History of Flight
On October 15, 2023, about 0759 EDT, a Czech Aircraft Works SPOL SRO SportCruiser (N72FU) departed from Cape Fear Regional Airport / Howie Franklin Field Airport (SUT) on a personal flight. The student pilot had conducted a preflight inspection and reported no issues. After starting the engine and allowing it to reach operating temperature, he taxied to runway 5 and performed an engine runup, with all systems indicating green. Shortly after takeoff from runway 5, the engine lost power. The pilot followed engine-out procedures, gliding over trees at the north end of the runway, and landed in a vacant lot. During landing, the left wing struck a palm tree, causing the airplane to spin and come to rest. The pilot sustained minor injuries, and the airplane was substantially damaged.
In a postaccident exchange, the pilot stated that he had checked carburetor heat during the runup, as taught by his flight instructor. However, the manufacturer’s published guidance for the airplane did not direct the use of carburetor heat before or during takeoff; a note in the emergency procedures section indicated its use during long descents and in areas of possible carburetor icing.
Aircraft and Pilot Information
The pilot held a student pilot certificate with a second-class medical issued August 3, 2022. He reported about 101 total flight hours, including 23 hours in the accident make and model.
The airplane was a single-engine, two-seat, all-metal, low-wing SportCruiser, equipped with a fixed tricycle landing gear and a 100-horsepower Rotax 912 ULS2 engine. It was manufactured in 2008 and had been previously registered as N173SP. The most recent annual inspection was completed on July 18, 2023, at 1,302 total flight hours.
Wreckage and Engine Examination
Postaccident examination revealed that the left wing had separated except for the spar, the fuselage was torn at the left wing root, and the left landing gear collapsed. The right wing showed crush damage, and its outboard portion was missing the wingtip. The fuel strainer was clean and free of debris, with no water contamination.
The carburetor heat control lever, labeled "CARBURETOR AIR, PULL HOT," was found in the pulled-aft (on) position.
Engine examination found oil in all rocker boxes and drivetrain continuity. Thumb compression was present on all cylinders. All eight spark plugs were heavily carbon fouled, and the cylinder heads and piston tops showed heavy carbon deposits.
Both carburetors were removed and examined. The floats were within weight limits with no fuel absorption, and float bowls were dry with a white powdery residue. Main jets were clear. On the 1/3-cylinder carburetor, the float bracket was properly adjusted, but the tube assembly for the choke cable was bent, and neither the choke nor throttle cable was attached. On the 2/4-cylinder carburetor, the float bracket was bent and out of adjustment, the choke cable was absent, the throttle valve lever was bent, and the throttle cable was fractured near the attachment.
The spark plugs were last changed on December 4, 2019, at 1,213.1 hours, with about 88 hours of use, and were within the 200-hour replacement interval. The air filter, a K&N type, was cleaned and re-oiled on June 12, 2021, at 1,260.2 hours, with about 41.3 hours of use, and was within the 100-hour inspection interval.
Additional Findings
Data from the Dynon EMS D120 recorded 11 flights from September 19 to October 15, 2023. The accident flight recording lasted about 11 minutes 55 seconds. The highest fuel flow was 8.875 gph, fuel pressure remained above 5.25 psi, and engine rpm showed a gradual steady degradation. The sequence included takeoff roll beginning at 0757:33, maximum engine speed of 4,852 rpm at 0757:47, and subsequent reductions in rpm and groundspeed until the last recorded data at 0759:07 (groundspeed 50 kts, engine speed 2,656 rpm).
The NTSB materials laboratory examined the carburetors and found that the material in the 1/3-cylinder float chamber was corrosion product from oxidation of the zinc alloy float chamber, which had built up on the interior base and around the float chamber jet orifice.
Rotax Service Bulletin SB-912-079 notes that hot air conditions could be caused by incorrect use of carburetor heat, and that elevated intake temperatures with carburetor heat activated during high power settings can contribute to engine issues, potentially resulting in detonation, loss of power, and vibrations.