CEN13LA525

The pilot reported that he had flown a group of skydivers to altitude for an intentional parachute jump about 3 miles north of the airport and was returning for landing at the time of the accident. The airplane was on final approach when the engine lost power. The pilot's attempts to restore engine power were unsuccessful, and he ditched the airplane into a lake short of the runway. The pilot reported using carburetor heat during the descent; however, the pilot did not periodically apply engine power (clear the engine) during the descent. According to FAA Advisory Circular 20-113, Pilot Precautions and Procedures to be Taken in Preventing Aircraft Reciprocating Engine Induction System and Fuel System Icing Problems, "Heat should be applied for a short time to warm the induction system before beginning a prolonged descent with the engine throttled and left on during the descent. Power lever advancement should be performed periodically during descent to assure that power recovery can be achieved." A postaccident engine examination did not reveal any anomalies consistent with a preimpact failure or malfunction. Local weather conditions were conducive to the formation of carburetor icing.

**This report was modified on 1/30/2014. Please see the public docket for this accident to view the original report.** On September 1, 2013, about 1100 mountain daylight time, a Cessna 182 airplane, N6460A, was substantially damaged when the pilot ditched the airplane into a lake following a loss of engine power on approach to the Boulder Municipal Airport (BDU), Boulder, Colorado. The pilot sustained minor injuries. The airplane was registered to and operated by N6460A LLC under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed for the flight, which was not operated on a flight plan. The local flight originated from BDU about 1035. The pilot reported that he had flown a group of skydivers to altitude for an intentional parachute jump about 3 miles north of the airport and was returning for landing at the time of the accident. The airplane was on final approach to runway 8 (4,100 feet by 75 feet, asphalt) when the engine lost power. His attempts to restore engine power were unsuccessful and he subsequently ditched into Hayden Lake short of the runway. He reported a clear sky with a light and variable wind. A postaccident engine examination conducted by a National Transportation Safety Board investigator did not reveal any anomalies consistent with a preimpact failure or malfunction. Approximately 11 gallons of fuel were recovered from the airplane after the accident. The Pilot's Operating Handbook for the accident airplane noted that up to 5 gallons of fuel is unusable in all flight conditions, with 2 gallons of fuel being unusable in level flight. Weather conditions recorded at the Rocky Mountain Metropolitan Airport (BJC), located about 9 miles southeast of BDU, at 1047, included an ambient temperature and dew point of 21 degrees Celsius and 11 degrees Celsius, respectively. According to a Federal Aviation Administration (FAA) inspector, the pilot had reported using carburetor heat during the descent after the skydivers left the airplane; however, the pilot did not periodically apply engine power (clear the engine) during the descent. Information provided by the FAA regarding carburetor icing noted a possibility of serious icing at glide power under those conditions. According to FAA Advisory Circular 20-113, Pilot Precautions and Procedures to be Taken in Preventing Aircraft Reciprocating Engine Induction System and Fuel System Icing Problems, "Heat should be applied for a short time to warm the induction system before beginning a prolonged descent with the engine throttled and left on during the descent. Power lever advancement should be performed periodically during descent to assure that power recovery can be achieved."