Kit Plane Technique May Benefit Cessna

[Guest Chainsaw]

BY MOLLY MCMILLINThe Wichita Eagle

If Cessna moves forward with its light sport aircraft concept, it might build the plane using a manufacturing method used heavily by the kit plane industry. The technique, called matched-hole drilling, would cut costs, require less tooling and shorten assembly time, Cessna officials say.

 

"We decided to experiment to see whether that would have a benefit for us," said Jack Pelton, Cessna president and chief executive. "For light, thin-gauged aluminum airplanes, it makes a lot of sense."

 

With the method, holes are predrilled into the aluminum skins or other parts using computer numerical control machines. When assembled, the holes on each part are matched up and riveted together by a mechanic.

 

"It's very accurate," Cessna's Neal Willford said Friday. Willford is the lead engineer for the company's light sport proof-of-concept airplane.

 

The process "allows you to put holes in your parts pretty quickly," Willford said. Punching holes ahead of time saves assembly time.

 

It worked well with Cessna's light sport proof-of-concept plane displayed last week at the AirVenture air show in Oshkosh, Wis.

 

The plane was met with enthusiasm by the public.

 

The company will decide early next year whether to launch the program. It estimates a market for 600 planes a year -- as long as Cessna can offer it for around $100,000 or less, Pelton said.

 

That means Cessna has to look at every place possible to decrease costs. With matched-hole drilling, suppliers could be used to assemble the plane, Pelton said.

 

Cessna is using a somewhat similar technique on its business jets, but "not quite to that extreme," Pelton said.

 

In Cessna's single-engine line, holes are drilled in one part, but before mechanics assemble it to another piece, they use the pre-drilled piece as a guide to drill into the other component, Willford said.

 

It was Willford's idea to use matched-hole drilling for Cessna's light-sport airplane. He has spent several years building a kit plane in his spare time -- a two-seat Thorp Sky Scooter -- using the process.

 

"So I knew it worked," Willford said.

 

The process especially makes sense given today's technology in computer numerical control machines, which are run using detailed computer programs, Willford said.

 

The idea is not a new one. The process was used in the construction of the Eiffel Tower, Willford said. Planemaker Luscombe used the process in a two-seat airplane in the late 1930s, he said.

 

The process isn't appropriate for every part of a plane, he said.

 

"It's not a one-size-fits-all kind of thing," he said. It works well for areas that don't have much contour to them.

 

The process was used in the wings and tail of Cessna's light sport aircraft and in a piece of the aft fuselage.

 

The method works best with brand-new designs, Willford said. That's the time to experiment, he said. And once a process is set in place, it's difficult to change.

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