Editor’s Note: Drawing on decades of experience tracking accident data and writing for the community, Ron Wanttaja provides this series of summaries on the mechanical side of Experimental aviation safety. This is the first article in the series.
While flying about 800 feet above a river during a personal flight, the pilot advanced the throttle to climb, but the engine started to lose power. The pilot elected to land on a nearby island, during which the airplane nosed over.
Post-accident examination of the airplane revealed that the throttle cable set screw on the aft side of the throttle body arm had backed out of its original position and was no longer securing the throttle cable. As a result, the cable moved freely with no corresponding motion on the throttle body arm. Maintenance records revealed that the pilot built and installed the throttle body arm about seven months and 204 flight hours before the accident.
A spring, to give it full throttle if the cable breaks or loosens, is how to ensure power isn’t lost. I had it happen to me, on one carb on a 912S, and the spring got me home. I landed deadstick.
What Tom said: Why was there no spring?
Anyone flying without such a spring has not been thinking and has not been listening.
Who signed this airplane off for first flight?
My airplanes have two!
KS
i do’t know if here is a spring.i have no ga exper.
OK, mechanicals happen. What I don’t understand is how he managed to flip a tundra-tired taildragger on what appears to be a relatively firm sand surface.
All those footprints are pretty deep, indicating soft sand.
And look at what appears to be one tire track out in front of the nose. Deep.
Appears is the operative word here. Note the deep impressions made by the shoes of the pilot as he walked, no doubt unbelieving… around the turtled kitfox. I know from experience: a dry-looking surface can easily hide several inches of sticky, gooey mud.
WPR18LA111
The full report notes, About 800 ft above the Columbia river, he advanced the throttle to climb when the engine started to lose power. The pilot elected to land on a nearby treeless island in the river. The airplane landed uneventfully, and during the landing roll, the main wheels sunk into the ground and the airplane nosedover and came to rest on its back.
was he an a&p ?
The NTSB report states that the pilot had an ATP but no mention of an A&P. The airplane total time was 1296 hours, and the pilot’s time in type was also 1296 hours. If the aircraft was licensed as Experimental Amateur-Built (EAB), the pilot probably was the original builder and had the Repairman Certificate for the airplane.
However, a curiosity: The NTSB report states that the airplane was Experimental Light Sport. But the FAA registry shows it as Experimental Amateur-Built (EAB).
My guess is that the NTSB report writer got tripped up by the age-old confusion: The airplane was Experimental and met the Light Sport definition in 14CFR Part 1, but that does not legally make it an Experimental Light Sport Aircraft. It remains an Experimental Amateur-Built, and all the certification/maintenance rules of the EAB world still apply.
In my opinion, 20 years ago the FAA *seriously* botched up with coming up with the designations. They’ve attempted to correct that in the MOSAIC regulations, but like the term “conventional gear” for taildraggers, I guess it’s going to be dragging behind us for the next one hundred years……
Here’s what the certification tree looks like….
What kind of carburetor is generally used on Rotax 9xx engines? The Bing carbs typically used on Rotax 2-strokes have a spring pulling the throttle closed, whereas the Stromberg or Marvel carbs used on legacy engines have no spring at all. Many years ago the throttle linkage came loose on my Taylorcraft at mid throttle, leaving me with not quite enough power to maintain level flight, but enough for a long shallow descent to the nearest airport, where I safely landed by blipping the ignition.