Understanding airworthiness is one of the toughest parts of becoming a pilot. Do you know how to make sure you're legal to fly a particular airplane?

There Are Three Pillars Of Airworthiness

Understanding what makes an airplane "airworthy" is one of the toughest parts of passing your first few checkrides. If you don't have a mechanical background, this topic might seem intimidating, so we'll break it down into three parts. Keep in mind, there's a lot that goes into making an airplane airworthy, and we can't cover it all in one article.

So, what does it mean for an airplane to be airworthy?...

• 1) It meets approved type design
• 2) It's in a condition for safe operation
• 3) Maintenance and alterations are performed in accordance with 14 CFR parts 21, 43, and 91.

Failing to comply with ANY of the above three criteria automatically makes an airplane not airworthy.

Maintaining vs. Determining Airworthiness

There's a big difference between who's responsible for maintaining vs. determining airworthiness. Here's what the FAA has to say about who's responsible for maintaining airworthiness under 14 CFR 91.403:

But who's responsible for determining that an airplane is in an airworthy condition? 14 CFR 91.7 says:

Understanding Airworthiness Certificates

Airworthiness certificates are valid forever, as long as it meets the 3 pillars of "airworthiness" we first discussed. They must be displayed "at the cabin or cockpit entrance so that it is legible to passengers or crew" (14 CFR Part 91.203).

Required Maintenance Inspections

The annual inspection of the airplane must be completed no later than every 12 calendar months. You can find a list of what must be inspected in Appendix D of 14 CFR Part 43. Once an annual inspection is completed, the aircraft must be granted a return-to-service by an A&P with an Inspection Authorization (IA).

What about if you're flying for hire or flight instruction, if given for hire? You must now complete a 100-hour inspection under 14 CFR 91.409. You can overfly this 100-hour limit by up to 10 hours, but only to reposition the aircraft for its required 100-hour inspection.

An annual inspection can be completed instead of a 100-hour inspection. While the inspections are nearly identical, the only tangible difference is that an annual inspection must be given by a mechanic with IA qualifications.

Alternatively, your operation might be approved to complete a set of "phase inspections." These allow less maintenance time for each individual inspection. And while the entire aircraft is inspected each time, mechanics focus on specific portions of the aircraft per each "phase."

There are a few other inspections that must be completed on a rotating basis:

• Emergency Locator Transmitter (VFR/IFR every 12 calendar months or when the ELT has been used for 1 hour or 50% of useful battery life) - 14 CFR 91.207
• Transponder (VFR/IFR every 24 calendar months) - 14 CFR 91.413
• Static System (IFR every 24 calendar months) - 14 CFR 91.411
• Each Altimeter (IFR every 24 calendar months) - 14 CFR 91.411
• Automatic Pressure Altitude Reporting System (IFR every 24 calendar months)

Reading Aircraft Maintenance Logbooks

Depending on where you fly, you can look in the aircraft logbook, dispatch logbook, or dispatch release for required maintenance entries. If you're flying an airplane for the first time, you should look at the maintenance logs to make sure the airplane you're about to fly has received the required inspections.

What Else Do You Want To Know?

Airworthiness is a complicated topic. What else do you want to know? What experiences have you had with aircraft logbooks or maintenance discrepancies? Tell us in the comments below.