N712AZ

On January 31, 2017, about 1500 central standard time, an experimental, amateur-built Cook Smith Aviation Replica SU airplane, N712AZ, sustained substantial damage when it struck trees and impacted terrain during a forced landing after a loss of engine power near Justin, Texas. The pilot received minor injuries and the passenger received serious injuries. The airplane was registered to Clear Blue Marketing, Inc., and was operated by the pilot under the provisions of the Title 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed for the flight, which was not operating on a flight plan. The flight departed from the Northwest Regional Airport (52F), Roanoke, Texas, about 1440 on a local flight.

The pilot reported that he departed with 10 gallons of fuel in the left fuel tank and 15 gallons of fuel in the right fuel tank. He had flown for about 15 minutes in straight and level flight when he flew a practice forced landing to a wheat field. He stated that during the recovery from the practice maneuver, he turned off the carburetor heat, applied full power, and raised the nose to a steep pitch attitude of about 35° to 40° nose up. He stated that the engine experienced a total loss of power in the climb about 200 to 500 ft above ground level. He pushed the stick full forward to maintain airspeed and he chose to land straight ahead. He stated that the engine started to "sputter" and regain power about the time that the airplane struck the trees, which resulted in substantial damage to the wings and fuselage. The pilot and passenger were able to exit the airplane. The pilot stated that he turned the fuel selector to the OFF position and disconnected the battery cable.

The 52-year-old pilot held a private pilot's certificate with airplane single-engine land and airplane single-engine sea ratings. He held a third-class medical certificate issued on January 1, 2016. The pilot reported that he had 1,054 total flight hours with 176 flight hours in the make and model of the accident airplane.

The experimental, amateur built Cook Smith Aviation Replica SU, N712AZ, serial number 30-6, was manufactured in 2008. The high-wing airplane was a two-place tandem seat airplane equipped with the 180-horsepower TMX Mattituck O-360 engine and had a maximum gross weight of 2,400 lbs. Leading edge slats were installed along the entire span of the right and left wings, which allows the airplane to be flown at a very high nose up attitude. The fuel system was a gravity feed system to the carburetor. Each wing had a 24-gallon metal fuel tank, but there was no header tank installed. The 3/8-inch diameter fuel lines went from the fuel tanks to the fuel drain located in the belly of the airplane aft of the engine firewall. Then the fuel lines were then connected to the fuel selector before being routed to the carburetor through a fuel transducer which measured the fuel flow. The airplane was not equipped with an electric fuel boost pump.

Airplane maintenance records indicated that the airplane was previously involved in a nose over accident. Maintenance was performed to bring the airplane into an airworthy condition, which was completed on November 3, 2016. At the time of the inspection, the maintenance logbooks indicated that it had 124.60 hours total time on the airframe, and the tach read 0.0 hours. The pilot reported that at the time of the accident, the engine had a total time of 145 hours and 21 hours since the last inspection.

Figure 1 - View of the airplane wreckage at the accident site

A Federal Aviation Administration inspector examined the airplane at the accident site. He reported that the left wing had impacted the trees and remained lodged in the branches. The left-wing fuel tank was separated from the wing and was found lying on the ground. It exhibited minor impact damage. The fuel cap was off, and no fuel was found in the tank. The main airplane wreckage was located about 40 ft from the tree that was struck by the left wing. The fabric-covered right wing was found with the main wreckage, but it was broken and fractured at numerous places. The right-wing's metal fuel tank's leading edge was crushed about 12 inches, which was consistent with an impact with a tree. The fuel tank was compromised, and the fuel cap was off. The inspector reported that the carburetor bowl plug was removed, and no fuel drained from the bowl. There were no apparent fuel stains on the fabric covered wings. The propeller did not exhibit rotational damage.

The engine was shipped to the Continental Motors facility at Fairhope, Alabama, for examination and engine run. The engine was installed on an engine test stand and an engine run was conducted. The engine operated through a range of engine RPMs between 1,200 to 2,700 RPMs, and at idle. The engine was not equipped with an engine driven fuel pump.

At 1454, the surface weather observation at the Fort Worth Alliance Airport (AFW), Fort Worth, Texas, located 6 nautical miles southwest of the accident site, was: wind 190 at 6 kts; 10 miles visibility; sky condition few clouds at 25,000 ft; temperature 26° C; dew point -4° C; altimeter 29.88 inches of mercury.

The Smith Aviation Replica SU airplane kit is no longer in production; however, Backcountry Super Cub manufactures a similar airplane kit. The owner of Backcountry Super Cub reported that all their engines are equipped with engine driven fuel pumps, and he recommends that aircraft builders install electric fuel boost pumps to ensure adequate fuel flow to engines that demand more fuel at high power settings. He reported that the slats on the leading edge of the wing allow for a very high nose up attitude, about 40-50 degrees up, which could possibly cause fuel starvation unless there is adequate fuel head pressure to deliver the fuel to the carburetor.