The National Transportation Safety Board did not travel to the scene of this accident.
Additional Participating Entity:
Federal Aviation Administration / Flight Standards District Office; Tampa, Florida
Aviation Accident Final Report - National Transportation Safety Board: https://app.ntsb.gov/pdf
Docket And Docket Items - National Transportation Safety Board: https://dms.ntsb.gov/pubdms
Aviation Accident Data Summary - National Transportation Safety Board: https://app.ntsb.gov/pdf
NTSB Identification: ERA15LA168
14 CFR Part 91: General Aviation
Accident occurred Tuesday, March 24, 2015 in Live Oak, FL
Probable Cause Approval Date: 02/13/2017
Aircraft: TRICK TRIKES 582 CYCLONE STORM, registration: N993RA
Injuries: 2 Minor.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
While flying about 1,000 ft above ground level (agl) during a flight test for the issuance of a sport pilot certificate, the sport pilot examiner instructed the sport pilot applicant to reduce power to idle for a simulated loss of engine power. The applicant chose a suitable field, began a spiral descent, and positioned the weight-shift-control aircraft for the simulated off-airport landing. When the aircraft was about 50 ft agl, the maneuver was terminated, and the examiner told the applicant to add power and go around. The applicant immediately started turning away from the field and then rapidly advanced the throttle. The engine sputtered and did not respond to the throttle input, and the aircraft then impacted trees. The applicant reported that at no time during the descent with the power reduced did he clear the engine nor did he recall the examiner telling him to clear the engine while descending at a reduced power setting. The applicant added that he mistakenly turned the aircraft before adding power and that, if he had not done so, he could have successfully landed it in the field.
Postaccident examination of the aircraft, which included an operational test of the engine, revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. The applicant’s failure to clear the engine during the prolonged descent and his subsequent rapid advancement of the throttle after terminating the simulated loss of engine power likely caused excessive fuel in the cylinders, which would have led to the engine’s failure to respond to throttle input.
The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
The student pilot applicant’s failure to clear the engine during a prolonged descent of a simulated engine failure and his subsequent rapid throttle input at the completion of the maneuver, which resulted in the engine’s failure to respond. Contributing to the accident was the sport pilot applicant's decision to turn the aircraft away from a suitable landing area before adding power.
On March 24, 2015, about 1915 eastern daylight time, a privately owned and operated Trick Trikes 582 Cyclone Storm weight-shift control aircraft, N993RA, was substantially damaged when it collided with trees during a forced landing near Live Oak, Florida. The sport pilot applicant (SPA) owner and sport pilot examiner (SPE) sustained minor injuries. Visual meteorological conditions prevailed at the time and no flight plan was filed for the instructional flight that was conducted under the provisions of 14 Code of Federal Regulations Part 91. The flight originated about 1845, from a private airstrip near Live Oak, Florida.
Earlier that day the SPA flew the accident aircraft with his instructor for about 1 hour and no discrepancies were reported with the engine during that flight. Following the flight, the SPA drove to the SPE's location and passed the oral portion of the practical test for issuance of a sport pilot certificate. The SPA then drove to where the aircraft was located, fueled it, performed a preflight inspection, and then flew to the location of the SPE, landing uneventfully.
Before departure of the accident flight, a preflight inspection and an engine run-up were performed; no discrepancies were reported. The flight departed with "at least" 5 gallons of fresh fuel on-board that he mixed with a little more than a 50:1 ratio of fuel to two-cycle engine oil. After takeoff, the SPA performed maneuvers, and while flying about 1,000 feet above ground level (agl) with fields nearby, the SPE informed the SPA that they would be performing emergency power off procedures, and asked him to reduce power. He did so, selected a suitable landing field, and surveyed the condition of the field while in a spiral descent. He set up to land in the field, and when the aircraft was aligned with the field about 50 feet agl, the SPE said the maneuver was terminated and to add power and go-around. The SPA immediately started turning, and then added power, but the engine sputtered and did not respond to the throttle input. The aircraft subsequently impacted trees. The SPA indicated that at no time during the descent with the power reduced did he add power to "clear" the engine, nor did he recall the SPE advising him to "clear" the engine while descending at a reduced power setting. He also indicated that he mistakenly turned before adding power, and otherwise could have landed "OK" in the field he had selected. In hindsight, he believed that the sputtering was related to the lack of clearing of the engine during the descent while at a reduced throttle setting.
The SPE stated that he informed the applicant to turn to a heading of 090 degrees, and as the right turn was started, he informed the SPA to reduce the throttle to idle to simulate an engine failure, and asked him to designate an emergency landing field. The SPA indicated the field below them was suitable, and began a spiral descent. The field below was an open 1.5 square mile area of cattle farm, which consisted of flat grassland with cows and small isolated groves of trees. During the spiral descent he did not recall the SPA "clearing the engine," and thought in hindsight that he should have. At 200 feet agl, he informed the SPA to "throttle up go-around." When the SPA advanced the throttle, the engine did not regain power. The intended landing field was straight ahead, but the aircraft turned left and began to climb immediately. The SPE attempted to recover, but the aircraft entered a left descending turn and hit trees no taller than 15 to 20 feet. The aircraft impacted the ground at an estimated speed of 30 mph. He and the SPA evacuated from the aircraft and walked to a house to summon assistance. The SPE further stated that the engine's failure to respond could have also been due to SPA's rapid throttle application, which he described as "a little fast."
According to the Federal Aviation Administration inspector-in-charge, during his examination of the aircraft, the frame near the nose gear was slightly bent to the right, and the right side diagonal frame tube was significantly bent. One propeller blade of the three bladed propeller was impact damaged, and approximately 5 gallons of uncontaminated fuel were recovered from the aircraft's fuel tank. The examination of the Rotax 582 engine did not reveal any apparent damage. Both carburetor bowls were removed and inspected, no contamination was noted. The aircraft was fueled with the recovered fuel and the impact damaged propeller was removed. The engine was then started immediately and ran to an idle power setting with no issues.
Following recovery of the aircraft, the SPA/owner inspected the engine with the exhaust removed and reported there was no scuffing or scoring of the sides of the pistons; honing marks in each cylinder were present. A replacement propeller was installed and after setting propeller blade angle, the engine was started and achieved near full red line rpm with no discrepancies noted.
According to the engine operator's manual, the engine by design is subject to sudden stoppage, which can result in forced landings or no power landings. The manual also indicated, "Do not idle for prolonged periods as normal rich condition present at this power setting can cause unnecessary carbon deposits and spark plug fouling." A representative of the engine manufacturer reported that during a long underpowered descent, a two-stroke engine such as the accident engine "loads up" because not all fuel is burned in the cylinders. With a rapid throttle advance, the fuel/air ratio becomes too high, causing hesitation until the excess fuel is cleared out.
The aircraft had been operated for about 19 hours since its last condition inspection, which was performed on April 14, 2014. At that time, the aircraft total time was 180 hours.