Accident Overview
On February 10, 2015, at 1330 Pacific standard time, a Vans RV-7 amateur-built experimental airplane, registration N513BW, was substantially damaged following a total loss of engine power and a subsequent forced landing near Belfair, Washington. The airplane was owned and operated by the airline transport pilot, who was the sole occupant and received a minor injury. Visual meteorological conditions prevailed for the local personal flight conducted under 14 CFR Part 91. No flight plan was filed. The flight departed Tacoma Narrows Airport (TIW), Gig Harbor, Washington, about 1315, with the destination being Bremerton National Airport (PWT), Bremerton, Washington.
Pilot Actions
The pilot reported that while en route back to PWT at about 1,500 feet mean sea level, the engine abruptly quit running. He pushed the nose down to maintain airspeed, switched fuel tanks, turned on the boost pump, and pressed the starter button repeatedly, but the engine would not turn over. During the descent, he continued attempts to restart the engine unsuccessfully and elected to land on a gravelly split. During the landing roll, the airplane's small tires sunk into the pea-sized gravel, causing the airplane to nose over onto its back and substantially damaging the rudder.
Engine Examination
On March 2, 2015, under the supervision of the NTSB IIC and FAA representatives, the engine was examined at Avian Aeronautics in Bremerton, Washington. The examination revealed that the crankshaft was fractured adjacent to the aft radius of the #3 cylinder rod journal. The crankshaft was subsequently sent to the NTSB Materials Laboratory for further analysis.
Metallurgical Analysis
An examination by a Senior NTSB Metallurgist showed that both fracture faces had post-fracture rotational damage. Beach marks and other fracture face markings were visible and consistent with fatigue cracking through about two-thirds of the journal cross section. The fracture markings indicated fatigue initiation occurred in the vicinity of the aft radius of the journal. Closer optical examinations found a large ratchet mark, indicating fatigue initiation at two locations near or at the surface of the aft journal radius, though exact origins could not be determined. A radial metallographic section uncovered a cracked bright white layer on the journal surface, consistent with electroplated chromium. The plated layer blended smoothly into the journal surface and measured up to 0.0037 inches thick. An engineering representative from Lycoming Engines stated that chromium plating on bearing journals was not an approved repair. The radius appeared non-uniform with a flattened region and circumferential cracks ranging from less than 0.002 inch to more than 0.020 inch. The rod cap and bearing were heavily damaged on the aft side, consistent with continued rotation after crankshaft fracture. The bearing shell was stamped "SL-13521-M06" and date marked "9-99", indicating a 0.006 inch oversized bearing manufactured in 1999, consistent with markings on the propeller flange indicating undersized bearings.
Maintenance History
All engine logbooks were not available during the investigation. A partial review of maintenance records revealed: May 20, 1980: major overhaul with a new crankshaft installed (serial number not recorded); tach times 5.99 and 4.99 hours, with annotation "Engine logs lost." September 1, 1999: major overhaul at tach time 90.0 hours; crankshaft 74251 installed. January 7, 2000: major overhaul at tach time 95.0 hours since most recent overhaul; non-ferrous metal parts inspected by Zygloe Method. November 1, 2000: major overhaul (tach time not noted); ferrous parts inspected by Magnaflux Method and non-ferrous by Zygloe Method.