Chinedu Eze The Nigerian Safety Investigation Bureau (NSIB) has released its preliminary investigation on Arik Air Flight W3740 and said that catastrophic failure of a fan blade in the left engine led to its explosion and diversion of the flight to Benin Airport on February 11, 2026. NSIB said the aircraft, a Boeing 737-700 with registration mark, 5N-MJF, was enroute from Murtala Muhammed International Airport, Lagos, to Port Harcourt International Airport when the incident occurred during climb to about 07:35a.m. The aircraft, with 87 souls onboard, had just passed flight level 260 and was climbing toward FL290 when the crew heard a loud bang followed by intense vibration and grinding noise from the number-one engine. The agency reported that the malfunction caused the aircraft to veer left and begin losing speed, forcing the crew to disengage the autopilot and stabilise the aircraft manually. After confirming severe damage to the engine, the crew shut it down in line with emergency procedures and declared a Mayday. Air traffic control advised the crew to divert to the nearer Benin Airport in Benin City, where the aircraft landed safely about 30 minutes later. All passengers and crew disembarked without injuries. NSIB said a post-incident inspection revealed extensive damage to the left engine and surrounding airframe. Investigators found that the number six fan blade of the engine had broken off, while the remaining blades were chipped and damaged. The engine cowling had torn open, and fragments caused cuts and dents on the wing, stabiliser and other parts of the aircraft. The preliminary findings indicate that the fan blade failure inside the CFM56-7B engine likely initiated the chain of events that led to the emergency diversion. The engine, which had previously been installed on other aircraft before being fitted to the incident aircraft in 2022, had undergone ultrasonic inspections in March 2025 with no defects reported at the time. The NSIB said further metallurgical examinations of the broken fan blade and the remaining blades, as well as a full teardown of the engine, will be conducted to determine the exact cause of the failure as the investigation continues. Confirmed sources indicate that this specific problem (fan blade failure) is associated with the CFM56-7B engine, particularly in older Boeing 737-700/NG fleets, and this involves fan blade fatigue, potential uncontained engine failures, and high-pressure turbine blade wear. Manufacturers of the engine acknowledged that the engine’s fan blades have exhibited low-cycle fatigue cracks at the root, which caused severe failures leading to inlet cowl damage and high-cycle engine wear. The most critical incident linked to the problem before that of Arik Air is that of Southwest Flight 1380, which indicates a low-cycle fatigue cracking in the fan blade dovetail area, often found in engines with high operating cycles. The solution recommended by the manufacturer is this, “Following the fan blade failures on CFM56-7B engines (which power the Boeing 737-700), manufacturer CFM International—in coordination with the FAA (US Federal Aviation Administration) and EASA (European Union Aviation Safety Agency)—recommended a series of mandatory, repetitive ultrasonic inspections to detect fatigue cracking at the fan blade dovetail.”