What a Certified Homebuilt Looks Like

I flew down to Battle Creek to pick up my friend Randy Greene, who had flown his Waco Classic in from New York. Randy heads up Safe Flight, a family-owned company that is the leader in developing and producing flight safety technologies. Randy’s dad, Leonard, holds the fundamental patents on stall warning and measuring angle of attack and those became the foundation of the company more than 60 years ago.

Randy was returning his airplane to the Waco factory to have the 275-hp Jacobs radial replaced by the relatively new 300-hp version. The extra horsepower, and a new MT propeller that the bigger engine spins, adds 30 percent to takeoff and climb performance, and several knots more cruise speed for the classic biplane.

I have been to Waco’s factory before, but the place continues to amaze me. The whole operation is really quite small. Waco president Peter Bowers points out that they build more airplanes per square foot of factory than any other company.

An upper wing assembly. Every wing rib has dozens of part numbers, each with an FAA-approved specification.

Waco’s factory looks more like a homebuilder’s hangar than any other airplane factory I have ever been in. The woodworking shop is on a platform that is built above the main hangar floor. There are jigs to hold the tubing in place to weld up the fuselage frame, and over in one corner the finished fuselage and wing frames are covered in fabric. A skilled homebuilder would use essentially the same techniques.

But as usual, appearances can be deceiving. The Waco factory is very different from a homebuilder’s shop because the Waco Classic YMF-5 is an FAA-certified airplane. What that means is that every beautiful classic biplane that rolls out of the factory must conform exactly to the type certificate so that the FAA, and more importantly the new airplane owner, knows exactly what he is buying.

When we think of certifying an airplane what usually comes to mind are flight tests to demonstrate controllability and performance, and load testing to confirm that the airframe is strong enough to meet all of the requirements. Flight and load testing certainly are crucial aspects of certification, but the fundamental aspect of certification is the documentation and process control that confirms that a finished airplane conforms to what was tested.

Peter’s favorite example of how the certification process works is a Waco wing rib. The rib is the typical wood bow and truss design that looks like the ribs that youngsters build on their first try at Oshkosh. But at Waco, every wing rib has dozens of part numbers, each with an FAA-approved specification.

Glass panel on a classic design means it’s not your father’s Waco.

Each gusset on the rib has a part number that defines every detail of its size, shape, and material – in this case, which kind of wood. The stainless steel staples that fasten the gusset have a part number and approved description. Even the glue has a unique part number and approved specification.

Does all of this documentation and material tracking make the Waco wing rib better and stronger than one a skilled homebuilder would fabricate? I doubt it. But that’s not the point of certification. What certification does is make certain to the greatest extent possible that every wing rib produced at Waco is the same as the others.

This conformity to a detailed specification does two things: First, it ensures the airplane and its structure will perform the same as the airplane that was tested and approved. Second, conformity provides a method to correct problems that occur during an airplane’s life. When all components and construction methods are consistent and documented a problem in one airplane is likely to appear in others, so an airworthiness directive can be developed to solve the problem in all like airplanes.

It may be a new Waco but the look is unmistakable.

Waco Classic has made hundreds of improvements to the original 1930s design and each change has been approved and documented under normal certification rules. Most of the changes are to improve pilot convenience and the overall durability and serviceability of the airplane, but some changes improve the basic structure such as changing to a stronger steel for the fuselage frame tubes. Even when a change is a clear improvement – such as using stronger steel alloys – the change must be tested, approved, and fully documented.

The Waco Classic factory is a great lesson in why we need both homebuilts and certified airplanes, and how different the two airplane building methods are even when they appear to be very similar on the surface.

The homebuilt rules allow a builder to experiment, to try new methods and materials while still remaining within the bounds of accepted aircraft construction techniques. A homebuilder is creating an airplane for himself and has a great deal of freedom to change a design that may not originally be his own to make it better, or at least to make it unique.

On the other hand, a certified airplane is built for any pilot. Certification does not make an airplane perfect, or even desirable. But the entire process of establishing a standard and then sticking to it in excruciating detail gives the airplane buyer what he is expecting. I think it is impressive – even amazing – that the FAA’s certification process is able to accommodate an airplane like the Waco Classic.


Waco Classic has made hundreds of improvements to the original 1930s design and each change has been approved and documented under normal certification rules. All photos courtesy Waco Classic Aircraft Corporation.

The Waco was a good design nearly 80 years ago; it’s better now, and the certification system makes certain each individual airplane conforms to that design. When I get frustrated with the FAA I try to remember Waco and that if an airplane has a sound design and the factory is willing to document its procedures, the certification system works.

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18 Responses to What a Certified Homebuilt Looks Like

  1. One important difference you neglect is price. The new Waco Classic is probably a 500K machine. A Hatz Classic (scaled down Waco clone) is around 30K. A large sum for certified parts.

  2. Mac says:

    Hi Daniel,

    You’re right. Complying with certification standards adds cost and that’s why we need both certified and homebuilt airplanes. It’s great to have a choice.

    Mac Mc

  3. Simon says:

    I have to say, that looks absolutely amazing – congratulations on the hard work.

  4. Thomas Ivines says:

    A good, no nonsense article that applies to the likes of most EAA members. Glad to see you doing some writing on subjects like this. Keep up the good work.

    • Mac says:

      Hi Thomas,

      Thanks for the kind words. I think all of us have been guilty at times of vilifying the FAA certification process. Waco shows how a company can work with the regulators to build a certified airplane that gives pilots the option to buy a new “antique” instead of building or restoring an airplane on their own. There is nothing better in life than having choices.

