On December 2, 2010, at 1522 eastern standard time, an experimental amateur-built, light sport Easler Rans S6ES airplane, N26PP, operated by a private individual, was substantially damaged during a forced landing near Saint Augustine Airport (SGJ), Saint Augustine, Florida. The certificated airline transport pilot incurred minor injuries. The personal flight was conducted under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed and no flight plan was filed for the local flight that departed SGJ about 1515.

The pilot reported that the accident flight was the first flight after the airplane's engine was removed and replaced with a used Rotax 912 ULS, 100-horsepower engine. The airplane was fueled with 23 gallons of 100-low-lead aviation gasoline. After an extended engine run-up, the airplane departed on runway 31, a 7,996-foot-long, 150-foot-wide, asphalt runway. The takeoff and initial climb were uneventful; however, when the airplane reached an altitude of 1,200 feet mean sea level and began to turn right, an engine vibration developed, with a corresponding partial loss of engine power. The pilot then pushed the throttle lever forward, which "smoothed" the engine for about 5 seconds, and he turned back toward the airport. The engine subsequently lost about 80 percent power with a severe vibration, followed by a total loss of engine power. The pilot established a glide to land on runway 13, or the adjacent highway if the airplane did not reach the runway. Repeated attempts to restart the engine were unsuccessful, and at 30 feet above ground level, just prior to runway 13, the airplane impacted utility wires. The airplane then rolled right, impacted the highway, and came to rest upright on a grassy area next to the highway.

Examination of the wreckage by a Federal Aviation Administration (FAA) inspector revealed substantial damage to the wings and fuselage. The wreckage was recovered and stored outside, unattended at SGJ. On January 19, 2011, the FAA inspector and a representative from engine manufacturer completed an examination of the engine. During the examination, no mechanical discrepancies were noted that would have prevented normal operation. A low fuel level was noted in the carburetor float bowl and mechanical fuel pump. Following the examination, the engine was started and it ran uninterrupted.

The airplane owner stated to the investigators and several witnesses that prior to the accident, he observed the mechanic who installed the engine on the accident airplane. He questioned the mechanic about the routing of the carburetor vent lines. Specifically, the lines were looped upward and tie-wrapped at the top of each carburetor. The mechanic responded that it did not matter if the vent lines were routed upward or downward. The owner further stated that when investigators arrived to examine the engine on January 19, someone must have tampered with the wreckage, as the carburetor vent lines were found routed downward. However, the owner subsequently provided a photograph taken of the engine during installation, but prior to the accident, which showed the carburetor vent lines routed upward and tie-wrapped. The owner conferred with the representative from the engine manufacturer and confirmed that upward routing of the lines into an area of positive static pressure could result in fuel starvation.

During a telephone interview, the mechanic initially stated that it did not matter if the carburetor vent lines were routed upward or downward, as long as they were within 5 inches of the intake. He further stated that there was no guidance published in the Rotax maintenance manual, and the installation manual simply stated that the lines have to be routed into a ram-area and vacuum free zone, but the installation manual did not specify upward or downward. During a subsequent telephone interview, the mechanic stated that in the past he had routed carburetor vent lines upward, but could not remember which way he routed them on the accident airplane. He further stated that after the accident, he conferred with a maintenance instructor, who stated that routing the lines upward was not recommended. The mechanic added that although it may not be recommended, it was not prohibited.

Review of Rotax installation manual excerpts, provided by the mechanic, revealed:

"15) Carburetor...CAUTION: The float chamber venting lines (3) lines have to be routed in a ram-air and vacuum free zone or into the airbox, according to the requirements and release of BRP-Rotax...These lines must not be routed into the slipstream or down the firewall."

Further review of the excerpts revealed:

"15.1.1) Drainage piping on airbox and drip trays...WARNING...Route the lines with a continuous decline."

According to the representative from the engine manufacturer, the low fuel level found in the carburetor float bowl and the mechanical fuel pump indicated a possible fuel issue such as fuel tank venting, airframe plumbing or fuel selector issue, or incorrect carburetor vent hose routing.

The recorded weather at SGJ, at 1458, included clear skies and wind from 340 degrees at 5 knots.

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