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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. 99-NM-333-AD; Amendment 39-11995; AD 2000-23-22] 
          - RIN 2120-AA64 

# AGENCY:

Federal Aviation Administration, DOT. 

# ACTION:

Final rule. 

# SUMMARY:

This amendment supersedes an existing airworthiness directive (AD), applicable to certain McDonnell Douglas Model DC-9-10, -20, -30, -40, and -50 series airplanes and C-9 (military) airplanes, that currently requires a one-time visual inspection to determine if the doorstops and corners of the doorjamb of the forward passenger door have been modified, various follow-on repetitive inspections, and modification, if necessary. This amendment requires a reduction in the inspection threshold and repetitive intervals for a certain doubler configuration and an increase in the grace period for a certain other doubler configuration. This amendment is prompted by a determination that certain inspection compliance times were incorrect. The actions specified by this AD are intended to detect and correct fatigue cracking, which could result in rapid decompression of the fuselage and consequent reduced structural integrity of the airplane. 

# DATES:

Effective January 2, 2001. 

The incorporation by reference of McDonnell Douglas Service Bulletin   DC9-53-280, Revision 02, dated July 26, 1999, as listed in the regulations, is approved by the Director of the Federal Register as of January 2, 2001. 

The incorporation by reference of certain other publications, as listed in the regulations, was approved previously by the Director of the Federal Register as of January 22, 1999 (63 FR 70005, December 18, 1998). 

# ADDRESSES:

The service information referenced in this AD may be obtained from Boeing Commercial Aircraft Group, Long Beach Division, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Technical Publications Business Administration, Dept. C1-L51 (2-60). This information may be examined at the Federal Aviation Administration (FAA), Transport Airplane Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. 

# FOR FURTHER INFORMATION CONTACT:

Wahib Mina, Aerospace Engineer, Airframe Branch, ANM-120L, FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California 90712-4137; telephone (562) 627-5324; fax (562) 627-5210. 

# SUPPLEMENTARY INFORMATION:

                    A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 98-26-09, amendment 39-10949 (63 FR 70005, December 18, 1998), which is applicable                           ( print page 70651)                        to certain McDonnell Douglas Model DC-9-10, -20, -30, -40, and -50 series airplanes and C-9 (military) airplanes, was published in the                     **Federal Register**                     on April 5, 2000 (65 FR 17818). The action proposed to require a reduction in the inspection threshold and repetitive intervals for a certain doubler configuration and an increase in the repetitive inspection interval for a certain other doubler configuration.                 

## Comments 

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received. 

## Compliance Times 

One commenter requests that the compliance time specified in paragraphs (c)(1) and (d) of the proposed AD be revised to include “or prior to the accumulation of 48,000 total landings.” The commenter states that some of its airplanes have accumulated less than 44,425 total landings. The initial compliance thresholds in paragraphs (c)(1) and (d) of the proposed AD do not take into consideration those airplanes on which: (1) The initial inspection required by paragraph (a) of the proposed AD is going to be accomplished at 48,000 total landings, which is the later of the two thresholds in paragraph (a) of this proposed AD; and (2) the landings since accomplishment of the previously modified doorstops and corners of the forward passenger door doorjamb is unknown. In this situation, those airplanes would exceed the compliance times specified in paragraphs (c)(1) and (d) of the proposed AD. 

A second commenter requests that the FAA clarify the compliance times specified in paragraph (c)(1) of the proposed AD for the doorjambs with steel repairs installed. The commenter states that, since paragraph (c)(1) appears to “allow up to [5],999 flight cycles for existing repairs to be inspected initially,” a repetitive inspection interval of 3,000 flight cycles specified in paragraph (c)(1)(i) of the proposed AD should be increased to 3,575 flight cycles. The commenter states that such an interval would maintain at least an equivalent level of safety. 

The FAA partially concurs. For the reasons provided by the first commenter, the FAA concurs that paragraphs (c)(1) and (d) of the final rule should include a compliance time of “prior to the accumulation of 48,000 total landings” and has revised the final rule accordingly. 

