Meteorological / Weather

The twin engine aircraft departed Ganzhou Airport at 1440LT on a cloud seeding mission over the Jiangxi Region. While flying in clouds, the aircraft entered an uncontrolled descent, entered a spin and eventually crashed in a residential area. All five occupants were killed and one people on the ground was slightly injured.

The crew departed Elizabeth City CGAS in North Carolina to deploy weather buoys in the Atlantic Ocean. Several landings were completed successfully. While taking off, the seaplane struck an unkknown object floating on water and came to rest some 680 km east off Cape Hatteras, North Carolina. All five crew members evacuated the cabin and were later recovered by the crew of a container vessel. The aircraft sank and was lost.

Following an uneventful cloud seeding mission over the region of Mopti, the pilot was returning to Bamako-Senou Airport. For unknown reasons, the aircraft made a belly landing and slid for few dozen metres before coming to rest on the right side of runway 06/24. The pilot escaped uninjured and the aircraft was damaged beyond repair.

The airplane was equipped with an air sampling system used to collect air samples at various altitudes. The accident occurred when the pilot was returning to the airport after taking air samples at various altitudes over oil fields. As he was being vectored for an instrument approach, the airplane overshot the runway's extended centerline. The pilot then reported that he had a fire on board. The airplane lost altitude rapidly, and radar contact was lost. Examination of the accident site indicated that the airplane struck the ground at high velocity and a low impact angle. One piece of the airplane's shattered Plexiglas windshield exhibited soot streaking on its exterior surface. This soot streaking did not extend onto the piece's fracture surface, indicative of the smoke source being upstream of the windshield and the smoke exposure occurring before windshield breakup at impact. Both nose baggage compartment doors were found about 2 miles south of the main wreckage, which indicative that they came off at nearly the same time and most likely before the pilot's distress call. Although there was no soot deposits, thermal damage, or deformation to the doors consistent with a "high energy explosion," the separation of the luggage compartment doors could have occurred due to an overpressure caused by the ignition of a fuel air mixture within the nose portion of the airplane. The ignition of fuel air mixtures can create overpressure events when they occur in confinement. An overpressure in the nose baggage compartment may have stretched the airframe enough to allow the doors to push open without deforming the latches. If it was a lean fuel air mixture, it would likely leave no soot residue. Post-accident examination revealed no evidence that the air sampling system, which was strapped to the seat tracks behind the copilot's seat, was the cause of the fire. The combustion heater, which was mounted in the right front section of the nose baggage compartment, bore no evidence of fuel leakage, but a fuel fitting was found loose.

On final approach to Shenyang-Taoxian Airport, the twin engine aircraft stalled and crashed on a road short of runway, bursting into flames. All three occupants escaped with minor injuries and the aircraft was totally destroyed by a post crash fire. The crew was returning to his base in Shenyang following a cloud seeding mission over the Liaoning Province.

The aircraft departed Chanthaburi Airport for a cloud-seeding mission with four passengers and a pilot on board. Shortly after takeoff, while climbing, the engine failed. The aircraft stalled and crashed, bursting into flames. A passenger was seriously injured while four other occupants were killed.

The flight crew, an airline transport certificated captain, and a commercial certificated co-pilot, were flying a restricted category, icing research equipped airplane in instrument meteorological icing conditions under Title 14, CFR Part 91. The purpose of the flight was to locate icing conditions for a prototype helicopter's in-flight icing tests. While in cruise flight, the airplane encountered icing conditions, and had accumulated about 1" of ice on the leading edges of the wings. The captain reported that he activated the wing deicing pneumatic boots, and the ice was shed from both wings. About 4 minutes after activating the deice boots, both engines simultaneously lost all power. The crew attempted several engine restarts, but were unsuccessful, and made a forced landing on frozen, snow-covered terrain. During the landing, the airplane struck several small, burned trees, and sustained substantial damage. The airplane's ice control system is comprised of two separate systems, one an anti-ice, the other, a deice. The majority of the wings' surfaces are deiced by pneumatic, inflating boots. The inboard section of the wings, directly in front of the engine air inlets, and the engine air inlets themselves, utilize a heated, anti-ice surface to preclude any ice accretion and potential for ice ingestion into the engines. The anti-ice system is not automatic, and must be activated by the flight crew prior to entering icing conditions. A researcher in the aft cabin photographed the airplane's wings before and after the activation of the deice boots. The photographs taken prior to the deice boot activation depicted about 1" of ice on the wings, as well as on the anti-ice (heated) inboard portion of the wings. The photographs taken after the deice boot activation revealed that the ice had been removed from the booted portion of the wings, but ice remained on the inboard, anti-ice segment. An engineer from the airplane's manufacturer said that if the anti-ice system was activated after ice had accumulated on the wings, it would take 2-4 minutes for the anti-ice portion of the wings and engine inlets to heat sufficiently to shed the ice. A postaccident inspection of the anti-ice components found no anomalies, and there was no record of any recent problems with the anti-ice system. The flight crew reported that the anti-ice activation switch is on the captain's side, and they could not recall if or when the anti-ice system was activated. They stated that they did not discuss its use, or use a checklist that addressed the use of the anti-ice system. A section of the airplane's flight manual states: "Failure to switch on the [anti-ice] system before ice accumulation has begun may result in engine damage due to ice ingestion." An inspection by an NTSB power plant engineer disclosed catastrophic engine damage consistent with ice ingestion.

