SMITH EDWARD I LANCAIR IV-P — Hilton Head Island, SC

What happened

**This report was modified on 8/8/13. Please see the docket for this accident to view the original report.**

The pilot stated that while in cruise flight he observed the instrument panel begin to vibrate heavily and oil begin to cover the wind screen before hearing a loud "bang." The engine then lost power as oil continued to obscure the wind screen. The pilot had no forward visibility and could not maintain the airplane's altitude. He elected to make an emergency landing on a nearby beach and during the landing the airplane struck and killed a pedestrian. Examination of the airplane revealed that the propeller assembly separated from the crankshaft and was missing. The propeller assembly and propeller flange were not recovered. An examination by the NTSB Materials Laboratory of the crankshaft revealed that the aft face of the fracture contained crack arrest marks. The fracture of the crankshaft was caused by multiple-origin fatigue cracks that emanated at the aft relief radius for the propeller flange. The records for this engine and airplane do not show an entry of a propeller strike. However, multiple-origin fatigue cracks that extend nearly 50% around the circumference of the aft relief radius for the propeller flange suggest that the propeller had struck an object prior to fracture of the crankshaft. In the absence of material anomalies, the fatigue cracking appears likely to have been caused by external impact stress, such as a propeller strike.

An editorial "what led to it / how to avoid it" analysis for this accident is generated separately and will appear here.