Hey man,
I dont think you are allowing for the lapse rate from ISA conditions of approx 2C per 1000 ft on a standard day
i.e. I think you are using the surface temp and then applying that at altitude which it wouldnt be (it would generally be colder)
if it is 30C at sea level it would be about 23C at 3500 ft.
In the UK use the met office chart F214 to determine temp at altitude or the OAT gauge in the aircraft BEFORE you attempt to hover OGE.
assume it is 23C at altitude the max OGE hover ceiling would be about 3800 PA which would be about 3560 QNH with 1005 set
which would be about 5500 density altitude using chart 5.3, note the R22's max operating altitude and VNE limitations are expressed as Density Altitude not pressure altitude or Indicated altitude, which on a hot day like your one can come into play earlier than you would expect
you follow ?
regards
CF