‘Mayday’: Rare event on flight

[Admin]

However, within moments of the Airbus A330’s wheels lifting off the tarmac, the late-night flight on July 3 last year was hit with a rare event, and new details have emerged highlighting just how serious it was.

 

First, one of flight D7207’s engines began experiencing vibrations at around 2300 feet (0.7km), then loud banging noises could be heard on-board, signalling an engine stall.

 

The crew called air traffic control and were then hit with an engine failure alert. As they continued to climb to 4000ft (1.2km), they received a call from a flight attendant on board who advised of a “starboard engine fire”, which could be seen from the aircraft cabin.

 

The flames had first been spotted by one of the company’s pilots who was traveling as a passenger. The crew took action, including discharging the fire suppression system.

 

Next came the distress call.

 

According to a new investigative report by the Australian Transport Safety Bureau (ATSB): “The flight crew upgraded the distress phase to a mayday with air traffic control and requested a diversion and approach to runway 01 at Brisbane Airport for an overweight, single engine landing.”

 

The aircraft, which had taken off at 10.49pm local time landed safely 20 minutes later in Brisbane. There were 359 people on board.

 

Bird remains and engine debris were later found on the runway at Gold Coast Airport. Footage taken of the runway showed flashes of flames coming from the engine during the takeoff roll, which occurred near where the debris was found.

 

The bird was identified as a masked lapwing, which are usually around 30-37cm long and around 0.23-0.40kg. These images released by the ATSB show the incredible damage done by the tiny creature.

 

What makes this case unusual is that most birdstrikes involving large aircraft do not result in damage (about 95 per cent), according to the ATSB. About 10 per cent of birdstrikes involving aircraft with turbofan engines result in the bird being ingested into an engine.

 

Engineers who examined the plane at Brisbane Airport discovered that a single fan blade-tip section, approximately 140mm by 125mm, had fractured from a fan blade and the fan rear seal was broken into pieces and scattered throughout the bypass areas of the engine. There was also evidence of fire within the engine.

 

It was shipped to Hong Kong for further investigation where debris from multiple masked lapwing birds were found on the fan, but evidence suggested a single bird had hit the blade itself.

 

The engine manufacturer, Rolls Royce, concluded that the loss of material from the blade had caused it to run out of balance, which led to high vibrations releasing the fan rear seal — which then broke up and fragments entered the core of the engine.

 

This ended up causing significant damage to the compressors, resulting in the compressor stalls. Oil also leaked, igniting in the engine.

 

The ATSB concluded: “Although aircraft engines are designed to withstand most types of birdstrikes — including those involving medium-sized birds such as a masked lapwing — this event appeared to involve a rare scenario comprising a combination of aircraft and engine speeds, the height of the fan blade at which the birdstrike occurred, and its angle of incidence.

 

“It is extremely unlikely such a scenario would occur on multiple engines simultaneously.”

 

AirAsia spokesperson Kris Taute said the airline welcomed the report, which followed a 10-month investigation.

 

“The report underlines the calm, skilful actions of the crew of AirAsia X Flight D7207 in diverting and landing the plane and its guests safely in Brisbane,” he said.

 

“This was an unprecedented incident and, as the report confirms, the crew were well-trained and prepared to manage this rare and unexpected situation. Safety at AirAsia has always been our number one priority.”

 

 

 

 

[eightyknots]

“It is extremely unlikely such a scenario would occur on multiple engines simultaneously.”

 

I am not convinced. Birds often fly in flocks.

 

 

[facthunter]

More often than not they are in flocks. I went through a flock of seagulls LANDING at Sydney. Many hit the windscreen and some went through the engines. You can smell them as the air conditioning and pressurising air is bleed air. On critical take offs it's often turned off to provide more power for a short time.

 

On take off it's a different matter where you actually need all the engines to deliver ALL the power they are capable of. A multiple engine failure caused the Airbus of Sully to land on the Hudson River as it had NO power after hitting a flock of Geese. Engines are usually tested by throwing many frozen chickens into engines at full power. that is the sort of bird they are supposed to cope with. A small bird isn't supposed to fail a motor..

 

Those sort of statements are designed to assure customers falsely that everything is "normal" Obviously the crew did as the book directs but all that stuff is not in the "normal OPs" section of the manual. Nev

 

 

[Bruce Tuncks]

Nev, I don't think the chooks were supposed to be frozen. I think that was a mistake and the chooks are supposed to be thawed out first.

 

 

[facthunter]

Certain I've seen shots of them frozen, and being used. for engine testing. It's long before video photoshopping happens. I did my first Jet and turbine stuff before 1970 .The OAT's at cruise are about minus 60 degrees C so perhaps that was taken into consideration. Ducks fly higher than Mt Everest.. Big chill factor in those circumstances. Nev

 

 

[antonts]

there is a common anecdote about testing highspeed rail loco with similar procedure, chicken was fired into front glass from catapult... breaking thru and making heavy damage to internal equipment and even walls. Unexperienced rail engineers forgot to defrost it.

 

Flying bird can not be at -60C, if it flies - it is alive, if it is frozen - it is dead.

 

 

[Phil Perry]

“It is extremely unlikely such a scenario would occur on multiple engines simultaneously.”I am not convinced. Birds often fly in flocks.

Yes Indeed. . . . . try asking 'SULLY'. . . the FIRST ever recorded loss of Both engines due to a birdstrike. . .

 

 

[Phil Perry]

there is a common anecdote about testing highspeed rail loco with similar procedure, chicken was fired into front glass from catapult... breaking thru and making heavy damage to internal equipment and even walls. Unexperienced rail engineers forgot to defrost it.Flying bird can not be at -60C, if it flies - it is alive, if it is frozen - it is dead.

