Annual Inspections


This article originally appeared in Light Plane Maintenance, Apr. 2005.

Attitudes about annual inspections vary widely. Some like to get right in there and do the owner-assist thing. (We hope most LPM readers fall into this category.) Others either won’t or can’t participate in their annual, and instead hand over the keys and maybe a squawk list.Still others — the ones mechanics both love and hate the most — simply drop the airplane off and expect a call when the annual is done. These types earn the mechanic’s love and loathing because there’s so much latitude to make money, while at the same time the annual inspection becomes a sort of bizarre, detective game, with the mechanic trying to figure out what’s wrong with the airplane without any helpful hints from the owner. Unfortunately, the mechanic is not the beneficiary of all the diagnostic finery befitting your typical Miami CSI crime lab, so many things can be overlooked.But whether you get a real kick out of greasing your landing gear or you would rather just sign the check at the end, there’s plenty you can do to cut down your annual bill, sometimes by a rather dramatic amount.And not all of it requires getting dirty. The place to start with all of this is before your annual inspection is due. Depending on your own nature and schedule, and the general condition of your aircraft, six weeks to two months before the annual is scheduled is a good time to begin. But once you decide when to begin, the question becomes where to begin.

What’s Wrong?


The best place to start your pre-annual activities is to simply draw from your experience with your aircraft. Nobody knows it better than you do, right?The first step is to sit down and develop your squawk list. Take your time and consider it carefully. List every malfunction, defect, quirk or whatever has come up during the last year, including stuff that broke and was fixed. List everything, no matter how minor it seems to have been.A partial list for something like a Piper Arrow might include things like these:

  • Post light over airspeed inoperative;
  • No.1 Comm scratchy;
  • VOR needle occasionally jerky;
  • Windshield leaks over right instrument panel; and
  • Pilot seat sometimes hard to adjust fore and aft.

Once you have your list, go over it again. This time put down as much information about each item as you can. For example, something simple like the dead post light perhaps needs no more comment than noting when you first noticed that it quit.Something that may require a little more digging deserves more detail, like the jerky VOR needle. Is it jerky only under some conditions consistently (like flying in precipitation), or only when something else is turned on or off? Or for no apparent reason? Take this list and set it aside.Then, go out and fly your airplane. Make another, separate list during the course of the flight. Consider it a test flight — you want to check the operation of everything. Even things you don’t normally use should be exercised. Again, note every deficiency, no matter how small.During your run-up, do some of the power-checking procedures. This time, for any defects noted, supply all the extra information you can that’s pertinent. Having done that, take your second list and match it up with the first one. Combine the two into one. For previously repaired items, have any of them failed again? If so, that may be something that merits further investigation during your annual, such as an electrical problem of lights blowing.

Dig In

Armed with your master squawk list, decide which are items within your ability — and worth your while — to fix. Then schedule a Saturday afternoon (or two or more if needed) and go fix them.For example, that inoperative post light is a pretty easy self-repair item, and certainly cheaper for you to fix than your mechanic. If it’s just the bulb, five minutes of your time and a low-cost bulb from Aircraft Spruce and Specialty fixes the problem.Perhaps the battery is several years old. Why pay list price for a new one from your shop, plus installation? The rules permit you to replace it yourself.Obviously, there are things that are simply going to be beyond your knowledge, experience or ability to fix — leave those to your mechanic. Tackle those you can deal with and leave the rest for the pros to handle.Now, while you’re out at your airplane — provided you’ve decided to actually exercise some hands-on control of your financial destiny — you can really start doing things that will save you some bucks during your upcoming annual. When you’ve taken care of everything you can on your squawk list, it’s time to go looking for trouble — in effect, conduct your own pre-annual annual inspection.As with anything else, your pre-annual inspection should be methodical. A good place to start is with the manufacturer’s annual-inspection checklist from your aircraft’s maintenance manual. If you don’t have the manual, ask your mechanic for a copy of the checklist from his.Failing that, make up your own checklist. (Get your mechanic’s guidance in making up your list, if possible.) But, no matter what, use a checklist. You cannot count on your memory, no matter how well you think you know your plane.

