Its been a long time since I have flown an Aztec, though I think my memory is alright. The left engine has the hydraulic pump. ( I believe there was an option to have one installed on the right engine also in later models) You lose gear and flaps without the engine-driven pump. There is a hand pump on the center console which may be used for both gear and flaps. (seperately of course) There is also a blow-down bottle which uses CO2 as a last resort as it contaminates the hydraulic system.