N5940

HISTORY OF FLIGHTOn July 25, 2016, about 0945 eastern daylight time, a Yakovlev Yak-11, N5940, was substantially damaged by fire after landing at Allegheny County Airport (AGC), West Mifflin, Pennsylvania. The commercial pilot was fatally injured. The airplane was privately owned and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan was filed for the personal flight, which originated at Chester County Airport (MQS), Coatesville, Pennsylvania, about 0830.

The accident occurred during the first leg of a multiple leg cross-country flight to the Experimental Aircraft Association (EAA) fly-in and convention (EAA AirVenture Oshkosh), held at Wittman Regional Airport (OSH), Oshkosh, Wisconsin. According to air traffic control information from the Federal Aviation Administration (FAA), the pilot first contacted the tower controller at AGC when he was about 20 miles east of the airport and advised that his transponder was inoperative. The controller instructed the pilot to "proceed straight in" for runway 28 and cleared the airplane for landing.

The pilot acknowledged the landing clearance and advised that he would be going to Corporate Air and would need progressive taxi instructions. Security video footage showed that the airplane touched down about 2,000 ft down the runway. The pilot was then advised by the tower controller to "make any left turn" and to contact ground control. After the airplane rolled past taxiway C, the pilot asked if he could turn the airplane around on the runway. He was given permission to do so and was again instructed to contact ground control. The pilot then advised he was switching frequencies to ground control. As the airplane turned and its right side became visible to personnel in the control tower, the ground controller advised the pilot that there was a fire under the airplane's wing. The airplane continued to turn left until it traveled off the side of the paved surface of the runway and rolled through the airport infield until it came to rest near taxiway G, with smoke and flames emanating from the right side of the airplane.

The pilot egressed and was transported by airport personnel via golf cart to a nearby hangar where a helicopter emergency service operator was based. Paramedics at the hangar began treating the pilot, who was clad in shorts, a T-shirt, socks, and tennis shoes, and had not been wearing his fire-retardant flight suit, gloves, or helmet. He had visible thermal injuries over 62% of his body. The pilot was subsequently transported to the hospital where he succumbed to his injuries about 6 days later. PERSONNEL INFORMATIONAccording to FAA records, the pilot held a commercial pilot certificate with ratings for airplane single- and multi-engine land and instrument airplane. While in the United States Navy, he had flown the T-34, T2C, TA4J, and S3B. He had owned and operated a Yak 50 and 52 and held a letter of authorization from the FAA to operate the Yak-3, Yak-9, and Yak-11 as pilot-in-command under visual flight rules. His most recent FAA second-class medical certificate was issued on April 5, 2016. He reported on that date that he had accrued about 3,100 total hours of flight experience. AIRCRAFT INFORMATIONThe accident airplane was a two-seat, low-wing, military trainer equipped with a variable pitch propeller. The main landing gear was retractable, and the tailwheel was fixed. The flight controls were not boosted and were conventional in operation. The elevator and ailerons were controlled through push-pull rods and the rudder was operated by cable. With the stick held back, the tailwheel could be locked for takeoff or landing, and with the stick forward, the tailwheel was unlocked for short-radius turns.

According to FAA and sales records, the airplane was manufactured in 1952 and was operated by the Egyptian Air Force from 1952 through the 1980s.

During a rebuild in 1990, the 700-horsepower Shvetsov Ash-21 7-cylinder radial engine and VIS-111-V20 two-blade constant speed propeller were replaced with a 1,350-horsepower Pratt & Whitney R1830-75 14-cylinder radial engine and a Hamilton Standard 3-bladed constant speed propeller. The fuel system was modified as part of the engine replacement. This included removal of the primer pump and hand fuel (wobble) pump, and installation of an electric fuel pump.

On December 5, 1990, the airplane was classified by the FAA as experimental, and a special airworthiness certificate was issued in the racing, crew training, and exhibition category.

