RAF Lightning
Further to fantom, my dad was a RAF engines & airframes bloke.
I remember him telling me how, when the Lightning was introduced with its astonishingly-high pressure hydraulic system (to save weight), quite a few techies sustained injuries - including amputated digits.
It seems that the standard way to identify the location of a leak was to run a finger along the hydraulic line. This was fine with the older, low pressure systems, but very not with the Lightning.
Dean