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…

Click…

…immediately followed by !^&%+()&.

Having not flown my own airplane for nearly 4 weeks, I tried my best to sneak in a 30-minute hop over lunch at the end of the week, knowing that a second consecutive weekend of poor weather was about to blow through. Skipping food didn’t feel like an option today, so a cheap sub went with me to the airport, consumed with one hand while the other hand untied ropes, uncovered cabin, pitot, and fuel vents, unlocked door, and de-plugged the cowl. Finished before doing the fuel sumps.

Grabbed the headset and kneeboard, crawled in, cleared prop, primed, hit the master, turned the key, and…click. Prop moved about an inch at the tip, and that’s it. I’m not going anywhere today.

I knew this battery was getting near the end of it’s useful life (18 months is typical for a firewall-mounted battery in this climate, and this one was installed 6/2009 before a Montana trip, thus it was on borrowed time). It had been cranking somewhat sluggishly the last couple of months. No surprise that after sitting for 2 days short of 4 weeks that it’d be weak. I could have charged it for a bit and tried again, but I was just out of time and needed to get back to the office.

Removed the old battery, stopped by a local shop on my way back to work to get a fresh one, and $195 later, back to work I went. Now my workbench looks like this:

New G-25 Charging Up

So what do I have here?

• A fresh G-25 filled and on the charger, adjusting electrolyte levels per the activation instructions that accompany it.
• A meter for testing
• Acid-proof paint
• Baking Soda and Water

New aircraft batteries are delivered dry-charged so that they store well, with the accompanying electrolyte delivered in a weak solution in 2 quart bottles.

The startup process is to fill the new battery with electrolyte and equalize the level between all 6 cells (I use a drinking straw and a thumb to make fine adjustments). Install the caps loosely, rock it a little and wait 30 minutes for any trapped air to work out and heat from any reactions to settle, then adjust level again if needed. Electrolyte level will appear low, just leave it that way for now.

Next step is to charge for about an hour at a few amps, making sure the temperature doesn’t rise. As the battery charges, the electrolyte level will rise subtly with the change in specific gravity of the solution.

After this, I’ll usually charge in 1 hour cycles over the course of a day, with a final electrolyte adjustment at the end. You can either check specific gravity, or use stability of the on-charge voltage (12.6+) as an indicator of completeness of the charge. Tighten the caps, and we’re ready to go.

Meanwhile, since the battery activation process takes a little time, this is a good time to clean up the box. Any metal battery box (typically aluminum) is liable to have some corroded spots if a drop or two of electrolyte finds its way down the sides or into the bottom. I use a solution of baking soda and water to wash out the box, followed by clean water. Make sure the water flows through the vent hose OK. The baking soda neutralizes any residual acids and leaves a clean surface free of corrosion salts. If there is any exposed metal, once cleaned, it can be touched up with some acid-proof paint to protect it.

With this done, the new battery can go in. Of course, if you choose to do this as an owner maintenance item (battery replacement and service is listed as preventive maintenance under part 43 appendix A (c)(24)), it does need to be performed under the airframe and battery maintenance instructions, and the work logged before the aircraft can return to service.

With this done, I can take trips over the coming summer with a little less concern of getting stuck. When summer 2012 arrives, I’ll probably need to do this again, of course.

Maybe I can get out this week and fly. 4 weeks of an airplane sitting around is just sad…