History of Flight
On August 17, 2015, about 1850 central daylight time, a Zenair LTD CH 2000 airplane, registration N26ZA, impacted terrain after departing from McAllen Miller International Airport (MFE) in McAllen, Texas. The flight instructor and student pilot were fatally injured, and the airplane was destroyed. The airplane was registered to a private individual and operated by McAllen Aviation under 14 Code of Federal Regulations Part 91 as an instructional flight. Visual meteorological conditions prevailed, and no flight plan was filed. The local flight was originating at the time of the accident.
Air traffic control communications revealed that the flight instructor intended to complete four to five landings in the traffic pattern. The pilot was cleared for takeoff but aborted the attempt about 90 seconds later. Unable to clear the runway in time, an incoming airplane was instructed to go around. The pilot taxied back to the departure runway and stated they were ready for departure again. The controller issued a takeoff clearance and instructed him to make right traffic patterns. About two minutes after being cleared for takeoff, the pilot transmitted that the next landing would be a full stop. The tower controller advised that a helicopter was one mile south inbound for landing. Shortly after, the controller observed the airplane in a descent into terrain, describing that the airplane appeared to have very low airspeed when it made a hard right turn, winged over, and descended straight down.
Witnesses described the wind as strong and gusting. They observed the airplane after departure making a right turn and then appearing to stop in the air before descending to the ground.
The operator's chief flight instructor flew the airplane for 1.7 hours on the morning of the accident to determine if it was suitable for conversion to an instrument flight rules (IFR) training airplane. He gave the airplane very high marks and noted no abnormalities. He was also told by a hangar tenant that wind gusts were very strong around the time of the accident.
Personnel Information
The flight instructor, age 32, held a commercial pilot certificate with ratings for airplane single engine land, multi-engine land, and instrument airplane. He also held a flight instructor certificate for airplane single engine and instrument airplane. He was issued a first-class medical certificate on January 6, 2015, with no limitations. On his last application, he reported 840 total flight hours with 50 hours in the preceding six months. According to his résumé and the airplane owner, he had accumulated 896 total flight hours.
The student pilot, age 42, was a Mexican national with Transportation Security Administration (TSA) approval for flight training. The flight school reported that the student pilot had completed three training flights since June 17, 2013, for a total of 4.1 flight hours and one discovery flight with another school in 2011.
Aircraft Information
The Zenair CH 2000 was a two-place, low-wing, fixed tricycle landing gear airplane manufactured in 1997, serial number 20-0026. It featured two side-by-side, independently adjustable seats and dual flight control yokes. The airplane was equipped with a 116-horsepower Lycoming O-235-N2C engine driving a two-bladed, fixed-pitch metal Sensenich propeller. It had two wing fuel tanks holding 14 gallons each, for a total of 28 gallons.
A review of maintenance logbooks revealed that an annual inspection was completed on March 10, 2015, with a tachometer time of 1,639.1 hours. On August 13, 2015, two engine spark plugs were serviced and reinstalled.
The airplane was sold by the listed registered owner on August 8, 2015, but the updated registration paperwork was never sent to the FAA.
Meteorological Information
At 1853, the automated weather observation at MFE reported wind from 080 degrees at 19 knots, gusting to 25 knots, 8 miles visibility, scattered clouds at 8,500 ft, temperature 95°F, dew point 72°F, and barometric pressure 29.81 inches of mercury.
Air traffic control communications included multiple wind reports: about 15 minutes prior, wind from 080 degrees at 6 knots; about 6 minutes prior, wind from 070 degrees at 7 knots; about 4 minutes prior, wind from 050 degrees at 10 knots; about 2 minutes prior, wind variable from 060 to 100 degrees at 10 knots, gusting to 15 knots.
An outflow boundary (gust front) was present near MFE at the time of the accident, capable of producing low-level wind shear across the region.
Wreckage and Impact Information
The accident site was located about 0.2 miles south of the departure end of runway 13 at MFE, at 95 ft mean sea level, in thick brush and shrubs. The ground west of the accident was burned by a post-impact fire.
