The hydraulic pressure drops and is unrecoverable after engine start when following real life manual start up procedure regarding the cowl flaps. The proper procedure as per the actual operating manual for the F4U-1D is to fully open the flaps before even turning the battery on but in the dcs Corsair if you do this it depletes your hydraulic pressure and it is unrecoverable https://imgur.com/a/2FEbYN8