Originally Posted by
IO540
Fuel injected engines simply can never be allowed to run dry as they may prove to be impossible to restart.
Why would that be?
If an engine can be started on the ground then it can surely be started in the air.
A
fuel injected engine is stopped on the ground by turning off the fuel at the FCU. If you run a tank dry then there will be air from the tank pick up, fuel lines through the fuel pumps, FCU,and fuel spider. The danger is that an air lock can occur which will prevent fuel from reaching the engine. A similar situation can be experienced trying to start a heat soaked engine on a hot day.
re; the no both selection for low wing aircraft, avoiding giving giving the fuel pump the choice of fuel or air is most easily done by positively separating the tanks. As an aside my low wing Nanchang CJ6A has two wing tanks but only a fuel on off valve. It however, has a small centerline collector tank that is lower than both wing tanks and from which the engine draws fuel.