In-Flight Engine Shutdown on Bombardier CRJ Flight EXY1123 (ZS-NMI)

Incident Overview and Flight Details On 16 May 2018, a scheduled commercial flight operating under the call sign EXY1123 departed from O.R. Tambo International Airport (FAOR) for Mafikeng International Airport (FAMM). The aircraft, a Bombardier/Canadair Regional Jet CL-6002B19 with registration ZS-NMI, was operating under Part 121 Air Transport Operations. The flight carried 4 crew members and 19 passengers. ## Sequence of Events After take-off from runway 21R, the aircraft was climbing and passing 8,000 feet above mean sea level when it suddenly yawed to the left. The flight deck crew identified the issue as an engine flame-out on the left-hand engine (number 1). The crew noted that there were no prior cockpit indications warning of a possible engine-related problem. The crew transmitted a PAN-PAN call to air traffic control (ATC), informing them of the engine flame-out and requesting to be vectored to a holding point. ATC routed the aircraft to the VOR beacon MEV. The crew carried out Quick Reference Handbook (QRH) procedures for an engine shutdown and configured the aircraft for landing. The decision was made not to attempt an engine restart, as the crew planned to return to FAOR, which was their maintenance base. The aircraft returned to FAOR and completed an uneventful single-engine landing on runway 21L. The flight duration was 34 minutes. There were no injuries reported, and the aircraft did not sustain any damage. ## Investigation and Findings The Accident and Incident Investigation Division (AIID) was notified, and an investigating team was dispatched to the aircraft maintenance organization (AMO) at FAOR, where the aircraft had been towed into a maintenance hangar. The engine did not display any visible damage. During the investigation, the engine fault-finding checklist was followed. It was recommended that the drive shaft between the fuel pump and the fuel management unit (FMU) be inspected for continuity. The FMU was removed where it was attached to the fuel pump, and the drive shaft was found to display signs of excessive wear on the side of the FMU. The gear train on the FMU also displayed evidence of wear that had caused the drive gear to slip in operation. This disrupted the fuel supply to the engine, resulting in the engine shutdown. ## Probable Cause The probable cause of the incident was the failure of the FMU drive gear and shaft splines, leading to an engine flame-out. ## Maintenance and Safety Recommendations The engine that experienced the flame-out was a leased engine that had been in the possession of the AMO since 13 January 2017. It had previously been installed on an aircraft with registration ZS-NMF before being fitted to ZS-NMI on 14 July 2017. The engine was a General Electric (GE) CF34-3B1 with serial number 807321C. At the time of the incident, it had 40,904 hours since new and 35,877 cycles since new. On 2 November 2004, General Electric released an Alert Service Bulletin (ASB: 73-A0035-R6) for an inspection of the main fuel control input drive shaft spline, main fuel pump control drive shaft spline, and main fuel pump secondary drive shaft spline. The operator did not incorporate the service bulletin as required by the manufacturer prior to the incident. A safety message was issued stating that the operator needs to review their maintenance control to ensure that safety alerts (service bulletins/airworthiness directives) are incorporated to prevent incidents such as this one from reoccurring. The interconnecting drive shaft and the FMU were replaced on the engine. A ground run was carried out, and the aircraft was returned to service the following day, 17 May 2018.