Fallon, NV, USA
N101BY
American Champion Aircraft 8KCAB
The certified flight instructor (CFI), seated in the front seat, reported that the airplane started to drift to the right during the landing roll. The student pilot, seated in the rear seat, applied left rudder to counteract the drift, but the airplane continued to the right. The CFI took control of the airplane and applied full left rudder and full power; however, the airplane continued to the right until the left main landing gear collapsed and the airplane nosed over. The airplane was equipped with dual lap belt aerobatic harnesses. Postaccident examination revealed that, when full left rudder was applied, the front seat pilot's upper lap belt caught on the rear seat right rudder/brake pedal assembly and activated the right brake. As a result of this finding, the manufacturer issued an Airplane Flight Manual Supplement (AFMS) that provided guidance for pilots to examine the front seat lap belts for proper tension and clearance from the rear seat rudder pedals during their prestart and preflight checks. In addition, the Federal Aviation Administration issued a Special Airworthiness Information Bulletin (SAIB CE-10-39) that addressed proper installation of the dual lap belt system and informed pilots of the issuance of the AFMS pertaining to the lap belts.
On January 26, 2010, about 1630 Pacific standard time, an American Champion Aircraft 8KCAB, N101BY, departed runway 3 on landing and came to rest inverted at Fallon Municipal Airport (FLX), Fallon, Nevada. The airplane sustained structural damage to the collapsed left main landing gear and tail section of the airplane. The certified flight instructor (CFI) and the owner/pilot were not injured. The flight had departed FLX about 1530 for the local area flight, and no flight plan had been filed. According to the CFI, the flight was to familiarize the owner/pilot with a conventional landing-gear airplane. The owner was seated in the rear seat, and the CFI was seated in the front seat. The CFI demonstrated one landing prior to the flight departing the pattern for the local practice area in order to familiarize the pilot with the flight controls. They performed several turns, descents and climbs, and then returned to the airport for landing. The pilot performed two uneventful landings, and on the third landing just after touchdown, the CFI noted a moderate drift to the right. The CFI stated that the pilot had applied left rudder to counteract the drift, but the airplane continued to the right. At that point, the CFI took the flight controls and applied full left rudder and full power. The airplane continued to the right until the left main landing gear collapsed and the airplane nosed over. In the RECOMMENDATION section of the National Transportation Safety Board (NTSB) accident reporting form, the CFI reported that the front seat 5-point Hooker Aerobatic harness had a tendency to drape itself over the right rear cockpit rudder/brake pedal assembly. He stated that this could have caused the right brake to be inadvertently activated when full left rudder was applied. The airplane and seat belt mechanism were inspected by an airworthiness inspector from the Federal Aviation Administration (FAA). The FAA inspector confirmed the CFI's observation that with the application of full left rudder, the front pilot's seatbelt could catch on the right rudder/brake pedal assembly as it was moving aft due to left rudder input. This action inadvertently allowed the application of the right brake. The NTSB docket for this accident contains a video that demonstrates this interaction. The FAA inspector also examined the dual lap belt installation. According to the airplane manufacturer, American Champion, the only dual lap belt installation they use is the Hooker Aerobatic harness. That harness consisted of two lap belts sewn in parallel with one another on top of a large pad that is worn across the lap of the pilot. The FAA inspector reported that the two lap belts were connected to a single point, the outer lug on the floor. According to a drawing from American Champion, the dual lap belt should attach to two separate locations instead of just the outer floor lug. FAA inspectors from the Chicago Aircraft Certification Office visited both American Champion in Rochester, Wisconsin, and Gauntlet Warbirds, in Aurora, Illinois, to review possible rudder interference by the lap belt installation on the 8KCAB model airplane. They found that the lap belts typically cleared the rudder pedals by less than 1 inch. Factors that affected the clearance included seat cushion padding, physical size of the pilot, centering of the belt cushion on the pilot, and tightness of the lap belt when secured. As a result of that review, an Airplane Flight Manual Supplement (AFMS) was issued by American Champion, and approved by the FAA. It called for both a pre start and pre flight check of the lap belts for proper tension and clearance from the aft seat rudder pedals. The FAA also issued a Special Airworthiness Information Bulletin (SAIB CE-10-39, dated July 23, 2010. The SAIB notified pilots of the AFMS issuance. It also recommended that airplanes equipped with the Hooker Aerobatic dual lap belts use floor mounted attach lugs. The upper or secondary lap belt should be moved from the outside of the outer attach lug to the inside of the outer attach lug per a service bulletin in order to provide additional clearance between the belt and pedal assembly.
Interference between the front seat lap belt and the rear seat rudder/brake pedal assembly that prevented normal operation of the rudder/brake system, which resulted in the pilots’ inability to maintain directional control.
Source: NTSB Aviation Accident Database
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