Have I entered a parallel universe???
Honestly so much rubbish posted on this thread.
CAT A Performance Profiles are hugely varied between the types of helicopters. There are profiles that accelerate almost level. Profiles that go up and backwards/sideways to/from a helipad and profiles that do a whole combination in between. All dependant on the space available and the obstacles around the TLOF.
Each manufacturer publishes a solution based on the engine and rotor performance. There are several different solutions for engine limitations alone.
Trying to explain the difference between a CAT A Departure and a CAT B Departure is really simple:
CAT A - In the event of critical OEI, the helicopter can either: continue the take-off, OR land safely.
CAT B - In the event of critical OEI, a forced landing will be required.
Strain on MGBs and other stuff is irrelevant. If it were there life of the transmission would be curtailed by the number and nature of the CAT Profiles performed.
That's it!
Where's JimL when we need him.