L. Ron Hubbard 
Sabotage in the Sky [EPUB ebook] 

Pilot Terry Lee has taught Bill Trevillian everything he knows about flying, enough that Bill’s know considered the ace of American test pilots just as war breaks out in World War II Europe. Unknown to Bill, Terry’s also taught his own kid sister, Kip, who’s now almost as good a pilot as Bill and quite the looker to boot.