History of Flight
On January 18, 2015, at approximately 1235 mountain standard time, a Beech A36TC, registration N3685W, sustained a nose landing gear collapse while landing at Flagstaff Pulliam Airport, Flagstaff, Arizona. The airplane was operated by the commercial pilot under 14 Code of Federal Regulations Part 91 for a cross-country personal flight. The flight originated from Brackett Field Airport, La Verne, California, at 0934 Pacific standard time. Visual meteorological conditions prevailed, and no flight plan was filed.
The pilot reported that the airplane crossed the runway threshold at 90 knots and touched down just beyond the displaced threshold. The airplane bounced, and the pilot applied back elevator pressure to dissipate energy. A second touchdown occurred on the main landing gear while the pilot maintained a nose-high attitude. The pilot surmised that the nose landing gear scissor link (upper torque knee) failed, allowing the nose wheel to overextend and detach. As airspeed decreased, the airplane came to rest on its nose.
Two air traffic controllers witnessed the event. The tower controller observed the airplane bounce two to three times after landing, followed by nose gear collapse. The ground controller reported seeing the airplane land hard on the nose wheel first, then porpoise up and down two more times, each time contacting nose wheel first, before collapse.
The airplane sustained substantial damage to the lower fuselage, and the lower nose landing gear assembly—comprising the nosewheel, fork, and lower torque knee—became detached.
Aircraft Examination
The airplane was equipped with retractable landing gear driven by an electrical actuator connected to a series of link rods. The nose landing gear extended forward and was held in the locked and down position by a wishbone-shaped aft brace and a single forward brace, both secured by control arms linked to the landing gear link rods.
Sections of the lower nose gear assembly were recovered and examined by the NTSB investigator-in-charge. The nose wheel fork and piston assembly had separated from the barrel. The fork casting was bent about 3 degrees aft relative to the piston. The lower torque knee remained attached to the fork via its pin; its connecting bolt for the upper torque knee was bent about 10 degrees and remained in place with bushings, washers, and nut.
The upper torque knee remained attached to the barrel assembly. Its attachment lugs were ground down to bearing surfaces with longitudinal score marks consistent with runway contact. The lug connecting the lower knee was twisted about 5 degrees; the forward section of that lug was missing. That lug exhibited similar grinding damage, and its attachment hole radius was elongated.
The forward landing gear brace had separated into three sections. Reassembly showed the brace had bent 30 degrees midspan downward prior to failure. The forward section remained attached to the barrel and brace assembly; the lug at the aft end had broken away.
The nosewheel tire remained attached to its axle and displayed a half-inch deep gouge over a six-inch portion of its center tread.
The separation surfaces of all components showed varying combinations of rough grainy texture, jagged edges, ductile dimpling, and 45-degree shear lip features. No ratchet marks, striations, or beachmarks were observed.