OK if we have established that the oxygen cylinder did fail
piece of cylinder found embedded
[understand not fragments of cylinder but parts from the regulator] then what was the reason for its failure. a reasonably new bottle
it couldnt be due to internal corrosion or pitting.... ????.
It would have to be due to two other alternatives
1. incorrectly fitted regulator..... but why fail after 6 months ????
2. over pressure... but how could this occur?
1. incorrectly fitted regulator... for a number of weeks now OJK had been flying around with an mel requirement to physically check oxygen pressure every transit....was it leaking??? possibly
The total pressure of all cylinders is summed to give a single reading in cockpit and a single low pressure would not be indicated there the only way to know if the cylinder was low in pressure is when the physical check is done.
2. If this bottle had shown a history of continually under-reading then it would have been replaced earlier due to the requirement of checking every transit for at least 2 weeks. The question of over pressure would only be acceptable if serviced outside of Australia. The servicing procedure here is to service from one single service point and all bottles are then equal in pressure. The procedure adopted by most overseas MRO's is to remove the low bottle/s and service them in a clean environment, which has its merits... but one of the negatives is you you don't have the uniform pressures, and one or more bottles could be over pressure.
Qantas have a standard procedure which requires those persons servicing oxy bottles to complete appropriate training.. we hope that other agents that work on our aircraft are also trained.