Coushatta, LA, USA
N260HP
Aviation Specialties Unlimited Challenger II
The commercial pilot departed the airfield for a local aerobatic flight. While performing aerobatic maneuvers, the airplane experienced a failure of the elevator control system. The 18,971-hour pilot was able to recover and maneuver the airplane to a safe altitude over an uninhabited area. Once over the safe area, the pilot elected to exit the airplane and deploy his emergency parachute. The airplane was destroyed upon impact with the ground. The elevator's push-pull tube assembly was located in the wreckage with a broken rod-end bearing. The elevator push-pull tube is fitted with two rod-end bearings, one in each end of the tube. The first rod-end bearing was unbroken, but slightly bent to one side. The unbroken rod-end bearing had the markings of FAFNIR on the side of the bearing retainer, and 2P on the side of the shank, at the base of the outer race or banjo. The second (failed) rod-end bearing's outer race was fractured in two places, leaving just the threaded shank and approximately the bottom one-third of the outer race. The top section of the failed bearing and associated parts were not located and therefore, no identification marks could be associated with the outer race. Nor were there any identification markings on the hollow shank. During load testing of similar rod-end bearings, three bearings failed at 870 pounds or less. These bearings had the markings of FEDERAL RE3ML6-2N MADE IN THE USA, on the side of the bearing retainer. Also, rod-end bearings identified as "FEDERAL" all had no additional identification marks on a hollow shaft. Rod-end bearings identified as FAFNIR all had solid shafts, and the markings of "2P" on the shank near the base of the banjo head. FAFNIR bearings used in the test all failed above 3,200 pounds. The ultimate (minimum) load requirement for the rod-end bearings is 1,500 pounds.
On April 4, 2006, approximately 1030 central daylight time, a single-engine Aviation Specialties Unlimited, Challenger II experimental airplane, N260HP, was destroyed when it impacted terrain during an uncontrolled descent after the pilot parachuted from the airplane near Coushatta, Louisiana. The airplane was registered to Pitts S2B., LLC., and was operated by a private individual. The commercial pilot, sole occupant of the airplane, was not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the 14 Code of Federal Regulations Part 91 personal aerobatic flight. The local flight originated from the Red River Airport, near Coushatta, Louisiana. A member of the pilot's ground crew stated during an initial telephone report that the pilot departed the airport and proceeded to a local aerobatic practice area. While performing aerobatic maneuvers, the airplane experienced a failure of the elevator control system. The pilot was able to re-establish pitch control with the aid of the elevator control trim and managed to maneuver the airplane to a safe altitude over an uninhabited area. Once over a safe area, the 18,971-hour pilot elected to exit the airplane and deploy his emergency parachute. There were no reported ground injuries. The unattended airplane was destroyed upon impact with the ground. The wreckage of the airplane was recovered and transported to a secure location for further examination. The elevator's push-pull tube was located in the wreckage and found with a broken rod-end bearing. The failed tube was retained for further examination and evaluation. The elevator push-pull tube, which measured about 28-inches long, is fitted with two rod-end bearings, one in each end of the tube. The first rod-end bearing was not fractured, but slightly bent to one side. The bent rod-end bearing had the markings of FAFNIR on the side of the bearing retainer, and 2P on the side of the shank, at the base of the outer race or banjo. The second rod-end bearing's, outer race was broken in two places, leaving just the threaded shank and approximately the bottom one-third of the outer race. The top section of the failed bearing and associated parts were not located and therefore, no identification marks could be associated with the outer race. Nor were there any identification markings on the shank. The threaded shaft was later identified as being hollow. The push-pull tube, along with several exemplar rod-end bearings supplied by the operator, were shipped to a private metallurgical lab for analysis. Four rod-bearings were load tested. The rod-end bearing similar in appearance to the fractured bearing in the push-pull tube, failed at 870 pounds. This bearing had the markings of FEDERAL RE3ML6-2N, MADE IN THE USA, on the side of the bearing retainer. The other three bearings used in the test all failed above 3,500 pounds. The ultimate (minimum) load requirement for the rod-end bearings was determined to be 1,500 pounds. The elevator push-pull tube, along with the remaining exemplar bearings were then shipped to the NTSB Materials Lab in Washington, DC. Two additional bearings were purchased from the same vendor as the operator's bearing source. The purchased bearings arrived in packages labeled RE3ML6-2N. These rod-end bearings were marked FAFNIR on the bearing retainer and 2P on the shank. The purchased bearings were shipped to the Material Lab. Additionally, rod-end bearings identified as FAFNIR were found to feature solid shafts, and the markings of "2P" on the shank near the base of the banjo head. A total of six of bearings were load tested, the two recently purchased FAFNIR bearings, and four supplied by the operator that came from packages labeled as RE3ML6-2N. These bearings had the markings of FEDERAL RE3ML6-2N MADE IN THE USA, on the side of the bearing retainer. It was noted that all of the rod-end bearings identified as "FEDERAL" featured a hollow shaft, and no additional identification marks on the shaft. Load testing of the bearings revealed that two of the four "FEDERAL" bearings failed at approximately 850 pounds, with the fracturing at the banjo head. The two remaining FEDERAL bearings failed at about 2,800 and 3,100 pounds. The two "FAFNIR bearings failed above 3,200 and 4,500 pounds. The airplane's last condition inspection was completed on 5 March, 2006. The total aircraft time was about 3,040 hours.
The loss of control due to premature failure of the elevator's push-pull tube rod-end bearing.
Source: NTSB Aviation Accident Database
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