Flying Lightnings.
Details are a bit hazy, but I recall a modification carried out on the Lightnings in the early 70s to the hydraulics, the AGS1186 bonded seals fitted to the hydraulic components ajacent to the jet pipes were leaking due to the heat, this caused a fine spray of hydraulic oil on to the jet pipe and caused a fire in the aft fuselage, and certainly a few were lost by this problem.( the tailplane gearbox failing if I remember)
The fix was to wire lock tape around the unions so when they leaked it merely dripped instead of spraying, thus reducing the risk of fire.
Thats possibly why they can't fly today. Sadly.
Best regards
om15