Chris Stevens

Aviation. Tech.

Annual Maintenance - Part One

As I mentioned in this post last week, we started the required annual inspection on our Mooney today.  This post covers the first few days of a typical inspection like this.

Step 1: Get the airplane to the shop.

This should be easy, especially since our awesome mechanic is at our home airport.  When I get to the hanger, the battery is not just dead, but completely and very pitifully dead.   Even the cockpit lights struggle to wake up from a deep slumber.  This is one of the big reasons that I try to fly every 10-14 days.  Your car runs almost every day and the engine and electrical systems receive almost constant exercise.  Airplanes (and their pilots) should be so lucky!

Step 2: Take off a bunch of very hot panels.

After fetching a fresh battery from the shop, it’s time to actually get started.  I drive around the airport for about 10 minutes to get the engine warmed up and then head over to the shop.  We remove the engine cowling and start draining the oil.  Airplane engines are air cooled, so without the normal 150 mph airflow, those metal panels and screws were nice and toasty.

I typically hang around for a few hours after dropping off to look over the naked engine and prop and to help remove some of the 30+ inspection panels.  Removing panels on a Mooney can take from 1-3 hours depending on the stubbornness of the 10+ screws per panel that have had at least the past year to work themselves in tightly.  That’s me on my back on the floor for 1-3 hours, but it’s definitely therapeutic for a mechanical engineer that spends 10 or more hours a day in front of a computer.  The mechanic and I also share some choice words for the 1960s-era engineers down in Kerrville that left us so very little room to do anything inside the airframe.  Thanks alot, fellas.

Step 3: Get out of Tom’s Way.

That’s about the extent of my involvement in the process.  The key is really to get out of Tom’s way (our mechanic).  While I was collecting grease with my face under the belly of the airplane, he’s already well into his “zone” working around the engine compartment:

  • compression and structural checks on each cylinder (roughly indicative of their health and remaining lifespan)

  • inspect the spark plugs, plug wires, magnetos, battery (hey, we have a new one now – that’ll be $300 please)

  • inspect the prop, hub, prop governor, carburetor

  • inspect the air intact and exhaust systems

  • inspect the vacuum pump, standby vacuum system, firewall

  • about 100 other things all called out in the official Maintenance Manual for our specific Mooney make and model

What’s Next?

Tom will spend the next few days looking at engine, airframe, landing gear, instrumentation, flight controls, and the rest of the Maintenance Manual.  After that is a bunch of paperwork, engine and systems testing and sign-off, and a quick test flight by yours truly.  More on those items next time.