NTSB Identifies Record-Keeping Loophole
One reason we don't know more about why Boeing aircraft suffered fuselage skin cracking can be tied to regulatory decisions made by the FAA. A Southwest Airlines 737-300 suffered a crack in its fuselage on April 1, and an American Airlines 757-200 suffered a tear in its skin last year. Both incidents led to the discovery of symptoms that could lead to similar problems on other jets. In the case of the 737, rivet work was questioned. In the case of the 757 the NTSB determined that the aircraft's skin was of nonconforming thickness -- it was thinner than it was supposed to be. But Boeing's records of how those and other affected planes were built and inspected were missing ... as directed by the FAA.
A study of the manufacturing processes for the jets could explain why or how each situation came to pass. Without the associated paper trail, such a study is not possible. In 2009, the FAA revised rules previously devised in 1964 that set limits for how long manufacturers should keep records of their manufacturing and inspection processes. Per the old rule, manufacturers records should be kept for two years. The new rule requires that record are kept for five years and 10 years in the case of critical components. Southwest's jet, which saw a 5-foot section of the fuselage tear open at 34,000 feet, was built in 1996, so Boeing kept no records. The American Airlines jet entered service in 1990 so, again, no records are available. The NTSB found that "incorrect manufacturing" led to the problem on the 757. And thanks at least in part to the FAA's 5-year rule, there were limits on what else the bureau could find. "Therefore," said the NTSB, "a cause for the manufacturing non-conformance could not be identified."