The party-loving princes have allegedly cut down on night outs to put in extra hours for Harry to pass the hardest stage of his training at the Royal Air Force"s base in Shropshire, where William is already stationed to achieve his dreams of becoming a search and rescue helicopter pilot.
Harry has purportedly been picking pointers from William about Squirrel helicopters and has been in 'ground school' for the last three weeks, preparing for take-off.
"William is proving an excellent coach for his younger brother. He has just completed his Squirrel training so everything is fresh in his mind," the Sun quoted a source as saying.
"The brothers share a house and have spent hours in the evenings preparing for Harry's first flight," the source added.