99-18-05

Aft Pressure Bulkhead

Effective Date - 10/05/1999
Recurring - Yes
Supersedes - N/A Superseded by - N/A
Amendment 39-11271.Docket 97-NM-03-AD.
Applicability:
All Model 727 airplanes, certificated in any category.
Note 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (d) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.
Compliance: Required as indicated, unless accomplished previously.
   
To detect and correct fatigue cracking in the forward flange of the vertical beam of the aft pressure bulkhead, which could result in the inability of the subject vertical beam to withstand the fail-safe loads, and consequent loss of cabin pressurization, accomplish the following:
Initial Inspections
(a) Perform a detailed visual inspection and a high frequency eddy current (HFEC) inspection to detect cracks in the forward flange of the vertical beam at left and right buttock line 17.8 from water lines 265 through 288 inclusive, in accordance with Boeing Service Bulletin 727-53-0210, dated April 1, 1993, as revised by Notice of Status Change 727-53-0210 NSC 1, dated June 17, 1993, and Notice of Status Change 727-53-0210 NSC 2, dated September 21, 1995; at the time specified in paragraph (a)(1), (a)(2), or (a)(3) of this AD, as applicable.
   
(1) For any vertical beam on which neither the preventative modification nor the splice repair have been accomplished, as specified in Boeing Service Bulletin 727-53-0210, dated April 1, 1993; or Boeing Service Bulletin 727-53-0055, Revision 6, dated February 28, 1986, Revision 7, dated March 5, 1987, Revision 8,
dated December 17, 1987, or Revision 9, dated August 3, 1989: Inspect prior to the accumulation of 20,000 total flight cycles, or within 1,500 flight cycles after the effective date of this AD, whichever occurs later.
   
(2) For any vertical beam on which the preventative modification has not been accomplished and the splice repair has been accomplished, as specified in Boeing Service Bulletin 727-53-0210, dated April 1, 1993, or Boeing Service Bulletin 727-53-0055, Revision 6, dated February 28, 1986, Revision 7, dated March 5, 1987, Revision 8, dated December 17, 1987, or Revision 9, dated August 3, 1989: Inspect prior to the accumulation of 20,000 flight cycles since installation of the splice repair, or within 1,500 flight cycles after the effective date of this AD, whichever occurs later.
   
(3) For any vertical beam on which the preventative modification has been accomplished and the splice repair has or has not been accomplished, as specified in Boeing Service Bulletin 727-53-0210, dated April 1, 1993, or Boeing Service Bulletin 727-53-0055, Revision 6, dated February 28, 1986, Revision 7, dated March 5, 1987, Revision 8, dated December 17, 1987, or Revision 9, dated August 3, 1989: Inspect prior to the accumulation of 40,000 flight cycles since installation of the preventative modification, or within 1,500 flight cycles after the effective date of this AD, whichever occurs later.
Note 2: For the purposes of this AD, a detailed inspection is defined as: "An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc. may be used. Surface cleaning and elaborate access procedures may be required."
Repetitive Inspections and Corrective Action
(b) If no crack is detected during any inspection required by paragraph (a)(1), (a)(2), or (a)(3) of this AD, accomplish either paragraph (b)(1) or (b)(2) of this AD, as applicable, in accordance with Boeing Service Bulletin 727-53-0210, dated April 1, 1993, as revised by Notice of Status Change 727-53-0210 NSC 1, dated June 17, 1993, and Notice of Status Change 727-53-0210 NSC 2, dated September 21, 1995.
   
(1) For any vertical beam on which the preventative modification has not been accomplished, as specified in paragraphs (a)(1) and (a)(2) of this AD, accomplish either paragraph (b)(1)(i) or (b)(1)(ii) of this AD in accordance with the service bulletin.
(i) Prior to further flight, install the preventative modification. Prior to the accumulation of 40,000 flight cycles following accomplishment of a preventative modification, accomplish the detailed visual and HFEC inspections specified in paragraph (a) of this AD for any modified area. Repeat those inspections thereafter at intervals not to exceed 6,000 flight cycles for that modified area. Or
   
(ii) Repeat the detailed visual and HFEC inspections specified in paragraph (a) of this AD for any unmodified area at intervals not to exceed 3,000 flight cycles.
   
(2) For any vertical beam on which the preventative modification has been accomplished, repeat the detailed visual and HFEC inspections specified in paragraph (a) of this AD thereafter at intervals not to exceed 6,000 flight cycles.
   
(c) If any crack is detected during any inspection required by paragraph (a)(1), (a)(2), or (a)(3) of this AD, prior to further flight, install a splice repair and preventative modification to all cracked door frames, in accordance with Boeing Service Bulletin 727-53-0210, dated April 1, 1993, as revised by Notice of Status Change 727-53-0210 NSC 1, dated June 17, 1993, and Notice of Status Change 727-53-0210 NSC 2, dated September 21, 1995. Prior to the accumulation of 40,000 flight cycles following accomplishment of the preventative modification, accomplish the detailed visual and HFEC inspections specified in paragraph (a) of this AD. Repeat those inspections specified in paragraph (a) for that repaired and modified area thereafter at intervals not to exceed 6,000 flight cycles.
Alternative Method of Compliance
(d) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO.
Note 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.
Special Flight Permits
(e) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.
Incorporation by Reference
(f) The actions shall be done in accordance with Boeing Service Bulletin 727-53-0210, dated April 1, 1993, as revised by Notice of Status Change 727-53-0210 NSC 1, dated June 17, 1993, and Notice of Status Change 727-53-0210 NSC 2, dated September 21, 1995. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
   
(g) This amendment becomes effective on October 5, 1999.
FOR FURTHER INFORMATION CONTACT: Walter Sippel, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington; telephone (425) 227-2774; fax (425) 227-1181.