The chances are minimal that most pilots will ever find themselves in the same circumstances as did James "Jimmy" Leeward on September 16, 2011. Comparatively few fly airplanes like Leeward's modified North American P-51 Mustang, The Galloping Ghost. Not too many pilots enter the Reno Air Races, and flying at 445 knots close to the ground likely isn't something you'll be doing at your local airport anytime soon.
Leeward was no aviation novice. He soloed in a North American military trainer at age 14, flew charters in a Beech 18 when he was 18, and began air racing while still in college. In 1976, he flew the P-51D Mustang he owned at the time in the Reno Air Races. He was a stunt pilot in several movies, including Smokey And The Bandit Part 3 and The Tuskegee Airmen.
At the time of the accident, Leeward was 74 years old and held a commercial pilot certificate for airplane single-engine land, single-engine sea, multi-engine land, instrument airplane, rotorcraft-helicopter and glider. He held type ratings for many airplanes and was authorized to fly a variety of experimental aircraft. His second-class medical certificate had no limitations. According to his entry form for the 2011 air races, he had more than 13,200 flight hours with more than 2,700 hours in P-51D airplanes.
It was at about 4:25 p.m., when the single-seat experimental P-51D crashed into the spectator-box seating area following a loss of control during the National Championship Air Races at Reno/Stead Airport. Leeward and 10 people on the ground sustained fatal injuries. At least 64 people on the ground were injured, with 16 classified as serious injuries. The airplane fragmented when it hit the pavement. Visual meteorological conditions prevailed. The plane had been airborne for about 10 minutes before the accident.
The accident airplane was in third place during the third lap of the six-lap race, trailing the second-place airplane (Voodoo, another experimental P-51D) by about 4.5 seconds and the lead airplane (Strega, also an experimental P-51D) by about 8.8 seconds. The accident airplane was traveling about 445 knots as it passed pylon 8 and experienced a left-roll upset and high pitch-up with extensive G loading. Investigators were able to use photographs, video recordings and telemetry data to examine the accident sequence in detail. During the upset, in less than one second, the airplane rolled from its established left-bank turn of approximately 73 degrees to a steeper left bank of approximately 93 degrees. The vertical acceleration reached about 11 Gs at that time. After the left roll upset, the airplane entered a right-rolling climb maneuver. During the rolling and climbing maneuver, the vertical acceleration peaked at 17.3 Gs. The left elevator trim tab link assembly had buckled and fractured in bending overload. A section of the left elevator trim tab separated in flight. Then, the airplane descended in a helical flight path until it struck the ground.
The Safety Board determined that the rapid build-up of G forces and the high-G level, meant that the pilot's time of useful consciousness once things began to unravel was likely less than one second. During the brief interval before losing consciousness, the pilot's physical performance would have been limited. The increased loads on his body would have made movement of his arms and legs difficult, and the decreased blood flow to his brain would have inhibited both thinking and reflex processes. As a result, the pilot soon became completely incapacitated. Photographic evidence showed the pilot was slumped in the cockpit during the aircraft's climb. The NTSB concluded that the airplane's continued climb and helical descent occurred without his control. The pilot's toxicological information and medical history revealed no evidence of drug or alcohol use or physical conditions that would have adversely affected his performance.
The automated weather system at the airport showed that at the time of the accident the wind was from 240 degrees at 15 knots gusting to 21 knots and visibility was 10 miles. A simulation showed that the wind at about 100 feet AGL was from 275 degrees at 20 knots.
