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THE BASICS OF AIRCRAFT BUILDING from Aircraft Spruce
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THE BASICS OF AIRCRAFT BUILDING

Why would I want to build an airplane? Do I have the necessary skills? What about regulations, tools, workshop requirements? How much will it cost, how much time is involved, what types of aircraft are available to build? These and other questions will be answered as we discuss the basics of building an experimental airplane for amateur-built purposes.

Building an airplane from a kit is not a new idea. It actually dates back to the 1920’s when the Heath Parasol was built from a kit. Several other attempts at constructing a homebuilt airplane were made with some degree of success. The government became involved and Congress officially approved the licensing of homebuilt aircraft in 1947. This approval stated that the construction would be for education and recreation and not for mass production and sale. That regulation still exists today. In 1953, Paul Poberezny founded the Experimental Aircraft Association to assist people interested in building their own airplane. Today the EAA is still achieving that goal with over 160,000 members worldwide. The term “homebuilt” was coined years ago and still is used today. I prefer the term “custom built” when referring to an airplane constructed by an individual. Custom aircraft building became more and more popular during the 1970’s when several kit aircraft were developed along with the introduction of composite construction by Ken Rand and Burt Rutan. By the 1980’s, custom aircraft building was literally taking off. Since that time hundreds of designs have been introduced and marketed by a number of companies. There are over 32,000 amateur-built aircraft registered in the United States today. Approximately 1,000 airplanes are being added each year.

Why build an airplane? Of course, there are many answers to that question. Probably one of the best answers is found in acquiring the satisfaction of completing an airplane project. Building your own airplane is very rewarding from a personal perspective. After many hours of hard work the long awaited day when the airplane first flies arrives. Talk about a sense of satisfaction—actually test flying an airplane for the first time that was built by you. I don’t know many experiences that will top that. There also are many other reasons to build an airplane. The cost versus performance issue is important. Generally speaking, you will get more for your money by building your own airplane. Many individuals build an airplane so they will understand the mechanical aspects of flying and in turn, with that knowledge they can maintain their own airplane. The cost of hiring a mechanic to work on your airplane is high. No one will know your airplane as well as you after having spent hours fabricating it. You can then legally maintain that airplane including signing off the annual inspection. The annual inspection on an amateur-built airplane is termed a “condition inspection.” Two other reasons to build (1) to learn new skills, and (2) to involve your family in a project. I highly recommend family involvement. To not involve other members of your family invites failure of the project.

A definition of the term experimental is in order. We all hear the term “experimental aircraft” regularly—what does it mean? First of all, all airplanes, except for ultralights, must possess a certificate of airworthiness to legally fly within the United States. Two categories of airworthiness certificates exist, standard and special. Special airworthiness certificates are further broken down into several categories one of which is experimental. So, an experimental aircraft will have an airworthiness certificate that states “Experimental” on the certificate itself. To further define the certificate, the experimental category has a number of terms describing the purpose of operation. The purpose that we are interested in is “amateur-built.” In other words, most custom built aircraft will have an airworthiness certificate that states “Experimental” with a further definition of operation for “amateur-built purposes.” FAR 21.191(g) is the primary Federal Aviation Regulation that pertains to amateur-built aircraft. That regulation states “Operating amateur-built aircraft. Operating an aircraft the major portion of which has been fabricated and assembled by persons who undertook the project solely for their own education or recreation.” This regulation basically defines custom aircraft building. Notice it states “major portion." That means you, the builder, must build 51% or more of the airplane. This is commonly referred to as the “major portion rule.” Further examination of the regulation states the word persons in the plural. More than one person may build the airplane as long as no compensation is received by any of the individuals. The final words in the regulation state very clearly that you must build the airplane “for your own education or recreation.” Clearly, it is important that we abide by this regulation. To not do so will invite further restrictions and regulations. You may not legally hire someone else to build an airplane for you and then certificate it under the experimental category for amateur-built purposes. I want to make this very clear because a lot of misunderstanding exists regarding this action. Obtain a copy of FAA Advisory Circular 20-27G. This document explains from a regulatory perspective what is involved in amateur-built construction.

You must have a pilot’s certificate to fly an experimental airplane. If you want to fly an aircraft without a pilot’s license you must build an ultralight. Ultralight airplanes are single pilot aircraft used for recreational purposes only. They must weigh less than 254 pounds when empty, not carry more than 5 gallons of fuel, and not be capable of more than 55 knots in level flight. FAR 103.1 defines the operation of ultralight aircraft.

Another recent category of experimental aircraft is termed Light Sport Aircraft. Certain restrictions apply to this category of airplanes that may be flown with a Light Sport Pilot license. One of the advantages of the Light Sport Pilot category is the fact that a FAA medical certificate is not required. If you possess an automobile driver’s license that will serve as proof of your medical competence.

Regarding the aircraft that may be certified under the Light Sport category several restrictions apply. Briefly, they are restricted to a maximum gross takeoff weight of 1,320 lbs or 1,430 lbs for seaplanes. The maximum stall speed is restricted to 51 mph (41 knots), maximum level flight speed of 138 mph (120 knots), and single or two seat aircraft only. There are other restrictions that may be found on the EAA website. Several antique and classic aircraft fall within the weight and speed range to qualify as Light Sport Aircraft.

There are simply few regulations pertaining to amateur-built airplanes. FAR part 91 applies just as it does to the operation of other airplanes. One of the restrictions on an amateur-built airplane is in the area of commercial operation. You may not operate an amateur-built for any commercial purposes including rental of the aircraft. This does not mean that you cannot use the airplane for your own business purpose, rather it restricts the use for purposes of direct compensation.

