Black Hawk, CO, USA
N8553S
CESSNA 182
The airplane entered clouds and snow showers while en route on an instrument flight plan. Temperatures compounded with relative humidity, placed the airplane in conditions favorable for structural and induction system icing. During the flight, the engine lost partial power and the pilot could not maintain level flight. During the descent, the engine was observed to lose and regain power. The pilot continued to manuever the airplane until it collided with terrain. An examination of the airframe and engine failed to reveal any anomalies which would have precluded the safe operation of the airframe or production of engine power.
HISTORY OF FLIGHT On May 8, 2008 at approximately 1545 mountain daylight time, a single engine Cessna 182H, N8553S, was substantially damaged upon impact with terrain following a partial loss of engine power near Black Hawk, Colorado. The private pilot was fatally injured and the passenger sustained serious injuries. The airplane was owned and operated by Winkmaggair, LLC. Instrument meteorological conditions (IMC) were reported by the passenger and an instrument flight plan was filed for the 14 Code of Federal Regulations Part 91 personal flight. The cross country flight originated from Glenwood Springs Airport (GWS), Glenwood Springs, Colorado at approximately 1508 and was destined for the Boulder Municipal Airport (BDU), Boulder, Colorado. In an interview with the NTSB investigator-in-charge, the passenger reported that at 16,000 feet mean sea level (MSL), the airplane entered clouds with light snow after they passed Eagle County Airport (EGE) which continued throughout the flight. While en route to Boulder, the airplane had difficultly maintaining altitude and the engine began to "sputter." The passenger recalled that the pilot stated that they were experiencing a "mixture problem" and began adjusting the mixture control. While still in the clouds, the airplane began a right turn and continued descending as the pilot attempted to troubleshoot the engine malfunction. Air traffic controllers queried the pilot's heading change and attempted to provide services and altitude warnings. While troubleshooting the engine malfunction, the pilot was observed by the passenger to be actuating all of the engine controls, but mainly the mixture control. The passenger, who is not familiar with light airplanes, was not positive if the carburetor heat was ever activated. According to the passenger, the engine would "sputter" and then "come back to life." Additionally he stated that when the engine would "sputter" the airplane would "nose over." The pilot continued to fly the airplane, and once visual contact with the ground was established, the pilot maneuvered to avoid mountainous terrain until the airplane collided with a mountain at 10,400 feet MSL. The passenger egressed the airplane, freed the pilot, called for emergency services, and attempted to provide medical assistance to the pilot. The accident site was discovered by a local news helicopter; search and rescue parties provided assistance. PERSONNEL INFORMATION The pilot, age 47, held a valid private pilot certificate with airplane single-engine land and instrument ratings. A valid third-class airman medical certificate was issued on October 2, 2006. The pilot's log book was retrieved at the accident site. The last entry in the pilot's log book was on January 13, 2008 for 3.6 hours of single-engine flight time. The co-owners of the airplane maintained an airplane tachometer time log. On the tachometer time log, the pilot recorded three additional days of flying including 3.5 hours recorded on April 23, 2008, which was the last flight prior to the mishap. AIRCRAFT INFORMATION The four-seat, high wing, fixed gear airplane, serial number 18256653, was manufactured in 1965. It was powered by a 230 horsepower Teledyne Continental Motors O-470-R engine. Review of the maintenance logbook revealed that the last annual inspection was accomplished on June 13, 2007. At the time of the annual inspection the tachometer recorded 2800.9 hours, and the airframe had 4652.9 hours logged. At the time of the accident, the tachometer displayed 2868.4 hours. METEROLOGICAL INFORMATION A detailed weather study was conducted by an NTSB Senior Meteorologist. The airplane was climbing to 16,000 feet MSL, when it passed near Eagle County Regional Airport (EGE), Eagle, Colorado, at approximately 15,600 feet MSL or approximately 9,000 feet above ground level (AGL). An automated weather reporting station at EGE reported weather from 220 degrees at 10 knots gusting to 16 knots, few clouds at 3,800 feet AGL, scattered clouds at 4,400 feet AGL, ceiling broken at 6,000 AGL, temperature 48 Fahrenheit, dew point 36 degrees Fahrenheit. At 1532 MDT the airplane passed 23 miles north of the Copper Mountain, Red Cliff Pass, Colorado weather observation system (KCCU). KCCU reported winds from the 310 degrees at 16 knots gusting to 32 knots, 1/2 miles visibility with [moderate] snow, ceiling broken at 400 feet, overcast at 700 feet, temperature 27 degrees Fahrenheit, dew