FAA today published a proposed rule that would require
Boeing 737-300/-400/-500 operators to inspect areas along the top of the fuselage just in front of the tail (specifically, at stringers S-1 and S-2 right, between station (STA) 827 and STA 847) "to detect cracks in the fuselage skin along the chem-mill step," and repair if necessary.
The AD was triggered by the probe into the July 13 incident in which a
Southwest 737-300 made an emergency landing in Charleston, W.Va., with a hole along the top of fuselage. The proposed checks are based on a Boeing Alert Service Bulletin issued Sept. 3 and must be done at 35,000 cycles or after 500 cycles following the AD's effective date, whichever comes later.
Interestingly, the proposed rule is strikingly similar to an October 2008 directive that calls for
checks for a seemingly identical problem farther forward on the top of the fuselage. That AD orders "detailed inspections or non-destructive inspections to detect cracks in the fuselage skin along the chem-mill steps at stringers S-1 and S-2R, between station (STA) 400 and STA 460."