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DAR Jon Ross checks an RV-4’s innards. (Courtesy Jon Ross)

Judgment Day

Inventive design or fatal flaw? On a homebuilt airplane, one person makes the call.

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(Continued from page 2)

The FAA provides a list of minimum requirements for an inspection, but each DAR has an area of special concern. Thomas’ is fuel flow. He won’t even look at an airplane until he has the flow data. (He’s not alone in his attention to the fuel system: Frank Sperandeo, an Arkansas-based DAR, says he makes his clients flush the system five times before he inspects it.)

Lying on his back on the concrete, New Balance sneakers jutting out from under the fuselage, Thomas checked the throttle linkage as Schupp opened and closed the throttle from the cockpit. Mixture, throttle, carburetor were all in working order, but Thomas suggested Schupp add a transmission screen to keep insects from crawling in. “Bugs have put more than a few people in the ground,” he says. If spiders crawl in and keep gas from making it to the engine, you’ll have just enough in the fuel lines to get 150 feet off the ground, he says—too high to have much runway left, too low to turn back.

The screen is just a suggestion; a DAR won’t deny an airworthiness certificate just because he would have done something differently. Gauthier explains to builders that three types of issues might come up during an inspection. First, the showstoppers: cotter pins or safety wire missing, bolts that are too short or too long. The builder must fix these before the DAR can put the pink certificate in his hands. Second, items that don’t conform with design: a fuel valve in a different place, a change to the instrument panel. In those cases, the builder and the inspector discuss the non-conforming item, and the builder must justify his decision. And finally, deviations from best practices: A builder deviating that way can get a certificate, but may also have to justify his decision. “We know from many years of flying that if you bury even the most innocent device where you have to reach awkwardly to reach it…it’s not a good idea,” Gauthier says.

The National Transportation Safety Board determined that a placement like that played a role in the 1997 accident that killed singer John Denver. The builder of Denver’s newly purchased Long-EZ had modified the fuel system from the plans, locating the selector behind and above the pilot’s left shoulder. Investigators found that one would naturally push the right rudder pedal when twisting left, consistent with witnesses’ reports of the airplane’s behavior before it plunged into the ocean near Pacific Grove, California. While investigators cited aspects of the builder’s nonstandard fuel system as factors in the crash, they attributed it primarily to Denver’s own actions. Unusual design decisions might not do you any favors, but they generally don’t kill you on their own.

Thomas will point out the potential hazard of nontraditional choices, but he values a builder’s freedom to make that choice. In a general aviation market dominated by a few, decades-old designs, the amateur-built category provides a venue for creativity. “We’ve gotten better airplanes because of it,” Thomas says, "but it has wasted a few lives.”

Schupp’s aircraft was by the book. For his first metal airplane, he had chosen a design from Van’s Aircraft’s line of easy-to-assemble RVs (they’re pervasive in the world of homebuilding—Thomas still flies his RV-4), and saw no need to stray from Van’s proven formula. Thomas felt the connection where the wing met the fuselage, then slid his camera into an inspection panel in the wing.

Airframe failures are less common than engine trouble. Inspecting the inner workings of the elevator—the tail section controlling the aircraft’s pitch—Thomas explains that he once found a bolt there with no nut. Unchecked, it could have wiggled loose, and the pilot could have lost control of the aircraft. Of all his inspections, Thomas says proudly, not one has crashed because of an airframe failure.

Six weeks later, Thomas learned that an aircraft he had inspected was involved in a fatal accident. On October 5, 2011, Harry L. Weber, a retired airline pilot, took off from the turf runway at Hedgesville, West Virginia, two days after the first flight on his Arion Lightning, an experimental light sport aircraft. Witnesses say the Lightning pitched up to a 45- or 60-degree attitude—too steep, it seemed, to generate the lift needed to keep the airplane aloft—and dropped to the ground, hitting a house and killing the pilot.

Months later, the crash still weighed on Thomas’ mind. “That’s the first one I lost in nearly eight years of doing it,” he explained at an inspection at Baltimore, Maryland’s Martin State Airport. Amid the bustle of the spacious maintenance hangar, he paused, lips drawn tight. “But I don’t know what I could have done.” The NTSB’s preliminary report on the accident cited no evidence of a mechanical problem, and Thomas doesn’t think the final determination will either. (As of press time, the final report was not in.)

Airmanship is as serious a concern as mechanical soundness. Of the test-flight accidents that occurred from 2005 to 2010, the NTSB attributed almost as many to the pilot’s actions as to a problem with the airplane; of the fatal accidents, only one was attributed to a mechanical problem. Pilots who spend their free time in a workshop spend less of it in the air, and even high-time pilots are more prone to fatal mistakes in unfamiliar aircraft. The FAA attempted to address this issue in early 2011 with new guidance for pilots transitioning to amateur-built or unfamiliar aircraft. The agency formulated the advisory circular, AC 90-109, in conjunction with the EAA, the Aircraft Owners and Pilots Association, the National Association of Flight Instructors, and the Lancair Owners and Builders Organization. The FAA says its goal “is to reduce the GA [general aviation] fatal accident rate per 100,000 flight hours by 10 percent by 2018.”

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