ERA12LA432

The pilot stated that during his preflight inspection of the airplane he determined that the fuel was not contaminated by water or debris. The pilot also checked the weather and determined that the formation of carburetor ice was unlikely. After taking off and flying along a river valley, the pilot turned the airplane to cross a mountain range. He added power to climb, and shortly thereafter, the engine lost power, and the pilot made a forced landing into trees. The pilot stated that he did not use carburetor heat during the flight, and, except for an instance in which the self-modulating pitch propeller moved to coarse pitch during a flight earlier that day, the pilot did not report any preexisting mechanical anomalies or unusual weather phenomena. The wreckage was not examined after the accident. Postaccident review of carburetor icing probability charts indicated a likelihood of carburetor ice formation while the airplane was in cruise flight along the river valley, which would likely have affected engine power during the attempted climb. However, because no follow-up examination was performed, it was not possible to determine why the engine lost power.

On July 6, 2012, about 1835 eastern daylight time, an experimental amateur-built Piel Emeraude CP-305, Canadian registration C-FBZZ, was substantially damaged when it impacted trees and terrain near Banner Elk, North Carolina. The Canadian commercial pilot incurred minor injuries. Visual meteorological conditions prevailed, and no flight plan had been filed for the flight, from Johnson County Airport (6A4), Mountain City, Tennessee, to Asheville Regional Airport (AVL), Asheville, North Carolina. The personal flight was conducted under 14 Code of Federal Regulations Part 91. According to the pilot, the accident flight was the fourth leg overall, and the first leg on the second day of a 3-day trip to the Blue Ridge Mountains. Although the pilot had not filed a flight plan for that leg, flight following was provided by his father. At 6A4, the pilot obtained fuel, but only to half-full tanks due to the weight of his baggage. Since the flight was the first flight of the day, the pilot sumped the single fuel tank, and noted no water or contaminants in the fuel. He also checked weather conditions via computer, and with the forecast conditions, was not concerned with carburetor icing. After departing 6A4, the pilot flew southwest at 1,000 feet above ground level, following lower terrain. He then made a left turn and followed a river valley toward Boone, North Carolina, before beginning a climb over rising terrain toward Elk River, North Carolina. About 30 seconds after commencing the climb, the pilot noted the rpm of the fixed pitch propeller Lycoming O-235 engine drop from 2,300 rpm to 1,900 rpm. As the pilot began a gradual turn toward lower terrain, the engine lost all power, and the airplane force landed into trees. The pilot did not utilize carburetor heat. The Federal Aviation Administration (FAA) did not examine the airplane, and except for the Aeromatic propeller going to coarse pitch the day before, the pilot did not report any preexisting mechanical anomalies. The approximate elevation of the crash site was 3,600 feet. Weather, recorded at the same time of the accident in Boone, North Carolina, located about 10 nautical miles to the east at an elevation about 3,000 feet, included clear skies, wind from 290 degrees true at 11 mph, temperature 26 degrees C, dew point 17 degrees C, altimeter setting 30.14 inches Hg. Utilizing those temperature and dew point figures on an FAA carburetor icing probability chart yielded conditions favoring serious carburetor icing at cruise power. Another carburetor icing probability chart, found in FAA Winter Flying Tips, P-8740-24, indicated "light icing – glide or cruise power." An edition of the "Lycoming Flyer Operations," published by the engine manufacturer, states: "The most subtle and insidious of the airflow blockage possibilities is probably refrigeration ice, known more commonly as carburetor ice that forms in the vicinity of the "butterfly" or throttle plate. Every pilot who flies an aircraft powered bya carbureted engine should be thoroughly educated about carburetor ice. They should know that under moist conditions (a relative humidity of 50 percent to 60 percent is moist enough), carburetor ice can form with an outside temperature from 20 degrees to 90 degrees F. It is most likely in the 30 degrees to 60 degrees F range. Temperatures in the carburetor can drop 60 degrees to 70 degrees (refrigerator effect) as a result of fuel vaporization and carburetor venture effect. It also happens that carburetor ice forms more readily when the engine in the lower power range. It is imperative that the pilot recognize carburetor ice when it forms during flight. The loss of power that occurs will cause a reduction of RPM when flying with a fixed-pitch propeller, and a loss of manifold pressure when a controllable-pitch propeller is used. In any case, it is a good idea to consider carburetor ice as the cause of any unexplained power loss during cruise flight." Calculated relative humidity for the ambient temperature and dew point was 57.69 percent.