I remember seeing a presentation by Airbus on savings by using Idle Rev and F3.
The conclusion was that it made sense to use F3 only in conjunction with LO BRK/IDLE REV. Anything more than that and F3 fuel savings will be offset by REV fuel consumption and/or increased brake wear. Surprisingly, the presentation stated that using FULL REV didn't affect engine wear - only used some extra fuel (~20kg IIRC)
Last edited by Stuck_in_an_ATR; 4th June 2013 at 06:35.