Accident Details
On August 27, 2009, about 0900 eastern daylight time, a Piper PA-25-235, registration N7339Z, was substantially damaged when it struck a tree during a forced landing near Decatur County Industrial Air Park (BGE) in Bainbridge, Georgia. The private pilot, who was the sole occupant, sustained no injuries. Visual meteorological conditions prevailed, and no flight plan was filed for the local solo aerial application training flight conducted under 14 CFR Part 91.
Flight Sequence
The pilot reported completing a pre-flight inspection, adding a few quarts of oil to the engine, and confirming the airplane was fueled. He also added water to the onboard container for training. After departure, he flew to a predetermined field to practice aerial application and empty the water container. Returning to BGE, he refueled, refilled the water container, and taxied for departure. During the engine run-up, he leaned the mixture briefly before returning to full rich, and the engine ran fine.
Following departure, the pilot flew to the practice location and performed several passes about 50 feet above ground level (agl). On the sixth or seventh pass, the engine quit suddenly. He landed in the field but could not stop before reaching surrounding trees. Attempting to avoid obstacles, the left wing struck a tree approximately 9 inches in diameter, causing wing damage.
Post-Accident Observations
The pilot examined the engine after the accident and found no external damage. The oil dipstick indicated a proper oil level with no visible metallic filings. He stated that everything was working at 100 percent until the engine failure.
The aircraft owner reported that the left magneto had been replaced about 12 flight hours prior to the accident, which was the only mechanical work accomplished.
A Federal Aviation Administration inspector reported substantial damage to the wing. One propeller blade exhibited a slight aft bend, while the other had no bending.
Engine Examination
During a follow-on examination, the propeller was rotated by hand without restriction or binding, and movement of all pistons was confirmed. Compression and valve movement could not be verified. The left magneto was removed and produced spark on all towers when rotated by hand. Its drive coupling was disconnected from the mating idler gear.
The accessory drive housing was removed, revealing rotational damage near the idler gear associated with the left magneto and camshaft gear. The magneto drive gear and camshaft gear teeth were damaged, and rotational scoring was observed on the crankcase at the idler gear attachment point. The idler gear, short shaft, attachment plate, and two attachment bolts were separated. The idler gear and short shaft were found in the oil sump. The lower bolt end was inside the engine case, and the upper bolt end was sheared. The oil pan contained only small metal particulates. The attachment plate and two bolt heads were not located.
Engine Maintenance History
According to the engine logbook, the engine was overhauled on January 13, 2004. The most recent annual inspection was recorded on December 1, 2008, at which time the airplane had 8,430.5 total hours in service and a recorded tachometer time of 1,171.2 hours. The last entry, on August 12, 2009, noted the left magneto replacement, with a tachometer time of 1,370.4 hours and a time since major overhaul of 1,286.4 hours.
Weather Conditions
The 1300 recorded weather observation at BGE included winds from 090 degrees at 3 knots, visibility 10 miles, clear skies, temperature 23°C, dewpoint 22°C, and an altimeter setting of 30.04 inches of mercury.