MANUFACTURER: The Boeing Company Model 737-300,
-400, and -500 Series Airplanes SUBJECT: Airworthiness Directive 2011-23-05 ACTION: Final rule; request for comments.
SUMMARY: The FAA is superseding an existing
airworthiness directive (AD) for certain Model 737-300, -400, and
-500 series airplanes. That AD currently requires repetitive
inspections for cracking of the 1.04-inch nominal diameter wire
penetration hole, and applicable related investigative and
corrective actions. This AD reduces the compliance times for those
actions. This AD was prompted by reports of cracking in the frame,
or in the frame and frame reinforcement, common to the 1.04- inch
nominal diameter wire penetration hole intended for wire routing;
and recent reports of multiple adjacent frame cracking found before
the compliance time required by the existing AD.
Such cracking could reduce the structural capability of the
frames to sustain limit loads, and result in cracking in the
fuselage skin and subsequent rapid depressurization of the
airplane. The FAA is issuing this AD to correct the unsafe
condition on these products.