DFW05FA188

The 1,500-hour airline transport rated pilot had just departed a 6,305-foot-long runway when, based on a viewing of security camera footage, a puff of white smoke exiting the back of the right engine shortly after the airplane became airborne. The airplane then began a right turn and flew on a westerly heading at a low altitude before it disappeared behind a tree line. A witness saw the airplane as it was in a right turn toward the north. He thought the airplane was going to land on a closed highway, but the nose of the airplane dropped and the airplane cartwheeled on the grass median west of the road. Examination of the right engine revealed that the crankshaft gear had failed due to a fatigue fracture in one of the teeth. The fatigue emanated from the pressure face of the tooth and intersected another crack emanating from the non-pressure face of the tooth, thereby producing separation of the tooth from the rim. Near the origin, post-fracture damage prevented the ability to determine if the crack initiated in fatigue or if a crack propagated in overstress through the case and then continued propagating through the core in fatigue. Upon completion of the materials examination it was evident that the microstructure of the gear was inadequate and more research into the manufacturing process was required. A review of manufacturing records indicated that approximately 2,400 crankshaft gears were made from the same batch of material as the accident gears, and were heat-treated in two groups. A review of the heat treatment records confirmed that furnace temperatures during the hardening step in each heat-treating process were not high enough to fully austenitize the material. Furthermore, the quantity and orientation of gears loaded in the furnace were greater when compared to other jobs completed for TCM. In addition, initial data from a test load similar to that used in the heat-treating process from the accident serial number gear, indicated that under these conditions, the gears might not have been fully equilibrated at temperature during the hardening step. As a result, TCM manufactured several other gears at different hardnesses and conducted failure testing to see if they could reproduce a similar failure. Even though some of the hardness levels were well below TCM standards, they were unable to produce a similar failure. In addition, there was evidence to suggest that the gear teeth may have been exposed to an excessive load at some point during its operation. The cause of the gear tooth failure could not be determined.

History of flight

On July 24, 2005, at 1752 central daylight time, a twin-engine Cessna 310Q airplane, N1971W, was destroyed when it collided with terrain shortly after takeoff from Runway 17 at the Ada Municipal Airport (ADA) near Ada, Oklahoma. The airline transport pilot, the two passengers, and a dog, were fatally injured. The airplane was registered to Stoneair Charter Services, LLC, of Centrahoma, Oklahoma, and was being operated by the pilot. No flight plan was filed for the flight destined for the Cushing Municipal Airport (CUH), near Cushing, Oklahoma. Visual meteorological conditions prevailed for the personal flight conducted under 14 Code of Federal Regulations Part 91.

Security cameras were installed and operational at various locations around the Ada Municipal Airport. A review of the images obtained by these cameras revealed that the movement of the airplane was captured during the following phases of flight: preflight, engine starts, taxi toward the runway, take off, and impact. The airplane's engine run-up (if conducted) and take off roll were not captured on video.

Between 1751:25 and 1751:30, the airplane appeared on video traveling from left to right just as it began its initial take off climb from Runway 17 (a 6,203-foot-long and 100-foot-wide asphalt runway). The airplane's altitude appeared to be just below the level of the tops of the trees that were located east of the runway. It was during this time that a sudden burst of white-colored smoke was observed coming from behind the right engine. The airplane is then observed entering a right hand turn toward the west with the landing gear extended.

Between 1751:30 and 1751:34, the airplane's movement was not recorded by any of the cameras. At 1751:34 to 1751:42, another camera captured the airplane as it flew toward the west at an altitude just above the airport hangars with the landing gear retracted. The airplane then flew out of camera range for approximately 10 seconds.

Between 1751:52 and 1752:47, the airplane was then recorded by another camera as it flew toward a tree line located west of the airport before it disappeared behind the trees. Shortly after, a pillar of dark smoke began to appear above the tree line where the airplane was last observed.

