Grounded!


Well, at least temporarily. It happens every year as the plane goes in for its annual checkup. As a result of taking my A36 to the American Bonanza Society Service Clinic in Palm Beach last month, I brought back a list of squawks for my A&P to look over while performing this year’s annual inspection.

For you non-pilots, Part 91 of the Federal Aviation Regulations requires a yearly inspection and sign-off by an authorized FAA licensed mechanic to deem an aircraft airworthy. This involves pulling all inspection plates and performing certain systems tests on the airframe, landing gear (if retractable) and power plant. Bushings are lubricated and all filters and engine oil are replaced as well.

Potentially, one of the most expensive repairs can result from a required compression check of each cylinder. This test indicates whether the cylinder is healthy and capable putting out full power. Sequentially, using an air compressor, the mechanic pumps 80 pounds of pressure into the top spark plug hole of each cylinder, and then measures any leakage with a calibrated master orifice. Any pressure leakage will be past either the piston rings or around the cylinder head valves. Excessive leakage (less than 38 pounds retained) requires removal and rebuild (or replacement) of the offending cylinder. Pulling one or more cylinders for rework or replacement is expensive and time-consuming, but flying in weather, over water or above the mountains is a bad time to find out you have a sick bird on your hands.

The good news is that all 6 of my TCM cylinders just passed their compression checks without any issues. Whew! A boroscope of each cylinder shows no signs of heat signature or excessive carbon buildup, and the exhaust valves show even wear, with no hot spots.

The two cylinders that I replaced last year due to low compressions held 78/80 psi this year. These were overhauled by Don George Aircraft Engines in Orlando and it seems they did a good job. I am convinced that by bumping up the fuel flow to approximately 30 gallons per hour on takeoff at sea level has also helped with cylinder life. The extra fuel on departure helps keep cylinder temps cooler, at high power and low airspeeds, thus less thermal heat damage to the alloys in the cylinder.

It’s looking like this year’s annual is shaping up to be the least costly in a long time. I make a point of fixing things as they wear or break during the year to minimize the squawk list at annual. We are in the process of putting the aircraft back together and are waiting for the delivery of just a few parts.

We are replacing the Main Landing Gear uplock springs due to a bit of corrosion, and the Nose Gear Door rod ends due to wear. Aircraft Spruce and Performance Aero are good places for replacement parts, and are a cheaper alternative to Beechcraft (RAPID) pricing. Additionally we are making some minor airframe rigging adjustments and adjusting the right main landing gear.

I have plenty to do out at the horse farm while the plane is down for maintainance, but it is frustrating having your plane in the shop for 10 days during the best time of the year to fly. Here in Florida the weather is beautiful, the azaleas are in full bloom and there are lots of places to go. And trips to customers now require driving long distances. This year, due to scheduling, we missed flying to Amelia Island for the Concours de’ Elegance at the Ritz Carlton. But eventually, by using the 13 month annual method, each year’s annual will be pushed out one month towards summer over the next few years.

 

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