SEA08LA090

During the initial climb after takeoff, the pilot heard a "loud bang" originating from the rear of the airplane, and he decided to circle around the airport and land. As the nose of the airplane settled during the landing roll, the nose wheel strut folded aft into the fuselage, resulting in structural damage to the airframe. Examination of the airplane revealed that the nose wheel fork assembly and tire had separated from the nose wheel strut during takeoff. Examination of the nose wheel fork assembly attachment stud/bolt revealed fracture features consistent with fatigue and overload. Evidence of oxidation and/or corrosion was also present on the fracture surface.

On March 9, 2008, about 1620 mountain daylight time, a Diamond Aircraft Industries DA 20-C1, N765DC, was substantially damaged during landing following an in-flight separation of the nose wheel at the Spanish Fork Airport (U77), Spanish Fork, Utah. The private pilot and his passenger were not injured. The airplane was registered to and operated by Airgyro Aviation LLC of Spanish Fork under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed and no flight plan was filed for the local personal flight that departed from U77 about five minutes prior to the time of the accident.

The pilot reported that during the initial climb after takeoff from runway 30 he heard a "loud bang" originating from the rear of the airplane and he decided to circle around the airport and land. During the landing roll, as the nose of the airplane settled, the nose wheel strut folded aft into the fuselage resulting in structural damage to the airframe.

Examination of the airplane revealed that the nose wheel fork assembly and tire had separated from the nose wheel strut during takeoff. The nose wheel fork assembly attachment stud/bolt was sent to the NTSB Office of Research and Engineering, Materials Laboratory Division for further examination.

The examination revealed that the fracture surface of the stud/bolt had an area of flat fracture bordered by smoothly curving crack-arrest markings consistent with fatigue cracking. The fatigue cracking appeared to have propagated through an estimated 60 percent of the cross section of the stud/bolt, with the remaining cross section fractured with overstress signatures. Substantial oxidation and/or corrosion of the fracture surface was observed.