Flight Details
The pilot departed Danbury Municipal Airport (DXR), Connecticut, en route to Grand Strand Airport (CRE) in North Myrtle Beach, South Carolina. After takeoff, the pilot leaned the fuel-to-air ratio and climbed to 9,000 feet mean sea level (msl), where he set the mixture lean of peak turbine inlet temperature (TIT) by 30 degrees. The flight remained at 9,000 feet for a period before climbing to 12,000 feet msl, where the pilot again leaned the mixture lean of peak TIT. He monitored cylinder head temperature (CHT), exhaust gas temperature (EGT), fuel flow, and other gauges, noting even fuel consumption between tanks. Approximately 10 minutes from the destination, while at 5,000 feet, the engine surged, experienced a power loss, but did not quit. The pilot enriched the mixture, activated the auxiliary fuel pump, and requested vectors from air traffic control to the nearest airport. The engine eventually quit, though the propeller continued rotating. Unable to reach the vectored airport, the pilot performed a gear-up landing on grass short of the intended runway.
Preflight and Fuel Calculation
The pilot reported performing a preflight inspection that included visual checks of both fuel tanks. He observed the fuel level in each tank was ½ to ¾ inch below the fuel filler cap sealing surface, estimating 50.0 gallons usable based on that level. He noted no discrepancies during engine start or run-up. The pilot calculated that each tank contained between 22 and 25 gallons usable (tank capacity is 25 gallons each when full, total 50 gallons).
Post-Accident Inspection and Fuel Quantity
An FAA airworthiness inspector examined the airplane before recovery. Only 3 to 4 ounces of fuel were drained from both fuel tanks, which were undamaged. No fuel staining was found aft of the filler caps or sump drain valves. With the battery connected, both fuel quantity indicators read empty.
Aircraft Modifications and Pilot History
The pilot had owned the airplane since 1998. In 2003, the aircraft was modified under separate Supplemental Type Certificates (STCs) with a turbocharger and an engine-monitoring instrument with fuel flow indication. The engine was overhauled on August 23, 2007, and installed on October 4, 2007. The pilot questioned whether the fuel flow transducer or engine-monitoring instrument contributed to fuel exhaustion. Safety Board review revealed two placards were missing from the instrument panel: one stating not to use the instrument to determine fuel level, and another directing that the primary fuel flow indicator should be used for reference, not the engine-monitoring instrument. This second placard conflicted with a flight manual supplement (FMS) for the turbocharger, which indicated the primary fuel flow indicator might not be accurate after the turbocharger installation.
Data and Fuel Flow
Data from the engine-monitoring instrument covered all but 14 seconds of the 4.26-hour flight. It indicated 44.5 gallons of fuel used, with an average fuel flow of 10.3 gallons per hour (gph). The pilot questioned whether the engine overhaul affected fuel consumption. Data from two complete flights before the overhaul showed average fuel flows of 10.1 and 10.2 gph, while two flights after the overhaul showed 9.6 and 9.7 gph. The pilot stated he had made the same trip safely many times over 8 years, typically landing with 7–10 gallons remaining. Invoices from Ramp 66 at CRE (records from 2002) showed only four fuel purchases for the airplane: 42.5, 45.0, and 31.8 gallons. The pilot also questioned whether changes in fuel pressure or flow due to the turbocharger installation played a role. The STC holder stated that full-throttle, rich-mixture fuel flow increases from a test maximum of 125.2 pounds per hour (pph) to 132 pph. The fuel flow transducer had a range of 0.6 to 60 gph (approximately 3.6 to 360 pph) and a working pressure of 200 psi.