ERA14FA327

The pilot's decision to land with a quartering tailwind and his failure to maintain directional control during the landing roll. Contributing to the severity of the pilot's injuries was the failure of the aluminum center safety belt bracket.

The commercial pilot of the tailwheel-equipped airplane was performing touch-and-go landings at his private airport with a right quartering tailwind. During landing roll, the pilot lost directional control, and the airplane departed the left side of the runway into a wheat field where it nosed over. Examination of the runway revealed that a prominent row of trees was located directly adjacent to the right side of the runway, and, given the prevailing wind, there would have been associated turbulence due to the disruption of the ambient wind flow as it passed over the trees. Tire marks and ground scars indicated that, when the airplane veered off the left side of the runway, it was carrying considerable energy, as the airplane traveled 390 ft from its touchdown point to where it nosed over. Examination of the airplane revealed no evidence of any anomalies that would have precluded normal operation. The crown of the fuselage above the pilot's seat displayed an outward bulge indicating that, during the nose over, the pilot's head contacted the overhead area of the cockpit interior, which likely caused the cervical spine fracture and positional asphyxiation injuries described in the pilot's autopsy report. Examination of the pilot's 4-point restraint system revealed that the aluminum center safety belt bracket, which was likely installed when the airplane was manufactured in 1946, had failed in shearing overstress during the nose over. This resulted in the pilot being partially released from the restraint system and subsequently contacting the crown of the airplane. Examination of the airplane manufacturer's records revealed that shortly after the airplane was manufactured in 1946, the manufacturer began installing a steel center safety belt bracket in new production airplanes. Following this accident, the manufacturer issued a service bulletin that called for inspection of the center seat belt bracket on all Cessna 120 and 140 airplanes to determine if the latest type (steel) bracket was installed and replacement of any older type (aluminum) brackets found with the latest type.

