On Tuesday, EAA and the EAA Vintage Aircraft Association (VAA) each filed comments opposing a sweeping airworthiness directive (AD) proposed by the FAA affecting almost every high-wing vintage Piper aircraft. The AD would require rudders built of 1025 carbon steel to be replaced with new rudders made from 4130N low-alloy steel. The FAA estimates that nearly 31,000 aircraft would be affected by the proposed AD.
The proposed AD is rooted in an NTSB report documenting the failure of the rudder posts of two modified seaplanes in Alaska, a PA-12 Super Cruiser and PA-14 Family Cruiser, as well as five other cases over a 44-year period documented by the Airworthiness Concern Sheet process. The aircraft documented by the NTSB report had aftermarket 160-hp engines and rudder-mounted beacon lights, which likely altered the stress on the rudder posts.
EAA and VAA both took issue with the broad scope of the AD, as well as the required replacement action. The AD allows, depending on the model of aircraft, between two and five years for replacement. At current production rates it would take 75 years to fulfill this requirement.
EAA’s comments recommend that the AD be rescinded and that more data be collected from the community before any follow-on action. VAA undertook an extensive engineering study that analyzed the applicability of the AD to various models and proposed an alternative inspection and repair technique that does not require a new rudder.
EAA urged the FAA to ensure that any further airworthiness action on this issue is “targeted and practical.”