A witness was standing just to the west of Highway 377, which was under construction and approximately 1 mile west of the Ada Municipal Airport. According to the witness, he did not hear the airplane approaching until it was almost right over him. The airplane was "extremely low," about 60-70 feet above the ground, with the landing gear retracted, in a shallow right turn towards the north. As the airplane crossed over the highway, it made a sharp right turn to the north and the witness thought the pilot was trying to land on the highway. However, as the airplane banked to the right, the nose of the airplane dropped, and the airplane rapidly descended toward the grass median located to the west of the highway. The right wing contacted the ground and the airplane cart wheeled before it came to rest on an embankment and caught on fire. The witness added that he did not see any fire or smoke trailing the airplane while in flight, but he did hear a "miss in the engine." He described the "miss" as a "pop," but not as loud as the sound of a backfire. The witness added that the airplane did not sound as loud as other airplanes do when they depart, and he felt that it was not making the power it needed to maintain altitude.

The accident occurred during the hours of daylight approximately 34 degrees, 47 minutes north latitude, and 96 degrees, 41 minutes west longitude.

Personnel information

The pilot held an airline transport pilot certificate with a rating for multi-engine land; a commercial certificate with ratings for airplane single-engine land, multi-engine land and rotorcraft-helicopter; and, a private certificate for airplane single-engine sea. He also held a flight instructor certificate for airplane single-engine land, multi-engine land, instrument airplane, and rotorcraft-helicopter. The pilot's last Federal Aviation Administration (FAA) second-class medical was issued on August 5, 2004. At that time, he reported a total of 1,500 flight hours. The pilot's personal logbook was never located.

Aircraft information

The airplane's last annual inspection was conducted on November 18, 2004, at a total aircraft time of 3,944.7 hours. At that time, the right engine was removed and a factory new engine was installed. The last entry in the airframe logbook was entered on June 28, 2005. At that time, the oil was changed on both engines. The right engine had accrued approximately 175.3 hours since new and the left engine had accrued 510.8 hours since major overhaul.

The pilot purchased 20 gallons of 100 LL aviation fuel prior to departure. According to the individual that fueled the airplane, he serviced each main tank with 10 gallons, which filled the tanks to approximately half- to 3/4-full.

Meteorological information

Weather reported at Ada Municipal Airport at 1752 was reported as wind from 160 degrees at 10 knots gusting to 18 knots, visibility 10 statue miles, clouds scattered at 6,000 feet, temperature 97 degrees Fahrenheit, dewpoint 66 degrees Fahrenheit, and a barometric pressure setting of 29.97 inches of Mercury. The calculated density altitude was 3,700 feet.

Wreckage and impact information

An on-scene examination of the airplane wreckage was conducted on July 25, 2005. All major components of the airplane were accounted for at the scene. The main wreckage, which included the left wing, left engine, fuselage, tail section, and the inboard portion of the right wing, came to rest upright on a magnetic heading of 280 degrees at a field elevation of approximately 1,016 feet mean sea level (msl).

The initial impact was a series of ground scars that began approximately 170 feet south of where the main wreckage came to rest and were aligned on a magnetic heading of 355 degrees. The scars included three sequential impact craters that were approximately 6-7 feet apart. Imbedded in the first impact crater were pieces of engine cowling. In the second crater were sections of Plexiglas, and the left propeller was buried in the third impact crater. Also found scattered beyond these initial scars and along the wreckage path were sections of the right wing, both main (tip) fuel tanks, and the right propeller. The right engine came to rest approximately 20-feet forward of the main wreckage.

A post-impact fire consumed the cockpit and fuselage. However, flight control continuity was established for all flight control surfaces to the cockpit. The landing gear was found in the extended position, and the flaps were extended 20 degrees. In addition, the aileron trim was found to be 15 degrees tab down, the elevator trim was 5 degrees tab down, and the rudder trim was extended beyond its normal range.

Both fuel selector handles were destroyed in the fire. Both of the left and right fuel selectors were found extended just beyond the "off" position.

Both engines were examined on August 17, 2005, at the manufacturing facilities of Teledyne Continental Motors, in Mobile, Alabama, under the supervision of the Safety Board. Examination of the right engine revealed it sustained impact damage. When the accessories were removed from the rear of engine, metal particles were found in the oil located on the interior walls of the accessory portals. It was also noted that several camshaft gear teeth were broken, ground down, and/or missing. This was also true for the crankshaft gears and to some of the associated accessory gears. Due to the damaged gears, the engine was not rotated so timing and continuity could not be verified.

Examination of the crankshaft gear revealed that 7 teeth were completely sheared, followed by partial shearing of appr