N10VD

HISTORY OF FLIGHTOn November 1, 2019, about 1310 eastern daylight time, a Grumman OV-1D, N10VD, was destroyed when it was involved in an accident near Stuart, Florida. The airline transport pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

The pilot informed his crew chief before departure that he was not going to attempt any aerobatic maneuvers due to the cloud ceiling and windy conditions. The crew chief also reported that the pilot’s, “…only reason to fly was to visually locate the aerobatic box so he would be ready [for] the [air]show on Saturday. His intent was to make a slow-speed low pass followed by a high-speed low pass and a normal landing to a full stop.” While taxiing, the pilot, “did a complete flight control check,” including elevators, ailerons, flaps, inboard ailerons, speed brakes and rudders, and all flight controls appeared to move and work normally.

Automatic dependent surveillance-broadcast (ADS-B) data depicted the airplane taxiing and the entire flight. Before departure, the pilot advised the airboss that he would perform a “low show.” There was no further communication from the accident pilot. The airplane departed from runway 30, and one witness reported that he saw the landing gear and flaps retract after takeoff. The flight continued and deviated slightly north of the runway while climbing, then, when near the departure end of runway 30, began a climbing left turn, which one witness (an airshow performer) described as a “dog bone,” followed by a descending left turn. The airplane proceeded north of runway 12/30, then turned right, briefly flying parallel to the runway along the 1,500-ft show line, and descended to about 500 ft mean sea level (msl). About the midpoint of runway 12/30, the pilot began a climbing left turn, followed by a climbing right turn. A pilot-rated witness reported that the airplane entered an approximate 15° climb, before the pitch increased to “at least 35°” nose up. The witness stated that it appeared that there was “a break in the weather at the point he established that 2nd climb.”

Multiple witness accounts, including airshow performers, fire rescue personnel, a pilot associated with the airshow, and Federal Aviation Administration (FAA) personnel were consistent in describing the final portion of the flight, with slight variation based on their location and experience. During the climbing right turn near the approach end of runway 30, the airplane banked to the right to between 10° and 45° past 90°, characterized by one witness as “overbank.” This same witness reported that the airplane was pointed down runway 34, while another witness characterized the right turn as, “…a crisp right roll to about 135° and stabilized in that position.” The witnesses were consistent in describing the airplane descending nose-low, with several witnesses indicating that the airplane was accelerating while descending with the pilot “pulling,” or applying aft elevator control input. The turn radius decreased and the nose-low attitude continued until impact. Several witnesses described the engines sounding normal, with one reporting that he thought the engines were at full power.

Fire rescue personnel on the airport responded immediately to the accident site, with a Quick Response Truck arriving in less than 1 minute. Additional firefighting vehicles and personnel arrived, and the fire was under control within about 5 minutes of their arrival.

PERSONNEL INFORMATIONAccording to the pilot’s statement of aerobatic competency, he was required to complete all maneuvers, except for takeoff or landing, no lower than 250 feet. He reported that the date of his last performance or practice was August 31, 2019. The Special Provisions of the waiver for the airshow for pilots performing aerobatics required documentation of performing or practicing their performance within the previous 15 days. The pilot’s most recent FAA second-class medical certificate was issued on October 25, 2019. On the application for that certificate, the pilot reported 8,000 total hours of flight experience with 225 hours in the previous 6 months. The pilot reported no medical conditions and no medication use.

AIRCRAFT INFORMATIONThe airplane was equipped in part with ejection seats and a manually jettisonable top canopy; the ejection seats were disabled. Earlier that day, a mechanic was dispatched to check oil lines in the right engine compartment due to the pilot finding residual oil inside the engine cowling. The cowling was opened, and the mechanic reported checking the flexible lines on the bottom right side of the right engine. The pilot told him it was time for him to go, and he then closed the engine cowling. The mechanic added that the pilot told him he had added 1 quart of oil to the right engine.