The P-51 first entered production in 1941, and was originally designed and built as a long-range military fighter airplane. The P-51D, which formed the basis of The Galloping Ghost, entered production in April 1944. The stock P-51D's empty weight was 7,635 pounds, and its maximum gross weight was 12,100 pounds. The airplane that became The Galloping Ghost was delivered to the Army Air Forces on December 23, 1944. After World War II, in July of 1946, it was declared surplus and sold. The airplane was raced from 1969 through 1982 with various modifications for racing before being acquired by Leeward through a company in July 1983. Leeward raced it until 1989 and then placed it in storage until 2007. Between 2007 and 2009, the airplane underwent overhaul and further modifications. A modified Rolls-Royce Merlin V-1650-9A engine powered the airplane. Special engine mounts were installed to hold the engine securely at racing speeds. The airplane was outfitted with a racing canopy and hinged to open upward rather than sliding open. The upper fuselage structure was modified to accept the racing canopy. A special system was installed to help cool the engine. Called a "boil-off" cooler, it uses a mixture of water and methanol to absorb heat. The heat makes the mixture boil, and the venting of vapor helps dissipate heat and prevent detonation. The original left wing fuel tank was converted to hold the coolant. The manufacturer's lower air scoop was removed and a custom structure installed.
The outboard section of each wing was replaced with a new wingtip. The wingspan was shortened from just over 37 feet as manufactured to just under 29 feet, making it the shortest of any modified P-51D racing in 2011. The length of each aileron was halved, to about three feet from a stock length of about seven feet. The right aileron trim tab was removed, and the trim for the left aileron was modified to run by an electric motor instead of the manufacturer's manual trim system. The horizontal stabilizer was shortened by about a foot. Modifications to the elevator, including its counterweights, upper rudder counterweight, vertical stabilizer incidence, horizontal stabilizer incidence and rudder were discovered by investigators.
The FAA issued a certificate authorizing the races to take place at the Reno airport. It said that all flights conducted at altitudes less than 1,000 feet AGL must remain north of runway 8/26 and within 1,000 feet horizontally of the depicted course. It also stated that race flight operations may be no closer than 500 feet horizontally from the primary spectator areas. However, an FAA Advisory circular cited by the NTSB stated that aircraft racing at more than 250 miles per hour needed to be 1,000 feet away from spectator areas.
Examination of the elevator trim tabs found that, of the three screws that attach each tab to its respective hinges, two screws in each tab were found intact. All of the intact screws could be rotated easily, even when fully engaged in their locknuts, and the locknuts' insert material was badly deteriorated to the extent that screw-retaining torque could not be maintained. Examination of the remnants of the two fractured screws (one in each tab) and their hinges showed evidence that these screws also had been loose before fracturing. The overload fracture of the right trim tab's center hinge screw showed evidence of directional bending occurring before a shearing action. The left trim tab's inboard hinge screw showed evidence of reverse bending fatigue, and corrosion on the fatigue fracture features indicated that the fatigue cracking had been present for a prolonged time before the screw ultimately failed in overload during the accident flight. The loose locknut connection allowed for larger load oscillations and the initiation and growth of fatigue cracks.
Investigators could not determine whether the airplane encountered wake turbulence from one of the other racers and it was responsible for beginning the upset. They did note that, regardless of whether the link assembly failure or a wake vortex encounter initiated the roll upset, the loss of the left trim tab's downward force on the elevator resulted in a sudden upward deflection of the elevator, a sudden and forceful aft movement of the control stick, the pitch-up of the airplane, and the rapid increase in G forces.
The screw looseness and cracking would have allowed for reduced stiffness of the trim tab system that could have allowed a flutter condition to develop. Flutter would be capable of producing sufficient dynamic loads to buckle and fracture the link assembly.
Investigators were unable to find documentation that all of the modifications had been subjected to complete engineering analysis and flight testing. The Safety Board raised the possibility that any adverse effects of modifications on the structure or flying characteristics could have been identified and corrected. The NTSB reported that neither the pilot's family members nor the airplane's ground crew were aware of any detailed drawings, engineering calculations, or other substantiating data for any of the modifications.
The NTSB determined that the probable cause of this accident was the reduced stiffness of the elevator trim tab system that allowed aerodynamic flutter to occur at racing speeds. The reduced stiffness was a result of deteriorated locknut inserts that allowed the trim tab attachment screws to become loose and to initiate fatigue cracking in one screw sometime before the accident flight. Aerodynamic flutter of the trim tabs resulted in a failure of the left trim tab link assembly, elevator movement, high flight loads and a loss of control. Contributing to the accident were the undocumented and untested major modifications to the airplane and the pilot's operation of the airplane in the unique air racing environment without adequate flight testing.