NTSB Factual Report

On March 14, 2016, about 1000 eastern daylight time, a Grumman G-164B, N6654K, was substantially damaged during a forced landing to an agricultural field near Myakka, Florida. The commercial pilot was not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the maintenance test flight, which departed a private grass strip in the vicinity of the agricultural field around 1000. The airplane was owned and operated by Southern Air Services, LLC and the flight was conducted under the provisions of 14 Code of Federal Regulations Part 91.

According to the pilot, the purpose of the flight was to perform a "short" post-maintenance flight to verify that the spray system was operating without anomaly. He performed a preflight inspection of the airplane, noted that it "had fuel," and was "good to go." He started the airplane and noted that during the takeoff that all the "gauges were in the green." Then, during the initial climb, the pilot adjusted the throttle and propeller controls, and the engine began to run "rough." Soon after, the engine lost total power and the pilot elected to land the airplane straight ahead in the field. The airplane touched down in the field, nosed over, and came to rest inverted.

According to a Federal Aviation Administration inspector, the wings, fuselage, vertical stabilizer, and rudder were substantially damaged. The leading edge of the wings exhibited crush damage and the rudder was bent to the left. A fuel sample was taken from the airplane and no debris or water was noted.

According to FAA records, the single-place biplane was manufactured in 1978 and registered to the operator in 2011. In addition, it was equipped with a Pratt & Whitney R1340-AN1, 550-horsepower, engine that powered a two-blade Hamilton Standard constant speed propeller. According to airplane maintenance logbooks, the most recent annual inspection was performed on February 1, 2016, at an airframe total time of 9132.5 hours. At the time of the accident, the airframe had accumulated 9,191 total hours of operation and the engine had accumulated 810 hours of operation since major overhaul.

Following the accident, the airplane was recovered from the field and the engine was removed from the airframe during the recovery. The engine control cables were cut during recovery, otherwise, the cables remained attached to their respective controls. Engine crankshaft continuity was confirmed when the propeller was rotated by hand. All cylinders remained attached to the engine and thumb compression was observed on all cylinders. The propeller remained attached to the engine and the blades were curled aft and rotational scoring was noted on both blades. Both magnetos were examined and spark was observed on all towers. The supercharger remained intact and sand was located inside the housing. The carburetor was impact-separated, damaged, and therefore the internal components integrity could not be examined. There were no other obvious mechanical anomalies observed with the engine.

The reported weather at Sarasota/Bradenton International Airport (SRQ), Sarasota, Florida, which was located 21 miles west of the accident location indicated wind from 210 degrees at 10 knots, 10 miles visibility, few clouds at 2,900 feet above ground level (agl), scattered clouds 6,000 feet agl, broken clouds at 9,500 feet agl, temperature 24 degrees C, dewpoint 19 degrees C, and an altimeter setting of 30.04 inches of mercury.

The carburetor icing probability chart from Federal Aviation Administration (FAA) Special Airworthiness Information Bulletin (SAIB): CE-09-35 Carburetor Icing Prevention, June 30, 2009, shows a probability of serious icing at glide power at the temperature and dew point reported at the time of the accident.

NTSB Probable Cause

A total loss of engine power for reasons that could not be determined because postaccident examination of the engine revealed no mechanical anomalies that would have precluded normal operation.