The NTSB reports are replete with unfortunate and preventable accidents caused by aircraft running out of fuel. Engine failures can also be caused by too much fuel. The issue with too much fuel is especially prevalent in the Continental TSIO-550 series engines that power some of the most popular high performance single engine aircraft, including the Cirrus SR22T and Cessna TTx.
The high fuel flow engine failures typically occur during the critical takeoff and climb out phase of flight. The high fuel flow, or fuel flow in excess of 40 gallons per hour, is cause for immediate concern and repair before further flight. In several documented cases the National Transportation Safety Board found fuel flow of 42-50 gallons per hour immediately prior to loss of engine power. Loss of Engine Power due to Excessive Fuel Flow in Cirrus SR22T Aircraft (ntsb.gov)
The high fuel flow has a number of potential causes including incorrect use of the electric fuel boost pump, defective or incorrectly adjusted slope controller, and other potentially yet undiscovered causes. Cirrus and Continental have undertaken efforts to warn pilots about using the electric booth pump in the HIGH BOOST/PRIME position during takeoff. (Cirrus Service Advisory SA18-02.) Cirrus also designed a software change designed to prevent improper use of the boost pump; however, this software feature did not function as designed and Cirrus issued Service Advisory SA19-01 to warn of this problem. The NTSB is concerned that all of the causes of high fuel flow engine failures have not been identified. Cirrus has not performed a Functional Hazard Assessment (“FHA”) for excessive fuel flow during takeoff and climb. Accordingly, the NTSB issued Safety Recommendation A-22-7. The NTSB is concerned that the objectives of Advisory Circular 23.1309-1E have not been accomplished for the Cirrus SR22T.
Pilots operating TSIO-550 series engines should be diligent to ensure the electric fuel pump position of HIGH BOOST/PRIME is not used during normal operation during take-off or climb. It should only be used to prime the engine or above 18,000 feet to suppress fuel vapor formation. Pilots should also be mindful of fuel flow during take off and climb. If the fuel flow appears to be excessively high or in excess of 40 gallons per hour the slope controller should be inspected by a mechanic before further flight.