Airworthiness Directive · Amendment 39-16719 · Stabilizers
The Boeing Company Model MD-90-30 Airplanes
This AD applies to The Boeing Company Model MD-90-30 airplanes, certificated in any category, as identified in Boeing Alert Service Bulletin MD90-55A014, dated June 24, 2010.
We are adopting a new airworthiness directive (AD) for the products listed above. This AD requires a detailed inspection to detect distress and existing repairs to the leading edge structure of the vertical stabilizer at the splice at Station Zfs=52.267; repetitive inspections for cracking in the front spar cap forward flanges of the vertical stabilizer, and either the aft flanges or side skins; repetitive inspections for loose and missing fasteners; and related investigative and corrective actions if necessary. This AD was prompted by reports of cracked vertical stabilizer skin, a severed front spar cap, elongated fastener holes at the leading edge of the vertical stabilizer, and cracked front spar web and front spar cap bolt holes in the vertical stabilizer. We are issuing this AD to detect and correct such cracking damage, which could result in the structure being unable to support limit load, and could lead to the loss of the vertical stabilizer.
Comply with this AD within the compliance times specified, unless already done.
Within 4,100 flight cycles after the effective date of this AD, do a detailed inspection for distress in and existing repairs to the leading edge structure of the vertical stabilizer at the splice at Station Zfs=52.267, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin MD90-55A014, dated June 24, 2010.
Before further flight after doing the inspection required by paragraph (g) of this AD, inspect for cracks of the left and right vertical stabilizer front spar cap, in accordance with either Option 1 or Option 2 as specified in the Accomplishment Instructions of Boeing Alert Service Bulletin MD90-55A014, dated June 24, 2010. If any crack is found, before further flight, evaluate and verify to confirm all crack indications, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin MD90-55A014, dated June 24, 2010.
(1) If any cracking is confirmed, before further flight, repair using a method approved in accordance with the procedures specified in paragraph (l) of this AD.
(2) If no cracking is confirmed, repeat the inspection thereafter at intervals not to exceed the applicable interval specified in paragraph (h)(2)(i) or (h)(2)(ii) of this AD.
(i) If the most recent inspection was done using Option 1, the next inspection must be done within 4,400 flight cycles.
(ii) If the most recent inspection was done using Option 2, the next inspection must be done within 3,000 flight cycles.
(i) If leading edge distress is found during the detailed inspection required by paragraph (g) of this AD, before further flight and after accomplishing the inspection required by paragraph (h) of this AD, repair the leading edge, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin MD90-55A014, dated June 24, 2010.
For airplanes on which no cracking is confirmed during the initial inspection required by paragraph (h) of this AD: At the applicable time specified in paragraph (j)(1) or (j)(2) of this AD, do a detailed inspection for indications of loose and missing fasteners, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin MD90-55A014, dated June 24, 2010. If any loose or missing fastener is found, before further flight, repair the leading edge, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin MD90-55A014, dated June 24, 2010.
(1) If the inspection required by paragraph (h) was done using Option 1, do the inspection required by paragraph (j) of this AD within 4,400 flight cycles after accomplishing the inspection required by paragraph (h) of this AD.
(2) If inspection required by paragraph (h) was done using Option 2, do the inspection required by paragraph (j) of this AD within 3,000 flight cycles after accomplishing the inspection required by paragraph (h) of this AD.
(k) For airplanes on which no cracking is confirmed during the most recent inspection required by paragraph (h) of this AD: Repeat the inspection for loose and missing fasteners required by paragraph (j) of this AD thereafter at intervals not to exceed the applicable time specified in paragraph (k)(1) or (k)(2) of this AD.
(1) If the most recent inspection required by paragraph (h) was done using Option 1, the next inspection required by paragraph (j) of this AD must be done within 4,400 flight cycles after accomplishing the most recent inspection required by paragraph (j) of this AD.
(2) If the most recent inspection required by paragraph (h) was done using Option 2, the next inspection required by paragraph (j) of this AD must be done within 3,000 flight cycles after the most recent inspection required by paragraph (j) of this AD.
