NTSB Factual Report

HISTORY OF FLIGHT

On December 6, 2015, about 1407 Pacific standard time, an Aero Vodochody L-39C, N39AY, was destroyed when it impacted terrain near Apple Valley, California. The airline transport pilot and the pilot-rated passenger were fatally injured. The airplane was registered to and operated by Jettran LLC as a Title 14 Code of Federal Regulations Part 91 personal flight. Visual meteorological conditions prevailed, and no flight plan was filed for the local flight, which departed Apple Valley Airport (APV) about 1406.

A friend of the pilot-rated passenger reported that the passenger was considering purchasing a partial ownership in another L-39 airplane that was based at his local airport. Additionally, the passenger was a fan of the accident pilot's performances in the Red Bull Air Races. After the friend introduced the passenger to the pilot, they arranged to fly together in the L-39.

Witnesses reported that, on the day of the accident, after refueling the airplane, the pilot delivered a 1-hour safety briefing to the passenger inside the airport terminal. Subsequently, they boarded the airplane, and the pilot taxied it to the airport run-up area. After a brief pause, the pilot taxied the airplane to runway 18 and began a ground roll. One witness reported seeing dark grey-colored exhaust coming from the exhaust nozzle as the airplane began its takeoff roll.

According to witnesses, when the airplane was about 3,400 ft down the runway (just beyond the halfway point), witnesses heard a "pop, pop, pop" sound, which was immediately followed by intermittent, bright orange flashes coming from the exhaust nozzle. Witnesses reported that the airplane was about 100 ft above ground level; multiple witnesses reported that they had observed the airplane reach an altitude of about 500 ft above ground level by this point during previous takeoffs. A witness reported that while the airplane appeared to have slowed down after the popping sound was heard, it did not appear to lose any altitude. As the airplane reached the departure end of the runway, it rolled into a left-wing-low attitude. Two witnesses reported that the airplane rolled 90° to the left. The airplane then descended rapidly, and the left wing impacted the ground followed by the nose. The wreckage slid and came to rest in the dirt between two taxiways, and a fire ensued.

A photograph of the airplane's departure captured the airplane about 2,200 ft down the runway and showed the airplane airborne in a slight nose-up attitude with the flaps deployed and the landing gear extended.

PERSONNEL INFORMATION

Pilot

A review of the pilot's logbook revealed that he had accumulated a total of 23,200.3 hours of flight experience of which 170 hours were in the accident airplane make and model. The pilot accumulated a total of 12.2 hours in the accident airplane between August 25, 2015, and November 20, 2015, which was the date of the last recorded logbook entry. The last entry in the logbook was a simulator flight in a Boeing 787 on November 20, 2015, and his last recorded flight in the accident airplane was on October 27, 2015, from APV to Reno Stead Airport (RTS), Reno, Nevada.

The pilot had been a competitive air racer since 1990 and was active in the Red Bull Air Races from 2004 to 2009. He won the Red Bull Air Race World Series Championship in 2005 and again in 2007.

A friend of the pilot who had known him for about 15 years reported that he worked with the pilot at Racing Jets, Inc. According to this friend, it was not unusual for the accident pilot to take passengers for rides in the L-39. It was customary for the accident pilot to conduct a 1-hour safety briefing with each passenger before departure. During this time, the pilot would address numerous safety items including: canopy operation, parachute deployment, safety belt operation, and the procedures for a manual bailout.

The pilot's wife, a professional career pilot and former aerobatic pilot, stated that it was not uncommon for the accident pilot to deliver a 1-hour safety briefing before flying with a new passenger. During a flight with a new passenger, the pilot might let them fly, but he would normally follow them on the controls, and, should an emergency arise, he would immediately resume control of the airplane.

Pilot's 72-hour History

The pilot was a first officer for a major airline. According to the pilot's wife, he left their home about 1500 on December 3, 2015, and drove to Los Angeles International Airport (LAX) where he boarded a commercial flight to Sao Paulo, Brazil as the first officer. The return flight arrived at LAX at 0900 on the morning of the accident flight.

According to the pilot's fellow crewmembers on the flights to and from Sao Paulo, the crew queried each other to ensure they had received adequate rest. A crewmember recalled that during the return flight to Los Angeles, the pilot had a total of two breaks consistent with the shift schedule. On his first break, he rested in a business class seat; however, the crewmember could not confirm if he slept during that time. During the pilot's second break, a 3-hour time period, he used the airplane's crew bunk. The crewmember surmised that the accident pilot was sleeping during this time as his bunk light was not illuminated. Another crewmember stated that he would have recalled if another crewmember had slept or not.

