Originally Posted by
vapilot2004
Interesting. Thanks TD.
I assume temperature is a factor in the digital decision making process? I wonder if time since shutdown also plays a role.
The logic looks at time since shutdown and residual EGT (for the GEnx bowed rotor it's between 30 minutes and 6 hours after shutdown) - if the time and/or EGT are outside the bowed rotor threat zone it just performs a normal start.
Fullwings, that's exactly what's being proposed for the GE9X on the 777X - a small electric motor on the gearbox will slowly rotate the N2 shaft for some time period after shutdown. We're calling it the rotisserie
JammedStab - yes, the GE90 will max-motor for several seconds (17 seconds IIRC) before turning fuel on to alleviate bowed rotor.