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On August 14, 2011, about 1430 mountain daylight time, a Cessna P210N, N7825K, impacted the terrain about one-eight mile off the departure end of runway 020 at Burley Municipal Airport, Burley, Idaho. The private pilot and his three passengers received fatal injuries, and the airplane, which was owned and operated by the pilot, sustained substantial damage. The 14 Code of Federal Regulations Part 91 personal transportation flight, which was in the takeoff sequence at the time of the accident, was departing for Provo Municipal Airport, Provo, Utah. No flight plan had been filed.
On the day of the accident, the pilot and his immediate family were brought to the airport by extended family members who they had been visiting. After loading the family’s baggage into the airplane’s aft baggage compartment, the pilot was observed preforming a preflight inspection and then loading his family into the airplane. He then started the airplane’s engine and taxied to the approach end of runway 20. Because the view of the witnesses was temporarily blocked, it could not be determined if the pilot performed a run-up prior to turning onto the runway. Also, because of the distance from which family members were watching, it was also not possible to determine whether he started his takeoff roll where he first turned onto the runway, or whether he pulled forward to the 300-foot displaced threshold line prior to applying takeoff power. The airplane was then seen accelerating down the runway and lifting off at a location that was identified by a witness, and later determined to be about three-quarters of the way down the runway. Just after liftoff, the main landing gear was seen moving aft, and then retracting into the fuselage with the jerky asymmetrical sequencing typical of retractable gear Cessna 210 airplanes. Then, almost immediately after the gear was fully retracted, with the airplane at an altitude estimated by witnesses to be about 75 feet above ground level, and the airplane not yet to the end of the runway, it was seen banking to the left and starting what appeared to be a left turn. Almost immediately after the airplane entered the left bank, it began a gradual descent. It then continued to descend toward the terrain in a left bank, ultimately impacting the surface of an asphalt road located immediately beyond the boundary of the airport property, in what nearby witnesses estimated was a 30 degree bank angle. The left wing tip was the first part of the airplane to contact the road, followed immediately by the airplane’s belly and propeller. The airplane then skipped back into the air, began rotating counterclockwise around its lateral axis, traveled about 75 feet further southeast before colliding with a set of railroad tracks. After colliding with the tracks, the airplane decelerated rapidly and slid about 55 feet further to the southeast before coming to rest. Almost immediately after the airplane came to rest, an intense fire, which had been initiated upon contact with the railroad tracks, engulfed the entire airframe.
The 42 year old private pilot held an airplane single engine land rating and an instrument rating. He had been endorsed to operate both complex and high performance airplanes. As of the last entries in his pilot log book, which were dated January 30, 2011, he had logged about 480 hours total flying time, with about 160 of those hours being in a Cessna 210. His last airman’s medical, a third class, was issued on November 3, 2008. The last flight review entered in his log book was completed on March 7, 2009.
The airplane was a 1979 Cessna P210N, with a Continental Motors TSIO 520-P (6) engine, and 3-bladed McCauley D3A34C402-C propeller. Its last annual inspection was performed on July 1, 2011, at which time the Hobbs meter indicated 820.5 hours. At the time of the last annual inspection the engine had accumulated 1,044.35 hours since remanufacture. Its last known maintenance was the replacement of its alternator and airframe battery on August 10, 2011. At that time the Hobbs meter read 839.6 hours.
The 1353 aviation surface weather observation (METAR) at Burley Municipal Airport indicated a wind from 030 degrees at 03 knots, 10 miles visibility, clear skies, a temperature of 90 degree F, a dew point of 36 degrees F, and an altimeter setting of 29.97 inches.
According to the airport manager, at the time of the accident, which was about 38 minutes after the aforementioned METAR, the temperature was 91 degrees F, and the wind was between 020 and 030 degrees at 6 knots.
The father of the pilot, who witnessed the takeoff sequence, said that although he did not know much about airplanes, he had noticed that there was a tailwind of about 5 to 10 miles per hour, which he thought was not normal.
Based upon the temperature of 91 degrees F, the dew point of 36 degrees F, an altimeter setting of 29.97 in Hg, and a field elevation of 4,150 feet mean sea level, the density altitude was calculated to be 7,116 feet.