The primary flight controls were controlled from the cockpit through mechanical linkages by the control stick and rudder pedals. In addition to the primary flight control surfaces, hydraulically powered inboard ailerons (used for additional control during takeoff and landing) were installed. The inboard ailerons were inoperative when the flaps were retracted. Trimming of secondary flight controls was performed manually by a cable and drum system that controlled the trim tab position.

AIRPORT INFORMATIONThe airplane was equipped in part with ejection seats and a manually jettisonable top canopy; the ejection seats were disabled. Earlier that day, a mechanic was dispatched to check oil lines in the right engine compartment due to the pilot finding residual oil inside the engine cowling. The cowling was opened, and the mechanic reported checking the flexible lines on the bottom right side of the right engine. The pilot told him it was time for him to go, and he then closed the engine cowling. The mechanic added that the pilot told him he had added 1 quart of oil to the right engine.

The primary flight controls were controlled from the cockpit through mechanical linkages by the control stick and rudder pedals. In addition to the primary flight control surfaces, hydraulically powered inboard ailerons (used for additional control during takeoff and landing) were installed. The inboard ailerons were inoperative when the flaps were retracted. Trimming of secondary flight controls was performed manually by a cable and drum system that controlled the trim tab position.

WRECKAGE AND IMPACT INFORMATIONThe airplane impacted the engineered material arresting system (EMAS) at the approach end of runway 30 on a magnetic heading of about 145°. A strong smell of jet fuel was noted in the area. Further examination of the initial impact point revealed two distinct impact craters consistent with each propeller/engine, which penetrated asphalt beneath the EMAS. Wreckage was noted on the EMAS and in grass north of the runway. The main wreckage, consisting of the cockpit, section of left wing, and empennage, were located about 150 feet from the initial impact location. The energy path between the initial impact point and the main wreckage was oriented on a magnetic heading of 055°. No bird remains were noted in the area of the accident site.

Examination of the airplane revealed extensive impact damage to the fuselage and aft empennage. The cockpit was destroyed by impact forces and the postcrash fire. Both wings exhibited extensive impact and/or fire damage. Examination of the right external fuel tank revealed impact damage to the front portion, which correlated to being about 38° from horizontal. Both landing gear were retracted, and the flaps appeared retracted. All primary and secondary flight control surfaces were connected or accounted for at the accident site.

Examination of the flight controls for pitch, roll, and the right rudder control system revealed multiple fractures or were cut for recovery, but there was no evidence of preimpact failure or malfunction. Examination of the left rudder flight control cable on the left side of the airplane between fuselage station (FS) 78 and about FS 107 revealed the cable remained attached at both ends, but was cut/fractured about 9 inches from the crank assembly near FS 107. Both ends of the cable and crank assembly were retained for examination by the NTSB Materials Laboratory, which revealed heat tinting and embedded particles with peaks of aluminum and oxygen, consistent with separation due to being cut from an aluminum oxide abrasive wheel during recovery.

The left elevator inboard edge exhibited a corresponding parallel static impact damage to the adjacent structure. The damage location was consistent with the elevator being at about 8° trailing edge up (nose up). The elevator trim tab was slightly tab-trailing-edge down (tail down), with the elevator in a neutral position.

Both engines exhibited extensive impact damage. The left engine was separated between the first and second stage axial compressor rotors, while the right engine was separated between the inlet guide vanes and the first stage axial compressor. Rotational scoring on both engines was noted in the second stage power turbine and the compressor sections. Borescope examination of both engines revealed rotational scoring on each impeller and impeller shroud. There was no evidence of preimpact failure or malfunction of either engine.

Examination of both propellers revealed that each had one blade remaining in the propeller hub and the remaining two blades from each propeller was separated but located in the debris field. Each blade that remained secured to the propeller hub exhibited forward bending; the remaining blade for the left propeller was slightly loose in the hub. Examination of the separated left propeller blades revealed both exhibited aft bending with sections of blade tip missing/separated. Examination of the separated right propeller blades revealed that one blade exhibited a slight twist toward low pitch, while the other bl...