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Wednesday, April 16, 2014

Engine Overhaul Tools

Aircraft engine crankcases must be separated to allow removal of the crankshaft, camshaft and other internal engine parts. Many Lycoming engines require special tools to push the crankcase halves apart. Until very recently MMS used a quickly improvised set of tools to do this. The old tools protected the engine parts from damage and undue stress, but were inefficient and had become quite worn. New factory-made tools for this operation are very expensive; however, the engine overhaul manual has pictures of the tools and a clear description of how they are used.

Several years ago money to purchase a milling machine was donated and MMS Director of Maintenance Tim Obarow is a skilled machinist. An adequate amount of heavy steel plate and some other material were purchased and Tim went to work. Using that milling machine and a lathe, Tim fabricated the various parts of the new tooling for the engine shop.

After all the parts were made, MMS aircraft maintenance Supervisor Dale Coates ordered a sturdy case to house the new engine tooling along with copies of instructions for its use. All this cost about $3,200 less than the same commercially available tooling.

After all external parts are removed from the crankcase, the plates are installed on both sides. Here Joel puts the plate on the right side of the engine.

The plates push on the long bolts that pass through the crankcase to separate the crankcase halves. As Joel and Dale begin, the case halves are still held together by dowels that align them (as indicated by the arrow in this picture).

As large nuts on the outside of the plates are tightened the crankcase halves separate until the dowels are disengaged after about 3/8" of movement. The plates are removed and the case halves are easily lifted away from the crankshaft that is bolted to the engine stand.

So, how did the new tooling work? To quote Dale, "Great!"


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