Hi Shawn,
Yes, but that is not the issue here; HEC Class D is not rescue, it is CAT hoisting. As I explained in my other posts, (in Europe) SAR is almost always alleviated from the performance requirements because it cannot be done within HEC Class D requirements - which are quite stringent.
If there is something that is unclear about the AD (and the interpretation of the rules) it is that the FAA (once again) appear to believe that an aircraft certificated in Category A must always have engine-failure accountability. Hence there is confusion about when HEC Class D applies.
I'm not sure Sikorsky are alone among the manufacturers in specifying limitations for the 'rescue hoist'; perhaps if they have erred, it is because they confused the issue by invoking text for HEC Class D.
This appears to me to be a continuation of the discussion about the Status of Transport helicopters certificated under 29.1(c) - i.e. those with "...a maximum weight greater than 20,000 pounds and 10 or more passenger seats" which must be type certificated as Category A rotorcraft. What the rule doesn't state (and should not) is that operations must always be conducted in Performance Class 1 or in accordance with HEC Class D masses.
As we have discussed before on PPRune, this is an attempt to regulate the operations of helicopters with certification rules. A helicopter may be certificated in Category A in accordance with Part 29 (or Part 27 Appendix C) but regulation of operations should be left to Parts 133 and 135 (or in Europe other operational regulations).
For example, and as has also been stated before, helicopter operations to helidecks are almost always conducted in Performance Class 2 - this has been recognised by the introduction of OpSpec 100 which neutralises the interpretation of FAR 91.1.
Jim