Learjet 36

The accident airplane took off as the lead airplane in formation with a second Lear Jet airplane flying as wingman in a close formation position. The purpose of the flight was to participate in an exercise with the United States Navy in an over-water training area. Shortly after entering the training area at 15,000 ft mean sea level (msl) the wingman positioned on the right side of the accident airplane, observed the flaps on the accident airplane were partially extended. They notified the pilot of the accident airplane who acknowledged the radio call. The wingman then observed the flaps retract and observed white or gray colored “smoke or gas” coming from the left aft side of the airplane. The pilot in the accident airplane then radioed that they detected an odor in the cabin. Seconds later, the wingman observed red fluid on the underside of the tail cone followed by flames coming from around the aft equipment bay (tail cone) access door. They informed the accident pilots that their airplane was on fire and the accident pilot declared an emergency along with their intentions to land at a nearby airfield on the island. The wingman took over leading the formation and maneuvered in front of the accident airplane. The wingman last observed and heard radio transmissions from the accident airplane a short time later as they descended through about 7000 ft msl. The flight was above an overcast cloud layer that obstructed the view of the island at that time. Recorded ADS-B data showed that the accident airplane subsequently made a series of descending turns before the data ended. The airplane wreckage was located underwater about 4 miles northwest of the last ADS-B data point. The wreckage was highly fragmented, and the debris field extended several hundred feet along the ocean floor. Salvage operations were able to recover about 40 percent of the airplane wreckage. Examination of the wreckage showed areas of smoke and fire damage in portions of the airplane from the center wing fuselage outboard through the left- and right-wing roots and aft throughout the empennage. The aft equipment bay forward bulkhead, which also served as the fuselage fuel tank aft bulkhead, exhibited damage on the upper left side consistent with exposure to a focused heat source such as a fire from a leak in a pressurized fuel or hydraulic line. Additional evidence of focused fire damage was identified in the left engine pylon, which was located outboard and adjacent to the aft equipment bay. The effected area of the pylon contained engine fire detection circuits. Examination of the hydraulic shutoff valves attached to the hydraulic reservoir found that the left hydraulic shutoff valve was closed and the right valve was in the open position. The position of the left hydraulic shutoff valve indicates the aircrew likely shut down the left engine due to a fire indication (A hydraulic valve will close if the FIRE PULL tee-handle switch is activated by the flight crew in the event an engine fire is detected). Investigators were unable to determine if the witnessed flap extension and retraction was initiated by activation of the flap selector switch or induced by fire damage. The aft equipment bay houses electrical equipment capable of providing an ignition source for a fire, and hydraulic and fuel system components capable of providing fuel for a fire in the event of a leak. The left fuel motive flow line was intact from the fuel pump up to the fuselage fitting, where the line passes through the fuselage skin into the aft equipment bay near the aft left engine mount. The fuselage fitting had the stainless-steel fuel line and b-nut attached on the outboard, engine side. The inboard, aft equipment bay side of the fitting did not have an aluminum b-nut attached or the line that connects the fitting to the motive flow valve. The left engine hydraulic pressure line and PT2 line, which pass through the fuselage into the aft equipment bay adjacent to the motive fuel line, each had aluminum b-nuts present on the interior side of their respective fuselage fittings and the interior lines for each was sheared at the fitting. The left fuel motive flow fuselage fitting and the hydraulic fluid return fitting were examined. No thermal damage was observed on the outboard nuts and attached portions of tubing. Examination of the threads on the inboard side of the motive flow fitting did not exhibit evidence of thread stripping and comparison between the two fittings did not reveal any physical differences to explain why one nut remained attached and the other did not. The reason the motive flow nut was missing from the fitting could not be determined. Observed fire and heat damage patterns indicate the fire likely started in proximity to the where the pressurized fuel motive flow line connected to the firewall fitting where the missing b-nut was located. A leak from the pressurized motive flow line would have sustained and allowed an uncontrollable fire to develop. The sustained fire likely affected controllability of the airplane and resulted in the pilots’ loss of control of the airplane.

