Root Cause Analysis of Field Failures in Agricultural Machinery Manufactured in Kebbi State

This research conducts a root cause analysis of field failures reported for agricultural machinery units manufactured by a fabrication company in Kebbi State, North West Nigeria. Agricultural machinery reliability is critical in Nigeria's irrigation farming zones, where equipment failures during planting or harvesting seasons can result in significant crop loss and financial distress for smallholder farmers. This study applies the Failure Mode and Effects Analysis method combined with fault tree analysis to systematically investigate thirty-seven field failure incidents reported across two farming seasons. Field investigation data were collected through structured interviews with equipment operators and supervisors, direct inspection of returned failed units, and review of the manufacturer's quality control inspection records. The most frequently reported failure modes include shaft fracture at power take-off connections, premature bearing wear in the threshing drum, and hydraulic seal failures in depth control systems. Root cause analysis identifies undersized shaft cross-sections relative to actual field torque loads, the use of non-specification bearing grades to reduce production costs, and inadequate hydraulic fluid contamination control during assembly as underlying causes. Recommendations include revising shaft design specifications based on field load data, establishing minimum grade standards for purchased bearings, and introducing a hydraulic assembly cleanliness protocol. Keywords: root cause analysis, agricultural machinery, FMEA, Kebbi State, field failure