ATSB Preliminary Report QF30 Depressurisation Event Manila

[Guest pelorus32]

ATSB prelimany report here:

 

http://www.atsb.gov.au/publications/investigation_reports/2008/AAIR/pdf/AO2008053_Prelim.pdf

 

Interesting reading.

 

Regards

 

Mike

 

 

[Ultralights]

im still amazed at how the oxy bottle could blast its way into the cabin, hit the door handle up, bounce around a bit, and still find its way back down the hole in the floor and then outside the airframe. though its interesting to note, the crew portable oxy bottle is missing as well.

 

very lucky no one was injured with a heavy steel bottle flying around the area of row 26.

 

 

[Guest Andys@coffs]

The whole report made sense until the last page...... so having made a hole in the floor, which the picture shows to be not much bigger than the diameter of the cylinder, the cylinder bashes the door, breaks, inverts biffs the roof, inverts again, falls down and neatly goes through the same hole that it made coming up...... If onlY i could be so lucky at lining up my lotto numbers........ Does this seem to be seriously stretching the co-incidences to anyone else.... Especially when you consider that in the sequence explained you have at least 3, possibly more pieces of cylinder, 2 of which were above the floor and none can be found......(well, actually the last drawing suggests that teh cylinder valve head was in the main cabin)

 

Not saying it couldn't happen just amazed at the likelihood of it occurring

 

Andy

 

 

[Guest pelorus32]

It also struck me that if the initial failure was in the bottle valve then the bottle would be going down not up (every force has an equal....blah, blah). That seems to suggest that the bottom of the bottle failed first, or that something caused the bottle to rotate after the top failed.

 

The whole story of the perambulating, peregrinating bottle is causing me a little doubt.

 

Until the next exciting episode.

 

Regards

 

Mike

 

 

[Guest Andys@coffs]

Mike

 

If you look at the last few pages you'll see that indeed they are suggesting that the bottom of the bottle failed. Bottom bit exits throught the skin. bottole minus bottom goes through floor and hits door in such a way that the valve head breaks off while the cylinder is inverting.....and so on.

 

Andy

 

 

[BLA82]

Hi all,

 

For your viewing:thumb_up:

 

Taken on the tarmac after the pax had disembarked

 

 

 

 

 

 

 

 

 

[facthunter]

Cabin airflow.

 

There is a massive amount of bleed air from the compressor stages of the engines available initially, but it is reduced when the engines throttles are closed for the emergency descent. Whenever there is a hole in the structure of the "cabin" ( passenger compartment , plus the pressurised cargo holds), there is a large amount of air exiting the system and anything near the hole would reasonably be expected to be carried away by the airflow. The analysis does not say whether the emergency descent was carried out at a high airspeed or at a low one( this is done when structural integrity is a concern, a low speed being employed when this might be a problem). I am a little surprised that this has not been mentioned and I wonder at what level of expertise is available in the system to make these judgements generally. I make these comments not as any implied criticism of the technique employed by the operating crew, but surprised that it was not commented upon. The trajectory of the oxy cylinder can probably be deduced from evidence of impact on the structure. In the absence of the cylinder in question, no conclusive assessment can ever be made. I would suggest that a failure of this nature is so rare that a repetition of the occurrence can almost be ruled out. However prudence would require that some examination of it's background may be necessary to appear to cover the usual "due diligence" aspects.. Nev..

 

 

[Guest Andys@coffs]

Actually Nev I think that you've identified the issue for me. Whether High or low power descent the cabin went from 12.5psi to 5.25psi in a relatively short period of time, and I presume that it all went through that hole in the floor..... Anything in the vicinity, including an energy spent cylinder, probably exited rapidly....

 

<stumbles away feeling somewhat foolish...>

 

Andy

 

 

[Ultralights]

i am thinking, if the air rushing our during depressurization, took the failed oxy bottle with it, then i would assume that it would have also dragged out the loose light pieces of the aircraft interior that were broken off during the impact.

 

 

[Guest pelorus32]

There is a massive amount of bleed air from the compressor stages of the engines available initially, but it is reduced when the engines throttles are closed for the emergency descent. Whenever there is a hole in the structure of the "cabin" ( passenger compartment , plus the pressurised cargo holds), there is a large amount of air exiting the system and anything near the hole would reasonably be expected to be carried away by the airflow. The analysis does not say whether the emergency descent was carried out at a high airspeed or at a low one( this is done when structural integrity is a concern, a low speed being employed when this might be a problem). I am a little surprised that this has not been mentioned and I wonder at what level of expertise is available in the system to make these judgements generally. I make these comments not as any implied criticism of the technique employed by the operating crew, but surprised that it was not commented upon. The trajectory of the oxy cylinder can probably be deduced from evidence of impact on the structure. In the absence of the cylinder in question, no conclusive assessment can ever be made. I would suggest that a failure of this nature is so rare that a repetition of the occurrence can almost be ruled out. However prudence would require that some examination of it's background may be necessary to appear to cover the usual "due diligence" aspects.. Nev..

G'day Nev,

 

I asked this question about descent mode of an ex QF B744 check and training captain. He dug out the flight manuals to check a few parameters. From my recollection the story is that at FL290 and 0.85 mach the a/c was above Vle so the descent would have been made gear up. Apparently they are trained for two scenarios - gear up and gear down. If you are above Vle then you don't try to slow to Vle, but rather just go for the speed brakes and max descent rate. In the case of gear down you max at the gear down limit speed and gear up you descend at barber's pole. Target ROD is 6000 fpm. They didn't make that - I think they got around 4000 fpm.

 

In any case I'm sure this is old hat for you.

 

Regards

 

Mike

 

 

[facthunter]

Technique.

 

Mike I won't go into details but the philosophy is

 

(a) If conditions are smooth and NO structural damage that might be considered to affect the safety of the aircraft is known or suspected, then the aircraft may be descended at Vmo,/Mmo. As far as the aircraft is considered, this entails ,power to idle and speedbrakes extend and increase speed to the limits above. This procedure gives the fastest descent, especially initially, and if a speed increase is needed I would expect a descent rate of over 6000 fpm to be achieved.

 

(b) the alternative procedure is to close the throttles and extend the speedbrakes as before, but maintain height till the speed washes off to permit the gear to be extended, and then descend at the maximum airspeed for that configuration. This does not get you down as quickly, which is the sole purpose of the exercise. ie where supplemental oxygen is not needed. (below 12,000/ 10,000.)feet.

 

It should be remembered that often the cabin will fog up, and the crew have to put on oxygen masks and establish communications to each other, and the outside world , turn off track and change the transponder channel, fly the plane to a very precise airspeed at at a unusually steep nose-down attitude, and make a calming PA announcement to the passengers that might persuade them that they are not going to die, otherwise it's just a day in the life of an airline pilot. Nev..

 

 

[Guest Teenie2]

Actually Boeing suggests following structural failure descend at a speed no faster than then the AC was traveling at when the failure occurred.

 

I must admit the chance of the bottle after bouncing around the cabin then going back out the hole in the floor then out the hole in the fus is just out of this world