The flight crew was supporting a United States Navy (USN) training mission and ended the flight early due to icing conditions. The flight crew calculated a landing reference speed (Vref) of 140 knots (kts) indicated airspeed (KIAS) and landing distance required of 4,200 ft for a wet runway and a flap setting of 20°. Due to underwing-mounted external storage, the landing flaps were limited to a maximum extension of 20°. The flight crew configured the airplane with 20° flaps and reported that the airplane touched down at 140 kts. Although the runway was 8,001 ft long, an arresting cable was located 1,701 ft from the runway threshold, resulting in a runway distance available of about 6,300 ft. After landing, the second in command (SIC) reported that the pilot-in-command (PIC) deployed the spoilers and brakes, then announced that the airplane was not slowing down. The PIC stated that the airplane did not decelerate normally, that the brake anti-skid system was active, and that the airplane seemed to be hydroplaning. He cycled the brakes, which had no effect.The airplane subsequently overran the departure end of the runway, breached an ocean sea wall and came to rest in a nose-down attitude on a sandbar. The airport weather observation system recorded that 0.06 inches of liquid equivalent precipitation fell between 18 and 9 minutes before the accident. In the 4 hours before the accident, the airport received 0.31 inches of liquid equivalent precipitation. A landing performance study conducted by the airplane manufacturer modeled a variety of landing scenarios considered during the investigation. The modeling used factual information provided by the investigation, including ADS-B data, as well as manufacturer-provided airplane performance data specific to the airplane. The study considered the effect on landing distance of both a wet and dry runway, a contaminated runway, both full and intermittent hydroplaning, a localized tailwind (which was not present in the weather data), and an inboard brake failure. The study showed that the most likely scenario, based on the available data, was that the airplane touched down with a ground speed well in excess of the 140 kts Vref speed reported by the crew, and that subsequent to the touchdown encountered full hydroplaning at speeds above 104 kts. The airplane sat overnight on the sandbar and was submerged in saltwater before the airplane was recovered. As a result, the airplane’s braking system could not be functionally tested. However, the physical evidence from the brakes as found post accident, combined with the results of the landing distance modeling, did not indicate that a brake failure occurred. Similarly, ADS-B data did not support the presence of a localized tailwind when such a landing was modeled in the study. Thus, it’s likely that the flight crew landed too fast and then encountered hydroplaning during the landing roll as a result of a recent heavy rain shower, which diminished the calculated stopping distance.

The crew departed Iwakuni AFB at 0900LT on a training mission over the Sea of Japan. At 1045LT, the aircraft returned to Iwakuni and the crew completed several touch-and-go manoeuvres on runway 02. During one of these procedures, the aircraft went out of control upon touchdown and crashed beside the runway, bursting into flames. All four crew members were killed.

The pilot (PIC) reported that during acceleration for takeoff (approximately V1 [takeoff decision speed]) the airplane collided with an elk. The PIC reported that after the collision, he applied wheel brakes and deployed the airplane's drag chute, however, the airplane continued off the departure end of the runway. The airplane came to rest in a marshy bog approximately 50 feet beyond the departure threshold. Currently, approximately 15,000 feet of the airport's perimeter is bordered with animal control fence. The airport recently received a FAA Aviation Improvement Program (AIP) Grant that will provide funding for an additional 9,000-feet of fence. Airport officials stated that the fencing project should be completed by summer of 2003. At the completion of the project, game control fencing will encompass the entire airport perimeter. The U.S. Government Airport/Facilities Directory (A/FD) contains the following remarks for the Astoria Regional Airport: "Herds of elk on and in the vicinity of airport..."

Learjet L36A (serial number 033), N14TX, was on an instrument flight rules (IFR) flight from Grand Rapids, Michigan, to Stephenville, Newfoundland. At 0216 Newfoundland standard time (NST1), N14TX was cleared by Gander Area Control Centre (ACC) for an approach to the Stephenville airport. The co-pilot contacted the St. John=s Flight Service Station (FSS) and advised that they would be conducting an approach to runway 28. The FSS specialist relayed the latest Stephenville weather observation and runway surface condition report to the aircraft and requested that the crew advise St. John=s FSS when they had landed. When the crew of N14TX did not report after landing at Stephenville, the St. John=s FSS specialist advised Gander ACC that the aircraft was missing, and a search was begun. Initial information received by the agencies searching for the missing aircraft did not include the aircraft=s last recorded radar position. The wreckage was located approximately three hours and ten minutes after the aircraft was reported missing, within the airport perimeter, close to the last observed aircraft radar position. The aircraft struck a service road embankment in an inverted, wings-level attitude. The two crew members were fatally injured. The accident occurred during the hours of darkness at approximately 0238 NST.

The aircraft departed Geneva-Cointrin on an ambulance flight to Accra with an intermediate stop in Zarzaitine, carrying two doctors and two pilots. The goal of the mission was to repatriate a patient to London via Geneva after a crew change. While descending to runway 05 at Zarzaitine-In Amenas Airport by night, the crew was informed by ATC that runway 23 was in service. The crew followed a circuit and started the descent to runway 23. On final approach in low visibility (dark night), the crew failed to realize his altitude was insufficient when the aircraft struck the top of a sand dune. The undercarriage were torn off and the aircraft crash landed 3 km short of runway, bursting into flames. Both doctors escaped uninjured, the female copilot was slightly injured and the captain was seriously injured. The aircraft was totally destroyed.

The aircraft was engaged in a low level ECM exercice when it crashed in the sea off Shikoku Island. All five crew members were killed. It is understood that the aircraft struck the water surface while cruising at low level and low speed.