I have a JR 206BIII and I'm experiencing the same problem for the past 2 years. I press the start button wait till 15% open my throttle and i start counting 1 2 3 seconds and then it fires up TOT between 850 - 870.
We swap every single component including the FCU and still the same problem, i called Rolls-Royce and they send me a field technician right away.
After 8 starts he removed the fuel nozzle to take a quick peek inside.
The conclusion was that the
COMBUSTION LINER is too far in.
The recommendation was to remove the
1st stage nozzle shield +
Combustion Liner +
Outer Combustion Case and send it to the shop where they can stack them up and compare with another set.
i will have the results next week.
keep you posted
Zohar