What types of airplanes are available to build? Basically, there are five different types of materials used in building amateur-built airplanes. They are sheet metal, wood, steel tubing, fabric, and composite materials. The majority of custom built aircraft require a combination of two or more of these materials. Several designs using sheet metal only are available and are popular. A large number of tubing and fabric airplanes are being built along with the composite aircraft. Composite aircraft are comprised of two or more basic materials, such as foam and fiberglass, that are combined to make a very strong structure. The type of aircraft that you choose is largely one of personal preference. You may have sheet metal experience that would enable you to feel more comfortable building that type of airplane. You may desire a fast, cross-country airplane that might lend itself best to a composite design. The choices are virtually unlimited. I would recommend that you decide what you want to do with the completed airplane. Do you want to fly cross-country, do aerobatics, take someone else with you, simply fly around the field in the evening—what do you want to do with the airplane?

The first step is to decide the type of design—tube and fabric, wood, sheet metal, or composite. Do not be afraid to choose a design that you know nothing about because you are going to have to learn a lot of new skills regardless of the type of construction. There are a number of workshops that are presented around the country by the EAA. They are called EAA/ SportAir workshops and will assist in preparing you for any type of construction. Aircraft Spruce is one of the major sponsors of the EAA/Sportair workshop program.

You then have the option of building an airplane from a set of plans or from a kit. Building from a set of plans will be more time consuming but will cost less than building from a kit. Kit manufacturers do a lot of the work for you. They present their kit to the FAA for evaluation to be placed on a listing of eligible kits. This simply means they prove to the FAA that if you follow their plans you will build the major portion of the airplane. So, the kit manufacturer sells you a partially completed airplane that you in turn fabricate and assemble 51% or more of the final product. This is in complete compliance with the regulations. Kit aircraft usually are more expensive but require less time to complete. So as you can see, with a kit you trade money for time.

Choosing the airplane to build can be very confusing. To review, once you have decided that you want to build an airplane, you first make the decision as to the type of design and the purpose of the airplane. With that in mind you then are confronted with the decision as to a specific type of airplane. There are many good publications that provide comparisons of various custom built airplanes. I would also recommend that you attend AirVenture, Sun ‘N Fun, or one of the major airshows. Most of the aircraft choices are available at these airshows and you can talk to the manufacturers along with the people that are actually building the airplanes. Your best source of information will be builders of the type of airplane you are interested in constructing. They are usually unbiased and they will be frank concerning the amount of money it will cost, the time it will take, the support of the manufacturer, the completeness of the plans, etc..

Tools needed to build an airplane vary with the type of construction. Sheet metal construction will necessitate a larger investment in tools than will composite construction. Basic tools are needed for each type of airplane. The bottom line is you can never have too many tools. You do not need to invest a fortune to begin but remember, the tools you buy are a life-time investment. Workshop space is a similar consideration. If you have a space the size of a two-car garage you have enough room. Once again, the type of construction will present different workshop problems. If you are doing dope and fabric work you will not want to do it in your basement. The fumes will not make you popular with the rest of the family. Noise is a factor with sheet metal construction. Fumes can also be a problem with composite work. As you can see, each type of airplane presents a unique set of considerations for workspace and for tools. I would recommend that you set up your workshop as close to home as possible. If it is at or near your home your family will become more interested and hopefully participate. Also, the more convenient the workshop the more likely you are to spend time working on the project. Driving to the workshop is usually not welcomed after a day at the office.

Time and money! Two of the most serious issues involved in the custom aircraft building decision. Underestimating these two factors is also responsible for a large number of failed projects. How much money will it cost? Of course, this is entirely dependent upon the type of airplane you decide to build. Kits are available from less than $5,000 to over $100,000. The type of engine and the avionics installed are two very significant variables. Suffice to say that you can spend anywhere from $5,000 to well over $200,000 on your airplane.

Time is another variable that is hard to predict. Usually it will take more time than you estimate. The airplane designers will provide you with an estimate that usually is somewhat optimistic. Their estimate is predicated on ideal conditions. Realistically, there are so many variables involved it is difficult to arrive at a definite time estimate. The following are several factors to consider: workshop space, tools, technical knowledge and skills, weather conditions, accuracy of plans, support of kit manufacturer, travel time to your workshop, time to prepare for actual work, etc.. You will end up making mistakes and having to redo certain parts of the project. That time is not included in the estimate. As you can see the variables are too numerous to list. A good ball park estimate is 1,000 to 3,000 hours for a kit aircraft and up to 6,000 hours or more for a plan’s built aircraft. Very simply, you need to be prepared for the amount of time required. If you simply want to fly an airplane you may be better off buying one. You need to go into a project to enjoy the building process. That is one of the primary reasons to build your own airplane. Enjoy the journey!

Building your own airplane is a learning experience that brings about a tremendous amount of self-satisfaction. If you believe you want to participate in this activity I recommend that you join the Experimental Aircraft Association. This organization has a number of local chapters throughout the world comprised of people that are actively building airplanes. They know where to go for information, pros and cons of different airplanes, and they will provide you with encouragement. Attend the major airshows and conventions around the country and ask questions. Enroll in the EAA/ SportAir workshops. These workshops will enable you to get “hands-on” experience in the actual building process. There are also internet newsgroups for general information and for information from people actually building specific airplanes. Most importantly, talk with other people that are building airplanes. They can answer most of your questions. Obtain a copy of Advisory Circular 20-27G. During Oshkosh and Sun ‘N Fun the FAA distributes copies of all the amateur-built advisory circulars bound into one publication.

Well, why aren’t you in the workshop building? One of the most satisfying experiences you will encounter is waiting on you when you build your own airplane. Thousands before you have been successful—you can be too!