IHL,. .That is the "modified Cat B" rule made for the North Sea a while back (30 years) The CAA recognized the safety of simple zero rate of climb, and allowed a special profile that carried more payload than Cat A enroute
True Cat B is purely the ability to hover, twin engine IGE and to make a safe landing along the route if an engine fails. Singles are operated Cat B.
Part 29 of FAR/JAR allows Cat B if the aircraft carries 9 passengers or less.
There are other watered down paragraphs for "Cat B, 9 passengers or less", such as tail rotor controllability. No demonstrated crosswind controllability is required 9 pax or less in a Part 29 helo, if the manufacturer applies for it. Thus the screwy Bell hover charts about wind from the nose vs wind from any direction, where extra payload is added at the expense of tail rotor authority. This is true for the 430 and the 412.
The logic of limiting the exposure for a less safe configuration is interesting!
[ 24 February 2002: Message edited by: Nick Lappos ]</p>