Gainesville, GA, USA
N7471C
North American T-6-AT6D
The pilot and CFI were conducting a series of touch and go landings when smoke was seen streaming from the right lower section of the engine cowling after take off. Witnesses also reported hearing a rough engine condition. At approximately the same time, the pilot initiated a left turn towards the airport. The airplane was last seen in a nose low attitude. The airplane disappeared below the tree line and collided with the ground. Examination of the engine revealed damage throughout the supercharger assembly. The supercharge impeller was not totally secure on the impeller shaft. The impeller shaft retainer nut was loose on its shaft. This nut as well as the impeller shaft gear-teeth showed signs of wear. These teeth were worn down and disfigured. Both the aluminum cover plate and the bottom of the impeller blades showed signs of circular scraping. Small pieces of metal were found throughout the engine. Disassembly of the oil filter revealed metal shavings throughout. No metal parts or gear teeth were found in the oil sump.
HISTORY OF FLIGHT On April 1, 2002, at 1500 eastern standard time, a North American, T-6-AT6D, N7471C, registered to U.S. Aircraft Inc, collided with trees, and the ground while maneuvering for an emergency landing at the Gilmer County Airport in Gainesville, Georgia. The instructional flight was operated by the private pilot under the provision Title 14 CFR Part 91 with no flight plan filed. Visual weather conditions prevailed at the time of the accident. The airplane sustained substantial damage, and the certified flight instructor (CFI) and the private pilot received fatal injuries. The instructional flight initially departed from Gainesville, Georgia, at 1425, on April 1, 2002. The pilot's wife reported they had recently purchased the T-6 and were not familiar with it. At the recommendation of the sales broker, the CFI was selected to train them. They had flown several hours with the CFI and on the morning of the accident she had flown about two hours. After her flight, the pilot and CFI took off and flew to Lawrenceville, Georgia, where the airplane was refueled. According to the pilot's wife, she and friends were seated on a bench near runway 29 when the pilot and CFI returned from Lawrenceville. They recalled that the pilot and CFI made several touch and go landings to runway 29. On the fifth landing and takeoff, they observed a light color smoke streaming from the right lower section of the engine cowling. They also reported hearing a rough engine condition. At approximately the same time, the pilot and CFI initiated a left turn towards the airport. The airplane was last seen in a nose low attitude. The airplane disappeared below the tree line and collided with trees and the ground about 1/4 mile from the departure end of runway 29. PERSONNEL INFORMATION Review of information on file with the Federal Aviation Administration (FAA) Airman's Certification Division, Oklahoma City, Oklahoma, revealed that the pilot being instructed was issued a private certificate pilot with ratings for airplane single multiengine land, and instrument airplane. Review of records on file with the FAA Aero Medical Records Division revealed that the pilot held a third class medical certificate issued July 24, 2001 with no restrictions. The pilot reported on his application for the medical certificate that he had accumulated 750 total flight hours. The CFI was issued an Airline Transport Pilot certificate (ATP) August 16, 2000. FAA airmen records showed that the CFI was rated for airplane multiengine ATP and single engine land commercial level as well as multiple type ratings. Medical records revealed that the instructor was issued a first class medical certificate on March 1, 2001. The CFI had accumulated a total of 6650 hours, however his total flight experience in the T-6 was not determined. AIRCRAFT INFORMATION On February 19, 2002 the airplane was purchased by U.S. Aircraft, Inc. LLC. The registration application paperwork was completed March 8, 2002 but was still being processed at the time of the accident. Review of maintenance records revealed that the last annual inspection was conducted on October 10, 2001 at a total airframe time of 5440.11 and a total engine time of 553.3 since overhaul. At the time of purchase the engine had approximately 500 hours. The review of the engine maintenance logs showed that the engine was last overhauled in 1976. The engine oil was changed about 25 hours prior to the accident, during the pre-buy inspection. The engine oil filter was examined during the oil change and no contamination was detected in the filter material. METEOROLOGICAL INFORMATION Weather data was recovered from the nearest observation facility at Dekalb-Peachtree Airport, Atlanta, Georgia. The surface weather