What about the Canada Goose which was struck by an airliner at over 30.000 feet, which penetrated the nose of the aircraft and broke the left leg of the first officer ? Odd things sometimes occur. . . . bet it's at least minus thirty at that height. . . . ?

 

 

[facthunter]

Well below minus 30 Phil on plenty of occasions. The tropopause is as cold as the poles. The jetliner's speed raises it locally by about 30 Plus degrees. The coldest OAT I recall flying in was minus 56 C. Nev

 

 

[antonts]

air temp -30C - easy (-56C at 36000f is standard temp), but goose with even +10 body temp will be a dead goose.

 

Also goose on 30000f is a bit fantastic, at least if it is not equipped with turbocharger from KGB labs. 10000f - easy, 3000 - every day. World record for birdstrike is 37000, but it was griffon vulture, soaring bird not spending energy for flight.

 

 

[Bruce Tuncks]

In a glider, I've shared thermals with eagles at 12,000 ft. What were they doing up there? I reckon they were escaping from the heat . It was far too high to be hunting.

 

 

[facthunter]

Birds have insulation Down, Feathers and Fat. and they are a lot more used to altitudes than we are .. Nev

 

 

[kgwilson]

Eagles enjoy thermalling to great heights. It is not done for hunting but a way to fly long distance without expending much energy, just like we do in gliders. Chucking a frozen chook into an engine would be like throwing a block of concrete or brick into it. I reckon the fan blades and most of the compressor blades would be stuffed if that happened.

 

 

[facthunter]

Broken compressor blades going through the engine do downstream damage that progressively gets worse, or the turbine (hot end) explodes due fatigue/temperature effects. Engines have to ingest hailstones at high velocity as well. it's not all good for big Turbofans. Nev

 

 

[Phil Perry]

Just googled 'Birdstrikes at 30,000 feet. . . .quite a few damage pics, and facts re high flying species. . 37,000 feet in one case ( Vulture ). Go have a goggly.

 

Can't find the one I read about Years ago, where a bird allegedly penetrated the nose And the front pressure bulkhead. . .I think the aircraft was a B-727 Looong time back.

 

 

[facthunter]

The radome is frequently demolished by hail in storms and all the forward facing surfaces are often extensively damaged. Eroded and dented.. I would be surprised if the forward pressure bulkhead was penetrated, though. Maybe deformed but it's really strong and carries nearly 9 psi of air pressure to hold it there. Nev

 

 

[Nico13]

Certain I've seen shots of them frozen, and being used. for engine testing. It's long before video photoshopping happens. I did my first Jet and turbine stuff before 1970 .The OAT's at cruise are about minus 60 degrees C so perhaps that was taken into consideration. Ducks fly higher than Mt Everest.. Big chill factor in those circumstances. Nev

I had to chuckle at this one Nev, I bet not too many ducks flying at that altitude are frozen, bloody cold maybe.

 

 

[facthunter]

I don't think anyone was suggesting that frozen poultry was exactly what would be likely to go into the engines but they were convenient and replicated some of the characteristics of what might be ingested by the engines including large hailstones at high forward speed in flight.. Obviously modern engines are more susceptible to FOD it would appear. In high bypass ratio engines many only go through the fan section and not into the smaller diameter axial flow compressor. which is in the centre. . Nev

 

 

[djpacro]

Certain I've seen shots of them frozen, and being used. for engine testing. ...

thawed before testing

[facthunter]

. How can you be sure of that. ? The only time I've watched an educational film " on this was as I've stated and as part of my training provided by a large company. Why would I make it up? . They can test engines any way they choose.. Nev

 

 

[kgwilson]

I guess no-one can be sure of that but I don't think there has ever been hail stones recorded a big as a frozen chook and apart from that they are just water not frozen flesh and bones which as I said earlier would be like chucking a brick into the engine.

 

 

[facthunter]

A "frozen" chook has plenty of fat and will crush under a car tire. You can chop one with a butchers chopper. Hail can be very large and as HEAVY as a frozen chook. I you fly in a hailstorm and it's severe you will write off the plane .. Sensible pilots avoid them completely. It's a very hazardous situation to be in.. Most sever engine damage is done either by large out of balance fan blade or engine bits going through the core and making more devastation the further they go through the engine. There's no room between the rows of rotating blades and static blades for anything to fit without smashing the whole show. That's for the compressor. At the other end The (HOT part) theTurbine wheel operates near white hot and often is not contained when it lets go and bursts the engine case open and red hot bits go in all directions In one Airbus A-300 B4 in Turkey, some of the shrapnel bounced of the tarmac and set the other engine on fire as well. They aborted the take off and got everyone off, but the plane was destroyed by fire. Not a good start to a plane ride. Nev

 

 

[djpacro]

Give thanks for the fowl shot into jet engines in the name of safety

 

https://www.ntsb.gov/news/events/documents/oklahoma_city_ok-2_web_bird_strike_cert_and_damage_john_ocallaghan.pdf

 

 

[Phil Perry]

. How can you be sure of that. ? The only time I've watched an educational film " on this was as I've stated and as part of my training provided by a large company. Why would I make it up? . They can test engines any way they choose.. Nev

I may be able to shed some light on that, an old friend has worked for a company in Melbourne called Australian Calibration Laboratories for many years and his company was given the task of Calibrating a test rig which fired chooks etc into windscreens. It was he who told me the story long ago.

 

I'll email him and ask. Watch this space ( ! )