The FAA does not concur with the second commenter that the repetitive inspection interval of 3,000 landings specified in paragraph (c)(1)(i) of the AD should be increased. The FAA determined that the cracking of the forward passenger door doorjamb is fatigue related (as discussed in the preamble of the NPRM). The 3,000-landing compliance time was calculated based on fatigue and damage tolerance analyses. Therefore, the FAA finds that the 3,000-landing repetitive inspection interval of paragraph (c)(1)(i) of the AD is warranted, based on the effectiveness of the inspection procedure to detect cracks, and the rate of crack growth in the forward passenger door doorjamb. However, the FAA inadvertently included an initial repetitive inspection interval of “within 2,000 landings after the effective date of this AD or within 3,000 landings from the last inspection in accordance with paragraph (c)(1) of this AD, whichever occurs later” in paragraph (c)(1)(i) of the proposed AD. The FAA's intent was that, if no crack is detected on the skin adjacent to the modification during any eddy current inspection required by paragraph (c)(1) of this AD, the eddy current inspection be accomplished thereafter at intervals not to exceed 3,000 landings, as indicated in the referenced service bulletin. Therefore, the FAA has revised paragraph (c)(1)(i) of the final rule accordingly. 

## Designated Engineer Representative (DER) Authority 

                    One commenter requests that the proposed AD be revised to allow approval of certain repairs (                    *i.e.*, cracking conditions beyond the allowable repair limits specified in the proposed AD, and for existing repairs that are not done per the DC-9 Structural Repair Manual or Service Rework Drawing) based on static strength analysis by a Boeing DER or airline DER, instead of the Manager of the Los Angeles Aircraft Certification Office (ACO). Then, the repair should be submitted to Boeing for a damage tolerance analysis, and subsequently, submitted to the Manager of the Los Angeles ACO. The commenter states that this provision would result in a more efficient and expeditious repair approval process.                 

The FAA does not concur. While DER's are authorized to determine whether a design or repair method complies with a specific requirement, they are not currently authorized to make the discretionary determination as to what the applicable requirement is. However, the FAA has issued a notice (N 8110.72, dated March 30, 1998), which provides guidance for delegating authority to certain type certificate holder structural DER's to approve alternative methods of compliance for AD-required repairs and modifications of individual airplanes. The FAA is currently working with Boeing, Douglas Products Division (DPD), to develop the implementation process for delegation of approval of alternative methods of compliance in accordance with that notice. Once this process is implemented, approval authority for alternative methods of compliance can be delegated without revising the AD. 

## Explanation of Changes to Final Rule 

The FAA finds that, as the proposed AD is currently worded, operators may misinterpret what type of eddy current inspection (i.e., low frequency or high frequency) must be accomplished. The FAA's intent was to follow the particular type of eddy current inspection indicated in the referenced service bulletin. However, because the service bulletin interchanges the use of low frequency eddy current inspection and high frequency eddy current inspection, the FAA has revised the final rule to only reference “eddy current inspection,” rather than a particular type of eddy current inspection. 

## Conclusion 

After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes previously described. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD. 

## Cost Impact 

There are approximately 809 airplanes of the affected design in the worldwide fleet. The FAA estimates that 572 airplanes of U.S. registry will be affected by this AD. 

The visual inspection that is currently required by AD 98-26-09, and retained in this AD, takes approximately 1 work hour per airplane to accomplish the required visual inspection, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the currently required visual inspection required by this AD on U.S. operators is estimated to be $34,320 or $60 per airplane. 

                    Should an operator be required to accomplish the eddy current or x-ray inspection, it will take approximately 1 work hour per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost                           ( print page 70652)                        impact of any necessary eddy current or x-ray inspection required by this AD on U.S. operators is estimated to be $120 per airplane, per inspection cycle.                 

Should an operator be required to accomplish the HFEC inspection, it will take approximately 2 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of any necessary HFEC inspection required by this AD on U.S. operators is estimated to be $60 per airplane, per inspection cycle. 

Should an operator be required to accomplish the modification, it will take approximately 8 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts will cost between $898 and $1,037 per airplane, depending on the service kit purchased. Based on these figures, the cost impact of the modification required by this AD on U.S. operators is estimated to be between $1,378 and $1,517 per airplane. 

The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions. 

## Regulatory Impact 

The regulations adopted herein will not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, it is determined that this final rule does not have federalism implications under Executive Order 13132. 

                    For the reasons discussed above, I certify that this action (1) is not a “significant regulatory action” under Executive Order 12866; (2) is not a “significant rule” under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption                     **ADDRESSES**                    .                

# List of Subjects in 14 CFR Part 39

      - Air transportation
      - Aircraft
      - Aviation safety
      - Incorporation by reference
      - Safety

## Adoption of the Amendment 

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows: 

# PART 39—AIRWORTHINESS DIRECTIVES 

1. The authority citation for part 39 continues to read as follows: 

Authority:49 U.S.C. 106(g), 40113, 44701. 

