Tracy, CA, USA
N1216Z
Petz Flying Boat
A single engine, amphibian, four person airplane, designed and built by the pilot, lost propeller thrust and collided with terrain. Witnesses stated the airplane took off and climbed to about 150 feet, when it started to turn back to the airport. As it turned, it descended into a gravel pit area, collided with a raised embankment, and was immediately engulfed in fire. Examination of the wreckage revealed that the engine exhaust outlet was about 9 inches from the composite propeller. Hot exhaust gasses from the outlet weakened the propeller blades, ultimately resulting in propeller failure and lost of propeller thrust.
HISTORY OF FLIGHT On August 28, 2003, at 0838 Pacific daylight time, an experimental Petz Flying Boat, N1216Z, lost propeller thrust and collided with terrain approximately 660 feet south of Tracy Municipal Airport, Tracy, California. The airplane was operated by the private pilot/owner under the provisions of 14 CFR Part 91. The pilot, the sole occupant, sustained fatal injuries, and the airplane was destroyed. Visual meteorological conditions prevailed and a flight plan had not been filed. The flight originated at Tracy Municipal Airport about 0835. Witnesses reported that the airplane took off and climbed to about 150 feet when it started to turn back to the airport. As it turned it descended into a gravel pit area, collided with a raised embankment, and was immediately engulfed in fire. PERSONNEL The pilot was issued his private pilot certificate on June 10, 1993, with single engine land, single engine sea, and instrument airplane ratings. The pilots flight log book was not recovered but family members report that he had at about 1,400 hours of flight time and that he had experience flying sea planes in Alaska. The pilot possessed a valid third class medical dated September, 2002, with a waiver for glasses to correct for near vision. AIRCRAFT INFORMATION The airplane was the pilot's own design and construction. The design was loosely based on the Lake Amphibian type with the main fuselage shaped like a boat hull and the engine elevated over the top of the wing in a pusher configuration. The construction was entirely out of composite materials. The engine was a Mazda, turbocharged, rotary engine, utilizing three rotors and had an unknown horsepower rating. The Federal Aviation Administration had issued an Airworthiness Certificate on August 21, 2003, with Experimental Operating Limitations direction letter and flight test area limitations. IMPACT AND WRECKAGE The wreckage was located in a large gravel pit at the base of an approximately 100 foot embankment. The terrain was covered in prairie grass with no trees in the immediate vicinity. The wreckage was entirely consumed by fire. An FAA inspector reported that all major airplane components and control surface remnants were located with in the immediate wreckage area. TESTS AND RESEARCH The airplane wreckage was relocated to Plain Parts, Sacramento, California, and examined by an FAA inspector. All airplane control cables were laid out and the ends were connected to their respective control surface fittings, bell cranks, or turnbuckles. The control cable chains remained on the control column sprockets. The rotary engine was examined. The turbocharger exhausted into a straight steel pipe. The exhaust pipe traveled aft along the right side of the engine. The exhaust pipe opened at a location 9 inches from the composite propeller and 9 inches radially outboard of the propeller drive shaft at the 4 o'clock position. All four blades of the composite propeller were squarely severed in the chordwise direction at a location approximately 9 inches radially from the propeller hub. The blades all exhibited thermal damage. One blade had thermal damage at the root area but did not exhibit thermal damage on the outboard third of the blade and tip section.
The inadequate design of the engine exhaust system and inappropriate selection of propeller materials by the designer/builder, which resulted in separation of the propeller blades during takeoff/initial climb, and a subsequent in-flight collision with terrain during the ensuing off-airport emergency landing.
Source: NTSB Aviation Accident Database
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