NTSB Identification: CEN09LA526
14 CFR Part 137: Agricultural
Accident occurred Sunday, August 16, 2009 in Worthington, MN
Probable Cause Approval Date: 12/29/2009
Aircraft: THRUSH AIRCRAFT INC S2R-T660, registration: N660RB
Injuries: 1 Uninjured.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The pilot reported he heard and felt a “loud pop” at the end of a spray run and realized he did not have elevator control. The pilot controlled the pitch attitude using power and elevator trim as he flew back to an airport to land. The pilot decided to land at a higher than normal airspeed so he could maintain control of the airplane. The airplane bounced twice during the landing. During the second runway impact, the main gear collapsed. The airplane slid approximately 200 feet and veered off the right side of the runway prior to coming to rest and sustained substantial damage to the right wing. A post accident examination of the airplane revealed the elevator push-pull rod was fractured through the first full thread of the threaded shaft adjacent to the conical section. The remaining threaded section of the rod was threaded into the monoball spherical bearing fitting. A metallurgical examination revealed a fatigue fracture that initiated from both sides of the threaded shank on the rod end. Examination of the monoball bearing revealed several dents in the metallic bearing shield. The shape, size, and location of the dents and the deformation of the bearing shield were consistent with over-travel contact by the boss on the monoball bearing.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: A fatigue failure of the elevator push-pull rod which resulted in the pilot's inability to control the aircraft's pitch attitude while landing. Full narrative available
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