Now for more opinions, interpretaions and info. George is right that we shouldn't willie nilly slap extra stuff onto our A/C. Sometimes things are built as they are so they will flex instead of break. I also think that we with the benefit of our position in time,can look at the changes made by the manufacturers over the years and see where they have beefed up some areas due to demonstrated need. Such as our 170's. The 1956 172 and 182 use "skin" 0511295 and 0511295-1 as an overlaid finger doubler to beef up the LG bulkhead area. The later 180's and 185's extend the gear saddle belly skin aft an additional 5 inches in the exact area where the 170's tend to wrinkle, leaving the fuseladge middle area the same as ours. In addition they tied the stringers to the bulkhead flange where ours stop 1/16 to 1/8 inch away from the flange per the 100 seris SRM. All this suggests to me they saw a need and addressed it.
Getting to the info part, I talked with Duane Ayre at Cessna concerning this and he agreed this was a weak area. That the 172's and 182's had that doubler in that area to spread the stress out to a wider area since the "fingers" of the doubler follow the stringers in the belly.
Secondly I talked this over with my PMI and was told to write up what I had in mind as a repair/strengthening based on what Cessna had done with later models and he would Field Approve it. Duane Ayre had also suggested I sketch out what I had in mind and he would run it past engineering for their input. So now I need to settle on what I want to do and not choke in writing it up. I will keep you all posted.
For the interrpretaion part. The SRM section 19-53 is titled 'Replacement of Portions of Skin Panels' refering to a skin panel as the skin between structural members and lists those as stiffning members, stringers, bulkheads and the like. Meaning as I read it basicly a scab patch as long as it runs to a structural part in all four directions. I would personally find it difficult to just scab a patch on
but I am sure it has been done. Brian
