The annual is the rhythm of aircraft ownership. It is the one bill that is never optional, it is the one week a year somebody looks at everything, and it is the single largest variable in what a given airplane costs to own. Two owners with identical airplanes can pay very different annuals, and the difference is usually not the shop rate. It is how the airplane was maintained the other eleven months, and how much the owner understands about what is being done.
Nothing here is maintenance guidance or a substitute for your mechanic. It is a map of the process so you can be a useful participant in it.
What an annual actually is
An annual is a required inspection of the entire aircraft against a defined scope, performed by an appropriately authorized mechanic, resulting in a logbook entry stating whether the aircraft is airworthy. That last part matters: the inspection is an inspection. Repairs are a separate activity that follow from it, and the two get blurred in conversation and on invoices.
Expect the airplane to come substantially apart. Inspection panels off, cowling off, seats and interior panels out where access requires it, wheels and brakes apart. A large part of the labor on any annual is opening the airplane up and closing it again, which is worth knowing when you decide whether to combine other work with it.
The scope, in broad strokes
The engine and its accessories: compression check on each cylinder, borescope where the shop is thorough, oil and filter with the filter cut open and inspected, spark plugs cleaned, gapped and rotated, magneto timing and condition, exhaust system, baffling, hoses by age, mounts, and the induction and fuel system.
The airframe: control surfaces, cables and their tension, hinges, bearings, the structure at attach points, corrosion inspection in the usual places, and skins and fasteners.
Landing gear and brakes: tires, wheel bearings, brake wear, struts and their servicing, and on a retractable a full gear swing and rigging check.
Systems: fuel tanks, lines and drains, the electrical system and battery, the pitot-static and vacuum or air-driven instruments, lighting, the ELT with its battery date, seats and belts, and the emergency exits.
Paperwork: airworthiness directive compliance research and sign-off, which on some types is a substantial part of the bill on its own, plus weight and balance currency, required placards and the certificates aboard.
Squawks versus airworthiness items
The list at the end of the inspection separates into two piles, and you should insist your mechanic separates them clearly.
Airworthiness items must be corrected before the aircraft flies again. These are not discretionary, and they are the source of the sticker shock that turns a routine annual into a large bill, usually when a cylinder, a corroded part or an AD compliance gap appears.
Discrepancies that do not affect airworthiness are a maintenance list you can plan and budget. Some are worth doing now because the airplane is already open, and that is a real saving. Others can wait. Knowing which is which is the conversation to have before the work starts, not when the invoice arrives.
Ask for an estimate of the inspection labor separately from any repairs, and ask to be called before repair work begins.
The owner-assisted annual
Where regulations and the shop allow it, an owner can perform certain preventive maintenance and can assist with the opening and closing of the airplane under the supervision of the mechanic signing the inspection. This has two benefits and both are large.
The first is cost, since a meaningful share of annual labor is access rather than expertise. The second is knowledge: an owner who has spent a week with their airplane apart knows things about it that no amount of flying teaches, and tends to catch developing problems early for the rest of the year.
Arrange it in advance. Not every shop is willing, the rules about what an owner may and may not do are specific, and the mechanic signing the inspection decides what is acceptable.
Making the next one cheaper
Fly the airplane regularly, because corrosion and dried seals cost more than wear does. Keep the logbooks orderly and the AD compliance list current, since research time is billable. Fix small items when they appear instead of presenting the shop with eleven months of accumulated squawks. Hangar it if you possibly can. And use a shop that knows the type, which pays for itself in hours not spent figuring out your airplane.
Budget the annual as a fixed, expected cost alongside insurance and the hangar rather than as an event, and plan the ownership numbers with the maintenance interval planner and the weight and balance calculator.
If you are still shopping, the pre-buy checklist is where to start, since the condition of the logbooks at purchase sets the price of every annual afterward.
Garage, Galley & Hangar writes a model-specific owner's reference manual for the aircraft in the catalog, covering the recurring inspections, known issues and type-specific items that show up on the annual. Browse the aircraft catalog.
