Accident Details
On June 8, 2008, at approximately 1315 eastern daylight time, a Piper PA-44-180, registration N159WM, experienced a propeller blade tip separation while in cruise flight about 8 to 10 miles southeast of W K Kellogg Airport (BTL) in Battle Creek, Michigan. The separated blade tip impacted the airplane's nose, creating a large depression. The flight, a 14 CFR Part 91 instructional flight, had departed from BTL around 1230 and was returning at the time of the incident. Visual meteorological conditions prevailed, and the flight was not operating on a flight plan. The certified flight instructor and the commercial pilot receiving dual instruction were uninjured. The airplane landed without further incident at BTL.
Aircraft Information
N159WM was a 2002-model Piper PA-44-180, a twin-engine, four-seat airplane with serial number 4496159. The aircraft was powered by two Lycoming engines, each driving a Hartzell propeller. The propeller blade involved in the separation was a model FJC7666A-2R installed in a model HC-C2YR-2CLEUF hub assembly. The serial number of the blade with the tip separation was J73543. The airplane had accumulated a total time of 1,997 hours.
Examination Findings
The outboard section of the separated propeller blade was sent to the National Transportation Safety Board's Materials Laboratory for examination. A Senior Materials Engineer produced Materials Laboratory Factual Report number 08-097. The report noted that fatigue features emanated from a fatigue origin area located at the leading edge near the flat side of the blade. Angled file marks consistent with a leading edge repair were observed between the leading edge and the flat side of the blade. The report referenced repair data from the propeller manufacturer's website, which indicated that a 10x magnifying glass should be used to examine repairs to ensure damage, file marks, and any coarse surface finish are removed prior to returning the propeller to service.