N506XX

HISTORY OF FLIGHTOn March 11, 2015, at 1149 mountain standard time, a BAe Systems Hawk MK-67, N506XX, call sign BADGER1, collided with a truck during takeoff from the Yuma Marine Corps Air Station (MCAS)/Yuma International Airport (KNYL), Yuma, Arizona. The airplane was owned by Air USA, Inc., and operated as a public aircraft flight in support of the United States Air Force (USAF). The airline transport pilot and pilot-rated passenger were not injured. The driver of the truck sustained fatal injuries. The airplane sustained substantial damage during the accident sequence. The local area flight departed Yuma at 1148. Visual meteorological conditions prevailed, and a Military visual flight rules flight plan had been filed.

The airplane was being utilized along with a second similarly equipped Hawk (callsign BADGER2) by Air USA in support of the USAF as part of the Special Operation Terminal Attack Controller Course (SOTACC). They were performing a 15-second staggered takeoff, and their mission was to provide close air support (CAS) for the training of Joint Terminal Attack Controllers (JTAC's). The airplane was equipped with external fuel tanks on the inboard pylon of each wing, and bomb rack/dispensers loaded with practice ordinance attached to the outboard wing pylons.

At the time of the accident, a construction crew from the United States Marine Corps (USMC) was preparing a concrete pad at the left edge of runway 03L in preparation for the installation of an expeditionary arresting gear system. The pad was located 10 feet from the runway edge, about 6,500 feet from the runway 03L landing threshold. The construction operation, which included support vehicles, crew, and construction equipment, occupied the space from the runway pad outwards about 150 feet. The truck that was struck was located 140 feet beyond the runway edge, and was occupied by a Marine Lance Corporal who was providing operational escort and safety support for the construction crew.

The pilot reported that the preflight, engine start, taxi, and line-up on runway 03L were uneventful. The airplane was positioned on the right side of the runway, with BADGER2 positioned as the wingman to the left and aft. The pilot stated that once cleared for takeoff, he applied engine thrust and the engine spool-up, takeoff roll, and acceleration check speeds were as expected. He stated that he felt the airplane's nose wheel become light about the time they reached rotation speed. The nose of the airplane then lifted, and a short time later the main wheels became airborne. The left wing then dropped, and the nose yawed about 10 degrees to the left. He attempted to maintain a low angle of attack, applying slight rudder and aileron corrections. He considered aborting the takeoff, but due to the airplane's angle relative to the runway he was concerned the airplane might tumble if they entered the undulating adjacent terrain. He continued to apply corrective control inputs, but the airplane did not respond in a positive manner as he expected, and the left drift progressed. The airplane continued to bank left and then right, with the main landing gear and bomb dispensers striking the adjoining shoulder multiple times. The airplane was now flying directly over the gravel shoulder, about 100 feet left of the runway edge, when the construction crew came into view. The right wing struck the truck, and the airplane yawed to the right, coming to rest on the shoulder, about 650 feet beyond the point of impact. The truck came to rest about 160 feet beyond the point of impact. PERSONNEL INFORMATIONThe pilot held an airline transport pilot certificate with ratings for airplane single-engine and multiengine land along with type ratings, authorized experimental aircraft: AV-L39, Hawk. He held a first-class medical certificate issued on August 7, 2014; it had no limitations or waivers.

At the time of the accident, the pilot was a current and active A-10 pilot for the Air National Guard. The A-10 is a twin-engine, straight-wing, close air support airplane utilized by the USAF.

His aviation career began in 2000, initially as crew chief for the A-10; in 2008 he was commissioned to fly the A-10, having received training in both the T-37 and T-38. In March 2014 he began working as a contractor for Air USA, flying the L39.

The pilot reported a total flight experience of 2,116 hours, the majority of which (about 1,500 hours) took place in Tactical Jet aircraft, and primarily in the A-10. His total flight experience in the 12 months prior to the accident was 328 hours, and his total experience in the Hawk was 67 hours, with 55 as pilot-in-command. His last Federal Aviation Administration (FAA) checkride took place on January 19, 2015, and was for his airline transport pilot certificate.

