NTSB: Flutter Led To Reno Crash
Last year's fatal crash of a P-51 racing aircraft at Reno was caused by compromised stiffness in the elevator trim-tab system, which led to flutter and loss of elevator pitch control at race speed, said the National Transportation Safety Board in in its probable-cause hearing on Monday. At last year's race, veteran air racer Jimmy Leeward lost control of his Galloping Ghost P-51 after the home pylon turn, causing a sharp pitch up followed by a dive into a spectator area, killing him and 10 others. The NTSB's investigation revealed that the aircraft was flying faster than it ever had by some 35 knots, with higher engine power settings than previously used. The board also found that there was evidence of ongoing structural failure during the race, including a cracked canopy. Further, Leeward and his crew had made major modifications to the aircraft, including the removal of the P-51's iconic belly airscoop, that compromised the structural integrity of the fuselage. The crew notified the FAA of only one of these changes, a boil-off system used to improve oil cooling. The NTSB probe found that screws used to attach one of two trim tabs to the elevator were old or loose, possibly having last been replaced in 1986. This allowed the trim tab to flutter, failing the tab control rod and resulting in an instantaneous pitch-up moment that generated a calculated 17 Gs, which the board determined was beyond human endurance. In a video posted on AVweb yesterday, the trim tab can clearly be seen departing the elevator, but by that point, the control rod had already failed and Leeward had no trim control. The board had issued 10 safety recommendations in April, so the race organizers would have time to act on them before this year's races, and no new safety recommendations were issued on Monday.
NTSB Chairman Deborah Hersmann referred to the aviation writer Ernest Gann in her closing remarks, and said "Fate is no longer the hunter" for pilots who can rely on a wide range of safety advances that weren't available in Gann's time. Spectators at aviation events also need an assurance that they will be protected, she added. "Innocent bystanders should never have to rely on fate for their safety," she said.