SAMSON, AL, USA
N4242X
GRUMMAN G-164A
THE AG PILOT WAS SPRAYING COTTON, AND IN A 60 DEGREE BANK, WHEN HE NOTICED THAT THE AILERONS WERE INEFFECTIVE. HE REDUCED POWER AND ATTEMPTED TO LEVEL THE WINGS WITH RIGHT RUDDER. THE LEFT WING CONTACTED THE GROUND, FOLLOWED BY THE LEFT MAIN GEAR. THE AIRCRAFT FLIPPED SEVERAL TIMES BEFORE COMING TO REST INVERTED. FLIGHT CONTROL EXAMINATION REVEALED THAT AN AILERON TORQUE TUBE BOLT WAS FRACTURED, DISABLING THE AILERONS. METALLURGICAL EXAMINATION OF THE BOLT REVEALED AREAS OF LOW STRESS, MULTIPLE ORIGIN FATIGUE CRACKING.
On July 18, 1994, at 0830 central daylight time, a Grumman G-164A, N4242X, collided with the ground following a pull up from a swath run near Samson, Alabama. The local, aerial application flight operated under 14 CFR Part 137 with no flight plan filed. Visual weather conditions prevailed at the time of the accident. The airplane sustained substantial damage; the pilot was not injured. The flight's departure time from Samson was not determined. The pilot reported that he was spraying cotton, and at a 60 degree bank angle, when he was unable to level the wings. He retarded the throttle, and attempted to level the wings with right rudder. The wings leveled shortly before the left wing struck the ground, followed by the left landing gear. The aircraft flipped two or three times before coming to rest inverted. An examination of the aileron control system revealed that a torque tube bolt was broken, which compromised aileron control continuity. The broken bolt was submitted to the National Transportation Safety Board Materials Laboratory for inspection. The examination revealed the bolt failed about .7 to .8 inches from the underside of the bolt head. There was an area of wear, and a wear lip was found about .61 inches from the underside of the head. Visual examination of the bolt fracture surface revealed portions of the fracture adjacent to the fracture surface were smooth, flat, and slightly discolored, and contained crack arrest positions and ratchet marks, typical of low stress, multiple-origin fatigue cracking. For more details of the bolt examination, refer to the Metallurgist's Factual Report, attached to this report.
THE FAILURE OF THE AILERON TORQUE TUBE BOLT FROM FATIGUE, WHICH RESULTED IN AN INFLIGHT LOSS OF AIRCRAFT CONTROL AND COLLISION WITH TERRAIN.
Source: NTSB Aviation Accident Database
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