Incident Overview
The pilot of a single-engine aircraft reported that during the takeoff ground roll, after applying full power and accelerating through 30 knots, a loud explosion was heard. The pilot immediately aborted the takeoff and taxied back to the ramp.
Inspection Findings
Subsequent inspection of the aircraft revealed that a clamp which retains one of the feathering counter weights on the left propeller had separated. The counter weight then penetrated through the nose structure of the aircraft.
Analysis of Failed Component
The failed clamp assembly was sent to the factory under the supervision of the FAA Chicago Aircraft Certification Office for detailed analysis. Examination of the clamp showed that the fracture was of a fatigue type, with the origin located on the lower inside corner of the steel strap. Chemical and hardness tests of the assembly indicated that the part met specifications. However, the reason for the fracture initiation was undetermined.
Operational Outcome
No further details were provided regarding aircraft damage, occupant status, or subsequent actions beyond the aborted takeoff and the findings described.