New York, NY, USA
N40NY
CESSNA 414
The pilot stated that before landing, he confirmed all landing gears were down and locked. He performed a normal landing on runway 6 about 100 knots, and during the landing roll he applied the brakes. After rolling about 200 to 300 feet, while traveling about 70 to 75 knots, he began to apply right rudder to turn onto runway 10. During the turn, the right main landing gear slowly began to collapse causing the right wing to contact the runway. The airplane departed the runway and collided with a runway marker sign. Postaccident examination of the airplane revealed that the bellcrank was separated from the attach point on the right trunnion assembly, the aft lug of the right trunnion assembly was fractured, and the bolt that secures the bellcrank to the right trunnion assembly was also fractured in overstress. The fractured components were submitted to the NTSB’s Materials Laboratory for further examination, and the parts revealed no evidence of preexisting cracking. While the bolt diameter was less than the minimum specified, that condition did not contribute to the fracture trunnion aft lug or the bolt. Several days before the accident, a serviceable right trunnion assembly was installed during an annual inspection, and the airplane was approved for return to service. The airplane had been operated for about 2 hours since the serviceable trunnion assembly was installed. Cessna engineering personnel reported that overstress fracture of the trunnion aft lug can occur when the landing gear is improperly rigged such that the upper and lower side links of the main landing gear are not over center, which transmits the load path from the main landing gear to the trunnion lugs.
On March 14, 2011, about 1150 eastern daylight time, a Cessna 414, N40NY, registered to FJS Assets LLC, sustained substantial damage as a result of collapse of the right main landing gear and subsequent collision with a runway marker sign during the landing roll at the Long Island MacArthur Airport (ISP), New York, New York. Visual meteorological conditions prevailed at the time and no flight plan was filed for the 14 Code of Federal Regulations (CFR) Part 91 personal flight. The airline transport pilot and pilot-rated passenger were not injured. The flight originated about 5 minutes earlier from ISP. The pilot stated that the flight departed Bridgeport, Connecticut, and proceeded to ISP where the airplane was landed uneventfully on runway 06. During the landing roll he asked the tower if he could perform a touch-and-go landing for the purpose of checking the engine parameters with completely warm engines during takeoff power application. The tower cleared the flight for takeoff and he remained in the traffic pattern for runway 06. He extended the landing gear during the downwind leg and there were 3 green lights indicating all landing gear were down and locked. He turned base then onto final, and again confirmed there were 3 green lights for the landing gear. The airplane was landed normally on runway 06 at about 100 knots and the touchdown point was at or just before the intersection of runway 06 and taxiway A1. During the landing roll he applied the brakes, and after rolling about 200 to 300 feet, while traveling about 70 to 75 knots, he began to apply right rudder to turn onto runway 10 then immediately planned to turn onto taxiway Sierra. During the turn, the right main landing gear slowly began to collapse causing the right wing to contact the runway. The airplane departed the runway and collided with a runway marker sign. Postaccident examination of the airplane by several Federal Aviation Administration (FAA) inspectors revealed one lug of the right main landing gear trunnion assembly was fractured at the bellcrank assembly attach point. The attach bolt P/N NAS464P4-26 that secures the bellcrank assembly to the trunnion assembly was also fractured; the head of the bolt remained trapped inside the unbroken lug of the trunnion assembly, while the lower portion of the bolt with attached castellated nut and cotter pin remained trapped inside the bellcrank assembly. Additionally, one retainer of the nose landing gear was pulled from its structural attach point in the nose landing gear wheel well. The right main landing gear cylinder and trunnion assembly, bellcrank, and fractured bolt were retained for further examination. Examination of the right cylinder and trunnion assembly and fractured bellcrank attachment bolt P/N NAS464P4-26 was performed by the National Transportation Safety Board’s Materials Laboratory, located in Washington, D.C. The Materials Laboratory Factual Report indicated that the fracture surface of the aft lug of the trunnion was matte-gray in color with rough texture, features consistent with ductile overstress fracture. The examination of the bolt revealed it was fractured in the shank area where it intersected the forward lug of the trunnion. The fracture surfaces of the bolt had a uniform smooth appearance with deformation consistent with ductile overstress fracture under shear loading. Further examination of the bolt revealed the shank diameter measured 0.245 inch, while the specified minimum shank diameter for that bolt is 0.2483 inch. Hardness testing on 3 areas of the shank area of the bolt averaged 37.0 HRC; the minimum specified hardness is 36.0 HRC. During an annual inspection of the airframe annotated as being completed on March 1, 2011, discrepancies with the right upper strut assembly were found. The upper strut assembly was removed and sent to a FAA certified repair station (CRS) where it was inspected and rendered unserviceable. A replacement upper strut assembly was located and sent for inspection to the same CRS as the previous upper strut assembly. The records from the CRS indicate the replacement upper strut assembly was bead blasted, inspected, painted, and approved for return to service. The inspected upper strut assembly was installed during the annual inspection, and the airplane was returned to service. The airplane total time at the annual inspection was recorded to be 7,320.6 hours; a total of approximately 2 hours had accrued since the inspected upper strut assembly was installed. The airplane service manual contains information indicating that faithful following of the procedures pertaining to rigging of the main and nose landing gears will result in a proper rigged and efficient operating system. Additionally, engineering specialist with Cessna Aircraft Company reported that proper rigging of the landing gear system in the down and locked position results in the upper and lower side links of the main landing gear being over-center. Without the upper and lower side links being over center, the load path from the main landing gear is transmitted to the lugs of the trunnion.
The improper rigging of the right main landing gear, which resulted in ovestress fractures of a bolt and aft lug on the trunnion assembly.
Source: NTSB Aviation Accident Database
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