      Mac Mc

  5. Harry Foy says:

    Sorry about that,I don’t know who did it.taaxi them4 I worked on Wacos owned by Rosco Turner in the early was a thrill when I got to taxi them.

  6. Harry Foy says:

    I worked as an apprentice mechanic in the early 40s

  7. Joe Gauthier says:


    Not to split hairs here but, homebuilts are also certified in their category as amateur built. You might consider using the more recognizable terms in the homebuilt community of Standard Category vs Amateur Built Category. They all have airworthiness certificates issued by the FAA, Cessna, Waco et al have Standard Category Airworthiness certificates and the homebuilts are issued Special Airworthiness Certificates.

  8. Mac says:

    Hi Joe,

    You are absolutely right. A homebuilt is individually certified by the FAA in the experimental category as an amateur built airplane. Thus each AB, as many call them, are fully FAA certified. However, when it comes to hair splitting and the FARs, things quickly go off the rails.

    The airworthiness certificate–the actual piece of paper that we post near the passenger entry door–can be standard category. However, there is no standard category for airplane certification. The airplane is certified in normal category, for the majority of light airplanes, or experimental, for amateur built. Then an airworthiness certificate is issued to an individual airplane and that in the case of a production airplane is a standard airworthiness certificate even though the airplane is certified as a normal category airplane. So when we say AB for homebuilt we are referring to an aircraft certification category–experimental. When we say standard we are referring to an individual airworthiness certificate for an aircraft that is certified in one of the available categories. The FAA is sure generous with making hairs available to split.

    Thanks for your comments,

    Mac Mc

  9. Dean says:

    I wonder if the new Waco factory is actually making money especially in this economy. Or, if it’s just a labor of love. Even at $500k or so per aircraft, you’d need to sell quite a few each year to just to break even. Don’t get me wrong, I’m glad they’re doing this. It’s just something to ponder. I can’t imagine the cost of complying with all the FAA regulations and requirements for aircraft certification these days. Not only the parts cataloging and documentation but also things like the ever expanding Pilots Operating Manuals (that now have more legal warnings these days than actual helpful information).

    Who was it that said, “How do you make a small fortune in aviation? Start with a large fortune.”

  10. Mac says:

    Hi Dean,

    Waco is doing okay but took a hit during the financial downturn like everbody else. A key element of the company’s success is its restoration work which accounts for a large chunk of its overall business. Waco is, of course, expert in restoring and repairing Wacos of any vintage or type, but it also is expert in other airplanes built in the pre-war period. When I was there last summer Waco mechanics had just finished rebuilding the landing gear of a Spartan Executive and repairing the damage caused by the gear collapse. The original design of the Spartan gear is not nearly strong enough so the Waco staff designed and gained approval for a new forging that will be much more durable than the original. I’m sure other Executive owners will be by to have their gear upgraded because from what I hear the collapse of a Spartan gear is a “when” not an “if”.

    Waco is also well along on returning the Great Lakes biplane to production. The Great Lakes offers a smaller, more affordable classic biplane that is new and Waco has a number of orders in hand already. As it did with the Waco, the company will make many improvements to the Great Lakes as it returns it to production, including enlarging the cockpit and exchanging those darn heel brakes for modern toe pedals.

    Mac Mc

    • Dean says:

      Doing repairs, upgrades and restorations on vintage aircraft is a great solution to bring in additional revenue. Very smart! I’m glad to hear that they’re being creative with ideas for bringing in revenue any way they can find it! They’ll probably weather the downturn because of it!

  11. Alex Kovnat says:

    The Waco open-cockpit biplane (like the Stearman) no doubt meets the needs of many owner-pilots who like to face the onrushing 90-knot breeze. Now, here’s a question for you: The wooden fixed-pitch, two-blade propeller is part of the nostalgia, but would you rather have a controllable-pitch prop?

    • Mac says:

      Hi Alex,

      Waco does offer a constant speed prop, but it is a Ham Standard of the era, as that is all that has been certified. The metal–steel I believe–blades of the Ham Sandard prop add weight, but not that much performance. It turns out that other fixed pitch props are and have been developed that improve performance without the weight and complexity of a constance speed prop.


      Mac Mc

  12. Richard Bradberry says:

    Mac, my first ride was in the back seat of a Waco F5 in 1934, when I was five years old. My father wore a seat belt but I was loose and could move around. I remember looking over the sides of the cockpit at a world that I had never seen from anything higher than the bed of a wagon.The pilot was a friend of my father, an old barnstormer named Jim Davis who, I’m sure, gave us a free ride. Can’t say for sure but the flight may have had something to do with my spending the first 20 years of my adult life as a Navy fighter pilot. Thanks for the article and the memory it evoked.


  13. Mac says:

    Hi Richard,

    The best thing that Waco is doing is making memories for people like you, and for those like me who were not lucky enough to fly a Waco 70 or more years ago, but we can now.


    Mac Mc

  14. Thomas Boyle says:


    You note that it’s nice to have a choice.

    It would be nice to have a choice in factory-built aircraft, too. Why is Part 23 the only option for that (at least, above 1,320 lbs)?


  15. Mac says:

    Hi Thomas,

    The FAA is conducting a review of FAR Part 23 because it understands that trying to include light piston singles in the same rule that covers Commuter Category jets that can weigh more than 18,000 pounds is just too much. However, it’s unclear if the emphasis will be on adjusting the rule to suit the higher performance turboprop and jet end, or in simplifying the light piston end.

    Of course, many airplanes in production are actually certified under CAR 3 rules as is the case with the Waco. Bonanzas, Barons, Cherokees and Mooneys all go back to CAR 3 but many changes have been made to the designs over the years that bring them closer to FAR Part 23.


    Mac Mc

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