History of Flight
On August 2, 2023, at about 1036 Pacific daylight time, a Czech Sport Aircraft SportCruiser, registration N384SC, was destroyed when it crashed in Van Nuys, California. The flight instructor and student pilot were fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight.
ADS-B flight track data showed that the airplane initially departed runway 16L at Van Nuys Airport (VNY) about 1021:33. It entered the left traffic pattern and performed a touch-and-go landing at 1027:39. The airplane entered the left traffic pattern again, following a similar flight path. It touched down about 1033:57 and became airborne about 1,700 feet down the runway. After a 14-second data gap, the flight path continued above taxiway K, with ground speed decreasing from 60 to 50 knots. The flight path continued at that speed and altitude increased.
At 1035:09, the airplane made a left turn onto the crosswind leg while climbing to about 315 feet agl. It then turned to the downwind leg; these turns were closer to the runway and at a lower altitude than in the first two takeoffs. After a 15-second data gap, the track continued at 1035:42 with a ground speed of 71 knots and altitude of 430 feet agl, the highest altitude during this flight segment.
The airplane turned left toward the airport while altitude gradually decreased. Around 1036:12, about 830 feet from the runway, it made a slight right turn to parallel the runway. About 22 seconds later, abeam the runway 16L threshold, the ground speed was about 55 knots. The airplane then turned left at about 195 feet agl. The last flight track data point was recorded at 1036:39, located 255 feet east-northeast of the accident site, showing an altitude of 170 feet agl.
Numerous security cameras captured footage. After turning onto the downwind leg for runway 16L, the airplane maintained steady altitude. Around 1035:42, it performed a complete 360° turn with altitude fluctuations. Toward the end of the turn, it climbed. The airplane briefly flew toward the runway, descending before turning to fly parallel to the runway.
At 1036:35, the airplane initiated a left bank that steepened aggressively. As the bank angle increased, the nose dropped. The airplane impacted the ground in a near-vertical attitude. The parachute did not deploy, and the flaps appeared to be retracted.
The pilots were in communication with the Van Nuys airport traffic control tower. The student pilot made transmissions for the beginning portion of the flight. On the third takeoff, around 1735, the flight instructor told the controller, "we are having some power loss." The controller asked if they required assistance. The instructor stated, "priority landing," repeated several times. About 30 seconds after the "power loss" transmission, the controller cleared the airplane to land on runway 34R. The controller again asked if assistance was needed; the instructor replied, "negative, we are landing right now." About one minute after the power loss transmission, the controller cleared the airplane to land on any runway. About 10 seconds later, the controller asked the nature of the emergency; the instructor responded, "we are having exhaust gas temperature issues."
Aircraft Information
Engine logbooks showed the last maintenance was a 100-hour inspection on July 30, 2023, at tachometer time 925.0 hours. The engine was built in October 2014 and started regular operation in 2018.
No maintenance was conducted on the engine between February 2021 and February 2023. On January 19, 2021, at tachometer time 565 hours, the carburetor floats were replaced in compliance with a service bulletin. No logbook entries indicated further maintenance on either carburetor before the accident. The engine manufacturer stated that the carburetor piston slides would not have been removed as part of the service bulletin.
According to the pilot's operating handbook, at maximum takeoff weight of 1,320 lbs and an estimated bank angle of 30°, the stall speed would be about 38 knots indicated airspeed, with 270 feet of altitude loss during recovery.
The airplane was equipped with a Dynon Skyview system and one Dynon SV-D1000 screen, both burned beyond recovery of non-volatile memory. The Dynon alert system provides non-flightpath alerts through a flashing Alert Notification Indicator: red for warnings, yellow for cautions, gray for messages. In the event of high EGT in the red range, the system displays a flashing red warning and, if audio alerts are activated, announces "EXHAUST GAS TEMPERATURE" in the headset. The EGT red range starts at 1,616°F, the maximum EGT for the engine.
The engine was equipped with two Bing constant depression carburetors. These cross-draft butterfly valve carburetors have a variable venturi actuated by a carburetor piston suspended on a rubber diaphragm. The Rotax Heavy Maintenance Manual assembly procedure for the carburetor states that the diaphragm's index tabs must fit into the indentation of the carburetor piston, and the position is determined via these tabs. A highlighted notice cautions to not turn the carburetor piston assembly out of position while installing the chamber top.
Wreckage and Impact Information
The accident site was about 425 feet from the edge of runway 16L, with all wreckage found within the same area on a ground track of 300°. The farthest wreckage was part of the rocket from the parachute system. Small plexiglass shards were found in front of the main wreckage. There was no evidence of soot or oil on the airframe.
The wreckage was consumed by fire. The propeller was in front of the wreckage, and a divot in the concrete pad was consistent with first impact. The wings and tail remained attached. The flap position could not be ascertained due to thermal damage, but video footage suggested they were extended. The fuselage body was bent down at the empennage adjacent to the step, with the tail resting on the ground. The rocket had been deployed and was found ahead of the wreckage.
An external examination of the engine revealed the crankcase was fractured in numerous areas, with many accessories broken from their mounting flanges. The engine sustained thermal damage, and numerous fuel and oil lines were completely consumed. The ignition system was consumed by fire, precluding testing. Firefighters used fire suppressant and water to extinguish the fire.
The top spark plugs appeared in normal condition, and all electrodes were similar in shape. The combustion chambers and internal case were examined via a lighted borescope, with no evidence of valve-to-piston face contact. Camshaft lobes did not appear rounded, and no material deformation was observed.
Carburetor examination: The No. 1/3 carburetor was found with its piston slide misaligned when viewed through the venturi; the half-moon curve at the bottom of the slide was not aligned with the carburetor bore. After removing the carburetor top, the piston was extracted. The diaphragm's index tabs were not aligned with the corresponding slots in the carburetor top, indicating incorrect assembly.
The No. 2/4 carburetor piston slide had more misalignment than the No. 1/3 carburetor. After removing the carburetor top, the piston was extracted. The diaphragm had been consumed in the post-impact fire, preventing confirmation of proper alignment between the index tabs and housing slots.
According to the engine manufacturer, this misalignment can result in vibrations (experienced as a rough running engine), excessive decreases in rpm when operating on a single magneto (e.g., during a before-takeoff engine run-up), and a reduction in overall engine performance.