CEN11LA396

The flight instructor was demonstrating agricultural, low-altitude operations to the pilot. The instructor reported that he noticed a loss of engine power when making a turn; the airplane then descended and impacted the tops of several trees. The airplane fell nose first through the thick wooded canopy, coming to rest in the trees in a mostly nose-down attitude. The pilot reported that the instructor had been flying the airplane slowly while in wingover turns and that the stall light would regularly flicker on and off during the climbing turns. He added that the instructor did not increase the engine power setting before impact and that the airspeed was low immediately before the airplane impacted the trees. The instructor did not report using carburetor heat during his low-altitude operations but did report that he was operating at a reduced power setting. An examination of the airplane showed no preimpact mechanical malfunctions or failures that would have precluded normal operation. Although a carburetor icing probability chart indicated that an airplane operating in the ambient conditions at the time of the accident could expect a risk of carburetor icing while at cruise power and a serious risk of carburetor icing while at glide power, it is more likely that the airplane entered into an aerodynamic stall at an altitude too low for the pilot to recover based on the account given by the pilot.

On May 27, 2011, about 1430 central daylight time, a Grumman G-164A, single engine airplane, N2LU, was substantially damaged when it impacted trees near Oak Ridge, Louisiana. The airplane was registered to and operated by Barham Brothers, Inc. The certified flight instructor (CFI) and the pilot both sustained minor injuries. Visual meteorological conditions prevailed and a flight plan had been not filed for the 14 Code of Federal Regulations Part 137 agricultural training flight. The local flight had departed from Hooks Memorial Airport (M79), Rayville, Louisiana, about 1330. The CFI reported that he was flying the airplane at a low-altitude and was demonstrating a pass to the pilot. He had been flying about 80 to 90 mph during the low passes with the engine power set at 22 to 23 inches of manifold pressure. The CFI made a flat tear-drop turn to reenter the field when he noticed a loss of engine power and a slight loss of altitude. The CFI then leveled the wings to stop turning and to maintain altitude. The descent continued and the airplane impacted the tops of several trees. Forward movement briefly stopped and the airplane then fell nose first through the thick wooded canopy coming to rest in the trees in a mostly nose down attitude. The pilot reported that the CFI had been flying the airplane down to 60 mph while in wingover turns and that the stall light would regularly flicker on and off during the climbing turns. The pilot also reported that the CFI did not increase the engine power setting before impact and that the airspeed was 60 mph or less immediately before the airplane impacted the trees. The impact resulted in substantial damage to all four wings, the ailerons, the fuselage, and the empennage. The CFI did not report using carburetor heat during his low altitude operations, but did report that he was operating at a reduced power setting. According to a carburetor icing probability chart, an airplane operating in the ambient conditions at the time of the accident could expect a risk of carburetor icing while at cruise power, and a serious risk of carburetor icing while at glide power. The G-164A Pilot’s Handbook shows the power-off stall speed is about 67 mph, and the best rate of climb speed is 83 mph, when operating at 4,500 pounds on a standard day. The handbook also shows that a 50 percent power setting at that weight would require about 27.7 inches of manifold pressure which would yield a cruise speed of 99 mph. Before recovering the wreckage from the accident site the operator reported that they were able to successfully test run the engine. An examination of the airplane showed no preimpact mechanical malfunctions or failures that would have precluded normal operations.