Jetpilot From United States of America, joined May 1999, 3130 posts, RR: 32 Reply 1, posted (12 years 11 months 3 days 15 hours ago) and read 3750 times:
It is not uncomon for N1, and N2 limits to be above 100%.
Dufo From Slovenia, joined May 1999, 752 posts, RR: 4 Reply 2, posted (12 years 11 months 3 days 14 hours ago) and read 3736 times:
Tnx for this info, Jetpilot!
And I have another question related to this. What is the limiting factor on high altitude flights (let's say on a B777)? EGT, N1 or N2?
Regards,
Jernej
I seriously think I just creamed my pants without any influence from any outside variables.
DeltaAir From United States of America, joined May 1999, 1094 posts, RR: 0 Reply 3, posted (12 years 11 months 3 days 9 hours ago) and read 3717 times:
I believe this can vary between airline due to the fact that the engine software can be altered, but it isn't a good idea to go over 105% due to the fact that you are red lining.
AAR90 From United States of America, joined Jan 2000, 3410 posts, RR: 50 Reply 4, posted (12 years 11 months 3 days 7 hours ago) and read 3708 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, 538 posts, RR: 1 Reply 6, posted (1 year 1 month 3 weeks 5 days 8 hours ago) and read 1925 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.
Starlionblue From Hong Kong, joined Feb 2004, 15904 posts, RR: 66 Reply 7, posted (1 year 1 month 3 weeks 5 days 7 hours ago) and read 1895 times:
Quoting smartt1982 (Reply 5): What is the reason you can get over 100% then?, is 100% not the max?
You'd think so, but that would be too simple.
Typically the reason is that the engine was rated at X power during the design process, but at entry into service or later it has been rated higher. So if X is 100%, it can now go higher.
For example the Space Shuttle Main engines would go to 104.5% in regular service, and could go up to 111% in emergencies.
"There are no stupid questions, but there are a lot of inquisitive idiots." - from Citadel by John Ringo
N243NW From United States of America, joined Jul 2003, 1502 posts, RR: 21 Reply 8, posted (1 year 1 month 3 weeks 4 days 19 hours ago) and read 1615 times:
Quoting AAR90 (Reply 4): the CF6's on AA's 767s go up to 117.5% (N1) and 112.5% (N2)
That's pretty incredible - I jumpseated on a 767 test flight a while back, and we were empty and at 105% N1 all the way up to FL410. That thing climbed like a bat out of hell.
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