point 18 degrees Fahrenheit, with a remark for lightning in the distance to the north, east and southwest of the station. The upper air sounding for the Denver area reported that at 16,000 feet, winds were from 300 degrees at 22 knots, temperature 7 degrees Fahrenheit, dew point 5 degrees Fahrenheit. This placed the airplane flight path through a relative humidity of 94% with an approximate 50% chance of moderate clear icing conditions. Base reflectivity images for the accident flight shows the flight path through echoes between 15 dBZ and 25 dBZ, corresponding to very light precipitation. There is no record of the pilot receiving a weather briefing from a flight service station or the Direct User Access Terminal Service (DUATS). The pilot logged into a user account on www.fltplan.com to file his flight plan. A review of his session data by employees of the website revealed that the pilot did not check weather while logged in. It is unknown if the pilot checked weather using a different method. Flight planning paperwork found in the wreckage was absent of weather information. WRECKAGE AND IMPACT INFORMATION The wreckage came to rest in a heavily wooded portion of a mountain side. The airplane impacted at an estimated 140 degree magnetic heading. Several splintered trees revealed a shallow descending flight path before the airplane impacted rising terrain. In addition, the leaded edges of both wings displayed "accordion-style" crushing. The leading edges of the left wing and left horizontal stabilizer displayed signs of impact with bark deposits consistent with tree strikes. The left side of the engine and cabin compartments received a larger degree of crushing due to the relative angle at the moment of ground impact. The engine was found buried in snow and soil. An examination of the airframe was conducted at the accident site with the assistance of a technical representative from Cessna Aircraft. Control continuity was established from the left aileron and elevator control surfaces to the control yokes. The right wing was separated near the flap-aileron junction. The right aileron control cable displayed signatures consistent with overload. Rudder control continuity was established to both sets of rudder pedals. The flaps were set at approximately 10 degrees. The fuel selector was found in the "BOTH" position and the valve was found to be unobstructed. The firewall fuel strainer was examined and found to be unobstructed. Both fuel tanks contained fuel that tested negative for the presence of water using a water-detection paste. The carburetor heat control knob was found in the full forward position corresponding with an "off" setting. The throttle control was found in the full forward position corresponding with full throttle. The propeller control and mixture control knobs were found approximately mid-travel. No abnormalities were noted which would have precluded the safe operation of the airframe. MEDICAL AND PATHOLOGICAL INFORMATION Forensic toxicology was performed on specimens from the pilot by the FAA Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma. The toxicology report stated that no carbon monoxide, cyanide, ethanol, or drugs were present in the submitted specimens. An autopsy of the pilot was conducted as authorized by the Coroner of Gilpin County, Colorado. The medical examiner determined the cause of death was due to closed head injuries secondary to blunt force trauma. TESTS AND RESEARCH The engine was recovered and sent to Teledyne Continental Motors, Mobile, Alabama, for further examination. Impact damage was noted to cylinders #4 and #6 cylinders. Both cylinders were removed, examined, and exhibited no pre-impact anomalies. The magneto leads sustained damage and were removed, tested, and found capable of conducting current. In order to test run the engine, the #4 cylinder, #6 cylinder, and magneto leads were replaced with new components for the engine run. In addition, the following components were damaged during the crash sequence and replaced with stock components: the oil sump, oil cap, and oil screen. The engine was mounted in a test cell and started normally and produced engine power. No anomalies were noted with the engine which would have precluded normal engine operation. The airplane was equipped with a Garmin GPSmaps 496 which recorded flight parameters for the mishap airplane. Data downloaded from the GPS unit revealed that the flight remained level at 16,000 feet MSL for about 14.5 minutes after which the plane began to descend. Over the next 4.5 minutes, the airplane descended on average 1,100 feet per minute. Four “zoom” maneuvers, where the airplane's altitude increased while the airspeed is allowed to decay, were recorded. These maneuvers corresponded with the airplane's flight path avoiding mountainous terrain.
The loss of engine power due to induction icing. A contributing factor was the pilot's decision to continue flight in conditions favorable for structural and induction-system icing.
Source: NTSB Aviation Accident Database
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