Restraint System Examination On arrival at the accident site, first responders had discovered that the pilot was lying on his back, was only partially buckled in to his restraint system, and was deceased. Examination of the crown of the fuselage revealed that it was bulged outward above the pilot seat, in a manner consistent with the pilot having made contact with the crown of the fuselage during the nose over. According to the pilot's autopsy report, the most significant blunt force injury identified was a cervical spinal fracture at C6/C7 with compression of the spinal cord. Additionally, evidence of positional asphyxiation on the pilot's head and upper body was noted during the autopsy. According to FAA and airplane maintenance records, on May 24, 2003, the airplane's "existing seat belt restraints" were removed and "Aero Fabricators shoulder harnesses & seat belts" had been installed per Supplemental Type Certificate (STC SA1429GL). Examination of the pilot's 4-point restraint system revealed that the shoulder harness was intact, the bar slide was still in place, and the shoulder harness assembly was still attached by the triangular end fitting to wing spar. The left (outboard) portion of the pilot's lap belt was intact and secured to its bracket. The right (inboard) portion of the pilot's lap belt was also intact, but was not secured to the center safety belt bracket that was used to attach the right (inboard) portion of the pilot's lap belt and the left (inboard) portion of the copilot's lap belt, to the fuselage. Examination of the center safety belt bracket revealed that it was broken. Further examination revealed that the left side of the bracket was deformed and a 45-degree fracture existed on the portion of the bracket where the right (inboard) portion of the pilot's lap belt would have attached. The center safety belt bracket was removed from the airplane and forwarded to the NTSB Materials Laboratory for further examination. Ridge Road West Airport was owned by the pilot and was a private use, non-towered airport. It was located three miles northwest of Spencerport, New York. The airport elevation was 400 feet above mean sea level. There were two runways oriented in an 18/36 and 9/27configuration. For noise control, runway 36 was the preferred runway for takeoffs, and runway 18 was preferred for landings. Runway 18 had a left traffic pattern and was turf, in good condition. The total length was 1,800 feet-long and 45 feet-wide. At the time of the accident, only 1,151 feet was usable, as 649 feet of the north end of the runway had not been mowed A hangar where the pilot would keep the airplane was located off the departure end of runway 18. Center Safety Belt Bracket Examination Examination of airplane maintenance records and the center safety belt bracket by the NTSB Materials Laboratory indicated that the bracket was most likely an original part (P/N 0425132) that was installed during manufacture of the airplane in 1946. The left side tang of the bracket was fractured adjacent to the forward foot for the left seat belt attachment. The fracture was oriented about 45-degrees at the juncture between the tang and the foot. Magnified optical examinations revealed fracture features and deformation patterns indicative of shearing overstress separation. The deformation patterns on the left tang also showed deformation patterns consistent with both pre and post fracture deflections, with no indications of preexisting cracking or corrosion. Chemical analysis and metallographic cross section confirmed that the bracket was made from either 2014 or 2024 Alclad aluminum alloy, and hardness and conductivity measurements of the core material were consistent with either a T3 or T4 temper condition for either alloy. Review of Engineering Drawings and Changes Review of the airframe manufacturer's Engineering Drawing, 0425132, Bracket-Seat Belt, indicated that the drawing became inactive in 1966. The latest drawing specified the bracket material as Society of Automotive Engineers (SAE) 4130 alloy steel, normalized after forming. The drawing also depicted a shape with two different widths. The drawing showed a forward 0.88-inch-wide section with a 0.75-inch-wide aft section. In comparison, the bracket recovered from the accident airplane measured 0.75-inch-wide along it entire length. The widths of the tangs on the fractured bracket also measured smaller than the drawing dimensions, 0.215 inch versus 0.25 inch on the drawing. Other dimensions including hole sizes, thickness, and bend angles appeared to be consistent with the recovered bracket and the original, pre-1966 drawing. Based on the 45-degree fracture across the tang, the bracket from the accident airplane had approximately 7-percent less cross sectional area than the latest version of the bracket. A review of Drawing Change Notices (DCN) also found a material change from "24ST ALC" to normalized SAE 4130 alloy steel. Further review also revealed that on October 21, 1946, DCN 6886A cited the material change and stated "Strengthen Part" as the reason. Additionally, DCN 9155, dated November 27, 1946, also showed the two width shape of the steel bracket and further listed the applicability as Cessna model 140 serial number 13582 on (with 3 exceptions) and Cessna model 120 serial number 13563 on. No drawings were found showing the shape and dimensions of the previous version of the bracket. Review of FAA Aircraft Registry Database A review of the FAA aircraft registry database found that approximately 2,310 Cessna model 140s and 862 Cessna model 120s were registered in the United States. Of these about 1,594 (69%) of the Cessna model 140s and 701 (81%) of the Cessna model 120s, were manufactured before the effectivity of the material change from Alclad 2024 T3 to SAE 4130 alloy steel. Aerospace Structural Metals Handbook According to the 1995 version of the Aerospace Structural Metals Handbook: - Alclad 2024 T3 typically has a yield strength of 40,000 pounds per square inch (psi). - Normalized (1,600-degree F) 4130 alloy steel typically has a yield strength of 68,000 psi. This represented a nearly 40% increase in yield strength for the steel bracket compared to the aluminum bracket. In order to improve safety, the airframe manufacturer took the following actions: 1. Issued an Owner Advisory notifying Cessna 120 and 140 owners that they wished to update the seat belt bracket for airplanes in the field to the latest design. 2. Issued a mandatory Single Engine Service Bulletin: SEB-25-03, affecting Cessna 120s (S/N 8000 thru 15075) and Cessna 140s (S/N 8000 thru 15075), requiring that within the next 100-hour or 12 months (annual type) inspection, that the seat belt bracket be inspected to determine if the latest type of seat belt bracket was installed, and if not installed, to replace the seat belt bracket with the new P/N 0425132 seat belt bracket, and to discard the old one. An autopsy was performed on the pilot by the Office of the Medical Examiner, Monroe County, New York. The listed cause of death was multiple injuries. Toxicological testing of the pilot was conducted at the FAA Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma. The specimens from the pilot were negative for carbon monoxide, basic, acidic, and neutral drugs. Testing for Cyanide was not performed. Review of recorded images from a motion-activated security camera system located at the airport revealed that prior to the accident one of the cameras had been activated three times by the shadow of an airplane passing by the camera, with the shadow activating the camera for the last time at 1205. Tire marks and ground scars on runway 18 indicated, that on the last landing, the airplane touched down 1,123 feet down the runway to the left of centerline, veered of the left side of the runway into a wheat field, and then nosed over, 390 feet from the touchdo