WRECKAGE AND IMPACT INFORMATIONS
After clearing a seven-foot high perimeter fence, the top of which was about the same height as the elevated roadway to its southeast, the airplane traveled another 39 feet, where it struck the crown of the asphalt road at a point 290 feet southeast of a line running perpendicular to the departure end of Runway 020. After skipping off the road, it continued on a track of 170 degrees magnetic, before impacting the railroad tracks about 110 feet past where its left wing tip initially contacted the road. Upon impacting the railroad tracks, both of which became and permanently bent and displaced about 6 inches to the south, the airplane continued on a magnetic track of 150 degrees for another 55 feet. Its fuselage ultimately came to rest about 15 feet south of the railroad tracks, at a point located 60 feet beyond the end of Runway 020 and 315 feet to the east of the end of the runway. Due to the intense nature of the post-crash fine, all of the airplane’s non-ferrous metal structural components were consumed or destroyed by the fire, except for the rudder, right elevator, a portion of the engine cowling, and the outboard half of the right wing. The fuselage itself, from the firewall aft to the empennage, had suffered severe thermal damage, with only the ferrous metal components, such as seat frames and control cables, remaining intact. The left wing structure, except for portions of the inboard half of the upper and lower spar caps had been thermally destroyed. The left horizontal stabilizer and elevator had been thermally destroyed. Most of the structure of the vertical fin and vertical stabilizer, as well as the right horizontal stabilizer, had been thermally destroyed. Continuity of flight control, trim control, and flap control cables from the cabin of the airplane to the associated surfaces was able to be established, but due to the extent of the damage, correct movement of the control surfaces could not be determined. The trailing edge of the right elevator trim tab was about one inch up (nose down trim) from the trailing edge of the elevator. The left elevator trim tab was destroyed. The outboard 18 inches of the right flap, which was all that remained, was about 10 degrees extended. Both wing-mounted speed brakes were in the retracted position. The instrument panel and its associated instruments had been destroyed by the impact and fire, but the throttle and propeller controls were determined to be in the full forward position. The mixture control was in the full out (off) position. The fuel selector was on the right tank. All three landing gear were in the retracted position.
The engine had separated from the airframe, and was sitting just forward of the inboard portion of the left wing. It had sustained significant thermal damage. It was recovered and taken to the facilities of SP Aircraft in Boise, Idaho, for further examination. The turbocharger assembly had separated from its engine mount and exhaust stack, but remained attached to its hydraulic lines, which were tight and secure on both the engine and the turbocharger. The wastegate was in the open position, and the turbine shaft was able to be rotated freely by hand. The over-boost valve separated and was found with the main wreckage. All of the engine accessories remained attached to the accessory case. The magnetos were removed from the accessory case, and when rotated by hand the impulse couplings engaged normally. No spark was able to be generated by either magneto when rotated by hand. The magnetos were therefore disassembled, whereupon it was determined that the internal components displayed significant thermal damage. The oil filter was removed and disassembled, and no debris was noted in the folds of the filter material. The oil scavenge pump and oil pump were disassembled and were found to be undamaged. Impact marks were visible in the pump cavity. The cylinder rocker covers were removed, which revealed that the overhead components were lubricated and undamaged. All six cylinders were boroscoped, and the combustion chambers and piston heads were found to be undamaged with no sign of anomalies. The crankshaft was rotated and cylinder compression and valve continuity was obtained. The upper spark plugs were removed and the electrode areas had (Worn out-Normal) wear conditions when compared to the Champion AV-27 condition chart. The no. 5 upper shell had impact damage. The no. 1 and 3 electrode areas had a light coating of light grey deposits. The remaining plugs were saturated with oil. The propeller assembly remained attached to the crankshaft propeller flange, and had impact and thermal damage. One blade separated from the hub and had similar damage. All three blades had been ground down at their tips where they had come in contact with the asphalt roadway. Each blade displayed severe chord-wise scarring in the area just inboard of the portion that had been ground off. Two of the blades displayed twisting of more than 180 degrees along their longitudinal axis, and on all three the area near the ground off tips was bent directly aft. At the completion of the engine examination it was determined that no preimpact anomalies that would have kept the engine from producing rated horsepower had been found.
MEDICAL AND PATHOLOGICAL INFORMATION
An autopsy was performed on the pilot by the Cassia County Coroner’s Office. The cause of death was determined to be thermal injuries secondary to an aircraft accident.
The Federal Aviation Administration’s Civil Aerospace Medical Institute performed a forensic toxicological examination on specimens taken from the pilot. The examination was negative for ethanol in the vitreous, cyanide in the blood, and for drugs in the urine. The test for carbon monoxide in the blood revealed a level of ten percent, which is higher than the average adult range of two to eight percent.
ALTERNATOR REPLACEMENT AND REFUELING
On Tuesday August 9, five days prior to the accident, the pilot and his family departed an airport near their home in Glendora, California, for the flight to Burley, Idaho. While en route the airplane’s alternator stopped functioning, so the pilot decided to deviate to Twin Falls, Idaho, where he could get the alternator repaired or replaced. Once on the ground there, it was determined that the alternator needed to be replaced, which was a maintenance action that had been required two other times since the pilot bought the airplane. The airplane was therefore left in Twin Falls for maintenance action, and after being picked up by another family member, the pilot and his family continued on to Burley via automobile. The next day, August 10, both the alternator and the airframe battery were replaced and tested by Myers Aircraft Maintenance, Inc., of Twin Falls.
