Long Ranger L3 crash
Saw the same thing about 10 yrs ago while working for the (probably!) same utility company. If I remember rightly the eventual cause was routing/ clamping of the P3 line, which caused it to be IN TENSION all the time. It may also have been a (slightly) wrong part no, of subtly different length. ( was a long time ago!) With the natural hi-freq vibe of the engine/ MRGB, the line was vibrating which caused either chafing at a P-clamp and/or fatigue fracture, on a bend possibly.
Hope this helps Mugsy. Long time no see. Man those Line Audits were fun! (?)