AAR90 From United States of America, joined Jan 2000, 3526 posts, RR: 44
Reply 4, posted (14 years 11 months 2 weeks 4 days 16 hours ago) and read 5433 times:
Not normal "in cruise", but quite normal during takeoff. Especially with older engines that have received multiple upgrades. i.e. the RB211 engines on AA's 757s have redlines at 110.0% (N1), 101.3% (N2) and 100.2% (N3); the CF6's on AA's 767s go up to 117.5% (N1) and 112.5% (N2).
*NO CARRIER* -- A Naval Aviator's worst nightmare!
113312 From United States of America, joined Apr 2005, 590 posts, RR: 1
Reply 6, posted (3 years 2 months 1 week 4 days 17 hours ago) and read 3650 times:
It is not unusual that early designs of a particular powerplant establish a nominal 100% value. Later versions of the same engine, utilizing improved components, can be rated at higher power output with a higher RPM. Without changing the indicating system, the result is a power setting above 100%.
The limiting factor can be any of the N1, N2 or EGT. Which limit is reached first depends upon environmental factors. On most modern engines, the N1 limit is usually reached first.