Despite the issues with its structure in the Far East, the Mossie still had a pretty effective combat record.
The early structural failures were found to be a combination of poor mate-up of some structural elemants & poor gluing practices leading to failed glue joints. This was most apparent among Far East aircraft after prolonged outdoor storage. It was also apparent that swelling of the top skin could lead to the securing screws pulling through. Examination of ETO aircraft found a much lower prevalence of joint defects and no skin lifting. Further testing and investigation done in India identified 2 main issues, the wing spar scarf joints and the spar boom joints with the plywood skin and other ply elements, leading to the lifting of the surface plywood skin.
As a result, Mod 638 was adopted which added a spanwise plywood strip to seal the upper surface skin joint along the length of the front spar. Adoption of aluminium dope finish to Far East theatre aircraft was also adopted in 1945 to help.
This improved things greatly, although the combination of heat and water soakage in the tropics causing shrinkage and swelling, did still plague Mossie ops well in the mid 50’s.