The annual inspection for my Warrior is approaching.
As I’ve mentioned before, as a Canadian private aircraft owner, I have the final responsibility for determining that the annual inspection has been completed. In the U.S., on the other hand, it’s not the private owner but an Inspection Authority (IA) who makes that determination and signs a logbook entry returning the plane to service after the inspection. In both countries, of course, the pilot is ultimately responsible for airworthiness before each flight, no matter who has written and signed what in the logs.
In Canada, the Aircraft Maintenance Engineer (AME) performing the annual inspection will typically follow CAR 625, appendix B: part 1 lists a set of standard inspection tasks for any small airplane, such as testing cylinder compression or the torquing and safety wiring of propeller attachment bolts. However, most aircraft manufacturers also publish a customized inspection list for each aircraft, that goes into more detail and includes additional tasks (unfortunately, the manufacturers’ inspection lists are rarely, if ever, available free online).
I’m skipping the 100 hour/annual inspection here, since it isn’t all that different than the generic one in the CARs (aside from a bit more detail). What is more interesting is that the checklist for the PA-28-161 Piper Warrior II includes tasks for 50 hours (i.e. at each oil change), 500 hours (~4-5 years), and 1,000+ hours (~8-10+ years), all inspections not specifically covered in the CARs and not necessarily familiar to owners. I don’t agree with all of these — for example, I’m not automatically going to recondition a fixed-pitch propeller at 1,000 hours if it’s still in excellent shape — but overall, these look like intelligent recommendations, and I’m going to try to make space for them in my maintenance planning. At best, I might avoid a forced landing or worse; at a minimum, I’ll be able to pass on a better-maintained plane to the next owner, and will be able to hold my head up during the prepurchase inspection.
The 50 hour inspection
This one looks huge, but most of the tasks are simple ones, and a good number qualify as elementary work (I’ll post on that in the future). Some of these are things any pilot would do before every flight, such as checking the tire pressure, oleo extension, and alternator belt, and others are part of a normal oil change, like draining the sump or cleaning the plugs. Because my Warrior is blessed with a fully-opening cowl (rather than just a tiny oil door), I can also perform a good visual inspection of the engine, hoses, sparkplug leads, and engine mount before every flight. Still, there’s a lot here that is not part of my normal 50-hour oil change. If I’m changing the oil anyway (say, in the late fall), and already have the plane up on jacks to remove the nosewheel fairing, I think it might make sense to pay for 2 hours or so of an AME’s time to perform the other tasks in this list. It looks like a relatively easy way to maintain a safe plane, and a lot less expensive than the questionable fairy-dust-style safety expenditures many owners make, like backup vacuum pumps (for fixed-gear planes) and traffic alerting systems.
- Inspect [propeller] spinner and back plate for cracks.
- Inspect [propeller] blades for nicks and cracks.
- Remove and inspect engine cowling for damage.
- Drain oil sump.
- Clean suction oil strainer at oil change. Inspect strainer for foreign particles.
- Clean pressure oil strainer or change full flow (cartidge type) oil filter element. Inspect strainer or element for foreign particles.
- Inspect oil lines and fittings for leaks, security, chafing, dents, and cracks.
- Fill engine with oil per information on cowl or service manual.
- Inspect spark plug cable leads.
- Inspect rocker box covers for evidence of oil leaks. If found, replace gasket, torque cover screws 50 inch-pounds.
- Inspect condition of carburetor heat air door and box.
- Inspect all air inlet ducts and alternate heat duct.
- Remove, drain, and clean fuel filter bowl and screen. (Drain and clean at least every 90 days.)
- Inspect condition of flexible fuel lines.
- Inspect exhaust stacks, connections and gaskets. Replace gaskets as required.
- Inspect engine mounts for cracks and loose mountings.
- Inspect condition and tension of alternator drive belt.
- Inspect security of alternator mounting.
- Check condition and security of hydraulic line and fluid in brake reservoir; fill as required.
- Reinstall engine cowl.
- Check landing, navigation, cabin and instrument lights.
- Inspect battery, box and cables (Inspect at least every 30 days). Flush box as required and fill battery per instructions on box.
- Remove, drain, and clean fuel strainer bowl and screen. Drain and clean at least every 90 days.
- Lubricate [fuselage and empennage] per lubrication chart.
- Check emergency locator transmitter battery replacement date and transmitter for operation.
- Lubricate [wing] per lubrication chart.
- Inspect oleo struts for proper extension (N-3.25 in./M-4.50 in.). Check for proper fluid level as required.
- Check tire pressure. (N-30 psi, M-24 psi.)
- Lubricate [landing gear] per lubrication chart.
- Inspect all hydraulic lines and attaching parts for security, routing, chafing, deterioration, wear, and correct installation.
The 500 hour inspection
The 500 hour inspection includes only three tasks not already in the 100 hour/annual inspection:
- (400 hours) Remove rocker box cover and perform a valve inspection.
- Remove and flush oil radiator.
- Replace auxiliary vacuum pump.
- If installed, replace central air filter.
- Clean and lubricate stabilator trim drum screw.
I have my stab trim screw cleaned and lubed regularly because it becomes stiff in cold weather, but I can find no record of the oil cooler ever having been removed and flushed — any gunk caught in it can circulate back into the cylinders, wearing them down and forcing an early overhaul; this year, I plan to have this work done as cheap insurance for my engine. I don’t have an auxiliary vacuum pump in the plane, only the main engine-driven one.
The 1,000+ hour inspection
There are only a few 1,000+ hour tasks:
- Recondition propeller.
- Replace magneto.
- Overhaul or replace engine driven and electric fuel pumps.
- (2,000 hours) Complete overhaul of engine or replace with factory rebuilt.
- Replace engine driven vacuum pump.
- Clean and lubricate all exterior needle bearings.
OK, now it’s time to be realistic. I am not going to replace my engine at 2,000 hours if it’s still going strong. In fact, I think that doing so would actually be more dangerous — the only forced landing I’ve ever seen happened right after a new engine was installed, because the shop attached something incorrectly; two other local forced landings I’ve heard about had similar causes. As long as my compressions are good and there’s no metal in the oil filter, I’d rather stick with an engine that has all its bugs shaken out than a new, unproven one. The vacuum pump, on the other hand, is cheap to buy (a few hundred dollars) and easy to install (about 30 minutes of an AME’s time) — I’ve already had one fail on me, and preemptive replacement here might make sense. I’ll have to think about that one.
Just in case anyone has the mistaken idea that I — who, as a teenage boy, preferred reading books to fixing cars — actually know much about nuts-and-bolts (so to speak) of maintenance, I’ll finish with a simple question: What’s a needle bearing?