Georgetown, SC, USA
N18GT
FOLLAND AIRCRAFT CO LTD GNAT T 1
Witnesses at the airport reported that the pilot radioed them while on approach to let them know he was coming in to land, and they went outside to view the landing. The airplane crossed over the midfield of the airport and entered a right downwind. The airplane then made a high-speed flyby over the runway between 100 and 200 ft above ground level. At the end of the runway, the airplane pitched up about 30 degrees and began rolling left. According to the witnesses, the first 180 degrees of the aileron roll was "perfect," but, when the airplane reached about the 190-degree point, it abruptly pitched down to the right and collided with the ground. A postcrash fire ensued. Postcrash fire damage precluded a determination of whether a hydraulic system failure led to the loss of the tailplane/elevator pitch control. However, examination of the two switches on the control stick that operate the electric standby tailplane trim system, which can be used in the event of a hydraulic failure, revealed that the nose-down side of the right switch was inoperative. If a hydraulic failure occurred and this switch was inoperative, the pilot would not have had full tailplane authority during his aerobatic flight maneuver. Although the airplane was equipped with an additional, independent switch that would have allowed control of the tailplane/elevator in the event that this switch failed, the functionality of this switch could not be determined due to damage. Regardless of whether a mechanical problem initiated the pitch anomaly, the low altitude at which the pilot performed the flight maneuver allowed insufficient time for him to regain airplane control before the airplane impacted the ground.
HISTORY OF FLIGHTOn July 29, 2013, about 1320 eastern daylight time, a Folland GNAT T 1, airplane N18GT, collided with terrain during an uncontrolled descent near the Georgetown County Airport (GGE), Georgetown, South Carolina. The pilot was fatally injured, and the airplane was destroyed. The airplane was registered to Foogair Inc, and operated by the airline transport pilot as a personal flight under the provisions of 14 Code of Federal Regulations (CFR) Part 91. Visual meteorological conditions prevailed, and an instrument flight rules flight plan was filed for the flight that departed Yeager Airport (CRW), Charleston, West Virginia, destined for GGE. According to witnesses, the pilot radioed the airport on approach, and they went outside to see him land. The pilot crossed over the midfield and entered a right downwind for runway 23. The airplane made a high speed flyby over the runway between 100-200 feet AGL. At the end of the runway, the airplane pitched up approximately 30 degrees and began an aileron roll to the left. According to the witnesses, the first 180 degrees of the aileron roll was "perfect," but when the airplane reached about the 190-degree point, it abruptly pitched down and to the right and collided with the ground. An explosion was heard, followed by a plume of smoke. There were no distress calls prior to the accident heard over the radio according to the witnesses. PERSONNEL INFORMATIONThe pilot, age 79, held an airline transport pilot certificate for airplane multi-engine land and a third-class airman medical certificate with limitations for corrective lenses. The pilot reported his flight experience included 4,506 total hours and 52 hours in the last 6 months, as of his last exam dated March 28, 2012. The pilot's logbook was not recovered for examination. AIRCRAFT INFORMATIONThe single-seat, low-wing, retractable-gear airplane, serial number XS105, was manufactured in 1963. It was powered by a Rolls-Royce Orpheous turbojet, producing 4,705 lbs. of thrust. Maintenance logbooks were not available for review. METEOROLOGICAL INFORMATIONThe reported weather at GGE at 1335 was: winds calm, visibility 10 miles, scattered clouds at 3,400 and 7,500 feet, temperature 31 degrees Celsius, dew point 24 degrees Celsius, and altimeter 30.10 inches of mercury. AIRPORT INFORMATIONThe single-seat, low-wing, retractable-gear airplane, serial number XS105, was manufactured in 1963. It was powered by a Rolls-Royce Orpheous turbojet, producing 4,705 lbs. of thrust. Maintenance logbooks were not available for review. WRECKAGE AND IMPACT INFORMATIONThe wreckage was located in a heavily wooded area 1 mile southwest from GGE. The airplane was examined on scene on July 30 and 31, 2013. All major components of the airplane were accounted for at the accident site. A debris path revealed freshly broken tree branches at an approximate 45-degree angle. The debris path extended on a 309-degree magnetic heading, and various pieces of the airplane were located within path. The engine, fuselage, and the sections of the wings and cockpit were located at the end of the debris path and had been consumed by a postcrash fire. Flight control continuity to the flight controls was not confirmed due to the fragmentation of the