Incident Overview
On 24 December 2008, a Cessna 208B Grand Caravan, registration N21070, operated by Ultimate Aircraft Services, departed St. John's International Airport (CYYT) at 10:43 UTC on a delivery flight to Santa Maria Airport (LPAZ) in the Azores. Approximately three hours into the flight, the pilot detected a malfunction in the fuel transfer system from the auxiliary tanks to the main tank. Unable to resolve the issue in flight and with insufficient main tank fuel to reach the intended destination, the pilot declared a fuel emergency and requested a diversion to Flores Airport (LPFL), which was along the route and normally restricted to domestic flights. Authorization was granted, and the aircraft landed safely at Flores at 16:58 UTC. The pilot, the sole occupant, was uninjured, and the aircraft sustained no damage.
Flight History
The aircraft was being delivered from Moundridge, Kansas, to Bahrain International Airport. After arriving in St. John's on 21 December, the aircraft was refueled and stored in a hangar. Due to icing conditions on 23 December, the flight was delayed until 24 December. The aircraft departed with full fuel tanks (692 US gallons, providing approximately 13 hours of endurance) and one pilot on board. The climb was to flight level 130. The pilot followed operational instructions for fuel management: takeoff on main tanks, then selecting the right main tank at cruise, and activating auxiliary tanks after consuming half of the right main tank. After passing 040°W (about three hours), the pilot noticed no fuel transfer from the auxiliary tanks to the right main tank. Attempts to troubleshoot were unsuccessful.
Aircraft and Fuel System Information
The Cessna 208B (serial number 208B2014) was equipped with an auxiliary fuel system designed by Weaver Aero International, Inc. The system consisted of two 180-USG tanks installed in the cabin, with two electric pumps and valves. Fuel flowed from the auxiliary tanks to the right main tank, then to the engine. Operational notes required that at least half of the right main tank be consumed before using auxiliary fuel, and the level of the right main tank was to be monitored. The aircraft’s maximum takeoff mass (MTOM) was increased to 11,826 lbs (5,364 kg) for the delivery flight.
Weather Conditions
Environment Canada provided route weather information. On 24 December, a ridge of high pressure extended east of St. John's, with good weather at departure. A low-pressure core at 47N 036W with an associated cold front was expected to pass over Flores around 16:00, bringing rain, mist, and showers with northwest winds up to 40 knots. METAR reports for St. John's showed clear conditions with light winds. METAR reports for Flores indicated deteriorating conditions around the time of landing, with rain, mist, and gusty winds.
Aftermath
The following day, the fuel transfer system became operational, and the flight continued to its final destination. No further anomalies were reported.