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AACs - Part 1-9 - Airworthiness Articles
Part 1 - Airworthiness Articles
Fletcher FU-24 Main Landing Gear
An FU24 was recently involved in a landing accident following the in-flight loss of the left main wheel and oleo strut. The cause was found to be failure of the torque link lower attachment bolt. The bolt was not recovered and the precise reason for its failure was not determined.
Perusal of the Major Defect Records show that there have been four reported bolt failures since 1980, all apparently resulting in similar accidents. The reports suggest that bolt failure is a common problem, but there are only the four formal reports on record.
The failures have been variously ascribed to wear of both bolt and bolt holes, corrosion and fretting, loss of nut torque, lack of lubrication, and fatigue.
It is recommended that particular attention be paid during periodic maintenance to the condition of the bolts and links. A modification involving larger diameter bolts is also available.
AAC articles 22-5, 31-1, 76-3 and 176-4 also focus on landing gear problems, many of which are common to fixed gear and retractables alike.