On the List


If you use the manufacturer’s checklist, there are going to be items on there that you shouldn’t be doing … some because they’re beyond the average Joe’s ability or equipment, and others because they are going to be done during an annual inspection anyway. With a little common sense, you can easily winnow down the checklist to suit your needs and abilities.Check with your IA as to what routine things he does as part of the annual, such as changing the oil. You don’t want to do preventative maintenance in annual preparation of something the IA will be doing anyway. Any airframe greasing is a good area to understand what he and you do not want to be duplicating as pre- and annual maintenance procedures.You don’t want to try yanking off your mags to inspect the impulse couplings and check the E gap; not only is it probably beyond the knowledge of most owners, but depending on mag model, your IA may be required by law to go back and redo it.However, some items you should most certainly check out during your pre-annual inspection would be:

  • Battery and Battery-Box Condition: Is your battery dead, or just in need of some fluid and a charge? Either way, deal with it yourself. Order your battery discount from one of the many suppliers listed in Trade-A-Plane if you need a new one. Wash out your battery box and clear the drain lines.Figure that if you order your new battery yourself at even a reasonable discount, activate it with a home battery charger and install it in your airplane, you’ve likely just saved yourself about $100 off your annual.
  • Wing Undersides: Look for fuel stains. This is best done at least a month before the annual. If you see any fuel stains, clean them off. Then, when the airplane gets into the hangar for the annual, if new stains are apparent, you’ve got legitimate leaks. If not, you’ve saved the price of having your mechanic chase a nonexistent leak — and maybe the cost of a fuel bladder and installation.
  • Tires: Replace any questionable tires yourself. It’s easy, and legal, so there’s no excuse not to — unless you like the idea of paying someone else to do it. If you are not sure of the procedure, get some advice. Split rims are not something everyone has come across, and a little advice will keep you from damaging a stuck rim.
  • Brakes: Check the pad and disk thickness as well as the condition of the rotor. Replace anything out of specification.
  • Engine Compartment: Look for leaks of any sort. You may not be able to correct many or even any, but you should at least take note of them. If you’re planning on flying some more before your bird gets into annual, wash the engine. That way, any oil that is found during the inspection is fresh, making leak sources that much easier to locate, and making the fix-or-forget decision that much easier, too.Also, take a mallet and give your muffler a whack. If you hear things rattling around inside, order up a replacement from Wal-Colmonoy and save big dollars over the factory part.
  • Spark Plugs: Yank, clean, inspect and gap or replace any plugs as needed. Order them yourself at discount. Voila: Your airplane has perfectly sound plugs when it rolls into the shop for the annual, saving you from paying for the same job and perhaps list-priced, new plugs. Note: if you find lots of deposits or oil, make sure your mechanic is aware rather than trying to hide any problems for fear of the expense — it’s your neck on the line.
  • Air Filters: Order your own and install new ones. (You do this regularly anyway, right?)
  • ELT Battery: Is it nearing its expiration date? Order up a replacement (again through a Trade-A-Plane discounter) and install it yourself. Depending on your mechanic, this item alone could amount to major savings.
  • External Lights: Turn them on, check them out. Replace any burned-out ones you find.



Having gone through all the above items, you may easily have clipped a couple hundred dollars off your pending annual bill. This is the power of doing your own work and ordering your own parts. But there’s one more job that can really cut down on the number of hours of labor your bird is going to require during the annual, and that’s getting out stuck screws.Whether you participate heavily in your annual or leave most of it up to your mechanic, remedying stuck screws before the inspection is going to significantly cut down the time required by your mechanic for the most basic of inspection jobs, that of removing access panels. It will definitely put you on your mechanic’s Christmas card list.For this job, budget at least a morning, perhaps a whole day if you’ve got lots of rusty screws. Arm yourself with a screw gun, drill, screw extractor, quality screwdrivers and a bag of fresh cad-plate screws.Go around the airplane and remove every access panel screw one at a time. Throw away the rusted ones, and drill out and replace the really stuck ones. Take a few seconds to examine the threads on each screw and toss any that are damaged. Don’t leave access plates off unless that’s what your inspector wants — normally they leave one screw loosely attached for easy orientation and keeping track of access plates.If you’re really thorough, you might take this opportunity to dab each screw with a touch of Permatex anti-seize. Just a dab on the few end threads will do. Be stingy with this stuff because it sticks to everything, including your fingers, and then gets all over everything else. One treatment will make future screw removals much easier for years to come.

