What happened
On December 7, 2012, a SAAB 2000, registration HB-IZJ, operated by Darwin Airline, was conducting a scheduled IFR flight from Rome Fiumicino to Geneva. While flying approximately 22 nautical miles southwest of Geneva Airport, the crew encountered issues regarding the fuel filters on both engines. Following the encounter with these technical difficulties, the crew elected to divert to Geneva, where the aircraft landed successfully without any injuries to the 19 passengers or the crew.
The investigation
Investigators examined the circumstances surrounding the fuel filter malfunctions to determine if fuel contamination or mechanical bypass issues were present. The inquiry established that there was no evidence of fuel contamination in the system, nor was there any associated fuel by-passing occurring during the incident. The investigation also looked into the maintenance history of the aircraft, specifically focusing on the preceding flight leg from Geneva to Rome.
Findings
Technical analysis revealed that the failure to perform a required inspection of the fuel filter mechanical bypass indicator (the pop-out mechanism) on the previous flight from Geneva to Rome was a primary factor. Because this inspection was omitted, the warning indicator remained active and reappeared during the return flight. The investigation concluded that the blockage issue on the left-hand engine was a carry-over from the previous leg due to this missed inspection, and that the crew's decision to land in Geneva was appropriate and executed according to standard checklists.