By Lisa Turner, EAA Lifetime 509911/Vintage 724296
This piece originally ran in Lisa’s Airworthy column in the September 2025 issue of EAA Sport Aviation magazine.
We talk about airworthiness, but what is it? We know it when we see it, but do we know it when we don’t see it? Once we have it, can we tell when we’ve lost it? What does it mean to be “airworthy?” How do we make sure our own airplane is airworthy?
Defining airworthy is a bit like describing a house we want to buy. The roof doesn’t leak, but it’s in poor shape. One person will say it’s fine, and another may say it needs to be replaced. The stairs are functional, but the carpet is bare. Is the house okay? Maybe yes. Maybe no.
With our airplanes, we do not want maybe. We need certitude and standards.
Without burdening you with excessive technicalities, we still need to begin with the formal definition of airworthiness. If you look this up, you’ll find something similar to: “Airworthy means the aircraft conforms to its type design and is in a condition for safe operation.”
Since “type design” refers to a certificated aircraft, we also need to consider the definition for experimental category aircraft. This definition is similar but simpler: Airworthy means “in a condition for safe operation.”
As simple as this sounds, you know that behind the definition is a mountain of regulations and complexities. If you follow any of these paths far enough, you’ll be in a rabbit warren with endless tunnels. Instead of taking you into a warren, I want to talk about basics that you should be aware of when it comes to keeping your airplane airworthy. You’ll find links to a number of relevant resources at EAA.org/Extras.
Perhaps this online Google search result sums it up the best: “An airworthy airplane is one that is deemed safe for flight, meeting both legal and physical standards. This means it conforms to its approved design, is in a condition for safe operation, and adheres to maintenance and alteration requirements.”
We can describe an airworthy aircraft to another pilot, and we can list things we would require for an airworthy aircraft. But what is most important? Here are five things you can do as a pilot and aircraft owner to make — and keep — your aircraft “airworthy.”
How You Conduct Inspections
If you’re a pilot, you already understand the importance of inspections. How well you cover all the items on your list is key. Thoroughness depends on four things:
- You have a structured way of conducting the inspection.
- Everything you need to inspect is on the checklist.
- You understand what to look for.
- You eliminate distractions.
Structure your inspections so that you use the same list and do the same items in the same order. This benefits from human nature, which is to learn something by doing it the same way repeatedly, creating a habit. When you do your inspections this way, you’ll be able to notice the things that are not the same as they were the last time you looked.
Make sure you have everything on your list. I was helping a pilot with an inspection of his Kitfox one day. When we got done, we compared notes.
“Did you see that divot in your prop face?” I asked.
“There’s a gouge in the prop? No, I didn’t see that. Show me.”
I went to the prop and pointed to the side the pilot sees from the cockpit, which we call the “face.” The nomenclature can be confusing for new pilots. In the outer third of one blade there was a deep cut, probably from a rock hitting it. “You should not fly until this has been inspected and repaired,” I said.
My friend was aghast. “I can’t believe I missed that.”
Have other experts and A&P mechanics help you determine if you have everything on your inspection list. The best source will be builders’ and/or owners’ groups and the manufacturer. Keep comparing until you know you have everything.
You understand what to look for. You can conduct an inspection, thinking everything is okay, without understanding what you are looking at. This is a normal condition for a pilot in training. Later, when you’re experienced, you will understand how the parts and pieces go together and why you’re inspecting them. If this is a weak area for you, consider some extra education or training to learn how the systems work together on your airplane.
Eliminate distractions. This is hard to do. You know how to do it, but our human nature is to allow our mind to wander. That’s when we miss things. Inevitably, our phone will ring or someone will stop by. When you resume your inspection, back up a few items and start again.
If you do your own annual (with an A&P mechanic) or your own condition inspection, these tips are even more important. For a primer on annual inspections, see “A Beginner’s Guide to Yearly Inspections,” Airworthy, EAA Sport Aviation, February 2024.
What Your Paperwork Looks Like
I’ve seen messes in both certified and experimental logbooks, along with missing certificates and registrations. It’s easy for this to happen when we aren’t checking for them regularly. I’ve also seen experimental aircraft operating without a Phase I sign-off, and certified aircraft where the data tag and the registration data didn’t match. Even though the aircraft may be physically fit for flight, incorrect paperwork can make it unairworthy.
You should check these three things to stay airworthy:
- Are paperwork checks on your checklist? What paperwork do you need in the airplane, and is it there? Where are your logbooks? Don’t keep them in your aircraft; keep them in a safe place, preferably with an online backup of some sort.
