N3508B - 1954 Aircraft Aircraft Registration

The failure of maintenance personnel to balance check the ruddervators after painting the airplane and unclear information contained in the compliance section of AD 94-20-04 resulting in the failure of maintenance personnel to balance check the out-of-balance ruddervators and subsequent in-flight flutter and structural damage. Findings in the investigation were 1) improper modification/repair to both propeller blades by unknown person(s) resulting in them being below specification for chord width, and one of the propeller blades being below specification for chord thickness, 2) wrong sized rivets near the trim tab of the right elevator were noted and the skin of both ruddervators was not trimmed correctly, 3) paint drips flowing towards the trailing edge of both ruddervators contrary to shop manual.