Lite Engineering and the Myth of Simplified Certification
by Alfred Scott
This article was published in the December 1992 Falco Builders Letter.
The sport aviation nest is all a-flutter these days with talk of the wonders of simplified certification and how airplanes are suddenly going to become affordable again. Not only that, but there will be a whole new genre of modern, composite machines the likes of which we've never seen. When I see an airplane like the Lancair ES knocked out in 53 days from the time Lance Neibauer emerged from his shower with a vision, and then presented to the world by aviation magazines as tomorrow's airplane, I find my head spinning and asking myself why it's so easy. Pardon me, in this Christmas season of warmth and festivities, but I've got a bucket of cold water I'd like to dump on this notion.
The two engineers that I know best are Dave Thurston and Stelio Frati. By any measure, they are masters of their craft, with enormous intelligence and experience. I've watched as Dave Thurston did his sums on the Sequoia 300, calculating the loads, designing the components and cranking out the drawings. It's a long agonizing process that requires thousands of hours for a single airplane. Even Frati, with his shop of twenty-some metal workers and engineers, takes well over a year to crank out a simple design.
Are Frati and Thurston old fools that the world has passed by? Can unschooled designers crank out airplanes of equal quality to those laid out by a great master? Is simplified certification a chimera? And are we in the kitplane business delivering designs of high quality, roughly equal to production airplanes?
Perhaps the easiest question to answer is the one about unschooled designers. The fatalities among hang gliders and ultralights have been very high, and poor design has played a big role in all of this. There was a famous ultralight years ago that suffered the indignity of a structural failure in level flight, right over a shopping center parking lot where it was being demonstrated for the local television station, whose cameras recorded the entire absurd, and fatal, spectacle.
There was the Adventure Mustang, a sexy Chevy-powered scaled-down P-51 that suffered an engine failure, crashed and killed the test pilot. There were a couple of other auto-powered scale fighters being marketed out of Tucson. Two of these designs suffered engine failures, crashed and killed the test pilots. This year at Oshkosh, an amphibian came apart in the air and killed the pilot and prospective purchaser. The infamous Poliwagen-perhaps the worst single design ever flogged as a kit-had a terrible accident record.
Yet it's also true that many acceptable designs have been executed by an amateur with little or no engineering training-the Steen Skybolt and Wittman Tailwind come to mind. I asked Ed Swearingen about this, and he refused to condemn non-engineer designers. For an airplane in the Cessna 150/Piper Cub class, he had seen many wonderful planes built with very little engineering in them. "The most important thing is how well they were tested." Many successful production airplanes, he said with a sardonic chuckle, were "just built" but then people who knew what they were doing tested and tweaked the planes, and they turned out fine. Another observer said that as far as he was concerned, "lite engineering done well is still better than heavy engineering done poorly."
A question I hear asked often these days by aviation insiders is, "What do you think of the Lancair IV?" It's an intriguing machine, viewed with a mixture of admiration and unease by the engineers I know. One man put it this way, "I have a jaundiced view of all composite airplanes" that went back to some time he spent with the Glasair folks in the early days. "I asked to see some drawings, and there were only a few sketches. At that time, there was no engineering in the airplane, and there were major structural deficiencies which have since been corrected."
Wander among the composite designs at Oshkosh and the signs of poor design are everywhere to be seen. One long-dormant design actually had a Hersey-bar wing, while another populer composite kitplane has sharp corners on the fuselage that its designer insists is a sensible design decision, and also has the landing gear forks held on with four quarter-inch fillister-head screws with threads in tension--a practice guaranteed to get a snort from any engineer. Many of the designs are short-coupled machines, whose designers seem to have little comprehension of the fundamentals of longitudinal stability.
Yet when I walk around the Lancair IV, I see no such obvious flaws; indeed once you accept the idea of a high wing loading, it appears in many ways to be an extremely elegant design. If, over time, the airplane proves to have no serious structural or maintenance problems, I think it will turn out to be a pinnacle airplane of this era, not unlike the Falco in the late fifties. Certainly it shares an elegance of form, and when you look at the performance you have to wonder why anyone is still fooling with pusher designs.
But the things that unsettle my engineer friends are the unknowns. "What is going to happen to the resins if it sits out on the ramp for 6 years in Phoenix? Do we know? I don't think we do", mused one. This is a complex airplane, with oven-cured carbon-fiber parts, but I worry about the ability of a proctologist in Dayton, perhaps with a few ideas of his own, to assemble these components in the uncontrolled conditions of his garage and then go out and operate this turbocharged 350-hp soon-to-be-pressurized machine in the frigid climes of 25,000 feet. Once you go over 200 mph, the margin for error goes down sharply, and this baby trundles along at 300-something.
And when I read the cheery articles in Sport Aviation by Lance Neibauer about his planes-hey, man, it's great up here at eighteen thou where we're cooking along at 300, and we haven't even opened it up yet-I reflect that this is not a man with years of experience with high-speed, turbocharged airplanes. Where is the engineer's caution, and the manner of talking that I've come to associate with all the really good engineers I've known? Is it really so easy, when it was so difficult for Beech?
Herb Andersen, chief engineer for Aviat (formerly Christen Industries) shares the concern, and like me hopes the work has been done and that they'll never have a problem. "I myself would never dream of buying a Lancair, Wheeler Express, or any of the other composite kits, build it in my garage, and then go out and fly it unless I had a parachute."
