crab, rolls is wrong, or the fellow who thinks rolls said that is wrong. As a test, turn an engine in and tell them you pulled 10 intervals of 2.5 minute power per hour, and see what the bill is.....
ALL engine operations are cumulative, and engine damage is accrued roughly proportional to the square of the temperature. In other words, you damage an engine each time you use it, but the amount of damage is calculated to allow overhaul and safe life according to the overhaul interval.
Pilots foolishly believe that no engine damage occurs if you fly 2.49 minutes into the 2.5 minute rating, lower the lever for a few seconds, you can then just launch into another 2.49 minute session. Legally true, all this does is accru the damage faster than if you did the routine once per flight, or once per month or once per year. The engine has just so many fatigue beans in its jar, and each hot/high power activity takes some out.
Last edited by NickLappos; 22nd February 2007 at 16:36.