Originally Posted by
eckhard
The Rolls Royce RB211-524G had about 56,000 lbs of thrust and the 524H had about 60,000 lbs of thrust at seal level (if memory serves). I believe it was a fairly simple tweak of the EEC plus a pin change for the FMS which decided which rating was available.
Just to clarify a bit, the engine rating is listed on the engine data plate - changing the engine rating requires changing the engine data plate and requires the implementation of an engine company service bulletin. There is a 'rating plug' that literally plugs into the EEC (aka FADEC) - the configuration of that plug tells the software what rating to select. The rating plug is attached to the fan case with a lanyard so it will stay with the engine when the EEC gets replaced (a fairly common maintenance practice).