Leyland Brothers : [2] The rear bulkhead repair was carried out by Japan Airlines engineers in Japan, not at the Boeing factory. Whilst Boeing did design and approve a repair scheme, the repair that was embodied by the Japan Airlines engineers was not in accordance with the approved design. The design called for a single doubler plate which straddled the horizontal joint, but what was embodied included two separate doubler plates, one either side of the horizontal joint.
just a minor correction to your post - but the repair may have been carried out by the JAL engineer's - but i think you will find that if you had researched a little more thoroughly you will have found out that the repair WAS in fact inspected by a Senior Boeing engineer who was based in Japan before this a/c was released for service becuase of the nature of the repair to a pressurised bulkhead.