ZH844,
Thanks for the update. Seems the web site that celebrated the turnover of the first EH-101 to the RN was in 1996, 9 years after first flight, where it underwent 2 to 4 years of test before being declared operational. In this case, it was somewhere between 11 to 13 years from first flight to operational use.
Regarding the design, the S-92 is an all new design. The parts fit on the Black Hawk family (main transmission, etc) but they are all new, of completely new type of design and to a set of design standards that are quite a bit tougher and harder to test to than older machines faced. Fully damage and flaw tolerant rotor parts and fuselage structure must be proven using more samples of the components, taking more test time. This made our job a bit tougher.
The engines did not hold the development of these aircraft, they were available from first flight. Otherwise it would have been first autorotation, wouldn't it?
I had a lunch with Rafael Longibardi, the late chief pilot of Agusta a long time ago, and he told me of the funding issues in the EH development that held them back. Often, development time is not a technical measure, it is a measure of the funding and political will of the developer.
One poster commented on the development time as measured from design start. For the EH-101, first designs were started in 1981 or 1982. This made flight about 6 to 7 years after design start. S-92 had a design start in 1992, and flew in 6 years.
None of this is intended to disparage two fine helicopters, Jerry Tracey and Colin Hague are friends, and I would like to be sure they invite me back to their lair at Yoevil when I am next in the UK!
Recall that this thread was started to discuss the seemingly long time to develop the S-92. It was not a long time, it was about half to 2/3 the time of the EH-101 and NH-90.