CEN14FA009

The airplane's encounter with severe icing conditions, which resulted in structural icing, and the pilot's increased workload and subsequent disorientation while maneuvering in instrument flight rules (IFR) conditions with malfunctioning flight instruments, which led to the subsequent loss of airplane control. Contributing to the accident was the pilot's decision to takeoff in IFR conditions and fly a single-pilot operation without a functioning autopilot and with malfunctioning flight instruments.

After climbing to and leveling at 15,000 feet, the airplane departed controlled flight, descended rapidly in a nose-down vertical dive, and impacted terrain; an explosion and postaccident fire occurred. Evidence at the accident site revealed that most of the wreckage was located in or near a single impact crater; however, the outer portion of the left wing impacted the ground about 1/2 mile from the main wreckage. Following the previous flight, the pilot reported to a maintenance person in another state that he had several malfunctioning flight instruments, including the autopilot, the horizontal situation indicator, and the artificial horizon gyros. The pilot, who was not a mechanic, had maintenance personnel replace the right side artificial horizon gyro but did not have any other maintenance performed at that time. The pilot was approved under an FAA exemption to operate the airplane as a single pilot; however, the exemption required that all equipment must be operational, including a fully functioning autopilot, flight director, and gyroscopic flight instruments. Despite the malfunctioning instruments, the pilot chose to take off and fly in instrument meteorological conditions. At the time of the loss of control, the airplane had just entered an area with supercooled large water droplets and severe icing, which would have affected the airplane's flying characteristics. At the same time, the air traffic controller provided the pilot with a radio frequency change, a change in assigned altitude, and a slight routing change. It is likely that these instructions increased the pilot's workload as the airplane began to rapidly accumulate structural icing. Because of the malfunctioning instruments, it is likely that the pilot became disoriented while attempting to maneuver and maintain control of the airplane as the ice accumulated, which led to a loss of control.