On February 7, 2005, about 0634, Atlantic standard time, a Cessna 340, N5790M, registered to and operated by Ward County Irrigation District N°1, impacted with terrain in a mountainous area in Mendoza, Argentina. Visual meteorological conditions prevailed at the time and the flight plan information is unknown. The pilot and copilot received fatal injuries, and the airplane was destroyed. The flight originated from Aerodrome San Rafael (SAMR), Argentina, earlier that day, at an unspecified time. The initial notification from Argentina's Junta de Investigaciones de Accidentes de Aviacion Civil ( JIAAC) stated the airplane was on a cloud-seeding mission to prevent thunderstorms from developing in that agricultural area.

The airplane impacted mountainous terrain in an extreme nose-down attitude following a departure from controlled flight. The purpose of the flight was to check the weather conditions for passenger tour flights that day. The pilot reported about 20 minutes prior to the accident that the ceiling was 6,500 feet mean sea level (msl). Radar data showed that following this weather report, the airplane's radar track continued eastbound and upon its return westbound, at an altitude of about 6,000 feet msl, the airplane entered a series of altitude fluctuations approximately 1 mile west of a ridge that was the location of the accident, descending at 4,000 feet per minute while turning northbound, and then climbing at 3,900 feet per minute while traveling eastbound, prior to disappearing from the radar. The airplane impacted on the eastern side of the ridge. There were no monitored distress calls from the aircraft and no known witnesses to the accident. Prior to the accident, there were reports of vibrations during flight on this aircraft, although many went unreported to maintenance personnel. The day (and flight) prior to the accident, a pilot experienced a vibration during flight with passengers and it was not reported to maintenance personnel because it was logged improperly in the operator's maintenance tracking system. No corrective actions were taken. During the post accident examinations, no portions of the right elevator and trim tab were identified in the wreckage, or at the accident site. The bracket attachment to the right elevator was found loose within the wreckage and was torsionally twisted counterclockwise (aft). Ground and aerial searches for the missing parts based on a trajectory study were unsuccessful. This aircraft was equipped with a foam cored elevator trim tab that was installed during aircraft manufacture. A service difficulty report (SDR) query showed that 47 reports had been issued on elevator trim tab corrosion and many included reports of vibrations during flight. On January 20, 2005, the Federal Aviation Administration (FAA) issued Special Airworthiness Information Bulletin (SAIB) CE-05-27, which addressed potential problems with foam-filled elevator trim tabs in the accident make/model airplane, and Cessna 206 and 210 series airplanes. The SAIB indicated that the foam-filled elevator trim tabs, manufactured until 1985, were reported to have corrosion between the tab and the foam. The SAIB further said, in part, "When the skin of the trim tab becomes thin enough due to the corrosion, the actuator can pull the fasteners through the skin and disconnect. When this occurs, the tab can flutter." Some reports indicated prior instances of "vibrations in the tail section and portions of the elevator tearing away with the trim tab." Prior to the issuance of the SAIB, Cessna Aircraft Company issued a Service Bulletin (SB) SEB85-7 on April 5, 1985, that addressed elevator and trim tab inspection due to corrosion from moisture trapped in the foam cored trim tabs. Based on a review of the airplane's logbooks, the SB was not complied with, nor was the operator required to do so based on the FAA approved maintenance specifications.

During the takeoff climb, the airplane turned sharply right, went into a steep bank and collided with terrain. The airplane began a right turn immediately after departure and appeared to be going slow. A witness was able to distinguish the individual propeller blades on the right engine, while the left engine propeller blades were indistinguishable. The airplane stopped turning and flew for an estimated 1/4-mile at an altitude of 100 feet. The airplane then continued the right turn at a steep bank angle before disappearing from sight. Then the witness observed a plume of smoke. White and gray matter, along with two ferrous slivers, contaminated the chip detector on the right engine. The airplane had a rudder assist system installed. The rudder assist provided additional directional control in the event of a loss of power on either engine. The NATOPS manual specified that the rudder assist switch should be in the ON position for takeoff, landing, and in the event of single-engine operation. The rudder boost switch was in the off position, and the rudder boost actuator in the empennage was in the retracted (off) position. The owner had experienced a problem with the flight controls the previous year and did not fly with the rudder assist ON. The accident flight had the lowest acceleration rate, and attained the lowest maximum speed, compared to GPS data from the seven previous flights. It was traveling nearly 20 knots slower, about 100 knots, than the bulk of the other flights when it attempted to lift off. The airplane was between the 2,000- and 3,000-foot runway markers (less than halfway down the runway) when it lifted off and began the right turn. Due to the extensive disintegration of the airplane in the impact sequence, the seating positions for the three occupants could not be determined. One of the occupants was the aircraft owner, who held a private certificate with a single-engine land rating, was known to have previously flown the airplane on contract flights from both the left and right seats. A second pilot was the normal copilot for all previous contract flights; his certificates had been revoked by the FAA. The third occupant held an airline transport pilot certificate and had never flown in the airplane before. Prior to the accident flight, the owner had told an associate that the third occupant was going to fly the airplane on the accident flight.