According to maintenance records, the airplane's most recent condition inspection was completed on August 28, 2015. At the time of the inspection, the airplane and engine had accrued 318.5 total hours of operation. METEOROLOGICAL INFORMATIONThe 0953 recorded weather at AGC, about 8 minutes after the accident, included variable winds at 5 knots, 6 miles visibility in haze, clear skies, temperature 28°C, dew point 23°C, and an altimeter setting of 29.99 inches of mercury. AIRPORT INFORMATIONThe accident airplane was a two-seat, low-wing, military trainer equipped with a variable pitch propeller. The main landing gear was retractable, and the tailwheel was fixed. The flight controls were not boosted and were conventional in operation. The elevator and ailerons were controlled through push-pull rods and the rudder was operated by cable. With the stick held back, the tailwheel could be locked for takeoff or landing, and with the stick forward, the tailwheel was unlocked for short-radius turns.

According to FAA and sales records, the airplane was manufactured in 1952 and was operated by the Egyptian Air Force from 1952 through the 1980s.

During a rebuild in 1990, the 700-horsepower Shvetsov Ash-21 7-cylinder radial engine and VIS-111-V20 two-blade constant speed propeller were replaced with a 1,350-horsepower Pratt & Whitney R1830-75 14-cylinder radial engine and a Hamilton Standard 3-bladed constant speed propeller. The fuel system was modified as part of the engine replacement. This included removal of the primer pump and hand fuel (wobble) pump, and installation of an electric fuel pump.

On December 5, 1990, the airplane was classified by the FAA as experimental, and a special airworthiness certificate was issued in the racing, crew training, and exhibition category.

According to maintenance records, the airplane's most recent condition inspection was completed on August 28, 2015. At the time of the inspection, the airplane and engine had accrued 318.5 total hours of operation. WRECKAGE AND IMPACT INFORMATIONExamination of the runway and accident site revealed that, after the airplane traveled past taxiway C and entered the left turn, it continued to turn left for about 294° until it traveled off the runway pavement on a magnetic heading about 346°. The airplane then traveled across a storm drain and the airport infield about 612 ft before coming to rest.

The metal and fabric fuselage skin in the areas of the cockpit, right wing, left wing root, and forward portion of the empennage were consumed by fire. The cockpit was completely destroyed. The remaining metallic skin on the outboard section of the right wing and empennage exhibited extensive thermal damage, including melting, oxidation of aluminum surfaces, and brittleness. The wreckage was sooted with areas of vertically-oriented re-solidified globules of aluminum aircraft structure. The tail section, engine cowling, and the left wing were intact.

All three propeller blades displayed minimal damage with no evidence of a propeller strike. Both magnetos were intact on the front of the engine, and the rear of the engine displayed minimal thermal exposure near several openings in the firewall.

Examination of the landing gear system revealed that the main landing gear was in the down and locked position. The brake disks showed no indications of overheating, pitting, or grooving. The brake calipers were intact and there was no sign of hydraulic leakage. The tailwheel was functional and undamaged.

There was extensive fire damage on the aft inboard trailing edge of the right wing and adjacent areas. The right side of the fuel system engine feeder (sump) tank was also located in this area. The feeder tank had multiple areas of melt-through on the upper surface. The wing structure outboard from the sump tank was intact. The inboard edges showed signs of melting, sooting, and thermal discoloration of the remaining paint. A section of aircraft structure was also found separated from the wreckage which displayed evidence of broomstrawing on both ends, consistent with being subjected to shock loading while being in a near-molten state.

Compression damage was discovered in the forward section of the right wing inboard of the right main landing gear, with portions of the airplane's tubular frame bent and displaced to the right side of the airplane's centerline.

Flight control continuity was confirmed from the flight control surfaces to the burned-out section of the cockpit. The mixture control was full rich. The fuel shutoff lever was about 3 inches forward of the aft (shutoff) stop, the throttle was full aft (idle), and the propeller was in the full forward (full rpm) position. ADDITIONAL INFORMATIONAccording to the airplane's previous owner, the belly of the airplane was a large aluminum panel held on with fasteners. When removed, it would expose the electric boost pump, "fuel plumbing," rudder control cables, torque tubes for the flaps and ailerons, the center fuel tank, and "all of the items" under the pilot's compartment. The previous owner further advised that, when it was open, you could "touch the bottom of the seats." Examination of the remains of this area did not reveal evidence of any type of fire blocking or fire blocking materials such as a fiberglass liner, thermal-acoustic insulation, or fire-resistant barrier fabri...