Airworthiness issues.
One specific area of Continued Airworthiness that is beginning to impact the world’s airlines is SFAR 88. This is an FAA Special Requirement which, as a result of the TWA 800 accident investigation, requires a review of fuel tank safety.
This exercise comprises a safety assessment of the basic fuel tank and system design (normally carried out by the manufacturer) and an operator review of their fleet to identify any modifications that affect the fuel systems. Once identified these modifications must be assessed by an approved design organisation to determine any unsafe conditions.
The JAA and UKCAA have produced harmonised requirements that reflect the content of SFAR 88 and it is worth noting that the FAA will recognise compliance with either of these.
In the UK, Airworthiness Notice 55 is the mandatory vehicle being used and is applicable to UK industry.
More;
One of the bottom lines is that on modified fuel systems a lot of work / rework needs to be carried out with regards to reducing risk of fire / explosion. Operators that do not comply will have to have the Aux fuel system made inoperable.
[B]Part of this mod is to install "dual wall" fuel pipes. At present, it is
allowable to shroud a standard rigid pipe with a larger flexible hose
type assembly, with a gland drain that can indentify the source of a
leak to within a certain distance. The hose will go.
This is a description I received of the AAR piping in Nimrod bomb bay.
"The fuel pipes you mentioned are all single skins. The AAR system, whilst being a lash up, has no double skin, simply a flexible pipe routed from the former escape hatch into the bomb bay via sleeves in the frames."
So not only does Nimrod MR2 and MRA4 lack fuel tank protection and bomb bay fire protection, it now looks as though it is coming up well short on more JAR/UKCAA/FAA commercial directives.
Military Airworthiness?