CHI98LA272

During the tailwheel airplane's landing roll, its left landing gear leg fractured and separated where the entrance step bolt hole goes through the leg. The airplane ground looped to the left. During the ground loop event the pilot's seat belt mounting bracket separated and the pilot was ejected through the left door. The seat belt mount was made from aluminum rather than the steel the manufacturer said it should have been made from. Fracture surfaces on the separated gear leg show a grainy surface texture. All 4 edges had shear lips on them. There was a series of small arrowhead shapes originating from the gear's leading edge and progressing aft to a point about midway between the bolt hole and leading edge.

On July 23, 1998, at 0830 central daylight time (cdt), a Cessna 140, N76601, piloted by a private pilot, was substantially damaged when its left main landing gear leg fractured during a landing roll. The airplane ground looped and came to a stop on the clearway between runway 32 (3,999' X 60' dry asphalt) at Brenner Field, Falls City, Nebraska, and its taxiway. Visual meteorological conditions prevailed at the time of the accident. The 14 CFR 91 personal flight was not operating on a flight plan. The pilot reported minor injuries after being ejected from the cockpit. The flight departed Falls City, Nebraska, at 0750 cdt.

The pilot's seat belt mounting bracket fractured during the ground loop event. The left door's top and bottom hinges broke when the pilot was being ejected from the cockpit. The left main landing gear leg had fractured at the pilot step's attachment point.

The seat belt mounting bracket was made from aluminum. According to a Cessna Aircraft Company representative, the bracket should be made of 4130 steel, not aluminum. There were no logbook entries showing seat belt bracket maintenance or changes. Examination of the landing gear leg fracture showed its surface had a grainy texture that was grey in color. Shear lips were present on all 4 edges of the leg's fracture surface. About 1/8th of the fracture cross- section had a series of arrowhead shaped marks that began at the leg's leading edge and went aft about halfway between the bolt hole that was drilled through the middle of the leg and the leading edge.