Maintenance

What the Aircraft Annual Inspection Covers and How to Prepare for It

A plain-English guide to the FAA annual inspection process — what's checked, how long it takes, what squawks typically surface, and how to keep your aircraft ready year-round.

Aloft360 Team·Aloft360·Dec 18, 2025·9 min read

Every aircraft operated under FAR Part 91 in the United States must undergo an annual inspection by an FAA-certificated Airframe and Powerplant (A&P) mechanic with Inspection Authorization (IA). Most aircraft owners know this, but fewer understand what actually happens during the annual, which makes it hard to plan for, budget, and avoid surprises.

The Legal Requirement

Under FAR 91.409, a certificated aircraft must be inspected within the preceding 12 calendar months. "Calendar month" is significant — not 365 days from the last inspection. An aircraft annualed in November 2024 is due by November 30, 2025 regardless of when in November 2024 the inspection occurred.

The annual inspection must be signed off by an IA (not just an A&P). An A&P can perform the work, but the IA must make the airworthiness determination and sign the logbook.

What the Inspection Covers

The annual inspection is guided by FAR Part 43, Appendix D, which lists the items that must be checked for each area of the aircraft. This isn't a checklist in the pilot sense — it's a comprehensive examination of the entire aircraft.

Airframe

  • Fuselage and hull: corrosion, cracks, delamination (for composites), fabric condition (for fabric aircraft)
  • Wing and control surfaces: spar condition, skin damage, hinge pins, rivet condition
  • Landing gear: struts, brakes, tires, fairings, alignment
  • Seats and seat rails: rail condition (a recurring issue on Cessnas — cracked seat rails have caused fatal accidents)
  • Windows: crazing, cracks, seals

Powerplant

  • Engine mounts: cracks, corrosion, security
  • Engine baffles and seals: critical for proper cooling
  • Exhaust system: cracks, leaks, security — carbon monoxide risk
  • Engine accessories: magneto timing, carburetor or fuel injection, starter, alternator
  • Engine oil: analysis is often performed; metal content indicates internal wear
  • Fuel system: tanks, lines, fuel caps, sump drains

Propeller

  • Blades: nicks, cracks, erosion — nicks on the leading edge require dressing or repair; deep nicks or cracks are cause for rejection
  • Hub: security, corrosion
  • Spinner: cracks, security

Avionics and Electrical

  • Wiring condition: chafing, security, proper routing
  • Battery: load test, corrosion
  • All placards and markings: required placards must be present and legible

Required Inspections Within the Annual

Several recurring inspections may align with the annual or need to be performed separately:

  • ELT battery and transmitter check (FAR 91.207) — 12-month inspection; battery must be replaced at expiry or if the unit has been used
  • Transponder and altimeter system (FAR 91.411/413) — required every 24 calendar months for IFR flight; not part of the annual itself, but often done concurrently
  • Pitot-static system — same 24-month requirement as transponder/altimeter

If these are due and you're already at the shop, do them concurrently. Separate trips cost more.

Common Squawks Found During Annuals

Every mechanic has a list of issues they reliably find on specific aircraft types. Knowing these ahead of time lets you budget realistically.

Cessna 172/182:

  • Fuel cap seals (O-rings dry out and leak)
  • Seat rail cracks (critical airworthiness item)
  • Cracked exhaust risers
  • Soft brake cylinders
  • Cowling hinge wear

Piper PA-28 (Cherokee/Archer/Arrow):

  • Wing spar corrosion (particularly on older aircraft with history in humid climates)
  • Fuel selector valve wear
  • Cracked nosegear pivot forks
  • Elevator trim tab hinge wear

General common squawks:

  • Chafed wiring
  • Induction air box cracks
  • Oil filler door latches
  • Cracked baffle seals

Every annual will find something. The question is how significant the findings are.

How Long Does an Annual Take?

For a simple single-engine piston with no known issues, plan on 3–5 business days at most shops. Complex aircraft (retractable gear, turbo, multi-engine) take longer. An aircraft that hasn't been well-maintained or hasn't flown much — corrosion is worse on infrequently-flown aircraft — can take significantly longer.

If the shop finds a significant squawk (engine teardown for investigation, control cable replacement, brake master cylinder replacement), add time for parts procurement and additional labor.

Realistic planning guidance:

  • Book the shop 4–6 weeks out (good IA shops are scheduled)
  • Plan for the aircraft to be unavailable for 1–2 weeks
  • Have a contingency for parts delays — backordered items from Continental or Lycoming can take weeks

How to Budget

Annual inspection costs vary by region, aircraft type, and shop. Rough ranges for a typical GA single:

ComponentTypical Range
Shop inspection labor$800–$2,000
Oil change and filter$100–$200
Routine consumables (filters, gaskets)$100–$300
Repairs (squawks — variable)$0–$5,000+
ELT battery (if due)$150–$400
Transponder/IFR cert (if due)$300–$600

Budget $1,500–$3,000 for a clean aircraft with no known issues. For an aircraft with deferred maintenance or approaching an engine-critical inspection, budget more.

The Maintenance Reserve Principle

The right way to approach the annual is to build toward it all year, not absorb the full cost in one month. If your aircraft costs $2,500/year in annual inspections and routine maintenance, that's roughly $208/month, or about $12.50/hr on a 200-hour/year aircraft.

Putting that reserve aside monthly (or per-hour in a flying club context) means the annual is a planned expense, not a surprise. Flying clubs that don't charge a maintenance reserve inevitably face special assessments when the annual comes in high.

Preparing Your Aircraft Between Annuals

The best annual is one where the IA finds nothing significant. Getting there requires attention between annuals:

  • Log every squawk your pilots notice. A soft brake pedal or a slightly rough mag don't seem urgent, but logged squawks give the annual IA a roadmap of what to look at closely.
  • Address deferred items before they become major. A weeping fuel tank seal is a $300 fix early; ignored for a year, it can lead to fuel contamination and a wing tank reseal.
  • Keep the aircraft flying. Aircraft that sit develop corrosion, flat spots on tires, and stuck valves. An aircraft that flies regularly has less corrosion and more visible wear patterns.
  • Track your inspection calendar. Know when your transponder cert, ELT battery, and pitot-static cert are due relative to your annual — batch them at the annual to save shop visits.

Aloft360's maintenance tracking keeps all of this organized: inspection due dates, squawk board, and maintenance logs per aircraft. When it's time for the annual, you hand the IA a complete history rather than a shoebox of logbook scraps.

After the Annual: The Airworthiness Signoff

When the inspection is complete and all discrepancies are corrected, the IA signs off the maintenance logbooks with the date, the aircraft's total time, and the language "I certify that this aircraft has been inspected in accordance with an annual inspection and was determined to be in airworthy condition." This entry is what makes the aircraft legally airworthy for the next 12 calendar months.

If any discrepancy was found but cannot be immediately corrected, the IA may list it as a logbook entry noting the condition and any operating limitations, and the aircraft cannot be returned to service until the discrepancy is resolved.

The annual inspection is an opportunity to catch developing issues before they become airworthiness items. Maintaining good records between annuals — logged squawks, tracked inspection intervals, documented maintenance history — gives the IA a clear picture of the aircraft and reduces the time and cost of the inspection itself.