The pilot of the tailwheel-equipped, amateur-built airplane, who was also an airframe and powerplant mechanic, reported that, during approach to a sandbar near Monroe, Washington, he side-slipped the Just Aircraft Highlander. The engine then lost power because he was “too aggressive with the throttle and pulled it enough to bend the [carburetor] idle stop screw bracket.”
The engine was normally quiet, the airplane was sound proofed, and the pilot also used a noise-cancelling headset, which prevented him from being aware of the power loss until he attempted to add power to no avail.
He did not have enough time to restart the engine, so the plane settled onto the water about 15 to 20 feet short of the sandbar. Subsequently, the airplane hydroplaned and then came to rest on the sandbar inverted.
The airplane sustained substantial damage to the left wing lift strut, left wing, and rudder.
The pilot reported that the reason he was aggressive with the throttle was because of a lean mixture that tended to overheat the engine during takeoff or cruise on hot days.
An FAA inspector reported that the pilot had modified the number and position of the last hole in the fuel spray bar. By doing so, he was able to get the engine to “barely run” to perform short-field landings. During the accident landing, it “must have cut off the flow of fuel enough to make the engine quit.”
The pilot reported that he had previously attempted to mechanically enrich the mixture by drilling holes in the fuel spray bar, but had drilled a hole “at the location where the engine wanted to idle,” meaning that, if the hole was open, the engine would idle high, and if the hole was closed, the engine would “die.” He added that it was not a problem unless he was trying to land short.
Probable cause: The pilot’s improper engine modification and operation, which resulted in a total loss of engine power due to fuel starvation, and the pilot’s failure to maintain an adequate approach path, which resulted in the airplane landing short of the runway.
This October 2018 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.