D328 prop ?

[chperplt]

Under the engine, just aft of center (at least the right one) there is a moving door that opens and closes in flight.. What the heck is it?

 

[Tim47SIP]

If it is like the ATR, the doors are thermally operated and regulate the amount of air traveling over the oil cooler. Maybe something else though.

 

[Dragonbravo]

Oil Cooler

Tim47SIP is correct.

 

[chperplt]

Thanks