The pilot's experience with the Hawk was gained exclusively while at Air USA, where he began his Hawk training in August 2014. The training was composed of flight manual study, followed by 2 days of ground school, cockpit familiarization, and ejection seat training. He then flew three graded instructional flights including five cross-country flights to establish basic and advanced aircraft handling along with instrument procedures, after which he was cleared to take the checkride for type rating with an FAA designated pilot examiner (DPE). Having gained his type rating, he went on to receive further instruction gaining initial qualification, mission qualification, air-to-ground qualification, and flight lead upgrade training, and after about 12 hours of total flight time, he was approved by Air USA to fly solo missions. Documentation provided by Air USA revealed that he scored 100 percent on all written examinations, and during air-to-ground training received the following comments, "Had some A-10 pilot tendencies during tight turns," "Has adjusted to the increased speed of the Hawk very well."

Air USA was the only private operator of the Hawk in the United States, and as such, the FAA DPE who performed the pilot type rating checkride did not have direct experience flying the Hawk. (The United States Navy operates the T-45 Goshawk, which is a Hawk variant).

The pilot-rated passenger was not an employee or contractor for Air USA. He had flown on the two previous missions with the pilot in the accident airplane, and was flying as a potential future pilot for Air USA in a "ride along" capacity. AIRCRAFT INFORMATIONThe Hawk MK-67 was a swept-wing, two-seat, advanced trainer/light attack airplane, powered by a single Rolls-Royce Adour turbofan engine. The accident airplane was manufactured in 1992 by BAe Systems in the UK as part of a group of 20 Hawks configured specifically for export to the Republic of Korea Air Force (ROKAF). The airplane was then utilized by the ROKAF for training until it was sold to Air USA, along with 11 other Hawk MK-67's in September 2013. The sale included documentation for the fleet, along with a series of spare parts. The airplane was subsequently exported to, and registered in, the United States, where it was issued a special airworthiness certificate by the FAA in the experimental/exhibition category in March 2014.

The later variants of the Hawk remain in production, with over 900 built since 1974.

Maintenance

Maintenance was performed in-house by Air USA mechanics on a continuous airworthiness basis, utilizing an OEM (original equipment manufacturer) inspection program. At the time of the accident, the airplane had accrued a total flight time of 5,625.3 hours. The engine total time was 3,782.7 hours, with the last overhaul occurring 155.7 flight hours prior.

Fuel System

The airplane's fuel system was comprised of an internal fuselage bag tank connected to integral wing tanks, with a total system capacity of 3,006 pounds. Two wing-mounted external "drop" tanks, mounted to the inboard wing pylons, increased fuel capacity by an additional 1,078 pounds per side. Fuel flowed from each external tank to the fuselage tank, and during transfer the integral tank system was automatically kept above 2,400 pounds until the external tanks were empty.

The external tanks structural integrity was maintained through a series of internal ribs and stringers; the tanks did not contain baffles, and the fuel was free to move within the tanks during flight. The external tank fuel quantities were the subject of handling and maneuvering limitations in-flight, but no limitation existed regarding the fuel quantity held in the tanks during takeoff. The airplane's flight manual, "External Wing Fuel Tank - Limits" section noted the following, "10 seconds of straight-and-level flight is recommended before jettison to permit the fuel contents to stabilize."

The accident pilot reported that the Hawk was the only airplane he had flown that does not place limitations on partially filled external tanks during takeoff, and that in his experience, takeoff with partially filled tanks is not recommended due to the increased sensitivity of pitch control, decrease in lateral directional control at low speeds, and the potential for tank damage. A BAe test pilot was interviewed during the investigation. He stated that although there are no external tank quantity limitations for takeoff, his personal practice is to always takeoff with the external tanks either full or empty, so that should they need to be jettisoned during departure, they will fall from the airframe in a predictable manner. The Air USA Chief Pilot reported that 75 percent of all Air USA missions were conducted with the external tanks partially filled at takeoff, and that they had no previous issues.

The airplane had been experiencing intermittent external tank fuel transfer problems in early February 2015, when it was performing live fire exercise for the USMC in North Carolina. The external tanks were not consistently transferring fuel automatically to the internal tanks, and the airplane was flown to Air USA's primary maintenance facil...