Accident Details
On September 17, 2019, about 1230 eastern daylight time, a Robinson R44 helicopter, registration N827JE, was substantially damaged when it impacted trees and terrain near Sardis, Georgia. The pilot, who was the sole occupant, sustained serious injuries. The helicopter was being operated as a Title 14 Code of Federal Regulations Part 137 aerial application flight.
According to the pilot, he was flying approximately 100 feet above ground level while applying spray when he heard a "pop," followed by alarms and lights activating in the cockpit. The helicopter subsequently lost engine power, and the pilot performed an autorotation. During the autorotation, the helicopter struck trees and terrain.
Examination and Findings
A Federal Aviation Administration inspector examined the accident site and observed that the helicopter came to rest on its left side. The fuselage sustained damage, and the tail boom had separated from the main structure.
A teardown examination of the engine was conducted. It revealed that the left crankshaft idler gear was not engaged with the teeth of the crankshaft gear or the camshaft gear. The idler gear was removed, and the idler gear shaft was found not attached to its mounting location on the left crankcase half. According to an engine diagram, the idler gear shaft was supposed to be secured to the left crankcase half by a bolt and a crankcase stud. Worn fragments of the bolt and crankcase stud, along with the stud nut and safety wire fragments, were recovered from the oil sump.
Metallurgical examination of the crankshaft idler gear, shaft flange, and gear shaft fasteners (bolt and stud) showed evidence of wear. The worn gear shaft fasteners exhibited a rotating bending fatigue failure. Detailed analysis is contained in the Materials Laboratory Factual Report in the public docket for this accident.
Maintenance Records
According to maintenance records and information from the operator, the engine had been operated for about 1,900 hours over a 20-year period since its last major overhaul. Review of Lycoming Service Instruction (SI) 1009BD, superseded by SI 1009BE, indicated a recommended time between overhauls (TBO) of 12 calendar years or 1,500 hours of operation for engines used in crop dusting or other chemical application, whichever occurred first.