Originally Posted by
BEagle
From the AAIB report:
Thanks Beagle. That's what I was saying above. "....an obligation to address issues and factors that, while they may not have contributed directly to a particular accident, were nevertheless identified as failings.........".
Rolls Royce: "The fuel pump governor diaphragm.... showed significant signs of distress. The degradation of the rubber on both faces of the convolution, due to the effects of age, loss of flexibility and chemical interaction with fuel have resulted in a diaphragm that has exceeded the known predictable functional capability of the design. Whilst the diaphragm had not failed, its continued integrity would be severely affected by the degraded condition of the rubber both above and below the “Tide-Mark”."
The AAIB said: "The engine manufacturer concluded it would not have affected the normal operation of the engine". Nowhere in their published reports do Rolls Royce say this.
"Exceeded the known predicable functional capability" is difficult to reconcile with "would not have affected....." Where does the truth lie? Somewhere in between? The answer is very difficult, and that is why you build defences and mandate periodic inspections. You don't ignore such a violation. You jump on it and withdraw approvals until it's fixed.
I find it incomprehensible that every Hunter operator the AAIB spoke to claimed not to understand the effects of fuel degradation. The AAIB, as usual, is too polite. It cites the Air Publication that spells it out, but does not comment on the apparent inability of any operator to understand plain English. For example, the following was not undertaken:
"In addition, ground run every 30 days and repeat application of anti-corrosion inhibiting fluid to compressor. If the engine is not to be ground run, drain engine oil, inhibit fuel system, apply anti-corrosion paper. Grease the control and inlet guide vane ram linkages".
This was a 'requirement', and hence mandated. The AAIB cites numerous violations in the 3 years preceding the accident. What actions have been taken to prevent recurrence? The CAA did publish a directive in 2016, but it merely repeated what the operator was meant to have done. What is invisible is any sanction over the failure to do this properly in the first place (while signing to say it HAS been done), and lack of oversight.
There's pages of this stuff, so may I suggest people look at the report, starting at page 63.
Savings at the expense of safety?