Ask the DAR

One-offs, forms and island test flights.



Question: I saw the question about one-of-a-kind aircraft in KITPLANES®. Like the other writer, I am considering using the wings from one kit and the tail surfaces from another and designing the fuselage myself. I am hoping you can direct me to some resource that might guide me about what engineering data an inspector might ask for. This is the pivotal issue for me in considering building a one-off design. I can imagine the testing and documenting costing tenfold the actual cost of designing and building. Is there some way for me to get a design reviewed/approved before I start construction?

Answer: Actually there are no hard requirements for you to submit engineering data. As the designer and builder you are pretty much on your own in this respect. Having said that, I must add that some inspectors my ask for engineering data in the interest of safety. Typically FAA inspectors are not engineers, and if you have some design that is unproven, it may be questioned.

My first advice would be to contact an FAA DER (Designated Engineering Representative) or other aeronautical engineer. First to enforce your own confidence and second so you will have something to show the inspector if you are questioned.

My second bit of advice would be to contact the inspector you plan to use, show him your plans, and ask what kind of data he would like to see. Our goal as DARs is to see that you get into the air safely.

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Question: I have the AC 20-27G checklist received from the EAA. However, there are no instructions about how to write the numbers in the columns KIT MANUFACTURER/BUILDER. Are these numbers supposed to be a percentage? Then, do I divide the totals by the number of lines on the checklist to get the total percentages? I am using some salvaged parts from an amateur-built, which were made from materials from a kit. My salvaged kit airframe had to be at least 50% rebuilt, and I cut the materials and modified it, with someone else doing the welding. Same with the wings: They were built once, but had to be taken completely apart and rebuilt with parts I made. This cannot be called a “kit plane.”

Answer: Actually, you just didn’t read far enough. Full instructions for completing the form are there on page 8-10 and page 8-11 of AC 20-27G. They are too long to include here, but they are there. I promise. Remember that parts taken from the original airplane and rebuilt, do not count as “built by you.” They are considered a “repair.”

Question: I live on an island, St. Croix in the U.S. Virgin Islands, and I want to build. My concern is whether I will be able to get an approved test and alternate landing area. We only have the one airport in Class D airspace and not much in the way of off-airport alternative landing areas other than in the water. I would hate to go through the expense of having a kit/supplies shipped here and the effort of building only to find I can’t test-fly my aircraft. How can I find out before I get started?

Answer: My research shows you would be under the jurisdiction of the South Florida FSDO, San Juan Facility. It is located on Highway 52m about a mile south of a line drawn between Luis Muñoz Marín International and Isla Grande Airport. You can reach them at 787/764-2538.

Please send your questions for DAR Asberry to with “Ask the DAR” in the subject line.

Mel Asberry is an experienced Designated Airworthiness Representative specializing in Experimental/Amateur-Built aircraft. He and his wife, Ann, have built seven amateur-built airplanes including two ultralight types, a Moni Motorglider, a Dragonfly Mk2, two RV-6s and a Zenair CH 601HDS. They are currently building a scratch-built biplane.


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