What happened
On October 4, 2018, an Air Tractor AT-401B bearing registration 5N-BTV, operated by Skypower Express Airways Nigeria Limited, was conducting agricultural aerial spraying operations at the Olam rice farm in Rukubi, located approximately 90 nautical miles southeast of Abuja. The aircraft was engaged in its third and final sortie of the day, carrying 600 liters of liquid chemical for a series of 22 runs.
At approximately 09:04 local time, the pilot took off from the Rukubi airstrip toward the NE05 field. After completing six spray runs, the aircraft climbed to an altitude of roughly 150 feet and turned left to align with the next run, heading west. During this phase of the flight, the pilot reported hearing the engine sputter and backfire before it ceased operation entirely. Instrument readings for oil pressure, oil temperature, and fuel pressure were all within normal operating ranges at the time of the failure.
The pilot attempted to restart the engine by priming it, but the engine cranked without igniting. With no power available and considering the low altitude, the pilot initiated an emergency procedure. The liquid chemical load was jettisoned to reduce weight, and the pilot maneuvered to avoid a nearby residential area, telecommunications mast, rice mill, and school. An alternate landing site along a road between fields N9 and N10 was identified but deemed unsafe due to the presence of people, livestock, bicycles, and a parked pickup truck.
Consequently, the pilot executed a forced landing on marshy, undulating farmland designated as field N803, situated about 1.5 kilometers from the point of engine failure. The aircraft touched down with its right main landing gear first, followed shortly by the left main gear approximately three meters away. The right main wheel sheared off upon impact, and the aircraft skidded for roughly 38 meters before flipping over. The pilot exited the wreckage unassisted and sustained no injuries.
The investigation
The Accident Investigation Bureau (AIB) of Nigeria conducted a post-accident assessment at the site. Investigators examined the wreckage and removed the engine-driven fuel pump for inspection. They found that the fuel pump shaft was stiff, which likely prevented it from supplying adequate fuel to the carburetor, leading to fuel starvation and loss of power.
Further technical examinations of the engine were pending at the time of the report's issuance to determine the root cause of the pump stiffness. Fuel and engine oil samples were analyzed and found to meet the Aviation Fuel Quality Requirements for Jointly Operated Systems (AFQRJOS). The pilot held a valid Commercial Pilot Licence with appropriate ratings, and the aircraft maintained a valid certificate of airworthiness, though its insurance was noted as invalid at the time of the incident.
Findings
The investigation established that the engine failure occurred at low altitude during agricultural operations. Key findings included:
- The pilot was properly certified and qualified for the flight.
- The aircraft's maintenance records indicated compliance with regulations.
- Fuel and oil quality met required standards.
- The fuel pump drive shaft exhibited stiffness, suggesting a mechanical issue preventing proper fuel delivery.
- No safety recommendations were issued in this final report.
Safety action
No specific safety actions or recommendations were recorded in the source material for this incident.