NST, the difference is that Sikorsky are RECOMMENDING that the modification be carried out before next flight through the issue of an ASB. This does not stop any operator from ignoring the recommendation and flying an unmodified aircraft.
A "grounding" will only come about once the FAA issue an AD, which if they say "before next flight" will ground any S92 until compliance with the AD is complete. Alternatively an individual regulator can issue their own AD (something that is pretty rare, but does happen!) which would ground any S92 registered in the country of that regulator.
This may sound pedantic, but hopefully explains why the S92s are not (technically) grounded?
Last edited by Variable Load; 21st Mar 2009 at 15:18.