📘14 CFR §91.409 - Required Aircraft Inspections

AV1ATES – How to Know if Your Aircraft Is Legal to Fly

✏️ Plain-English Summary:

To be airworthy, an aircraft must complete a set of required inspections on a specific schedule. If even one of these is overdue, the aircraft is not legal to fly — regardless of how well it runs. This reg is essential for both checkride prep and real-world decision-making.

Use the AV1ATES acronym to remember what needs to be checked.

✅ AV1ATES –

A – Airworthiness Directives (ADs)

• Issued by the FAA for known issues (safety-critical)

• Mandatory and must be complied with as stated

• Some are one-time, others are recurring

• Found in aircraft logbooks and FAA databases

V – VOR Check (Every 30 days – IFR only)

• Only required for IFR operations using VORs

• Not required for VFR flight

1 – 100-Hour Inspection

• Required if aircraft is used for hire or flight instruction

• Must be done every 100 hours of flight time (based on tach time)

• Can be overflown by up to 10 hours, but only to reach a location where inspection will be done

• The next 100-hour interval is still based on the original due time

A – Annual Inspection

• Required for all aircraft operating under Part 91

• Must be completed every 12 calendar months

• Must be signed off by an IA (Inspection Authorization) mechanic

• Cannot be overflown (no exceptions unless you get a Special Flight Permit)

T – Transponder Inspection

• Must be checked every 24 calendar months

• Required if operating:

  • In Class A, B, or C airspace

  • Within 30 NM of a Class B (Mode C veil)

  • Or above 10,000’ MSL

E – ELT Inspection

• ELT must be inspected every 12 calendar months

• Battery must be replaced if:

  • Used for >1 hour cumulative, or

  • 50% of battery life has expired

• Must be logged in the maintenance logs with the expiration date

S – Static System / Altimeter Check (IFR only)

• Required every 24 calendar months

• Only needed for IFR operations in controlled airspace

• Includes the altimeter, static system, and automatic pressure altitude reporting (encoder)

✈️ Scenario:

Your 100-hour inspection was due at 1,220 tach time, but you flew to a nearby airport and landed at 1,225. ✅ Legal — only if the inspection is done immediately after and the flight was solely to get to the inspection location. ❌ But your next 100-hour is still due at 1,220 + 100 = 1,320.

You haven’t had an annual in 13 months — even though the plane runs great. ❌ That flight is not legal under any circumstances — annual inspections must be current.

🧠 Memory Tip:

AV1ATES = Airworthy You can fly VFR without VOR or IFR inspections, but everything else must be current for every PPL flight.

🎓 CFI Teaching Tip:

Have students highlight or tag the AV1ATES entries in the logbooks during ground sessions. Use real aircraft examples to quiz them on what’s due next.

Ask:

“If you’re flying solo XC tomorrow, what inspections must be current?” Walk them through how to verify each.

📚 References:

• FAR §91.409 – Annual and 100-hour inspections

• FAR §91.207 – ELT

• FAR §91.413 & §91.411 – Transponder, Altimeter, and Static System

• FAA Airworthiness Inspector’s Handbook