FAA Issues Proposed AD on Aeronca Sedan Wing Spars
April 7, 2011 — The FAA has issued a proposed Airworthiness Directive (2010-CE-033-AD) to alert Aeronca (Rodgers) 15AC and 15ACS Sedan owners of potential corrosion of the aircraft’s wing spar caps. EAA has requested the comment deadline be extended 90 days, from May 19, 2011, to August 19, 2011, to allow adequate time for owners and operators to respond.
According to the aircraft’s type certificate holder, Burl’s Aircraft of Chugiak, Alaska, 34 wings on Sedans have been found with cracks and “intergranular corrosion” (exfoliation) in the spar caps, requiring their replacement. There are 255 15AC Sedans on the FAA register. Instructions to gain access, along with procedures to inspect the interior of the aircraft’s wings, will be included in mandatory service bulletin 15AC06-08-10. (You can access the service bulletin and sketch to accompany the proposed Airworthiness Directive here.)
The AD proposes an initial inspection per the service bulletin of the spar’s outer portion (areas visible from the aileron bay) within 10 operating hours of the AD’s issuance, along with the installation of a series of inspection holes in the wings to be done within 25 operating hours - or six months - of the AD issue date. A follow-up inspection of the entire spar would be done concurrent with the installation of the inspection holes, looking for cracks and/or moderate-to-severe corrosion (both surface and exfoliation), with particular attention paid to the extruded aluminum spar caps. After inspection, if little or no corrosion is found, the spars and spar caps are to be treated with liquid corrosion inhibitor. The inspection would then become part of each subsequent annual inspection of the Sedan.