What happened
On 11 May 1999, a Cessna 525, registration G-RSCJ, was conducting a private flight from Palma, Majorca, to Luton. While the aircraft was near the 'BARLU' reporting point over the Cherbourg Peninsula, the pilot observed the right-hand FUEL BYPASS LIGHT illuminate. Fearing fuel contamination, the pilot notified Air Traffic Control (ATC) of a potential emergency and initially intended to divert to Southampton. Following radar vectors, the pilot subsequently changed the diversion destination to Bournemouth.
During the descent toward Bournemouth, the pilot informed controllers that, following a checklist review, a total loss of power from both engines was a possibility. The aircraft was vectored for an ILS approach to Runway 26. The pilot maintained visual contact with the runway from 3 nm out and completed a safe landing at 0842 hrs. There were no injuries and no damage to the aircraft.
The investigation
Following the landing, maintenance engineers inspected the aircraft's fuel systems. Upon removing the fuel filters from both engines and draining the fuel, they discovered that the fuel within the filter housings was cloudy and contained an icy slush. The engineers continued to drain the fuel until the cloudy appearance disappeared and confirmed that the bypass warning system was functioning correctly. New filters were installed, and the aircraft was refuelled with fuel containing an anti-icing additive.
Further investigation revealed that the fuel uplifted at Palma, Majorca, lacked the required anti-icing additive. The pilot later contacted the handling agents at the departure airport to report the issue.