History of Flight
On December 1, 2012, about 1319 eastern standard time, an experimental amateur-built Thorp T-18, registration N118GG, was destroyed when it broke up in flight over Pahokee, Florida. The flight was conducted under 14 CFR Part 91 as a personal flight. The airline transport pilot was fatally injured. Visual meteorological conditions prevailed, and no flight plan was filed. The flight departed Pompano Beach Airpark (PMP), Pompano Beach, Florida, at 1259.
According to family members, the pilot was en route to Lakeland Linder Regional Airport (LAL), Lakeland, Florida. The pilot was overdue on arrival, prompting an alert notice. During the search, an emergency distress signal was received from the airplane's emergency locator transmitter, and local authorities located the airplane the following day at 0610.
According to information from the West Palm Beach Air Traffic Control Tower (ATCT), at 1313, the pilot contacted Palm Beach Approach on frequency 124.6 at 6,500 feet msl on a heading of about 335 degrees. The approach controller issued the current altimeter setting for Palm Beach. The pilot was then issued a traffic advisory at 6,500 feet msl, and the pilot reported climbing to 8,500 feet msl.
At 1315, Palm Beach Approach instructed the pilot to maintain 7,500 feet msl and advised of traffic at his 12 o'clock, 5 miles southeast-bound. The traffic was identified as a Boeing 757, and a wake turbulence caution was issued. Radar data showed the Boeing 757 at 8,000 feet msl heading 144 degrees. The pilot advised descending back down.
At 1316, the pilot reported the traffic in sight; radar data showed horizontal separation of 1 to 2 miles and vertical separation of 300 to 500 feet at the time.
At 1317, the pilot requested climb to 8,500 feet msl and was cleared. Radar data showed the accident airplane turned right and continued adjacent to the Boeing 757's flight path. Approximately 3 minutes after the separation event, the accident airplane climbed to 8,300 feet msl before descending to 7,200 feet msl and was lost from radar. The Boeing 757 had passed the point where the accident airplane was lost from radar about 5 minutes earlier at an altitude of 9,900 feet.
Pilot Information
The pilot, aged 80, held an airline transport pilot certificate for airplane single-engine land, multi-engine land, and rotorcraft-helicopter issued May 27, 2008, and a third-class airman medical certificate issued August 31, 2011, with a limitation for corrective lenses. The pilot's logbook was not recovered. According to FAA records, the pilot reported 30,000 total flight hours and 28 flight hours in the 6 months preceding the medical certificate issuance.
Aircraft Information
The two-seat, low-wing, tailwheel airplane, serial number 949, was manufactured in 1980. It was powered by a Lycoming O-360 engine built by the pilot/owner, equipped with an Aymar-Demuth two-bladed wooden propeller. Maintenance logbook records showed an annual inspection completed March 15, 2012, at an airframe total time of 2,561.7 hours and an engine time of 1,715.6 hours.
Meteorological Information
Weather recorded at Okeechobee County Airport (OBE), about 28 miles south of the accident site at elevation 33 feet, at 1315: wind 040 degrees at 9 knots gusting 16 knots, visibility 10 miles, scattered clouds at 4,900 feet above ground level, temperature 23°C, dew point 14°C, altimeter 30.20 inches of mercury.
Wreckage and Impact Information
The airplane impacted a sugarcane field about 2 miles southeast of Palm Beach County Glades Airport (PHK), Pahokee, Florida. The fuselage came to rest inverted in a flat attitude on a course of 315 degrees. The propeller remained attached to the engine, and the engine remained attached to the firewall and main landing gear, located about 200 yards east of the main wreckage. Fragmented parts from both outboard wings were near the engine. The instrument panel was not located.
Examination of the fuselage revealed the flight control stick connected to aileron and elevator control tubes. Rudder and tailwheel control cables were connected at their attachment points. The rudder pedals were not located, and the cables showed overstress failure. The fuselage and empennage were buckled. The left and right wings were separated at the spar attachment joint. The vertical stabilizer was partially separated from the empennage.
The engine sustained impact damage concentrated on its upper and lower sides. The starter motor remained attached; the alternator remained attached but was impact-damaged. All push rods were impact-damaged and bent. The engine had an Electroair direct ignition system and an E-Mag electronic magneto; the magneto mounting area was capped off. Both systems were impact-damaged. The vacuum pump was broken away from its mount and not recovered. All ignition leads had varying impact damage. Spark plugs were automotive NGK plugs fitted with cylinder sleeves; upper and lower plugs exhibited gray color on electrodes and combustion deposits. Cylinder combustion chambers were free of debris with normal combustion deposits. All fuel injection lines were impact-damaged and broken. The fuel sump was broken, and the sump screen was free of debris. The crankshaft was rotated, and compression and crankshaft continuity were established on three of the four cylinders during rotation. Valve train continuity was established on cylinders Nos. 2 and 4. Push tubes for cylinders Nos. 1 and 4 were bent, and valve movement could not be established; lifters for those cylinders moved when the crankshaft was rotated. The oil sump screen was clear. Examination of the engine and components did not reveal any preimpact mechanical malfunctions or failures that would have precluded normal operation.
The propeller blades were constructed of wood. One blade remained attached to the hub; the other was broken away at the hub root. The remaining blade exhibited small fractures and broken pieces of wood throughout the blade span.
Medical and Pathological Information
An autopsy was performed on the pilot on December 2, 2012, by the Office of the District Medical Examiner District 15, West Palm Beach, Florida. The FAA's Civil Aerospace Medical Institute performed forensic toxicology on specimens from the pilot with negative results for alcohol. Losartan and Metoprolol were detected in the muscle and blood cavity.
Tests and Research
The inboard sections of the left and right wing main spars were sent to the NTSB Materials Laboratory for examination. The parts received were attached to the respective adjacent outboard sections of the wing carry-through structure. The upper and lower spar caps of the carry-through structure were fractured just inboard of the doublers attached to the forward face of the structure. Close examination of the spar fractures uncovered features indicative of overstress fractures with no indications of preexisting cracking or corrosion. On both sides of the carry-through, the lower spar caps displayed tensile fractures with gradual bends. The upper spar caps showed compression buckling with overstress fractures in the highly deformed center of the buckles. The deformation associated with the fractures and surrounding areas was consistent with tip-up bending of both wings.