’t even discuss it when they realised that they had an additional problem at the end.

[Ex-Ascot]

OK I understand now and yes I agree with you. Just wondering how much yaw there would be chopping it short finals.

[TheGreenGoblin]

[TheGreenGoblin]

Bottom line is the crew could not set both engines to idle...

The landing was more dramatic than the video shows...

A few minutes later, approximately 83 kilometres (52 mi; 45 nmi) southeast of Chek Lap Kok, the aircraft was in a descent and approaching an altitude of 8,000 feet (2,438 m) when an "ENG 1 STALL" ECAM message was annunciated. The flight crew carried out the actions for a No. 1 engine compressor stall and declared a "mayday." The captain then moved the thrust levers to test engine responses. No. 1 engine's rotational fan speed slowly spooled up to about 74% N1, while No. 2 engine remained running at sub-idle speed, about 17% N1, providing sufficient thrust to level off at 5,500 feet and reach Hong Kong. As the flight approached the airport, the crew found that movement of the thrust levers failed to reduce thrust below 74% N1 on No. 1 engine.[3]

At 13:43 hours local time (05:43 UTC), 11 minutes after declaring the "mayday", the Airbus touched down hard on runway 07L (length 3800 m; 12,470 ft) at a groundspeed of 426 kilometres per hour (265 mph; 230 kn),[3] 176 kilometres per hour (109 mph; 95 kn) over the normal touchdown speed for an A330[6] and above both the maximum allowable flap-extension speed of the A330-300 and the speed rating of the tyres. The plane ricocheted and briefly became airborne again until it slammed down hard banking left, causing the left engine to scrape against the runway surface. Both wing spoilers deployed automatically. Only No. 1 engine's thrust reverser deployed and activated with the right engine’s thrust reverser unresponsive due to a technical snag, forcing the crew to bring the aircraft to a stop using manual braking. No. 1 engine remained at between 70% and 80% N1 until the crew shut down both engines upon coming to a stop.

Five of the aircraft's eight main wheel tires deflated. Airport firefighters reported that smoke and flames were emanating from the landing gear. The captain ordered an emergency evacuation, during which 57 passengers were injured, of whom 10 were transported to the hospital.

The cause of the engine malfunction was...

Analysis of the engines found that their fuel systems were contaminated with spherical particles. The Hong Kong Civil Aviation Department Accident Investigation Division concluded that the accident was caused by these spherical particles. The contaminated fuel, which contained particles of superabsorbent polymer (SAP) introduced into the fuel system when the aircraft was fueled at Surabaya, subsequently caused the loss of thrust control on both engines of the aircraft during approach to Hong Kong.

The SAP particles, a component of the filter monitors installed in a fueling dispenser at Juanda Airport, had caused the main metering valves of the fuel metering unit to seize. The valves were found to be stuck in positions corresponding to the recorded thrust output of each engine as it approached Hong Kong. Other engine components were found to be contaminated with the particles, while the variable stator vane controller of engine No. 2 was found to be seized. The entire fuel system, including the fuel tanks, was found to be contaminated with spherical particles.

Fuel samples collected at Juanda International Airport were contaminated with the particles. The fuel supply pipeline system used to refuel aircraft at Juanda International Airport had been recently extended during construction of new aircraft parking bays. The investigation discovered that not all procedures had been followed when the system was brought back into service.

https://wiki2.org/en/Cathay_Pacific_Flight_780

[TheGreenGoblin]

Full report to be found here...

[ExSp33db1rd]

Once the landing was guaranteed it seems unreasonable to have not removed the source of the high speed, I.e. the uncontrollable no. 1 engine ? Yes, yaw would have been an issue, but presumably he was already holding left rudder to combat the yaw being produced anyway, so doubtless it would have been controllable, or at least better than the high speed touchdown ?

[TheGreenGoblin]

Once the landing was guaranteed it seems unreasonable to have not removed the source of the high speed, I.e. the uncontrollable no. 1 engine ? Yes, yaw would have been an issue, but presumably he was already holding left rudder to combat the yaw being produced anyway, so doubtless it would have been controllable, or at least better than the high speed touchdown ?

Well maybe, but the incident reports says the following in conclusion about the stage, on short final, when the Captain realised they could not reduce the thrust on engine #1.

t. At that stage, there was no time for the flight crew to consider other strategy
nor procedure to cope with such emergency situation. The flight crew
concentrated on flying the aircraft for a safe landing.

One must also consider that engine #2 was also playing up on final approach, Engine #2 was stuck at 17% N1 (below idle) and thus delivering effectively nil thrust. As a result, the pilots elected not to shut down engine #1 until they were safely stopped on the ground.

Given all the anomalous engine indications they elected, sensibly, some may think, to stay with power and fly the aircraft with power on engine #1.

As you imply in your original post ExSp33db1rd, it was a command decision, made in extremis, close to touchdown. I guess if they had thrown the dice and had cut the engine and walked away from a greaser of a landing, the Gods would have smiled and the world would have applauded even more, but it could have gone the other way too. The fact that they and their passengers, walked (Ok some limped due to the usual litany of minor injuries as a result of the emergency exit) is a fair outcome from what was a pretty bad situation methinks.

[ExSp33db1rd]

Agreed, Just curious as I watched them wrestling with the beast as I watched the TV dramatisation.

Thanks for the comments.

[Ex-Ascot]

I do not think that any air-frame driver here is going to deny that this was a tricky one. You would not know what you would do unless you were in the seat at the time. Anyway a good result.

Love the bit where he has double engine failure and is cleared to 3,000'. Good job mate because I am heading in that direction anyway.

[Pontius Navigator]

Too much speed was probably better than too little.

[Ex-Ascot]

He would have gone almost exactly 100 m off the end of Kai Tak. Well the water would have slowed him down just like China Airlines in a brand new 747. That was a corker. https://en.wikipedia.org/wiki/China_Airlines_Flight_605

[Undried Plum]

You definitely don't want to be immersed in that water.

I worked on the seabed search and recovery of a turbine disc wot got tossed overboard by a departing Airbus at V1. Our divers were heavily pre-dosed with every broad spectrum antibiotic known to medical science and they still got severely ill.

I dunno whther it's still as bad as it was before HK's liberation from the Brits, but back then the oggin there was little better than liquidised human shite.

[TheGreenGoblin]

I am reminded of British Airways Flight 38. Different aircraft types, but both cases involved fuel system issues caused by contamination (icing in the BA Flight 38 case), and also because the crew were left with a major power/throttle issues on late finals, where Commander had to roll the dice and make a command decision in extremis, (e.g. "Meanwhile, the captain reduced the flap setting from 30 degrees to 25 degrees to decrease the drag on the aircraft and stretch the glide." in the Ba Flight 38 case).