Airworthiness Directives; The Boeing Company Airplanes

We are adopting a new airworthiness directive (AD) for all The Boeing Company Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), and DC-9-87 (MD-87) airplanes; and Model MD-88 airplanes. This AD was prompted by a report of fatigue cracking in a rear spar lower cap of the horizontal stabilizer. This AD requires repetitive inspections for cracking of the rear spar lower caps of the horizontal stabilizer, post-modification and post-repair inspections, and corrective actions if necessary. This AD also provides an optional terminating fatigue life enhancement modification. We are issuing this AD to address the unsafe condition on these products.