What happened
On August 15, 2019, a McDonnell Douglas MD11-F, registration N270UP, was operating a flight from Cologne/Bonn (EDDK) to Warsaw (EPWA). While cruising at FL330 within the Warsaw FIR, the crew received a FADEC1 MAINT alert for engine number 2. In response, the crew performed the FADEC maintenance checklist from the Quick Reference Handbook (QRH) to secure the engine. During this process, the pilots noted a lack of fuel flow indications.
As the aircraft descended toward Warsaw, the engine number 2 RPM decreased, leading to the complete shutdown of the engine. The crew promptly executed the ENGINE SHUT DOWN IN FLIGHT checklist and declared an emergency to Air Traffic Control. The aircraft landed on runway RWY 33 with the assistance of emergency services. After the aircraft exited the runway via taxiway SIERRA 2, the tower controller informed the crew that flames were visible from the engine number 2 exhaust. Although the crew could not confirm the fire from the cockpit, they initiated fire suppression procedures, and the Airport Fire Service engaged the engine fire from the ground.
The investigation
The PKBWL investigation focused on the mechanical failure of the engine and the failure of the fuel shutoff mechanism. The investigation examined the maintenance history of the Fuel Metering Unit (FMU) and the specific components involved in the fuel delivery system.
Findings
- During a recent overhaul of the Fuel Metering Unit (FMU, P/N 80100-4, S/N F28648) at Aero Accessories, a fuel metering valve spring seat was incorrectly installed in the Minimum Pressurization and Shutoff Valve (MPSOV) port.
- This installation error caused the fuel metering valve to malfunction.
- The malfunction prevented the FMU from completely cutting off the fuel supply to the engine, even after the crew had executed the ENGINE SHUT DOWN IN FLIGHT checklist.