Grumman American Avn. Corp. AA 5B N28578 accident near Willow Park, Texas

Probable cause

The improper reinstallation of the propeller assembly, which resulted in the subsequent in-flight separation of the propeller.

NTSB analysis

The pilot reported that he heard a loud noise during cruise flight and that the airplane then started losing altitude. He subsequently conducted a forced landing, which resulted in substantial damage to the airplane. A postaccident examination revealed that the propeller assembly had separated from the engine propeller flange. Four of the six propeller bolts were intact, consistent with the bolts backing out before the propeller separated. The remaining two bolts were unable to transfer the loads from the propeller, and they subsequently failed. The pilot reported that the propeller was removed during the most recent annual inspection, which was completed about 1 year before the accident. The airplane had accumulated about 14 hours flight time since the inspection. Although the airplane maintenance logbook entry for the inspection did not indicate that the propeller was removed or reinstalled, it is likely that the propeller assembly was improperly reinstalled at some point, which resulted in its subsequent in-flight separation.

Text from the NTSB. Open the NTSB docket for CEN14LA118 for the full record.