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The Propagation of a Broken Crankshaft

The fatigue crack had been with us from the start, biding its time, nibbling at the heart of the engine.

The author with Robert Parke in "Melmoth," circa 1974. [Photo courtesy of Peter Garrison]
Gemini Sparkle

Key Takeaways:

  • The author experienced subtle, then escalating, engine problems in his homemade aircraft, Melmoth, during a cross-country flight, requiring two unexpected landings.
  • An initial repair for a stripped ignition magnet gear failed to resolve the issue; a subsequent full engine teardown revealed a broken crankshaft.
  • The crankshaft had fractured due to a fatigue crack originating from a material inclusion, causing the deceptive symptoms and allowing the engine to continue operating partially, even after the author unknowingly took off with the severe damage.
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It was the spring of 1979. Robert Parke, then FLYING’s editor, was in Los Angeles. His next stop was Reno, and of course I offered to fly him there. My homemade airplane, Melmoth, had by then successfully crossed both the Atlantic and the Pacific, and so the intrepid Parke, who had piloted B-17s over Europe in World War II, was willing to chance it.

It was a clear, calm day. We climbed out of Whiteman Airport (KWHP) and through the Newhall Pass, turning northwestward toward Gorman. I leveled out at 10,500 feet. Mount Pinos crept past our left wing and the vast flatness of the San Joaquin Valley lay fading into the haze before us.

Peter Garrison

Peter Garrison taught himself to use a slide rule and tin snips, built an airplane in his backyard, and flew it to Japan. He began contributing to FLYING in 1968, and he continues to share his columns, ""Technicalities"" and ""Aftermath,"" with FLYING readers.

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