Many moons ago maybe even before Pprune I was capt of a 365N2 when we had a similar experience but this time just as we rotated away from the helideck with the co-pilot as HP (honest). There was a bang followed by a whooshing noise and my chin window filling with a grey balloon. Wasn't me guv was the first response from LHS
! Due to our being on min fuel for the beach we landed back on the rig as I didn't know what the excess drag would do to my fuel consumption (cruise in a N2 is about 135Kts but with floats inflated it is 90Kts).
Engineering advice sought - this was the days before 2 day risk assessments - advice from them was remove float covers and bring it back lad.
So brought it back to Aberdeen at 90kts - very noisy drumming from floats - told ATC I had to make approach to Red hangar side which was no problem - on short finals - hangar doors opened and most of company came out to watch
Five+ hours after inflation floats were still rock hard and supporting weight of helicopter - nose oleo fully extended. Which is reassuring
Fault traced to probable water contamination as a/c had been offshore in very wet weather.
Didn't even make local P+J newspaper.
HF