flight controls hydraulic system. Examination of the fuselage and the cockpit revealed that it was fragmented and consumed by post-crash fire. The flight control instruments were located throughout the accident site. All instruments were impact-damaged, and the readings were determined not to be reliable. Examination of the left and right wings revealed that they were impact- and postcrash-fire damaged. The left and right ailerons were located in fragments at the accident site. The hydraulic lines within the wing assemblies were melted from postcrash fire damage. The aileron control actuators were impact and fire-damaged. The left and right flaps were fragmented and fire-damaged. The left and right main landing gear were located in the main wreckage debris and fire- and impact-damaged. The forward section of the empennage was consumed by fire. The tailplane/ elevator and rudder remained attached to fragments of the remaining empennage. The tailplane/ elevator were partially connected to the power flight control Hobson unit and were impact-damaged. All hydraulic lines and electrical wiring leading to the power flight control Hobson unit were broken and fragmented. Examination of the engine revealed it was impact and fire-damaged. The engine revealed signs of power within the compressor section of the engine. Various impact cracks were located along the flattened engine casing. Examination of the rotor turbine blades revealed rotational scaring along the inner engine case. Dirt and debris was located in the inlet section of the engine and throughout the engine compressor section to the exhaust outlet section ADDITIONAL INFORMATIONTitle 14 CFR 91.303 defines "aerobatic flight" as "an intentional maneuver involving an abrupt change in an aircraft's attitude, an abnormal attitude, or abnormal acceleration, not necessary for normal flight." The regulation states that "no person may operate an aircraft in aerobatic flight below an altitude of 1,500 feet above the surface." MEDICAL AND PATHOLOGICAL INFORMATIONAn autopsy was performed on the pilot by the Department of Pathology and Lab Medicine, Charleston, South Carolina, on July 30, 2013. The autopsy report noted the cause of death as "blunt force trauma." Toxicological testing was performed on the pilot by the Federal Aviation Administration (FAA) Bioaeronautical Science Research Laboratory, Oklahoma City, Oklahoma. Review of the toxicology report revealed: Metoprolol detected in muscle and liver TESTS AND RESEARCHA review of the pilot's notes revealed that the flight surface responsible for pitch is called the tailplane. The tailplane and the elevators are normally locked together and move as one unit under hydraulic power, in response to control stick movement. However, the elevators may be unlocked from the tailplane in flight; the system then operates with manually controlled elevators moving in response to control stick movement and a powered tailplane. In addition, full manual operation may be selected for practice purposes or in emergencies. In this case the elevators are manually controlled but the tailplane angle can only be altered by use of the standby trimming system. The standby trimming system is an electric motor on the Hobson unit that can operate the tailplane in the event the hydraulic motor cannot be used for any reason. During the examination of the airplane, two primary flight control components were recovered and examined by Stevens Aviation under the oversight of the FAA. 1. Hobson Unit: tailplane actuator (hydraulic & electrical) The condition of unit was impact-damaged. The hydraulic inputs were severed, and the electrical motor was impact-damaged such that an operational check could not be performed. 3. Control Stick: Examination of the control stick revealed that it was impact-damaged, but the internal switches were still intact. Further examination of the tailplane control switches at the hand grip revealed there were two switches that must be synchronized in order to electrically operate the tailplane in the event of hydraulic power failure. The 'nose down' side of the right switch was inoperative. All other contact points of the switches made a 'click' noise when actuated. There is a tailplane control on the cockpit left side panel that is an additional control input and independent of the hand grip switches for tailplane control. This switch was not located due to the destruction of the cockpit panel. This switch allowed control of the tailplane in the event the control stick failed. The control stick actuation and movement appeared to show that there was full aileron and rudder control available.
The loss of airplane control for reasons that could not be determined due to postcrash fire damage. Contributing to the accident was the pilot’s decision to perform an aerobatic maneuver at low altitude, which did not allow sufficient time for him to regain airplane control.
Source: NTSB Aviation Accident Database
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