CEN12LA477

The pilot reported that after a seemingly normal takeoff, the airplane would not climb, and he believed that the engine was not producing full power. The airplane impacted trees on the right side of the runway. The pilot stated that before the attempted takeoff, he performed an engine run-up, during which he checked the operation of the carburetor heat; however, he did not leave the carburetor heat on at higher power settings for more than a few seconds. The pilot then taxied the airplane from the ramp area to the end of the runway for takeoff. The airplane was operating near or slightly over its maximum gross weight when the accident occurred, and the density altitude was calculated to be 3,347 feet. Postaccident examination revealed no preimpact malfunctions or anomalies that would have precluded normal operation. The atmospheric conditions at the time of the accident were conducive for serious carburetor icing at glide power settings. Glide power settings yield a throttle angle similar to low power settings used for taxi operations; therefore, it is likely that the airplane’s carburetor accumulated ice after engine run-up and during taxi, which was not detected by the pilot. This subsequent loss of power due to the carburetor ice accumulation resulted in a reduction in climb performance during takeoff and the resultant impact with trees on the side of the runway.

On July 22, 2012, about 1400 central daylight time, a Luscombe 8A, N71743, impacted trees during takeoff from runway 17 at the Kittie Hill Airport (77T), near Leander, Texas. The pilot and passenger received minor injuries. The airplane sustained substantial damage to both wings, wing struts, fuselage and horizontal tail. The pilot reported that the airplane would not climb after takeoff. It subsequently struck trees approximately 3/4 of the way down the runway on the west side. The airplane was registered to and operated by the private pilot under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed for the flight, which was not operated on a flight plan. The local flight was originating at the time of the accident. The pilot reported that he started the airplane and performed a pre-takeoff run-up checking the magnetos and the operation of the carburetor heat. He stated that the carburetor heat check resulted in an expected slight drop in rpm. He then taxied to the runway to take off. He said that during takeoff, the airplane seemed to accelerate normally, but once airborne, the airplane would not climb and he thought that the engine was not producing full power. He stated that he could not build airspeed and realized that they were going to crash. He said he pulled the control stick back at the last moment to stall the airplane into the trees. The airplane subsequently struck the trees and terrain about 3/4 down the runway on the west side. On his written report the pilot stated that he believed the engine may have developed carburetor ice from the time that he performed his run-up to the time that he took off. In a telephone interview, the pilot was asked about his procedure for checking the carburetor heat. He said that he would apply carburetor heat, note a slight drop in rpm to indicate that the carburetor heat valve was working and then pull the throttle to idle to make sure the engine would idle with the carburetor heat on. He noted that he did not leave the carburetor heat on for more than a few seconds at increased rpm. At 1348, the Georgetown Municipal Airport (GTU), Georgetown, Texas, about 9 miles northeast of the accident site, recorded the weather conditions as: Wind 170 degrees at 5 knots; visibility 10 miles; few clouds at 12,000 feet above the ground; temperature 88 degrees Fahrenheit; dew point 72 degrees Fahrenheit; altimeter setting 30.01 inches of mercury. The density altitude was calculated using the GTU weather information in conjunction with the 77T field elevation as 3,347 feet. According to a carburetor icing probability chart from the Federal Aviation Administration Special Airworthiness Information Bulletin SAIB CE-09-35 “Carburetor Icing Prevention”, the temperature and dew point at the time of the accident were conducive for serious icing at glide power settings. The chart did not differentiate between “glide” power settings and reduced throttlesetting such as would be encountered during taxi operations. Examination of the airplane after the accident did not reveal any pre-impact anomalies; however an engine-run was not performed. The Federal Aviation Administration Inspector that responded to the accident performed a weight and balance using the aircraft weight and balance information found in the glove compartment of the airplane, and pilot and passenger weights as reported by the pilot. Using this data in conjunction with the full fuel and oil loads resulted in a calculated loaded weight of 1,423 pounds. The maximum gross weight of the airplane is listed as 1,400 pounds. On his written report the pilot listed a gross weight at takeoff of 1,392 pounds.