N17250

A LOSS OF CONTROL OF THE AIRPLANE DUE TO THE PILOT'S INABILITY TO RAISE THE FLAPS WHICH RESULTED IN A STALL. THE FLAP FAILURE AND SUBSEQUENT FULL FLAP TAKEOFF WERE THE RESULT OF THE OPERATOR'S IMPROPER MAINTENANCE OF THE AIRPLANE AND THE OPERATOR'S USE OF A CUSTOM CHECKLIST THAT DEVIATED SIGNIFICANTLY FROM THE MANUFACTURER'S APPROVED CHECKLIST. CONTRIBUTING TO THE ACCIDENT WERE THE PILOT'S FAILURE TO ENSURE THAT THE FLAPS WERE FULLY RETRACTED PRIOR TO TAKEOFF, AND THE OPERATOR'S INADEQUATE INITIAL TRAINING OF THE PILOT.