"I wouldn't mind betting that the HYD systems on the Vertol design both carried on working in the event of a double-donk stop, unlike the Wessex." says Blud and Thunder.

Having had a double donk stop in the Wessex I can assure you that the hydraulics keep working - both of them as they are driven from the gearbox!! D

Interesting, Georg1na - on the Mk 2 we had to do all our autorotation practices HYD 2 'off' as we were assured we wouldn't have that system available in the event of double donk-stop. It's been a while - 38 years - since I last taught on the beast; perhaps Crab, or someone else more current than me, could explain why we were obliged to do this?

Never had the luxury of two engines on the Wessex, but in the Wessex HAS Mk1 the primary hydraulics were transmission driven and the secondary system was engine driven. I can recall that after 58 years but don't ask me what I had for dinner last night.