observation at 1453 EST was: clear sky, visibility 10 statute miles, temperature 21 degrees Celsius, wind from 290 degrees at 4 knots and barometric pressure of 30.01 inches of mercury. WRECKAGE AND IMPACT INFORMATION The examination of the accident site disclosed that airplane wreckage debris was scattered over an area approximately 40 feet long and 40 feet wide. The wreckage was orientated on a 200-degree magnetic heading. The accident site examination also showed that the airframe was separated into three major pieces. The left and right outboard wing sections were lodged in trees 20 feet northeast of the main wreckage. Both wing assemblies sustained leading edge crush damage. The main wreckage consisted of the engine assembly, empennage section, and the center carry-through wing section. Fuel was found in the engine driven fuel pump and fuel lines. The flight controls and surfaces were also examined at the accident site. This examination established flight control movement from the flight control surfaces to the cockpit. The airplane was equipped with two flight control sticks and two engine throttle quadrants. The engine assembly was attached to the airframe but was displaced aft at the bottom attach points into the engine firewall. The carburetor throttle control rods were also deformed and displaced from their normally installed positions. The propeller assembly was still attached to the engine. Examination of the engine revealed damage throughout the supercharger assembly. The supercharger impeller was not totally secure on the impeller shaft. The supercharger impeller shaft retainer nut was loose on its shaft. This nut as well as the impeller shaft gear-teeth showed signs of wear. These teeth were worn down and disfigured. The steel spacer that sits on top of the impeller shaft bearing retainer showed signs of rubbing against its aluminum cover plate. Both the aluminum cover plate and the bottom of the supercharger impeller blades showed signs of circular scraping. Beneath the steel spacer of the supercharger impeller the bearing retainers were found broken. Small pieces of metal were found throughout the engine. Disassembly of the oil filter revealed metal shavings throughout. Several teeth on the idler gear were found to be separated from the gear. The intermediate gear also had numerous separated teeth. The front spark plugs were saturated with oil. No metal parts or gear teeth were found in the oil sump. Examination of the airframe revealed that the right wing assembly was torn from the airframe outboard the over wing step area. The left wing was torn from the airframe at the wing root. The vertical fin and horizontal stabilizer assemblies were still attached to the airframe. The tubular structure of the airframe sustained deformation damage and was evident throughout the entire tubular network. Both cockpit areas maintained their shapes but also sustained deformation to the seat attach points. The airplane was equipped with seat belt and shoulder harness restraint systems for both pilot stations. The examination of the restraint systems revealed that they were functional. The forward cockpit instrument panel was in the normally installed position, however the rear cockpit instrument panel sustained deformation damage and was displaced forward. MEDICAL AND PATHOLOGICAL INFORMATION The Forensic Medicine Associates, Inc. conducted postmortem examination of both the instructor and the private pilot on April 4, 2002. The CFI's cause of death was determined to be multiple blunt force trauma. The private pilot's cause of death was determined to be multiple blunt force trauma. The Toxicology and Accident Research laboratory, Federal Aviation Administration, Oklahoma City, Oklahoma performed postmortem toxicology of specimens from the pilot and instructor. No carbon monoxide, cyanide, ethanol or drug was detected in the blood of the instructing pilot. No carbon monoxide or cyanide was detected in the blood and no ethanol was detected in the vitreous of the private pilot. Pseudoephedrine was detected in the blood of the private pilot. ADDITIONAL INFORMATION During previous instructional flights the pilot and CFI noticed oil on the cowling and windscreen, and concluded that there was a small oil leak. A line service manager stated that prior to the accident flight he had to wait to refuel the aircraft because the pilot and instructor were working near the engine with the cowling removed. At 0900, 41.7 gallons of aviation fuel was purchased on the day of the accident. The airplane wreckage was released to the family of the pilot.
A loss of engine power following a supercharger bearing failure and subsequent collision with the ground while maneuvering for an emergency landing.
Source: NTSB Aviation Accident Database
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