AD 2006-21-06

You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.

Within 6 months after July 24, 1996 (the effective date of AD 96-13-03), replace the FAA-approved maintenance inspection program with a revision that provides for inspection(s) of the principal structural elements (PSEs) defined in McDonnell Douglas Report No. L26-008, “DC-9 Supplemental Inspection Document (SID),” Section 2 of Volume I of McDonnell Douglas Report No. L26-008, “DC-9 Supplemental Inspection Document (SID),” Revision 4, dated July 1993, in accordance with Section 2 of Volume III-95, dated September 1995, of the SID.

Note 1: Operators should note that certain visual inspections of fleet leader operator sampling PSE's that were previously specified in earlier revisions of Volume III of the SID are no longer specified in Volume III-95 of the SID.

(1) Prior to reaching the threshold (N th), but no earlier than one-half of the threshold (1/2 N th), specified for all PSE's listed in Volume III-95, dated September 1995, of the SID, inspect each PSE sample in accordance with the non-destructive inspection (NDI) procedures set forth in Section 2 of Volume II, Revision 4, dated July 1993. Thereafter, repeat the inspection for that PSE at intervals not to exceed ΔNDI/2 of the NDI procedure that is specified in Volume III-95, dated September 1995, of the SID, until the requirements of paragraph (i) of this AD are accomplished.

(2) The NDI techniques set forth in Section 2 of Volume II, Revision 4, dated July 1993, of the SID provide acceptable methods for accomplishing the inspections required by this paragraph.

(3) All inspection results (negative or positive) must be reported to Boeing, in accordance with the instructions contained in Section 2 of Volume III-95, dated September 1995, of the SID. Information collection requirements contained in this regulation have been approved by the Office of Management and Budget (OMB) under the provisions of the Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et seq.) and have been assigned OMB Control Number 2120-0056.

Note 2: Volume II of the SID, dated July 1993, is comprised of the following:

Note 3: NDI inspections accomplished in accordance with the following Volume II of the SID provide acceptable methods for accomplishing the inspections required by this paragraph:

(g) Any cracked structure detected during the inspections required by paragraph (f) of this AD must be repaired before further flight, in accordance with a method approved by the Manager, Los Angeles Aircraft Certification Office (ACO), Transport Airplane Directorate, FAA.

Note 4: Requests for approval of any PSE repair that would affect the FAA-approved maintenance inspection program that is required by this AD should include a damage tolerance assessment for that PSE.

Within 12 months after the effective date of this AD, incorporate a revision into the FAA-approved maintenance inspection program that provides for inspection(s) of the PSEs, in accordance with Boeing Report L26-008, “DC-9 All Series, Supplemental Inspection Document (SID),” Volume I, Revision 6, dated November 2002. Unless otherwise specified, all further references in this AD to the “SID” are to Revision 6, dated November 2002.

(i) For all PSEs listed in Section 2 of Volume I of the SID, perform an NDI for fatigue cracking of each PSE in accordance with the NDI procedures specified in Section 2 of Volume II, Revision 6, dated November 2004, of the SID, at the times specified in paragraph (i)(1), (i)(2), or (i)(3) of this AD, as applicable.

(1) For airplanes that have less than three-quarters of the fatigue life threshold (3/4 N th) as of the effective date of the AD: Perform an NDI for fatigue cracking no earlier than one-half of the threshold (1/2 N th) but prior to reaching three-quarters of the threshold (3/4 N th), or within 60 months after the effective date of this AD, whichever occurs later. Inspect again prior to reaching the threshold (N th) or ΔNDI/2, whichever occurs later, but no earlier than (3/4 N th). Thereafter, after passing the threshold (N th), repeat the inspection for that PSE at intervals not to exceed ΔNDI/2.

(2) For airplanes that have reached or exceeded three-quarters of the fatigue life threshold (3/4 N th), but less than the threshold (N th), as of the effective date of the AD: Perform an NDI prior to reaching the threshold (N th), or within 18 months after the effective date of this AD, whichever occurs later. Thereafter, after passing the threshold (N th), repeat the inspection for that PSE at intervals not to exceed ΔNDI/2.

(3) For airplanes that have reached or exceeded the fatigue life threshold (N th) as of the effective date of the AD: Perform an NDI within 18 months after the effective date of this AD. Thereafter, repeat the inspection for that PSE at intervals not to exceed ΔNDI/2.

