History of Flight
On July 15, 2019, about 1426 Pacific daylight time, a Robinson R-44 II helicopter, registration N144TG, was substantially damaged during an instructional flight at Hayward Executive Airport (HWD), Hayward, California. The flight instructor was fatally injured, and the student pilot was seriously injured. The flight was conducted under Title 14 Code of Federal Regulations Part 91.
Data from FAA air traffic control audio and radar tracking, as well as a third-party GPS source, were used to reconstruct the flight. After several traffic pattern circuits, the helicopter performed hovering maneuvers on a taxiway designated for helicopter training. At 1422, the instructor requested takeoff clearance, but ATC denied the request and asked the instructor to stand by.
GPS data indicated the helicopter continued hovering before slowly moving west and entering a left turn over a patch of hard dirt and vegetation southwest of the taxiway. Surveillance video from an adjacent building captured the helicopter’s shadow during its final movements. The shadow entered the frame with the nose west, then performed a brief side hover to the south, followed by a rapid turn to the southeast, with ground speed increasing from about 2.5 mph to about 18 mph. In the final moments, the helicopter turned rapidly to the north with a high left bank angle, and a cloud of dust appeared before the shadow disappeared.
According to the student pilot, the accident occurred about 1 hour into the flight near the end of the lesson. The instructor appeared calm and confident. The lesson included left-hand traffic patterns, takeoffs, landings, hovering, and turns. The instructor asked the student to hover-taxi over the runway and return to a marked spot. The student reported that the instructor would take the controls when the helicopter was away from the taxiway over the grassy area. In the final minutes, the instructor took the controls, explaining that the student should keep his eyes on the horizon and not look down. The instructor requested takeoff clearance but was told to hold. He began a left turn, but the helicopter turned very rapidly and pitched left. The instructor then made a right turn, and the student observed another rapid turn with a right pitch before impact.
A study of the surveillance footage by the National Transportation Safety Board (NTSB) analyzed the helicopter’s roll angle in the last seconds. The exact height above ground could not be determined. Once over a berm on a southern heading, the helicopter rolled left about 70° as it neared a fence line. The roll angle then decreased to about 40° as the turn continued. As the helicopter turned north, the left roll angle increased to about 90°. The main rotor blades contacted the ground, and the helicopter came to rest.
Personnel Information
According to the student pilot’s logbook, he began flight training in July 2018 in the same helicopter make and model. The flight instructor who had previously trained the student stopped in December 2018. That instructor recalled that the student progressed slower than other students and made unnecessarily aggressive control inputs every few flight hours. During hover practice, the student would input too much pedal, shifting the helicopter, but usually corrected the movement on his own; occasionally, the instructor intervened.
Wreckage and Impact Information
The helicopter came to rest on its left side, about 50 feet from taxiway Zulu, at the top of a 3-foot-tall berm. The main wreckage was oriented on a magnetic heading of 052°. The first identified point of impact was a ground scar 95 inches long, 14 feet south of the main wreckage, consistent with a main rotor blade strike. Plexiglass fragments were found forward of the cabin beyond the berm. A 2-foot section of a main rotor blade tip came to rest about 250 feet southwest on a building roof.
Cyclic and collective control continuity was confirmed from the cockpit to the main rotor blades. Both main rotor blade pitch change links were broken, with overload fracture surfaces. The three main rotor servos operated smoothly when actuated by hand. The anti-torque pedals were crushed and could not be moved, but system continuity was traced to a separation at the bell crank.
The main rotor drive shaft rotated smoothly; oil was present in the gearbox. The tail rotor drive shaft was continuous from the transmission to the tail rotor blades except for a separation at bay 2. The four V-belts were in good condition but had skipped one groove aft in the upper sheave and were displaced in the lower sheave. Rotational continuity of the main and tail rotor drive systems was confirmed.
Both main rotor blades remained attached to the hub. One blade was bowed upward with chordwise creases; a 2-foot tip section separated with chordwise scuff marks. The spar was bent opposite the direction of rotation at the fracture. The other blade displayed slight downward bending opposite rotation, with chordwise creases and tip scuff marks. Both tail rotor blades remained attached; one had a chordwise wrinkle, and tree residue was observed on both blades.
Rotational continuity was established in all six engine cylinders when the crankshaft was rotated by hand; the engine showed no catastrophic internal failure. Both magnetos produced spark.
A punch tool about 5 inches long was found resting beneath the tail rotor control bell crank behind the aft bulkhead of the cabin.
Tests and Research
The helicopter’s hydraulic system components—pump, three servos, reservoir, and interconnecting lines—were removed and tested at the manufacturer’s facility. All parts passed acceptance test procedures. Inspection of hoses revealed a trace amount of dark particles but no obstructions.
The manufacturer performed tests to determine if the punch tool could interfere with tail rotor bell crank travel. The testing showed that the punch could have inhibited left pedal input by up to 40%.