Bob
Does this make any sense to you as I haven't a clue

The aluminium of the helicopter landing area was 30" thick, transverses are spaced 5'3" apart and both beams and deck planking run fore and aft. John Brown calculations in 1969 suggested that to avoid permanent deflection of the plating the static load applied by a single wheel should "not exceed anout 3,000 lbs". The deck should withstand a load of about 20,000 lbs on any square foot. minimum take off for helicopters in the Westland range run from 5,500 lbs for the Wasp to 13,500 lbs for the Wessex HU.S.
The Helicopter Deck was considered usable by small helicopters only particularly when fitted with wheels. If the skids are fitted and the helicopter lands with skids athwartships (ie across the longitudinals) the load per skid could be about 3,000 x number of beams crossed by the skid.
