Summary
We propose to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 737-100, -200, and -200C series airplanes. This proposed AD is intended to complete certain mandated programs intended to support the airplane reaching its limit of validity (LOV) of the engineering data that support the established structural maintenance program. This proposed AD would require repetitive detailed, high frequency eddy current (HFEC), and ultrasonic inspections of the center section rear spar upper clevis lugs and horizontal stabilizer rear spar upper lugs, as applicable, for any cracking, and related investigative and corrective actions if necessary. For certain airplanes, this proposed AD would require replacement of the center section rear spar upper chord with a new part and a serviceable center section assembly. This proposed AD would also require repetitive HFEC and fluorescent dye penetrant inspections of the center section for cracking of the front and rear sparupper clevis lugs or horizontal stabilizer front and rear spar upper lugs, and related investigative and corrective actions if necessary. We are proposing this AD to detect and correct cracking in the rear spar upper clevis lugs of the center section, and in the rear spar upper lugs of the horizontal stabilizer which could result in the loss of structural integrity and controllability of the airplane.