I asked Herb what he thought of the quality of design among kitplanes. He said he had noticed that "things bubble to the surface", like the Varieze with its stall problems and the effect of rain on the canard. "We had some very tragic things with ultralights and hang gliders." Herb said he was "under the impression that some of the planes are well engineered-the Glasair comes to mind. An airplane like the Steen Skybolt lends itself to shop engineering, but I worry about the cantilever-wing composites. The thing that amazes me is that there haven't been the structural failures."
My own conclusion is based simply on what I have observed over the years: the inflight-breakups of the RV-3s; the grounding of Lancair 320s in Australia for stability problems; the Glasair IIS's longitudinal stability problems; the early Kitfox's directional stability problems; and even our own screwups with fuel tanks and screwjacks. I'm astonished at the Lancair's low accident rate compared to all other high performance kitplanes. There's no question that the kitplanes of today are infinitely better than those of ten years ago, and the naive what'll-she-do purchaser is rapidly becoming a thing of the past-people now ask about engineering, component quality, drawing quality and builder support. My conclusion is that kitplanes are delivering airplanes that are in some respects superior to production aircraft, and our overall level of engineering and design is fairly good but not up to certification standards.
The simplified certification proposal began about ten years ago, when Paul Poberezny approached Frank Christensen to write a proposal to be submitted to the FAA. Frank says that he sees little wrong with FAR Part 23. It is simply a minimum engineering standard, and a very good one at that. If you are going to design something, you must have some engineering standards. The principal flaw is that the FAA keeps adding amendments to cover special situations.
So Frank proposed to take out the lightning-strike requirements, the need for redundant trim tab controls, and such, and then create an honor system whereby the company did the work in-house and was subject to audits by the FAA. This would eliminate waiting for FAA approvals in the process.
Christensen is a stickler on engineering. The Christen Eagle was designed by Herb Andersen, and when it was finished, Christensen hired another engineer to do a complete Part 23 analysis. "People said I was crazy to do this, since I wasn't going to produce the plane, but I wanted all the engineering data in my file in the event of a lawsuit." We have done the same sort of thing here with the changes with the Falco, and we've spent over $25,000 with Dave Thurston on various changes to the Falco.
Even as he wrote the original proposal, Christensen was adamant that certification costs had almost nothing to do with the cost of airplanes. The entire concept, he insists, is based on a false premise. The Husky, for example, was designed by 4 men over 16 months, and cost about $180,000. Much of that work was simply engineering work they would have to do in any case, certificated or not. So if you take the entire cost of design, testing and certification of the Christen Husky and amortise it over 500 airplanes, it comes to about $400-approximately the same as an artificial horizon or a set of Falco plans.
Herb Andersen agrees, and says he was asked to be on the EAA/SAMA team because he was the only guy in the U.S. who had recently certified an airplane to FAR Part 23. Herb says he doesn't understand how changing the engineering standard will substantially reduce the cost of an airplane. He's read the simplified certification document, and from his perspective it is simply FAR Part 23, through amendment 32 with two changes: simplified lightning-strike criteria and the elimination of dynamic testing of seats. Both are very welcome and significant changes. The dual control path for elevator tabs is still in there.
The honor system that Christensen proposed is not in there either, but Andersen says that's really not an important issue. The FAA only approves the basic loads report and only spot-checks the other things like wing and fuselage analysis. As a practical matter, any company that's going to produce an airplane will have FAA Designated Engineering Representatives on their engineering staffs who can sign off on things.
Andersen said that he thinks the entire sport aviation industry has talked to itself and convinced itself that the cost of certification is The Big Problem. He went to one of the EAA/SAMA meetings, and he described a lot of nice people with good intentions caught up in a libertarian's tulipmania. "At some point in the meeting, I was asked to describe the stack of paper I had to submit to the FAA," he said. "I told them it was about three inches high. There was the longest silence around the table. I think they were all envisioning a stack of paper a foot high. They have it in their mind that it is a bigger task than it is, and they don't really have an understanding of what is involved."
"The whole experience has led me to the conclusion that there are two worlds: the fantasy world and the real world. Everyone is just fooling themselves if they think any of this will affect the cost of airplanes, and I'm tired of hearing aviation writers rhapsodizing about composite structures. The composite work being turned out by kitbuilders today won't even begin to meet FAA minimum standards."
I asked him to compare the difficulty of designing, certifying and manufacturing two airplanes, a 180-hp four-seater built of composites and the same plane in aluminum. "Compared to conventional aircraft construction techniques, more expertise is needed to create a composite airplane-by a substantial margin." As I talked to Andersen, he was flipping through the pages of the regulations. "The quality control requirements are mind-boggling. You have to test every part to a limit load," and he began to read the sections about the damage-tolerance criteria developed for the Starship that are now part of the regulations.
When he looks at these requirements and then sees what kitbuilders are doing, he says he's mystified why it's "all so easy for them-either they know something the FAA doesn't know, or the FAA requirements are too stringent. Something's wrong." But then, he said, "To the simple, all things are simple."
The image that sticks in my mind is the photo of the Oshkosh announcement of the simplified certification program, with a dozen or so scruffy-looking kitbuilders, some squatting on the ground like goat-herders from the mountains, waiting to pick up their applications so they can certify and produce America's airplanes of tomorrow-and all of this is in the name of aviation's perennial runny nose, The Affordable Airplane. Gimme a break.