Originally Posted by
Duck Pilot
The Twin Otter has collector tanks that must have fuel in them at all times to prevent fuel starvation. The normal system is dependent on flapper valves and motive ventures to provide a positive fuel pressure to the tank boost pumps, which supports the engine driven pumps, hence the reason why the boost pumps are turned on for take-off and landing.
The AFT and FWD boost pumps are left on from start to shutdown for normal operations. Even when crossfeeding.