On August 11, three days prior to the accident, a family member drove the pilot and his sister back to Twin Falls to pick up the airplane. After departing Twin Falls, they flew to Nampa, Idaho, where the pilot had a meeting to attend. After that meeting, the pilot and his sister departed Nampa, and instead of flying southeast to Burley, the pilot flew about 7 miles northwest to Caldwell, Idaho for refueling. At that point the pilot explained to his sister that the reason he was refueling at Caldwell instead of Burley was that he was going to take on enough fuel so that he could fly, without further refueling, from Caldwell to Burley, from Burley to Provo, Utah, and then from Provo back to the family home in Southern California. He further explained that he felt that because of the amount of fuel he was going to take on, and the difference in the fuel price between Caldwell and Burley, he would save a significant amount of money filling up in Caldwell. After taking on 94.24 gallons of aviation fuel at Caldwell, the pilot and his sister flew directly to Burley, a distance of about 160 miles. According to the sister, there did not seem to be any electrical issues during any of the flight legs on August 11, and the pilot did not mention anything negative about the results of the alternator replacement.
WEIGHT AND BALANCE AND TAKEOFF PERFORMANCE
Although the exact weight of the airplane at the time of the takeoff could not be positively determined, takeoff gross weight and performance calculations were performed based on the assumption that all three fuel tanks (two mains and the auxiliary) had been topped off when the pilot refueled at Caldwell, and that about 70 pounds of fuel was used during the subsequent flight to Burley. This assumption was based on the fact that during the Caldwell refueling, the pilot took on more fuel than the two main tanks combined could hold (90 gallons maximum), and the fact that in an email to a friend after the flight from California to Idaho, the pilot mentioned that he had used the auxiliary fuel tank and was stuck with ¼ of its volume being unusable when he experienced the alternator failure. In addition, due to the degree to which the intense fire consumed the family’s baggage and other miscellaneous items onboard, the weight of those items had to be estimated. After analyzing what remained of those items, an estimated weight of 100 pounds total weight was used for the calculations. Based upon these fuel and baggage weight assumptions, the weights of the occupants, and the most recent weight and balance found in the airplane’s records, the takeoff weight was estimated to be within 50 pounds, plus or minus, of its maximum takeoff gross weight of 4,000 pounds (see weight and balance calculations in docket). Based upon the 4,000 pound estimated weight, the temperature of 91 degrees F, and the tailwind of 6 knots, the expected takeoff ground roll was determined to be 2,412 feet, and the 50 foot obstacle clearance distance was determined to be 4,048 feet.
According to the father of the pilot, who witnessed most of the takeoff and accident sequence, the pilot had taken off from Burley only one other time that he could remember. Although he could not remember exactly which month of the year the previous takeoff had taken place, he did remember that it was in winter, and that it was very cold outside. During that takeoff, the airplane got off the ground sooner and climbed at a much greater rate, but in much the same way as in the accident takeoff, the pilot initiated a left turn almost as soon as the landing gear was retracted. In that case the pilot maintained a left climbing turn that took the airplane over a set of hangars located in the southeast corner of the airport, and then continued his left climbing turn to the north. The father assumed that the pilot made the turn when and where he did in order that he and his passengers could keep the family members on the ground in sight during the initial part of the climb after takeoff.
According to the father, it appeared to him that on the day of the accident, the pilot was following the same basic takeoff profile, including the early turn. He said that when the pilot initiated the left turn, he expected to see the airplane continue its climbing turn over the hangar, in much the same way as it had before. Instead, right after the airplane entered the left turn, he saw it begin to descend, and ultimately it completely disappeared behind the hangar. Then, a few seconds later, he saw a billowing plum of black smoke rise from just beyond where the airplane had gone out of sight.
About 38 feet past the point where the airplane’s left wing tip contacted the surface of the road, there was a series of propeller impact gouges in the road’s asphalt surface. Although there appeared to be nine propeller impact gouges, only the first seven were well defined, as the last two were significantly distorted and hard to see because of additional impact scars and gouges created by the impact of the airplane’s belly. The distance between the first and second gouges was 16 inches, between the second and third was 14 inches, between the third and fourth was 13 inches, between the fourth and fifth was 10 inches, between the fifth and sixth was 14.5 inches, and between the sixth and seventh was 11.5 inches. Because the speed of the aircraft could not be accurately determined, and because the airplane was rotating counterclockwise around its vertical axis after its left wing tip hit the road, the distance between propeller strikes could not be used to calculate the engine’s rpm at impact.