Cactus 1539 was 10 years ago today - Had Capt Sully not immediately switched on the APU as both his engines rolled back (this was not a SOP) then he would not have been so successful in landing the aircraft as he did.
The QRH showed reference to close the ditching valve (which was not accomplished) but he and his FO only had about 200 seconds to deal with the whole scenario.