Airmann
18th Sep 2012, 21:17
With regard to the EPR rating limit on the E/WD during T/O on the 320 series V2500. I've noticed that the engines quickly race up to the initial flex EPR rating limit but once there the limit then increases further before finally settling down at one number. It's quite tricky when trying to judge whether the engines are stable and when T/O thrust has been set.
Two questions:
1) Why does this happen? Is it to ensure engine parameters are stable at a relatively high setting (but not entirely at full T/O power) before FADEC sets final power? Saving engine life? Or could it be that at the calculated EPR rating limit the desired thrust has not been obtained and the EPR must increase to meet required thrust.
2) When is "thrust set"? As PNF, and having to make this call before 80kts, I find it hard to judge. If thrust is set when the engines have fully stabilised at max EPR rating limit then with the changes it's very close to 80kts if not after.
Two questions:
1) Why does this happen? Is it to ensure engine parameters are stable at a relatively high setting (but not entirely at full T/O power) before FADEC sets final power? Saving engine life? Or could it be that at the calculated EPR rating limit the desired thrust has not been obtained and the EPR must increase to meet required thrust.
2) When is "thrust set"? As PNF, and having to make this call before 80kts, I find it hard to judge. If thrust is set when the engines have fully stabilised at max EPR rating limit then with the changes it's very close to 80kts if not after.