Airplane GEEK

Aviation News from around the world


By Lisa Turner, EAA Lifetime 509911

This piece originally ran in Lisa’s Airworthy column in the August 2021 issue of EAA Sport Aviation magazine.

“Friday would be great. What would you like me to do in preparation?”

“Have the cowling and covers off, have your builder’s log, registration, and other papers ready, and figure spending several hours going through the airplane.”

“I’m looking forward to it,” Beth said, ending the call with the FAA designated airworthiness representative (DAR).

Beth walked into the kitchen and poured out a hot cup of coffee. She carried it to the garage and sat at the workbench, looking over the completed airplane. More than 2,000 build hours, she thought. Now is the time. Her excitement was overwhelming. I hope he doesn’t find anything wrong.

Friday arrived, and at 9 a.m., Beth opened the garage door. It was a beautiful south Florida day in October with a hint of winter coolness in the light breeze wafting through the space. Brent arrived moments later. Beth took a deep breath.

Brent walked up to the airplane, and he opened up a fat briefcase.

“I can pull the airplane out to run it for you.”

“Okay, yes. Let’s see how everything looks first.”

Beth’s anxiety began to fade as Brent looked over her paperwork, nodding agreement.

“I’m really surprised that this is all in order. I almost always find errors right off the bat on the paperwork. You’ve filled everything out neatly and correctly. Believe me, that’s half the battle, and one reason why I didn’t want to get too far down the path looking at the airplane. The builder log with all the pictures and the data are helpful.”

Using a complex checklist, Brent began looking methodically at the airplane. The first thing he examined was the data plate. “Uh-oh,” he said, as he made a note in his checklist.

Beth felt the anxiety return. “What is it?”

“The serial number of the aircraft does not match what you put in the paperwork, specifically the registration.”

“Oh no!” Beth walked over to the inspector and crouched at the tail, looking carefully at the plate. “You’re right. The number should be 5592, and the plate has 5593.”

“It’s easy to miss these errors,” Brent said. “But it has to be exact.”

“Of course.”

“You’ll need to have a new plate made.”

Beth was disappointed but waited patiently as Brent asked questions and went through the systems. She had hoped to take the airplane out to the airport that weekend to start testing.

Over the next several hours, they both went over all of the systems and ran the engine.

“Everything looks good, Beth. The workmanship is impressive, and you’ve used great mechanic tricks like torque seal.”

“I got a technical counselor at the very beginning, and my neighbor is an A&P, so I’ve had a lot of good advice. I’ve never been too proud to redo something.”

“Let’s sit down and go over next steps, and review your test area.”

“Don’t you have to come back to reinspect the airplane after I get the data plate corrected?”

“No. I’m giving you your certificate today and expecting you to get the plate corrected before you begin testing. Send me a picture of it via email, please.”

“Thank you,” Beth said with a broad smile.

* *

The Pareto principle says that 20 percent of your effort will give you 80 percent of your results, or in the case of inspections, 20 percent of the items account for 80 percent of the problems. I did a survey with currently active DARs to find out what the 20 percent of the items were that account for 80 percent of their certification failures.

If you know ahead of time what these issues are and can pay extra attention to them, you’ve got a very good chance of getting your airworthiness certificate on the first try.

Operating Limitations and Certificate


Incorrect or nonmatching information is the top problem for both homebuilts and certified aircraft. The errors begin with the maze of forms. Every item, from the eligibility statement to the registration to the data plate on the airplane, must reflect exactly correct data.

How to correct

EAA has assembled all of the steps and forms in the certification process in the Homebuilders Step-by-Step Certification Guide, which is included in the “EAA Amateur-Built Certification Kit.” For $20 you can be spared hours of head-scratching and confusion. It even has a data plate in the package.

When it comes to the paperwork, take your time and have others look at it, too. Look for legibility, matching information everywhere, exact spelling, dates, and completeness.

Aircraft Data Plate


Close behind the paperwork errors, hardware troubles are rampant. Examples include self-locking nuts being used on rotating bolts that should have a castellated nut and pin, missing safety wire, missing lock nuts, AN bolts where clevis bolts should be, and sheet metal screws where machine screws should be.

How to correct

Get yourself a copy of the FAA’s AC-43.13-1B, Acceptable Methods, Techniques, and Practices – Aircraft Inspection and Repair. It’s free online as a PDF from the FAA, and less than $20 from many booksellers as a large paperback. This is the A&P/IA mechanic’s bible. The information is clear and simple, with excellent graphics and tables. The section on hardware covers everything from rivets to nuts, bolts, and control cables. Study it, and refer to it often even when you think you know how it should go.

Work with your technical counselor to learn techniques, such as safetying, and what goes where. Because the inspector may not (and is not expected to) look at every single nut, bolt, and cable, you need to.

Technical Advisor for Aviation

Lack of Labeling

Lack of labeling on components and switches. It’s remarkable that some experimental aircraft actually get in the air without switch labeling. I asked one owner why the switches were not labeled. He replied, “Simple. First is ignition, next is fuel, next is radios, next is lighting. Doesn’t that make intuitive sense to you?”

“No, it doesn’t,” I said. “What about the next owner?”

“Oh, I hadn’t thought about that.”

How to correct

Label everything. Then think about directions. So, if you label a fuel switch, make sure the operator knows what direction is ON and OFF. I know this sounds elementary, but in an emergency part of our brains disconnect. Make it as clear and as simple as possible.

Take a lesson from certified aircraft, which have lots of placards. Sit in your airplane and think about the information you would like to have in front of you in addition to the required items. An emergency checklist is the first thing I think of.

Controls routing and travel

When assembling things, we think about the assembly and sometimes forget what the control does. I’ve seen complicated routings for control cables that introduce friction into the cable that will only get worse with time. The other problem is controls that don’t operate fully.

How to correct

Make sure you have full travel on control cables — stop to stop — look at the specifications to make sure. Look carefully at plans and directions, and remember that the straighter the routing, the better the control will work. You don’t want to be in the air when you discover a problem. Taxi testing will not reveal all problems.

Lack of preparation for inspection 

This is a reason for certification failure for both homebuilts and certified aircraft. It’s a situation where the owner/builder just didn’t do all their homework and take the time to methodically go through all the systems, including the paperwork, ahead of time and have the aircraft really ready.

How to correct

Assemble a checklist of things to do and look for before the inspection. The EAA certification guide is a good start. Go over what you have several times and ask someone else to go through it. They will catch something you didn’t.

There are a couple of tricks that work well when it comes to getting ready for your certification inspection. The first is to have as many qualified people as possible take a look at your airplane and at your paperwork. Ask the A&Ps in the hangar next to you, seek out the experienced professionals at the field where you fly, and ask friends if they can find any mismatches in your written forms. The second trick is for you to do a mental reset. As the building comes to a close, we tend to get more and more excited about flying. This cloaks our aircraft in an “everything is ready to go” status. The mental reset allows you to drop back and consider that there might be things that you’ve overlooked on the airplane, and now is your chance to find them with an objective mindset.

Now you are ready.

Lisa Turner, EAA Lifetime 509911, is a manufacturing engineer, A&P, EAA technical counselor and flight advisor, and former DAR. She built and flew a Pulsar XP and Kolb Mark III, and is researching her next homebuilt project. Lisa’s third book, Dream Take Flight, details her Pulsar flying adventures and life lessons. Write Lisa at and learn more at

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