To Clean or Not

Appearances can mean a lot, and when it comes to your airplane and its annual inspection, how it looks when it rolls through the doors can mean the difference between getting a good annual for a fair price, getting a poor annual but saving money, or getting an annual conducted to a degree of thoroughness beyond your wildest dreams — and a bill sized to match.There are two schools of thought regarding cleaning your airplane before its annual inspection. The first school says that your airplane should be presented in spotless condition — perhaps to impress your inspector with the meticulous attention that you lavish on your bird.Mechanics, being only human, may tend to sum up your airplane based on their first impression. If the belly is oil covered, bits of bird nests are left in the engine compartment and the cowling has exhaust stains, the mechanic is likely to say to himself, “This airplane’s in sorry shape.” As a result, your annual is going to be conducted with a microscope and a fine-tooth comb. And you’ll be looking at a breathtaking bill at the end.So, says the first school, get your airplane squeaky clean before the annual. Your mechanic will be impressed and your annual will go much quicker, consequently your bill will be reduced.The second school says that the filth that builds up on your airplane can be revealing. The amount of oil on the belly gives an indirect picture of cylinder health (more ring blowby shows up as more belly oil). Oozing hydraulic fluid on the struts may indicate oleo seals going bad, and so on.Cleaning your airplane spotless will wipe out these valuable clues, perhaps causing your mechanic to miss certain defects. Thus, although your annual bill is reduced, your airplane comes out of the annual with some of the same defects it went in with, defeating the purpose of the inspection. As is usually the case, the best path is a combination of the two schools.Depending on your own utilization and habits, it might not be such a bad idea to give the airplane an extreme cleaning a month or two before your annual. Wash the engine, wipe the struts; get the bird up to that spic-and-span level. Then use it normally until the annual.Any leaks, stains and dirt build-ups are true indicators of the airplane’s health, just like the fuel-stain exercise mentioned earlier. Doing it this way, your mechanic won’t be disgusted and give you the micro-scope treatment, but he won’t be deprived of vital clues either.

The List

At the end of all this, take your master squawk list and go over it one more time. Cross off the items that have been taken care of and make a new list of any that are outstanding. If you’ve got intermittent conditions or conditional squawks, include as much additional information as you can.For example, remember the wandering VOR needle on the Arrow above? If the needle only jerks around when maneuvering, that’s a significant clue to what’s wrong. Obviously, there are going to be items that you just don’t have the time or ability to troubleshoot, but do as many as possible.Once your master squawk list is complete, turn it over to your mechanic just before you bring the plane in for the annual. Ideally, the two of you should be able to sit down and discuss your list, face to face. (By all means, don’t just leave the list at the shop’s counter figuring it will be sent to the proper person or destination — it probably will not be seen by the inspector unless he knows about it and has talked it over with you.)The more time he spends talking, the less time he’ll have to spend trying to figure out your squawks. Don’t feel you are taking money out of his pocket by doing these things.Most mechanics consider the “dirty work” of stuck screw removal as a royal pain. He will be appreciative of your efforts. Just be sure you don’t make matters worse by leaving a bunch of broken screws behind for him to fix. This active preparation is probably the best way for you both to save money, a win-win.This article describes some ways for an owner to get involved in an annual. If you have other ideas or suggestions, drop us a line.

More aircraft repair and prevention articles are available in AVweb’s Maintenance Index. And for monthly articles about aircraft maintenance, subscribe to AVweb’s sister publication, Light Plane Maintenance.