History of Flight
On May 22, 2016, at 1332 Pacific daylight time, a Czech Aircraft Works SPOL SRO SportCruiser, registration N1111X, departed the runway after a loss of engine power during the initial climb from Santa Monica Municipal Airport (SMO), Santa Monica, California. The student pilot was not injured, and the airplane sustained substantial damage. The light-sport airplane was operated by Santa Monica Flyers, Inc., under Title 14 Code of Federal Regulations Part 91 as an instructional flight. Visual meteorological conditions prevailed, and no flight plan was filed. The local flight departed SMO at 1330.
The student pilot had just completed two uneventful takeoffs and landings. While holding short of runway 21 for a third takeoff, an emergency declaration by another airplane led tower controllers to suspend takeoffs. The pilot kept the engine running at idle for about 20 minutes, with the airplane on a heading of approximately 350°. He monitored cylinder head temperatures and intermittently increased engine speed to keep the engine cool.
After receiving takeoff clearance, the takeoff roll and initial climb were uneventful until reaching about 500 ft above ground level (agl), when the engine began to lose power and the airplane descended. The pilot executed a 180° right turn to land on runway 3. After touchdown, full brake pressure was applied but the airplane could not slow sufficiently; it passed through a run-up area and taxiway, departed the elevated runway, and dropped onto the airport perimeter road 10 ft below. Both nose and main landing gear struck a curb, and the airplane came to rest on a grassy knoll about 180 ft beyond the threshold of runway 21. Substantial damage occurred to the firewall and lower fuselage; both wings and integral fuel tanks were intact and undamaged.
Aircraft Information
The airplane was manufactured in 2008 and equipped with a 4-cylinder, liquid-/air-cooled, Rotax 912-ULS engine.
Wreckage and Impact Information
Post-accident examination by the NTSB investigator-in-charge revealed that both wing fuel tanks and carburetor bowls contained fuel. A follow-up examination found no evidence of oil or coolant loss, and no airframe or engine anomalies that would have precluded normal operation. The engine was removed and tested at Rotech Flight Safety; no anomalies were noted, and the engine performed nominally at all speeds in an engine test cell.
Engine Monitor Data
The airplane was equipped with a Dynon EMS-D120 engine monitor. Data from two prior takeoffs showed fuel flow of about 1 gph at idle and 6.5 gph during takeoff, oil temperature around 175°F, cylinder head temperatures averaging 175°F on ground and 230°F during takeoff, engine speed about 5,100 rpm, and manifold pressure dropping from 29.1 to 27.8 inHg.
During the 20-minute hold short before the accident flight, cylinder head temperatures climbed, with cylinder 2 reaching about 330°F. Oil temperature rose to 222°F while oil pressure dropped from 46 to 30 psi. For the next 10 minutes, oil temperature continued rising with oil pressure dropping, and fuel flow began oscillating between 0 and 3 gph. About two minutes before takeoff, oil temperature reached a highest average of 270°F (with intermittent peaks to 337°F), and oil pressure dropped to 22 psi. During takeoff, fuel flow oscillated between 5.4 and 9.1 gph, engine speed reached 4,800 rpm for 30 seconds then dropped to about 4,300 rpm, and manifold pressure remained at 30.03 inHg until data ended. Two increases in engine speed of about 400 rpm were noted during the hold, consistent with the pilot's attempts to cool the engine, but they did not appreciably affect average temperatures.
Additional Information
Engine temperature operating limits, per the flight manual and EMS-D120 display, were: oil temperature normal 194–230°F, caution 230–266°F, maximum 266°F; cylinder head temperature normal 167–230°F, caution 230–275°F, maximum 275°F. The EMS-D120 could display alerts for exceedances, but the alert feature was not enabled. The SportCruiser pilot operating handbook (POH) prohibited takeoff if engine instrument values exceeded operational limits.
The airplane was equipped with a FloScan 200 series fuel flow transducer. According to FloScan representatives, air in the fuel lines can cause higher-than-normal fuel flow readings. Representatives from Electronics International Inc. noted that air in a rotor-style transducer can cause the rotor to spin at air velocity, leading to spikes or jumping fuel flow readings, characteristic of vapor lock.
Fuel analysis from the left wing tank showed the fuel was appropriate for the region and time of year, with a research octane number of 95.8. The operator used premium automotive gasoline from a local station, delivered that morning.
An August 1, 2012 amendment to the Rotax 912-ULS installation manual required a fuel return line to prevent vapor formation. The accident airplane, manufactured in 2008, did not have this return line installed. Czech Aircraft Works made the fuel return line standard on SportCruisers after September 2010. Subsequent safety alerts from Czech Aircraft Works (SA-SC-006 in 2017 and SA-SC-011 in 2018) mandated installation of a return line for pre-May 2009 airplanes and updated POH warnings about using climate-appropriate fuel to avoid vapor lock.
The Pilot's Handbook of Aeronautical Knowledge defines vapor lock as fuel changing from liquid to gas in the fuel system, disrupting fuel pump operation and causing power loss.