Latest Recommendations to the FAA:

The National Transportation Safety Board recommends that the Federal Aviation Administration:

Establish appropriate criteria (taking into account the size of the repair and other relevant considerations) to identify those pressure vessel repairs to transport-category airplanes that could be hiding damage that, if not addressed, may lead to multiple-site fatigue damage and fatigue cracking and could result in structural failure of the airplane. (A-03-07)

Issue an airworthiness directive requiring all operators of transport-category airplanes with pressure vessel repairs identified as a result of applying the criteria discussed in Safety Recommendation A-03-07 (other than those covered by Service Bulletin 747-53A2489) to:

1. immediately remove the repair doubler to determine whether hidden damage that could lead to multiple-site fatigue damage (MSD) or fatigue cracking is present and, if so, repair the damage in accordance with the applicable structural repair manual (SRM) or
2. perform repetitive visual and nondestructive inspections for MSD and fatigue cracking at appropriately conservative intervals until the doubler is removed and, if any cracking is detected, immediately remove the doubler and repair the damage in accordance with the applicable SRM.

The results of these inspections should be provided to the FAA. The only repairs that should be eligible for exemption from these requirements are those that are supported by credible and detailed engineering documentation substantiating that the repair was performed in accordance with the applicable SRM and only after a visual inspection to confirm that the repair conforms to that documentation. (A-03-08)

Inform maintenance personnel about the circumstances of this accident and emphasize that improper repairs to the pressure vessel may be hiding damage that allows the development of multiple-site fatigue damage and fatigue fracturing that could lead to structural failure. (A-03-09)

Require the manufacturers of pressurized transport-category airplanes to include in their structural repair manuals, training programs, and other maintenance guidance, warnings about the possibility of structural failure resulting from hidden damage. (A-03-10)

FMI: www.ntsb.gov