Annual Inspection 2011

Yes, there is life in this blog, even after a bit of an absence. I do have a good excuse, you see.

For the past 6 weeks or so, I’ve been prepping my little sky scooter for the summer.  This year, since I need to spend several weeks in AK during the course of the summer, I’d really like to take the airplane up there so I can make good use of it. If I do this, it won’t spend 5 months baking in the desert sun, or banging around in monsoon storms either. I’ll be able to fly in Paradise while I’m there for the warmer season.

Since the first trip is coming up in late April, I needed to make sure it was all ready to go in terms of maintenance. It’s annual inspection (plus the transponder and pitot static certification) is normally in May, but I moved it ahead to the first of April so it would be clean and ready to go later in April. This meant taking it offline a few weeks ahead of time to make sure that all the prep work was done, any potential surprises that I could control could be accounted for, and I would have time to work any issues that arose.

The process started a few weeks ago with a compression test. The most likely obvious potential maintenance problem with my little C-series Continental is a wheezy exhaust valve resulting from the lead salts accumulated in valve guides from avgas combustion. In 800 hours, I’ve had the two front cylinders redone, with the #3 needing rework last year. So, to make sure I should be OK, I borrowed a compression rig from a friend, flew it a bit, and tested it. Fortunately, all 4 checked out good (76/72/72/75). Checked timing, and looked all over the engine and cabling for anything loose, worn, missing, leaking, or cracked. Having a new crankshaft seal put in last year,. along with new rocker gaskets, and reswaged pushrod tubes (often an oil leak problem in a C-series), the engine bay was pretty clean, and I had a bit more confidence heading into the inspection.

At this point, I call my IA to schedule a day for him to perform the full inspection. Typically, I’ll do this as an owner-assist operation, with him doing all the inspecting, and me doing all the greasework, opening, and closing. I like this process, not because it saves a little money (it does save a little), but it allows me to personally know the state of the airplane myself. Besides, I like taking a half day away from the cubicle-cave to flip wrenches. It’s like a small vacation for me.

Next on the agenda was the altimeter. The last couple of pitot-static tests, I was told it was on the margins at high altitude, so I figured it ought to be recalibrated before testing this year (I’ve always kept this airplane IFR certified). So, out it came to go to the local instrument shop for rework.

This is where things got a little more interesting. This altimeter was an old MacLeod/Aerosonic, installed back in the 1970s after the original equipment United Instruments unit got pulled because of an AD. The shop had to do some checking to make sure that their “ancient” documentation was current and correct, and after a few days, I got a call to say that that the unit was reworked and ready for return to service. For 57% of the price of a new unit…

Meanwhile, I spent a Saturday cleaning and repacking wheel bearings, replacing the main gear tires and tubes, checking out the ELT, and lubricating airframe points that don’t require opening up. Now we’re ready for the IA with a weekend to spare.

At this point, a surprise personal issue comes up that requires travel on the spare weekend, and impinges on the inspection date. If I slip it, I’m cutting my discrepancy working window short. A round of phone calls confirms that we can move the inspection ahead before the travel weekend. It follows the morning after a night X/C with a student, but I can deal with it.

Two hours of sheetmetal screws later, then we can inspect

Inspection day comes, and the long round of sheetmetal screw removal begins (after 10 years of this, I’m getting fast!). Official compression test OK. Engine/accessories OK. Left wing OK. Tail OK (including the infamous Cessna 150 nutplates in the stabilizer spar). Right wing OK. Interior OK. Break for lunch, and then I’m cleared to start closing up, lubricating all the internal pivots, pulleys, and the flap jackscrew while the airplane is still opened up.

Now we know that we’re officially airworthy for another year, it’s a matter of paperwork, and finishing off the transponder and pitot-static certification. Little should stand in my way, right? Not so fast…

My avionics tech is out of town for a few days, but should be back about a week before I need to fly. The altimeter is freshly redone, and I’ve had no ATC squawks against the transponder or the altitude encoding, soI don’t expect an issue.

I meet him on a rainy, cold Saturday for the testing. Transponder checks fine, but turns out my freshly overhauled altimeter is off on the low end of the scale instead of the high end. He tests through 6000 feet, and there’s simply no point in going farther. The unit needs to come back out to go back to the shop, and I’ll have to arrange for another appointment for the testing. For the first time in years, the airplane will only be VFR-legal, and I don’t think there’s time to work the issue out before I need to go. I could have just left the altimeter alone, and been in the same position.

So, for all that trouble, I’m stuck on this corner issue…

In all honesty, this little airplane doesn’t have much business being in any kind of moisture aloft during this time of the year when freezing levels can still be very low. In all probability, I’ll make the entire trip VFR anyway, and it really won’t matter. Still, I want the ability to be able to ask for a clearance should something unexpected surprise me, and I just won’t be able to do that.

Can I resolve this in the next few days? Is it even worth it, really? We’ll just have to see. Stay tuned…