Textron published SEL-57-06 and SEL-57-07 on June 26, 2019, to address the possible failure of the carry through spar that’s mounted in the overhead area of the cabin on cantilever wing Cessna 210 and 177 series aircraft. This is an important issue that should be addressed by everyone as soon as possible.
This is NOT the same issue as is covered by AD 2012-10-04 for a one time inspection of the wing spar inboard lower cap. This new service letter addresses corrosion damage and potential cracks and failure of the wing spar carry through, which is the very large and heavy beam in the top of the cabin that the wings attach to.
For US registered aircraft operating under CFR 14 Part 91, manufacturer service bulletins and service letters are not mandatory compliance items, regardless of any verbiage included in the bulletin stating otherwise. However, most bulletins are published for a reason and should not be summarily dismissed without serious consideration. These two bulletins address a very important issue and some action by every owner of these planes is warranted.
As a minimum, all of these airplanes should have a thorough visual inspection of the lower surface of the carry through spar as described in the bulletin. Access will be the primary difficulty due to the headliner, possible foam padding glued to the spar, air conditioning or oxygen bottles. ANY corrosion pitting found on this surface is cause for concern and action.
This visual inspection should be repeated at every annual inspection. Most shops knowledgeable on these airplanes have been inspecting these spars for years, not because of any cracks found but because of known corrosion problems.
The worst corrosion cause is the bonding of the foam pad along the lower surface of the spar for the headliner. The pad and the glue easily trap moisture which promotes the corrosion problems.
If you choose to not complete the full eddy current inspection of the bulletin, at least perform a detailed and thorough visual inspection of the spar carry through. It’s an ounce of prevention that returns tons of cure.
Copyright © Paul New 2019. All rights reserved.