History of Flight
On September 1, 2013, about 1800 Pacific daylight time, a Flight Design CTSW, N102HA, lost engine power and landed about half a mile short of its intended destination, Sisters Eagle Air Airport in Sisters, Oregon. The light sport airplane, operated by the pilot under 14 CFR Part 91, sustained substantial damage. The pilot was not injured. The flight departed Whippet Field Airport, Sisters, at an unknown time. Visual meteorological conditions prevailed; no flight plan was filed.
The pilot reported earlier that day he departed Coeur d'Alene, Idaho, en route to Sacramento, California, and encountered strong headwinds and low clouds. He landed at Whippet Field, a private dirt airstrip about 5 miles east of Sisters Eagle Air, to check fuel levels. Estimating about 30 minutes of fuel, he departed. As he approached Sisters Eagle Air, the engine sputtered and stopped, then briefly restarted before stopping again. The airplane struck soft dirt; the pilot described it as an off-runway landing. He stated there were no mechanical problems and that the airplane ran out of fuel. He was renting the airplane from "World Adventure Series" but later listed himself as owner.
Subsequent examination revealed substantial damage to the firewall, forward cabin structure, and lower right fuselage.
The pilot did not submit an accident report or respond to interview requests. His attorney stated the pilot encountered strong westerly headwinds and bright sun, causing difficulty reading the fuel gauge.
Personnel and Aircraft Information
The pilot held a sport pilot certificate issued November 27, 2011, limiting him to daylight flying. The airplane was manufactured in 2007 by Flight Design GmbH and imported that year. The pilot purchased it from Flight Design in August 2010 and transferred ownership to a trust at his address in April 2011. It had accrued about 88 flight hours by 2010; the Hobbs meter showed 382.9 hours at the accident site. The engine was a Rotax 912ULS with a Neuform 2-blade composite propeller. The BRS parachute system was not activated. The most recent condition inspection occurred November 10, 2012, with 348.9 hours on airframe and engine.
Meteorological Information
Aviation weather stations along the route reported clear skies, 10 miles visibility, and light winds. Roberts Field Airport, Redmond (17 miles east, elevation 3,080 feet) reported at 1756: wind from 330° at 6 knots, clear skies, 10 miles visibility. At 1856, wind from 310° at 11 knots gusting to 18. No advisories for IFR, mountain obscuration, thunderstorms, icing, or turbulence. Winds aloft forecast at 6,000 feet: west-southwest 9-16 knots; at 9,000 feet: southwest 12-31 knots. Sunset occurred at 1940, civil twilight ending at 2010. At 1810, the sun was 15.6° above horizon at azimuth 265°.
Fuel Information and Examination
The pilot and his attorney provided three statements: one said the right tank contained 3 gallons (with "over 3 gallons" written), another said 4.5 gallons, and an email said 3-4 gallons. All stated the left tank was empty. The CTSW Operating Instructions state total fuel capacity 17 gallons per tank, 16.5 usable, gravity-fed, with an on/off fuel valve. Fuel consumption at takeoff is 7.1 gph; at 75% continuous, 4.9 gph.
Examination of the fuel system found no obstructions. Both fuel tanks were intact, caps and gaskets in place, vents oriented correctly. No debris or contamination. Photos showed a circular dust area around the right filler cap and a fluid-like streak, consistent with a prior overfill rather than post-accident leakage. No evidence of pre-impact engine malfunction; the engine started and ran properly during testing.
Recovery personnel drained about 1.5 gallons from the right tank; the left tank was empty. Subsequent measurement showed 1 gallon and 4 ounces (1.03 gallons) recovered. Fueling records at Coeur d'Alene Airport showed no transactions for the pilot or airplane in the week before the accident. Whippet Field had no refueling provisions. The last 170 miles of the route passed within 10 miles of 17 airports, 4 with refueling.
Fuel System Design
The CTSW has two integral wing tanks, each 17 gallons (16.5 usable), extending from the root forward of the main spar. Fuel quantity is indicated by sight tubes at each wing root. Wings have 2° dihedral. A rigid pickup tube with integral strainer is at each tank floor. Each tank has a single anti-sloshing rib 21 inches from the root. Fuel passes through holes in the baffle. Tanks vent through vented caps. A calibrated dipstick is used on the ground. Fuel feeds by gravity down two lines in the A-columns, joined at a T-fitting, then through a shutoff valve, filter, gascolator, and engine-driven pump. Both tanks feed simultaneously with no selector.
Fuel System Testing
Wings were reattached, airplane leveled, and fuel added incrementally. The dipstick generally matched tank quantity. Sight gauges were accurate within 1 gallon but prone to parallax error; small bank angle changes caused large fluctuations. With 3.5 gallons, lowering the right wing 2° dropped the indicated level to 1 gallon.
Additional Information
The source references a similar UK accident on August 12, 2009, involving a CTSW experiencing fuel starvation, with 1.32 gallons in the left tank while the right was empty. Testing showed that with 1.32 gallons and 8° bank, the sight gauge indicated almost half full. The AAIB recommended revising the unusable fuel assessment. P&M Aviation issued Service Bulletin SB 131 recommending monitoring fuel quantities and landing if any gauge reads empty.
Federal regulation 14 CFR 91.151 requires enough fuel to fly to the first point of intended landing and 30 minutes thereafter under VFR day conditions.