Action
Final rule.
Summary
We are superseding Airworthiness Directive (AD) 2008-26-07 for all The Boeing Company Model DC-8-11, DC-8-12, DC-8-21, DC-8-31, DC-8- 32, DC-8-33, DC-8-41, DC-8-42, and DC-8-43 airplanes; Model DC-8-50 series airplanes; Model DC-8F-54 and DC-8F-55 airplanes; Model DC-8-60 series airplanes; Model DC-8-60F series airplanes; Model DC-8-70 series airplanes; and Model DC-8-70F series airplanes. AD 2008-26-07 required repetitive inspections of the lower skin and stringers at certain stations, and corrective actions if necessary. This new AD continues to require the actions specified in AD 2008-26-07 and also requires an eddy current high frequency (ETHF) inspection for cracks of the fastener open holes common to the lower skins, stringers, and splice fittings at a certain station; installation of external doublers and fasteners and repetitive eddy current low frequency (ETLF) inspections around the fasteners for any crack; and corrective actions if necessary. This AD was prompted by certain mandated programs intended to support the airplane reaching its limit of validity of the engineering data that support the established structural maintenance program. We are issuing this AD to detect and correct cracks in the lower skins, stringers, and fastener holes of the splice fittings, which could result in the loss of structural integrity of the airplane.