Pilot-rated Passenger

The pilot-rated passenger, age 42, held a private pilot certificate with an airplane single-engine land rating. He was issued a third-class medical certificate on May 20, 2014, at which time he reported a total flight experience of 377 hours and 0 hours in the previous 6 months. A copy of his logbook was furnished by a family member and indicated that he had accumulated a total flight experience of 409 hours. The logbook showed that he had not amassed any time in turbine engine aircraft. According to the passenger's friend, he was a general aviation pilot who flew airplanes equipped with reciprocating engines. The witness was under the impression that his friend was not going to fly the airplane on the day of the accident.

AIRCRAFT INFORMATION

According to FAA records, the single-engine, two-seat tandem airplane was manufactured in 1993. According to Aero Vodochody, the airplane was manufactured in 1983. It was issued an FAA experimental special airworthiness certificate in the exhibition category on February 23, 2003, and it was registered to Jettran LLC on December 16, 2014.

The airplane was originally used as a military jet trainer, and it was powered by an AI-25 TL engine that was manufactured by Ivchenko (now Motor Sich). According to the manufacturer, the airplane was owned and operated by the Ukrainian military from 1991 to 2002, when it was decommissioned, transported to the United States, and repurposed as a civilian airplane. A logbook entry dated February 20, 2003, indicated that the airframe had accumulated 1,908 total flight hours, and the engine had accumulated 532 total hours. The airplane's records prior to entering service in the United States could not be located.

A maintenance entry from February 20, 2003 stated that the ejection seat rocket motors and charges had been removed, and the ejection system was no longer operative. The airplane's most recent condition inspection was completed on November 23, 2015, at which time the airplane had accumulated 2,062 total flight hours. The logbook entry for the condition inspection showed that the right- and left-wing flight controls and the aft flight controls were inspected. Additionally, the elevators, rudder, wing flaps, and ailerons were lubricated.

Engine History

The AI-25TL model engine was designed for use in the L-39 military trainer, and its first flight occurred in 1968. About 2,900 L-39 airplanes were built between 1968 and 1992, and the airplane remains in operational service with several air forces around the world. About 4,000 total AI-25TL engines were built during its production run.

The engine was originally intended to have a time between overhaul (TBO) of 750 hours and a life service limit of 8 calendar years. At the time of the accident, the engine had accumulated 686 hours and had been in service about 26 years. Recent service bulletins by the manufacturer have extended the life limit to 15 calendar years; however, the extension applies only to engines that have been operated and maintained in accordance with the manufacturer's approved instructions for continued airworthiness.

According to foreign documentation and industry consultants, the engine was installed on the airplane in 1991 as a replacement. When the airplane was imported into the United States in 2003, the engine passed an FAA-approved maintenance inspection. The AI-25TL engine record-keeping requirements do not require recording of cycles since new or cycles since overhaul. According to the logbooks, the engine was never overhauled.

During the most recent engine inspection on November 23, 2015, the 1st and 2nd stage turbine blades and wheel assemblies were inspected by borescope for condition, and no anomalies were observed. According to the maintenance personnel who performed the inspection, he performed a critical tip clearance inspection of the 2nd stage blades. The tip clearance inspection determines if the blades have stretched in operation due to an over-temperature condition. Normally, there is a small clearance between the 2nd stage blade tips and the outer tip shroud. If the blades have stretched, then the tips will contact the shroud and deform, producing a visible "curl" on the concave sides of the tips. According to the maintenance personnel, they did not detect any blade curl during the November 23, 2015, borescope inspection.

Further, according to the maintenance personnel, during the November 23, 2015, engine inspection, two engine performance check ground run-ups were accomplished, and the maximum fuel delivery pressure did not exceed the published limit during these run-ups. The maintenance personnel reported that a high fuel pressure would have been visible on the fuel pressure gauge in the cockpit. The high fuel pressure would also have manifested itself as an elevated interstage turbine temperature value during the high-power test. According to the maintenance personnel, neither of these discrepancies were observed.

Airport fueling records indicated that the airplane had been serviced with about 131 gallons of JET-A fuel before the accident flight. A fuel sample was taken from the fuel facility, and the fuel was clear and free of contaminants.

Maintenance Program

The owner's maintenance program for the airplane was originally approved by the FAA on July 11, 2002, and the first revision was approved on December 17, 2014. The program listed the engine under the "Life Limited Items" and requires a "Condition Inspection" at 1,500 and 3,000 hours and an engine overhaul at 4,000 hours. The engine "Condition Inspection" consists of the standard factory-prescribed engine run-up performance test and inspection, which, according to the Motor Sich Engine Manual, should occur at 100-hour intervals.