The airplane impacted terrain on a heading of 140 degrees in a nose-low and left-wing-low attitude. The airplane remained mostly intact, with a consolidated debris field; no ground impact marks were noted around the wreckage. The engine compartment, cockpit, fuselage, and empennage were mostly consumed by fire. The empennage was distorted and twisted toward the right wing. Both wings remained attached; wing roots exhibited thermal damage. The right wing leading edge was crushed aft, and its trailing edge, including flap and aileron, was partially consumed by fire. Both ailerons were extended down and moved freely by hand. Flaps were found extended but free to move, as the flap chain drive had separated in overload. The left wing sustained leading edge damage, crushed aft on the bottom side. Left flap and aileron remained intact with impact damage. Both leading edges exhibited accordion-style crushing. The nose gear was folded under the fuselage; main landing gear was detached and bent aft. Both seat belt buckles remained clasped, belts consumed by fire. Fuel tanks were breached and thermally damaged. Flight control cables were continuous from cockpit controls to aileron, rudder, and elevator attachment points.
The engine remained attached to the firewall and sustained thermal and impact damage; the cowl was consumed by fire. The propeller separated at the crankshaft flange and came to rest in front of the engine. One blade was partially embedded in the ground, bent aft about midspan, with a relatively straight tip, twisted, and with chordwise scratching and damage. The other blade was slightly bent aft near the root and otherwise unremarkable.
During recovery, the engine was separated and taken to a hangar for examination. The crankcase did not display the stamped serial number; the right half displayed case match number 3712, while the left half number was ground off. The crankshaft flange was bent. The starter, starter ring gear support, right magneto, and alternator were impact damaged. The carburetor induction air box was crushed. The engine-driven fuel pump, vacuum pump, and fluid lines were thermally damaged. Engine wiring and induction tube interconnects were mostly consumed by fire. The No. 1 top spark plug was impact damaged. Engine accessories and top spark plugs were removed to manually rotate the crankshaft; continuity to crankshaft, camshaft, and valve train was verified. Suction and compression were verified in all cylinders. The oil suction screen was free of particulates; the inlet fuel screen was also free of particulates. The carburetor was secure on its mount; the inlet screen was free of particulates. The carburetor bowl had a left side metal float dislodged from the actuator arm, resting in the float chamber with hydraulic deformation; the right metal float was secure. The carburetor contained a one-piece venturi. The right magneto produced no spark when rotated; internal components were melted. The left magneto could not be rotated due to internal thermal damage. The examination revealed no preimpact mechanical malfunctions or failures that would have precluded normal operation.
Remnants of a GoPro camera were found in the wreckage but were mostly consumed by fire; data recovery was not possible.
Additional Information
A witness who interacted with the flight instructor on August 14, 2015, stated that the flight instructor asked him to move vehicles because he was going to start the accident airplane and troubleshoot a throttle issue. The witness recalled the engine running at about 2,000 RPM and the throttle cable getting stuck, preventing proper RPM control. Other than the unexpected high RPM, the engine sounded normal. The witness told the flight instructor to inform the airplane owner of the throttle issues. The witness saw the flight instructor two to three times that day between 1200 and 2000. The airplane owner was present during some of that time.
Fuel receipts showed the last refueling was on August 13, 2015, with 12.9 gallons of 100 low-lead aviation fuel. The owner reported the airplane was flown two times after refueling for a total of 1.7 hours, not including the accident flight.
Medical and Pathological Information
An autopsy on the flight instructor, completed on August 18, 2015, by Valley Forensics, P.L.L.C., Edinburg, Texas, determined the cause of death as multiple traumatic injuries with thermal burns. The autopsy report noted both feet sustained fractures. The FAA's Civil Aerospace Medical Institute completed a Final Forensic Toxicology Fatal Accident Report, which was negative for tested drugs and other substances.
An autopsy on the student pilot, also completed on August 18, 2015, determined the cause of death as multiple traumatic injuries with thermal burns. The toxicology report was negative for tested drugs and other substances.
Tests and Research
The airframe throttle control assembly was removed and sent to the NTSB Materials Laboratory for examination. It was discolored and oxidized consistent with fire exposure; the aluminum alloy housing was wrinkled consistent with high heat. The control cable had been cut during removal and was bent about 90 degrees at the output end of the input tube; the spiral wrap around the cable housing wires was fractured and displaced at the bend. The input rod was slightly bent where it intersected the lock screw opening. The lock mechanism had a gap between the lock screw and lock bushings consistent with an unlocked position. The cable was straight in the segment within the input tube between the input rod and the cable housing. X-ray computed tomography (CT) confirmed it was unlocked. When the input rod was manipulated by hand, initially pushing the input knob inward (toward the panel as installed), the rod moved slightly; then pulling the knob in the opposite direction caused the input rod to slide completely out of the assembly with minimal hand forces.