Comments on: The full bottle on the latest Qantas thrill ride

By: Alan

Alan — Thu, 01 Jan 1970 10:00:00 +0000

I find it curious that any Crikey criticism of Qantas is almost always quickly refuted by some unspecified experts. I often wonder if some part of the company’s bunker is dedicated to monitoring Crikey & minimising any ‘damage’ by over-the-top rejection of the report or some attempt to discredit the author. I would put nothing past them.

By: L Bullock

L Bullock — Thu, 01 Jan 1970 10:00:00 +0000

Glen

I chuckled aloud at your comment " ... if the valve on the cylinder started leaking before it failed, then oxygen may have flooded the cargo space, and possibly into the cabin. Passengers would notice a feeling of wellbeing, and so I wonder if anyone of them reported this."

A feeling of well-being on a Qantas flight?

By: Philip

Philip — Thu, 01 Jan 1970 10:00:00 +0000

Another Qantas mechanical failure this morning on a flight from Adelaide to Melbourne. Wheels wouldn’t come down or something. Whatever it was they had to to turn back to Adelaide. The brand is really being trashed.

By: L Bullock

L Bullock — Thu, 01 Jan 1970 10:00:00 +0000

Dear Crikey

Every other day Crikey sends me tempting emails asking me to be come a paying subscriber.

If I undertake to purchase a subscription to Crikey, will Crikey undertake to ensure that its writers improve their sentence construction and grammar? Avoiding run-on sentences and incorrect use of prepositions would be a good start. Here are two examples from the Ben Sandilands article which really threw me:

"On 24 April CASA issued an airworthiness directive with an enforcement date of 5 June requiring urgent inspections of the supports that held oxygen bottles in place on Boeing 747s like the one that was only an hour into a Hong Kong-Melbourne flight with 365 people on board when it made an emergency descent into Manila with a large load of passenger luggage plugging a gaping hole below the cabin and forward of the wing."

"The question remains unanswered as to whether the fuselage blew first, because of an undetected imperfection, or over repair as some engineers have speculated, causing the luggage container to get sucked backwards to the hole and slamming into the oxygen bottle rack in the process, or the bottles initiated the failure by falling out of their supports and ‘going off’. "

In the light of other subscriber comments on this article relating to incorrect technical information, you will understand my indecision to commit to Crikey. One might wonder at the pressure your writers are under when they produce sub-standard work.

Looking forward to paying out soon...

By: Andrew

Andrew — Thu, 01 Jan 1970 10:00:00 +0000

I have used oxygen for high altitude unpressurised flying in gliders and i thought it was well known that grease in bottles can cause explosive combustion. I did a simple search and found

http://forums.jetphotos.net/showthread.php?t=44558&page=4

“The combination of grease and pressurised oxygen is explosive. The are famous photos of a P3 Orion where a crew oxygen bottle exploded and rocketed out the side of the aircraft. The aircraft was ultimately destroyed buy the ensuing fire, but this occured on the flight line.

If anyone does not know that precaution they should not be touching oxygen systems.”

So somebody needs to be educated here

I also recall that the apollo explosion was speculated to be due to a grease maintenance error

And i do have a chemistry degree.

Obviously if a bottle explodes the failure is only caused by pulse of pressure rather than a bomb like blast but even so if all of the gas immediately leaves the bottle it is going to do some damage as some pieces will behave like shapnel rather than remain as part of the bottle. If you look at an over pressure accident in a scuba bottle they tend to not totally fragment but bend and split massively .

By: Ben@Crikey

Ben@Crikey — Thu, 01 Jan 1970 10:00:00 +0000

Glen, Perhaps you should read my imperfectly written words again. Considerable qualified advice went into choosing them, however poorly strung together. While being briefed I was told oxygen overpressure as you describe it would have acted the way the investigation thinks it did, blowing parts of the valve up through the floor, although it is unclear if the pathway corresponded with built in pressure relief panels designed to mitigate sudden differences caused by decompression events in order to prevent that floor collapsing upwards or downwards depending on where the serious leak occurs. It could have readily punctured the fuselage as speculated, however it remains possible that the skin failed first, setting in train events that 'broke' the bottle.

The union by the way hasn't been silent, nor said anything silly about it and its comments were already in print.

Keep in mind that masks drop in a depressurisation because of the pressure of the emergency supply forcing the tiny hatches open. No pressure, no mask. And if you don't then pull the mask toward you the flow may not come through. It may be that people don't listen to that part of the cabin drill.

By: Glen

Glen — Thu, 01 Jan 1970 10:00:00 +0000

Sorry, but not a good article. Firstly, Ben, you seem to think that oxygen bottles can explode like a bomb. Oxygen is not itself explosive (altho enabling the combustion of other substances). If its valve failed, the oxygen bottle may have acted like a torpedo, and its motion may have pushed a hole in the skin of the jet. Or else the over-pressure of the gas inside may have popped the skin of the aircraft, in its vicinity. If the skin popped, it would probably occur along a join between panels, and if the gap faced forward, the airflow over the surface of the fuselage could tear off the panel which is now protruding into the airflow. My guess is on overpressure. Also, if the valve on the cylinder started leaking before it failed, then oxygen may have flooded the cargo space, and possibly into the cabin. Passengers would notice a feeling of wellbeing, and so I wonder if anyone of them reported this.

Also interesting, Qantas reported that this jet had only ever been maintained in Australia. The Union has been noticeably quiet about this incident. Anyone want to bet on if Qantas will soon suggest having maintenance moved overseas, to be done by more experienced maintenance organizations? The reported failure of the emergency breathing system does not bode well for Australian maintenance standards…