A few other things to consider that haven't been covered in enough detail are as follows:
Weight: true it is 14,500Kg AUW, but what needs to be considered is that on the Merlin variant there are only four wheels supporting this weight. Tire pressure is ~7 bar, so there is significant loading on these four points. Not sure what it is though, I only flew the thing ;o). Don't use gravel or loose particles, see area below.
Size: As mentioned above it needs plenty of room, if the helipad is for patient transfer, the approach is and landing is not always conducive to a good ramp to ambulance meeting. The pad should be large enough to allow the pilot to "castor" the aircraft. That is, to turn the aircraft on the ground about its main rotor mast (or there about).
Approach & Departure: Although most helicopter pilots will use the wind to there advantage, the 101 does give excellent out of wind performance, try to set up the helipad approach with the best wind advantage. If the aircraft is flying under military specification then Cat A performance may not necessarily apply, however, if under civilian certification then this will have to be taken into consideration. Again, Westland can provide this info, I don't have a RFM in front of me to give you the details on helipad approach and departure to meet Cat A specifications.
Area: While it is important to take size into consideration, the affect of rotor downwash is significant! I have blasted autos with sand picked up from a road running adjacent to the pad. Not good! A wind sock was blown down at a hospital pad by a fellow pilot I worked with. The wind generated is significant. Rotor diameter is 18.5 m, this may be holding 14,500 Kgs in the air! Grass is good surrounding material, not small trees or shrubs. Large coniferous trees can be pushed over, even on approach.
Lighting: Standard helipad lighting is enough, again, whether or not it’s a military operation or civilian one, NVGs will aid the military operator but not the civilian one (not sure on that however), so this will refer to approach and departure for night operations. Oh, and have the wind sock lit ;o)
Noise Abatement: The 101 is loud! It has three engines operating plus the whistle of the two rotors. Having a pad away from sensitive areas is crucial. Pilots can shut is down for this though.
Support: The 101 does not need anything special in aircraft support equipment, however, having the usual helipad gear such as fire extinguishers, two-way radio communication, have frequency visible to pilot as he flies over or published. A well written operation manual for persons at the helipad for 101 danger ares, how to approach, etc.
I can't think of anymore things at the moment, but this will get you started as others have given good information regarding contacts in the UK. As I am in Canada, I can't give you those things; however, Sikorskyfan has indicated 442 Sqn in Comox, BC. Ph 001 250 339 8116
Enjoy
