Two deteriorated locknuts were largely to blame for last year’s P-51 crash at the National Championship Air Races in Reno, Nev., according to an August 27 report by the National Transportation Safety Board (NTSB). The accident killed the pilot and 10 spectators, injuring 60 others. The report said the bad locknuts allowed the trim-tab attachment screws to loosen, initiating a crack in one. “This condition resulted in reduced stiffness in the elevator trim system, ultimately leading to aerodynamic flutter at racing speed that broke the trim tab linkages, resulting in a loss of controllability,” said NTSB investigators. The highly modified P-51, dubbed The Galloping Ghost, {ITAL} was in the third lap of the sixth race, passing Pylon 8 at approximately 512 mph when it experienced a left-roll upset followed by a pitch up recorded at 17.3 gs, quickly incapacitating the pilot. Seconds later, a piece of the left elevator trim tab separated before the aircraft descended and crashed. The board also identified a number of undocumented and untested modifications made to the P-51 that contributed to the accident.