Piper PA 28 N5948W accident near Lone Pine, California

Probable cause

The fatigue failure of a propeller blade due to a propeller strike by/of an unidentified object at an unknown time.

NTSB analysis

The private pilot reported that, 2 hours into the personal cross-country flight, he observed a "flash of something" depart the front of the airplane and that the airplane instantly began violently shuddering and vibrating. The pilot immediately landed the airplane in a clearing, and he observed that almost half of one of the propeller blades was missing.

A postaccident examination of the propeller assembly revealed that the propeller blade was fractured about 24 inches from the blade butt. Examination of the fracture surface revealed characteristics of fatigue failure that originated in a stress raiser located about 1.25 inches from the leading edge on the lower blade surface. A witness mark, in the form of a distinct score line, was present, indicating that the blade experienced a strike, which created a flaw of critical size at the fatigue origin site that ultimately propagated to failure. The investigation could not determine whether an object struck the blade or the blade struck an object or when the strike occurred.

Text from the NTSB. Open the NTSB docket for WPR14LA377 for the full record.