Until recently, the maintenance department at Emirates, the Dubai-based carrier, was operating by the book. Literally. Ground crews used detailed charts and calendar-based schedules to estimate when the engines powering its massive fleet of Boeing 777 jets needed service.

Airline managers scheduled maintenance every 400 to 600 flight hours — even if nothing was wrong — to perform routine preventative work on their GE90-115B engines, incidentally the most powerful jet engines in the world.