Oh, and it may not be the crank that fails first; early P&W 9-cylinder engines occasionally induced prop blade failures. A Lockheed 10-A shed a prop blade near Waco, Texas in 12/38, and it shook the engine out of the mount. Remarkably the plane landed intact, albeit "well shaken".
The fix was in the pair of dynamic balance dampers installed in the crankshaft counterweights; one tuned to cylinder firing frequency (4.5x crankshaft speed) and the other to double that (9x).