HISTORY OF FLIGHT On October 18, 2013, at 1017 central daylight time, N610ED, a Cessna 500, Citation, multi-engine turbojet airplane, collided with terrain during an uncontrolled descent near Derby, Kansas. The pilot and passenger were fatally injured, and the airplane was destroyed. The airplane was registered to and operated by Dufresne, Inc.; Murrieta, California. Day visual meteorological conditions (VMC) prevailed on the surface; however, instrument meteorological conditions (IMC) likely prevailed at altitude at the time of the accident. An instrument flight rules flight plan had been filed for the 14 Code of Federal Regulations Part 91 business flight. The airplane departed Wichita Mid-Continent Airport (ICT), Wichita, Kansas, at 1007 and was destined for New Braunfels Regional Airport (BAZ), New Braunfels, Texas. During climb to cruise, after leveling at 15,000 feet, the airplane departed controlled flight, descended rapidly and impacted terrain. Several witnesses described seeing the airplane below the clouds in a nose-down vertical dive and trailing either white smoke or black smoke. One of the witnesses reported the nose-down airplane was "spinning very fast". Many of the witnesses reported an immediate explosion with a fireball about 500 feet high followed by a column of black smoke. Evidence at the accident scene showed evidence of a postimpact fire with most of the wreckage located in or near a single impact crater. Several witnesses reported that after they heard or saw the explosion and fire they saw airborne debris tumbling and falling to the ground about one half mile west from the main wreckage. PERSONNEL INFORMATION The pilot, age 49, held a Federal Aviation Administration (FAA) commercial pilot certificate with ratings for airplane single engine and multiengine land, and instrument airplane. His private pilot certificate in airplane single engine land was initially issued on March 6, 2000, his private pilot rating in airplane multiengine land was issued on May 17, 2000, and his rating in instrument airplane was issued on January 7, 2006. On January 20, 2006, he was issued a commercial pilot certificate in airplane multi-engine land, and on February 6, 2006, he was issued a restricted type rating for CE-500 with a limitation "SIC privileges only". On December 13, 2008, he was issued an unrestricted type rating for CE-500. The pilot also held an FAA second-class medical certificate, issued on July 3, 2012, with a restriction "must have available glasses for near vision". A review of the pilot's three logbooks showed entries beginning on January 21, 1999, with the last entry in logbook number three on October 11, 2013. The logbooks showed that his total pilot experience was then 2,605 hours, with about 2,366 hours in multi-engine airplanes, and a total of 239 hours of instrument flying experience. He had logged at total of 1,172 hours of pilot experience in Cessna 500 and 550 airplanes which included 658 hours of second-in-command experience. The pilot completed a satisfactory CE-500 pilot proficiency check on October 4, 2012. One month later on November 10, 2012, he completed a satisfactory proficiency check for a single pilot exemption in CE-500 airplanes. Pilot logbook entries showed that since November 17, 2012, he had flown about 206 hours in CE-500 airplanes with all of that experience logged as a "single pilot", and without another pilot crewmember in the cockpit. AIRCRAFT INFORMATION The Cessna 500, Citation, serial number (s/n) 500-0241, was a multi-engine business turbojet airplane. The transport category airplane was originally issued a standard airworthiness certificate on June 12, 1975. It was powered by two Pratt & Whitney Canada JT-15D-1A turbofan engines, s/n 76522 and s/n 76209, each capable of producing 2,200 pounds of thrust. At the time of the accident the airplane was maintained on an approved aircraft inspection program (AAIP) and its most recent airframe inspection was completed on September 24, 2012, at an airplane total time of 7,560.9 hours. On that date the left and right engines had then accumulated a total of 7,212.8 hours and 10,435.2 hours, respectively. Based on a postaccident review of invoices, correspondence, pilot logbook entries, and other documents, the total flight time from September 24, 2012, to the accident date was estimated as an additional 249 hours. The airplane's type-certificate data sheet (TCDS) showed a maximum takeoff weight limitation of 11,500 pounds and showed the airplane was certified with seats for two pilots and a maximum of seven passengers. The limitations in the TCDS also required a minimum crew of a pilot and co-pilot for all flights. The airplane could be operated with only one pilot if the pilot had been approved under an FAA exemption which included completion of an FAA approved single-pilot training program. That exemption for single pilot operation also stated that all required equipment must be operational including a fully functioning autopilot, flight director, and gyroscopic flight instruments. An aviation maintenance person in another state reported that the pilot had telephoned him on the day before the accident. The pilot stated that he had just arrived at ICT and on his inbound flight he had several failure flags on the horizontal situation indicator (HSI) and artificial horizon (AH) gyro instruments, and that the right side (co-pilot side) AH gyro was "sideways". The pilot also stated that several times on the same inbound flight to ICT he had uncommanded drops in N1, N2, and ITT readings on one engine and those repeated changes in the engine power setting required re-trimming the aircraft. Maintenance records and interviews with maintenance persons at ICT showed that the pilot got their assistance to replace the co-pilot's AH gyro instrument. However, the pilot did not mention to them the problems with the malfunctioning autopilot, the malfunctioning pilot's flight instruments, or the malfunctioning engine. No evidence could be found that the pilot ever attempted to fix those problems. FAA registry documents show that the airplane was purchased by the current owner on March 14, 2005, and that since 1975 the airplane had been registered to 16 different owners. METEOROLOGICAL INFORMATION ICT was located 13 miles northwest from the accident site at an elevation of 1,333 feet mean sea level (msl). At 0953 the surface weather observation site at ICT reported wind from 010 degrees at 10 knots, 10 miles visibility, light rain, a broken ceiling at 4,400 feet above ground level (agl), overcast skies at 6,500 feet agl, temperature of 7 degrees Celsius (C), dew point temperature of 3 degrees C, and an altimeter setting of 30.15 inches of Mercury. McConnell Air Force Base (IAB) was located 6 miles north-northwest of the accident site, at an elevation of 1,371 feet msl. At 0958 the surface weather observation site at IAB reported wind from 020 degrees at 10 knots, 10 miles visibility, light rain, few clouds at 900 feet agl, temperature of 6 degrees C, dew point temperature of 4 degrees C, and an altimeter setting of 30.15 inches of Mercury. The observations from IAB and ICT indicated light rain at the surface at the time of the accident with cloud ceilings lowering over time. Pilot reports in the area indicated light to moderate icing conditions above 6,000 feet msl at the accident time. AIRMETs Sierra and Zulu issued at 0945 (1445 UCT), and valid at the accident time, forecasted IFR conditions for the accident site with ceilings below 1,000 feet and visibilities below 3 miles with precipitation and mist, and moderate icing conditions between the freezing level and FL180. Current Icing Potential (CIP) is produced by the NWS' Aviation Weather Center and is intended to be supplemental to other icing advisories (e.g. AIRMETs and SIGMETs). The CIP indicated a 40 to 80 percent probability of icing at the acciden