"Incidents of this type were not uncommon with around 20 involving major wing failures in Wellingtons noted over a 2 year period. The earliest known was when T2802 crashed. Vickers traced the problem to the design of the main spar boom joint and the materials used in the manufacture of the spar booms which had high levels of tensile strength. This could lead to fatigue cracking and structural failure. The solution was to use a modified spar boom joint using different material but this was not approved till July 1944."
Wimpy: A Detailed History of the Vickers Wellington in service, 1938-1953
By Steve Bond