The maintenance program also required a borescope inspection through the ignitor holes. No other details were specified, and no engine manual references were made. According to the Motor Sich Engine Manual, a borescope inspection of the hot section, which includes a close examination of the fuel nozzle condition, should be performed at intervals of 100 hours.

METEOROLOGICAL INFORMATION

The 1415 recorded weather observation at Southern California Logistics Airport (VCV), Victorville, California, located about 9.8 nautical miles west of APV, included wind calm, visibility 10 statute miles, scattered clouds at 12,000 ft, temperature 15°C, dew point -10°C, and an altimeter setting of 30.27 inches of mercury.

AIRPORT INFORMATION

APV was publicly owned and operated by the County of San Bernardino and was not equipped with an operating control tower. Runway 18/36 was 6,498 ft long and 150 ft wide with displaced thresholds at both ends. The airport elevation was about 3,062 ft above mean sea level.

The terrain beyond the airport perimeter along the extended centerline of runway 18 was mostly flat desert sparsely covered with brush.

WRECKAGE AND IMPACT INFORMATION

The airplane impacted an area of flat terrain between two taxiways about 800 ft beyond the departure end of runway 18, and about 150 ft to the right of the runway centerline. The debris path, which measured 263 ft long by 100 ft wide, was oriented on a 193° magnetic heading. The path was composed of airframe fragments and a black substance that resembled oil residue, which spanned the length of the debris field. The initial impact point (IIP) was identified by a V-shaped ground scar that scraped the northern edge of a taxiway. Red position light fragments (from the left wingtip navigation light) were observed around the left side of the debris path about 20 ft from the IIP, and several small pieces of plexiglass were scattered beyond the position light fragments.

All major structural components of the airframe were accounted for at the accident site. The main wreckage came to rest on a 080° magnetic heading and was comprised of the fuselage, empennage, and portions of both wings. The fuselage and engine compartment were destroyed by fire, but the engine and empennage remained intact. Visual examination of the engine case and exhaust shaft revealed no evidence of a catastrophic engine failure. An inspection of runway 18/36 following the accident revealed no evidence of foreign object debris.

The primary flight controls (aileron, elevator, and rudder) were activated by push-pull tubes and levers that were attached to two interconnected control sticks located in the forward and aft cockpits. Only two control tubes from the elevator and rudder assembly were recovered; one of the tubes had separated from the elevator/rudder bell crank and had fractured into 5 pieces that displayed signatures consistent with overload separation. The remaining control tubes were destroyed by the postcrash fire.

Most of the wings were destroyed by fire. The left aileron control turnbuckles and main aileron bellcrank were intact but were separated from their respective control tubes, which were destroyed by the postcrash fire.

The rudder control system consisted of two pairs of interconnected, adjustable rudder pedals. The front seat occupant's rudder pedal assembly remained intact and had been adjusted to the forward position. Both control tubes, which had separated from the pedals and bellcrank mounts, were destroyed by the postcrash fire. The rear seat occupant's rudder assembly was also intact; the control tubes remained attached; and the rudder pedal mounting tubes were straight. The airplane was equipped with two slotted fowler flaps interconnected by a single actuating cylinder and synchronized mechanically. One of three flap settings was achieved by depressing the appropriate control button on the left side control console. The inboard and outboard right-wing flap tracks had separated from the wing, but portions of the flaps remained attached to their respective tracks, which indicated a 25° deployed (takeoff) position.

The nose landing gear was in the extended position and the nose landing gear door was closed. Both main landing gear were collocated with the main fuselage, but their positions could not be determined due to postcrash fire.

The airplane was equipped with trim tabs for both the longitudinal and lateral axes. Longitudinal trim was provided by trim tabs that were fitted to the left and right elevators. The left trim tab was designed to deflect automatically when the flaps were deployed to the landing position to compensate for aerodynamic ballooning during landing. The right trim tab was controlled by the trim switch in either cockpit.

Continuity of the elevator and flap trim linkages were confirmed from their respective tail section control tubes to both trim tabs. Both the elevator and flap trim were in their neutral positions; the manufacturer indicated that a takeoff can be accomplished with the el

NTSB Probable Cause

A total loss of engine power on takeoff, which resulted from a sudden over-temperature condition due to an improperly adjusted fuel control unit and the deteriorated condition of the fuel nozzles.