Originally Posted by
tdracer
On Boeings, the EEC is not normally powered prior to engine start (putting the fuel switch to run or start switch to start provides aircraft power to the EEC since the PMA doesn't come alive until ~8% N2/N3) - and no one should ever be attempting an engine start before AIMS is fully booted and running. However, if someone leaves the EEC ground test power ON (contrary to SOP) (flight deck switches used for troubleshooting without have to run the engine), then the scenario you describe is a possibility. The cure it to turn of EEC ground test power, and follow the SOP to not power up the EEC until after AIMS is fully up and running.
Thanks for that additional information. I may have known all that when I was investigating the reported problem but it was a while ago. What I do remember is that the flight test data showed simultaneous initiation of AIMS and EEC power up and the data transfer timing issue that I described.
Perhaps that data was given to me because it represented the special case that produced the problem and not because it was typical of revenue operations.