- Are the checklists you are using to do your preflight, postflight, and annual/condition inspections up to date? Legible and thorough?
- What do your logbooks look like? Are they legible and up to date? Are your annual/condition inspections fully and legibly documented? Are all airworthiness directives (ADs) complied with? Even if you have an experimental aircraft, there may be an AD that applies to a part or component on your aircraft.
Who You Choose to Work on Your Airplane
You may have read this far and thought, “I don’t have to worry about this. I have a mechanic.” Many of us rely on A&P mechanics and shops to do our annual or condition inspections and our maintenance and repairs. This is fine, with a few caveats.
Realize that you are ultimately responsible for the airworthiness of your aircraft. You are responsible for paperwork oversight. We’re living in a world where it’s easy to point the finger at someone else when something goes wrong. Resist this temptation.
Choose the best people to work on your airplane. Do the research, talk to other customers, double-check credentials, and help them by reviewing the work completed and the paperwork that goes with your manuals and logs.
Service people want to do the best they can for you. In my experience, there are few lazy shops. However, it’s your job to make sure yours is not one of them.
Annual and condition inspections are critical. I once overheard an owner say, “Hey, go light on this, will you?” to the A&P mechanic about to begin the annual inspection. This will compromise both the airworthiness of the airplane and the professionalism of the A&P/IA mechanic. Yet, it’s not uncommon. It’s a tribute to the ruggedness of our airplanes that it’s not a bigger contributor to serious accidents.
How Thorough Your Postflight Inspection Is
You can jump out of your airplane after a flight and stick it in the corner, knowing you will look at it again on a preflight inspection, or you can take the short time now to look everything over. It takes only a few minutes, but it requires full attention focusing on the airplane instead of what you’re going to go do next in the day.
I returned from a flight in the Pulsar and was late for another appointment. I pushed the airplane into the corner of the communal hangar and was about to leave when I smelled oil. I looked at the Pulsar and didn’t see anything unusual until I got down on my knees to look underneath it. What I saw caused me to do a double take. I was looking at the belly entirely covered in a layer of oil from front to back.
After an inspection, I found I had overfilled the oil sump tank. I hadn’t followed the procedures for the oil level check. If I had not done the postflight inspection, I would have a big surprise on the next preflight and likely need to cancel the outing for a thorough inspection and cleanup.
How Well You Understand Yourself
Most of the inspection misses we see as contributors to accidents are not malevolent. The mechanic who forgot to put the bolts back in the seat track, the mechanic who failed to check the direction of the controls, and the owner who missed the gouge in the prop are all going about their business thinking they are checking everything.
We miss things for three reasons.
- Insufficient training. We don’t understand how an item works and were not trained how to inspect it. The Dunning-Kruger effect is a cognitive bias where individuals with low competence tend to overestimate their ability, while those with higher competence may underestimate their ability. We call this the “we don’t know what we don’t know” effect.
- The “one time” trap. We inspected the aircraft before leaving for the hamburger; the airplane looked fine when we tied it down and went into the restaurant; everything looked fine when we came out; why should we inspect again? You’re the only one who knows how thorough you have been. Don’t allow yourself to think that everything will be fine “this one time.” Be rigorous.
- Time pressures and distractions. If you’re the A&P mechanic in a shop, pressure is a way of life that you must manage so that it doesn’t degrade performance. If you’re taking your time inspecting your own airplane, realize that the same pressures can interfere with your work. In our fast-paced environment, it’s easy to get overloaded. When this happens, stop and take a break. Check for distractions and then resume with full attention.
Airworthiness is a composite of your aircraft’s readiness for safe flight and your own readiness for flight. When things go wrong in a big way, we usually find out that an inspection item was not done, it was not done correctly, or the pilot got distracted by something else. To prevent this, simply slow down, have a complete and detailed checklist in hand or in phone/tablet, and realize that the decisions and actions you take prior to flight can make all the difference between being airworthy and being unairworthy.
Lisa Turner, EAA Lifetime 509911/Vintage 724296, is a retired avionics manufacturing engineer, an EAA technical counselor/flight advisor, and A&P mechanic. Lisa has authored six books. Dream Take Flight details her Pulsar building and flying adventures. For the Love of an Airplane is the biography of Jerry Stadtmiller, a man who restored more than 100 antique aircraft to flying condition. Learn more at DreamTakeFlight.com. Write Lisa at Lisa@DreamTakeFlight.com.