Thursday, June 17, 2010






Disassembly And Cleaning
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The overhaul starts with removing the engine from the airplane. This is exciting but you'll do yourself a favor by taking time to document the installation before removal. Pay particular attention to the routing of control cables, wires, and hoses, and all of the clamps that hold those items to the engine compartment.
Before you pull the engine, drain the oil out the engine while it is still on the airplane. Since most flat aircraft engines have a wet sump, you want to minimize the amount of oil that's going to come out all over your hanger floor when you start pulling the engine itself apart. It is much better to dump only the residual quart vs. the full 7 to 10 quarts that your engine normally contains.

To get the engine off you'll usually have to remove the cowling, propeller, all of the controls and hoses, and the exhaust manifold. This is where you find out where all the dirt and grit you taxi over goes to. Further you get very familiar with any oil leaks your engine has because the oil ends up all over you.

Again you'll save yourself a lot of trouble and head-scratching later by taking the time to bag and tag all the parts as you're removing them, and to photo-document clamps, hoses, fittings, and the orientation of all of the above.

The first challenge after removal is to put the engine up onto the stand, which involves bolting the prop flange to the stand (easy) and then wrestling the engine into an upright position without dropping it during the process (tricky). Two or more people and potentially a block and tackle hoist separate from the engine crane are recommended.

Then the cylinders and pistons and finally undoing all the case bolts and splitting the case. Don't forget to remove the idler gear pin which ties the case together (doh!). As you pull the case apart lots of oil and some miscellaneous parts will fall out, so catch the ones you care about like the gears. Hopefully you won't need to use too much "persuasion" with the soft mallet for gooey drive pads and parts.

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