Note 5: Volume II of the SID, dated November 2004, comprises the following:

If any discrepancy (e.g., a PSE cannot be inspected as specified in Volume II of the SID or does not match rework, repair, or modification description in Volume I of the SID) is detected during any inspection required by paragraph (i) of this AD, accomplish the action specified in paragraph (j)(1) or (j)(2) of this AD, as applicable.

(1) If a discrepancy is detected during any inspection performed prior to 3/4 N th or N th: The area of the PSE affected by the discrepancy must be inspected prior to N th or within 18 months of the discovery of the discrepancy, whichever is later, in accordance with a method approved by the Manager, Los Angeles ACO, FAA.

(2) If a discrepancy is detected during any inspection performed after N th: The area of the PSE affected by the discrepancy must be inspected prior to the accumulation of an additional ΔNDI/2, measured from the last non-discrepant inspection finding, or within 18 months of the discovery of the discrepancy, whichever occurs later, in accordance with a method approved by the Manager of the Los Angeles ACO.

All negative, positive, or discrepant (discrepant finding examples are described in paragraph (j) of this AD) findings of the inspections accomplished under paragraph (i) of this AD must be reported to Boeing, at the times specified in, and in accordance with the instructions contained in, Section 4 of Volume I, Revision 6, of the SID. Information collection requirements contained in this regulation have been approved by the Office of Management and Budget (OMB) under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.) and have been assigned OMB Control Number 2120-0056.

Any cracked structure of a PSE detected during any inspection required by paragraph (i) of this AD must be repaired before further flight in accordance with a method approved by the Manager, Los Angles ACO, or by using a method approved in accordance with procedures specified in paragraph (p) of this AD. Accomplish follow-on actions described in paragraphs (l)(1), (l)(2), and (l)(3) of this AD, at the times specified.

(1) Within 18 months after repair, perform a damage tolerance assessment (DTA) that defines the threshold for inspection of the repair and submit the assessment for approval.

(2) Before reaching 75% of the repair threshold as determined in paragraph (l)(1) of this AD, submit the inspection methods and repetitive inspection intervals for the repair for approval.

(3) Before the repair threshold, as determined in paragraph (l)(1) of this AD, incorporate the inspection method and repetitive inspection intervals into the FAA-approved structural maintenance or inspection program for the airplane.

Note 6: For the purposes of this AD, we anticipate that submissions of the DTA of the repair, if acceptable, should be approved within six months after submission.

Note 7: Advisory Circular AC 25.1529-1, “Instructions for Continued Airworthiness of Structural Repairs on Transport Airplanes,” dated August 1, 1991, is considered to be additional guidance concerning the approval of repairs to PSEs.

Before any airplane that has exceeded the fatigue life threshold (N th) can be added to an air carrier's operations specifications, a program for the accomplishment of the inspections required by this AD must be established per paragraph (m)(1) or (m)(2) of this AD, as applicable.

(1) For airplanes that have been inspected in accordance with this AD, the inspection of each PSE must be accomplished by the new operator in accordance with the previous operator's schedule and inspection method, or the new operator's schedule and inspection method, at whichever time would result in the earlier accomplishment date for that PSE inspection. The compliance time for accomplishment of this inspection must be measured from the last inspection accomplished by the previous operator. After each inspection has been performed once, each subsequent inspection must be performed in accordance with the new operator's schedule and inspection method.

(2) For airplanes that have not been inspected in accordance with this AD, the inspection of each PSE required by this AD must be accomplished either prior to adding the airplane to the air carrier's operations specification, or in accordance with a schedule and an inspection method approved by the Manager, Los Angeles ACO. After each inspection has been performed once, each subsequent inspection must be performed per the new operator's schedule.

Inspections accomplished prior to the effective date of this AD in accordance with Boeing Report No. L26-008, “DC-9 All Series Supplemental Inspection Document (SID),” Volume I, Revision 6, dated November 2002, are acceptable for compliance with the requirements of paragraph (i) of this AD.

Boeing Report MDC 91K0263, “DC-9/MD-80 Aging Aircraft Repair Assessment Program Document,” Revision 1, dated October 2000, provides inspection/replacement programs for certain repairs to the fuselage pressure shell. These repairs and inspection/replacement programs are considered acceptable for compliance with the requirements of paragraphs (i), (l), and (m) of this AD for repairs subject to that document.