Originally Posted by
bernouli
Originally Posted by
Captain Tony
On the CRJ 700 you have to shut both fuel boost pumps during single engine taxi, or you get a large fuel imbalance. Maybe they forgot this and thought gravity cross flow would fix it faster. And also on all CRJs you can't sit more than 10 minutes with your lights on for cooling purposes. Sounds like these guys aren't too up on their systems knowledge. But hey, all DAL cares about is cheap feed...
You clearly don't have a practical knowledge of the airplane.
The boost pumps are part of our 'cleared to start' check, and they stay on throughout the entire flight (unless for a fuel check valve check). It's company SOP and evidently varies by operator.
Anyway - Taxiing single engine with both boost pumps on doesn't cause an imbalance. Not any more so than taxiing single engine with them off, anyway.
There's a reason the EICAS displays caution messages with an engine operating and the fuel pumps 'off'. If it were proper, there'd be no message(s).
Fuel sloshes, sometimes significantly when turning, but that's about it.
Taxing single engine with both pumps will cause an imbalance. The boost pump will detect low pressure and turn both pumps on, which will draw fuel to operating engine from both collector tanks. Some of that fuel will be burned and some will be returned to the collector tank, but only the operating engine collector tank, causing the operating engine side fuel tank to have more fuel than the shutdown side.