Lack of good pre-flight habits is a common problem, but usually by people who have gotten somewhat complacent due to lack of problems, especially with their own plane. I am a former dealer (American) cfi, charter and ferry pilot, with 5000+ hrs over 60 years, and have flown some 60 different makes and models of planes. I have never had a takeoff failure, and only two in-flight gear failures. Both a C-310 and an Aztec had the same failure, the hydraulic hose at the outlet of the hydraulic pump. Both occurred within about 3 months of each other. Fortunately, emergency extension procedures worked, with no resulting damage. But it sure had me taking a hard look at the "circulatory" systems, hydraulics, fuel, brakes! I have religiously done thorough preflights, especially water in fuel. BUT--I also performed the pretakeoff checks (mags, props, etc) PRE-shutdown! If a mag quit working while I was flying, I want to know about it BEFORE I try to go flying again! Lee Robinson ROBINAIRERC