Thank you all for some very interesting perspectives. We operate 2 x CBS4 and 2 x CBS5 with Allinson 250-C20B engines. A lot of the landing sites are only a small soccer field in a jungle clearing with 200' trees all around. Getting in is ok - its the next bit that can be exciting!!! And some are by the river so that you can come in and out from the river using a reasonably sensible approach/departure profile. I am going to recommend we limit the MTOW for some, but as suggested the guys must check the HOGE figures. Certainly operating at 2500kg would not work.
We just replaced a turbine on one over the weekend post labyrinth seal change and tested it today - seemed to run a little hot and when I shut down it smoked - again. Next check hover had the engine at 800 TOT in the hover and final hover check was 810 TOT - Told the boys to forget the Labyrinth seals for now and have a look at the compressor blades - I dont think it would cope with another start without surging! Has a similar problem on a Lynx HAS Mk 3 several years ago. When the engine bay opened it up the axial flow compressor turbines looked really ugly!
Anyway it will the the Filipino engineers from the overhaul facility here a bit longer.
But thank you all for your help and advice - really appreciate it. Hope we dont get a Medivac tomorrow as not really happy to fly this particular machine at the moment!