§ 39.13 

2. Section 39.13 is amended by removing amendment 39-10949 ( 63 FR 70005, December 18, 1998), and by adding a new airworthiness directive (AD), amendment 39-11995, to read as follows: 

**2000-23-22 McDonnell Douglas:**                             Amendment 39-11995. Docket 99-NM-333-AD. Supersedes AD 98-26-09, Amendment 39-10949.                         

*Applicability:*                             Model DC-9-10, -20, -30, -40, and -50 series airplanes, and C-9 (military) airplanes, as listed in McDonnell Douglas Service Bulletin DC9-53-280, Revision 02, dated July 26, 1999; 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 (g)(1) 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 doorstops and corners of the doorjamb of the forward passenger door, which could result in rapid decompression of the fuselage and consequent reduced structural integrity of the airplane, accomplish the following: 

# Note 2:

Where there are differences between the service bulletin and the AD, the AD prevails.

# Note 3:

The words “repair” and “modify/modification” in this AD and the referenced service bulletin are used interchangeably.

## Visual Inspection 

(a) Prior to the accumulation of 48,000 total landings, or within 3,575 landings after January 22, 1999 (the effective date of AD 98-26-09, amendment 39-10949), whichever occurs later, perform a one-time visual inspection to determine if the doorstops and corners of the forward passenger door doorjamb have been modified. Perform the inspection in accordance with McDonnell Douglas Service Bulletin DC9-53-280, dated December 1, 1997, Revision 01, dated July 30, 1998, or Revision 02, dated July 26, 1999. 

## Group 1, Eddy Current or X-Ray Inspection 

(b) For airplanes identified as Group 1 in McDonnell Douglas Service Bulletin DC9-53-280, Revision 01, dated July 30, 1998: If the visual inspection required by paragraph (a) of this AD reveals that the doorstops and corners of the forward passenger door doorjamb have not been modified, prior to further flight, perform an eddy current or x-ray inspection to detect cracks at all corners and doorstops of the forward passenger door doorjamb, in accordance with McDonnell Douglas Service Bulletin DC9-53-280, dated December 1, 1997, Revision 01, dated July 30, 1998, or Revision 02, dated July 26, 1999. 

                            (1)                             *Group 1, Condition 1.*                             If no crack is detected during any eddy current or x-ray inspection required by paragraph (b) of this AD, accomplish the requirements of either paragraph (b)(1)(i) or (b)(1)(ii) of this AD, in accordance with the service bulletin.                         

                            (i)                             *Option 1.*                             Repeat the eddy current inspection required by this paragraph thereafter at intervals not to exceed 3,575 landings, or the x-ray inspection required by this paragraph thereafter at intervals not to exceed 3,075 landings; or                        

                            (ii)                             *Option 2.*                             Prior to further flight, modify the doorstops and corners of the forward passenger door doorjamb, in accordance with the service bulletin. Prior to the accumulation of 28,000 landings after accomplishment of the modification, perform an eddy current inspection to detect cracks on the skin adjacent to the modification, in accordance with the service bulletin.                         

(A) If no crack is detected on the skin adjacent to the modification during any eddy current inspection required by paragraph (b)(1)(ii) of this AD, repeat the eddy current inspection thereafter at intervals not to exceed 20,000 landings. 

(B) If any crack is detected on the skin adjacent to the modification during any eddy current inspection required by paragraph (b)(1)(ii) of this AD, prior to further flight, repair it in accordance with a method approved by the Manager, Los Angeles Aircraft Certification Office (ACO), FAA. 

                            (2)                             *Group 1, Condition 2.*                             If any crack is found during any eddy current or x-ray inspection required by paragraph (b) of this AD, and the crack is 0.50 inch or less in length: Prior to further flight, modify the doorstops and corners of the forward passenger door doorjamb in accordance with the service bulletin. Prior to the accumulation of 28,000 landings after accomplishment of the modification, perform an eddy current inspection to detect cracks on the skin adjacent to the modification, in accordance with the service bulletin.                                   ( print page 70653)    

(i) If no crack is detected on the skin adjacent to the modification during any eddy current inspection required by paragraph (b)(2) of this AD, repeat the eddy current inspection thereafter at intervals not to exceed 20,000 landings. 

(ii) If any crack is detected on the skin adjacent to the modification during any eddy current inspection required by paragraph (b)(2) of this AD, prior to further flight, repair it in accordance with a method approved by the Manager, Los Angeles ACO. 

                            (3)                             *Group 1, Condition 3.*                             If any crack is found during any eddy current or x-ray inspection required by paragraph (b) of this AD, and the crack is greater than 0.5 inch in length: Prior to further flight, repair it in accordance with a method approved by the Manager, Los Angeles ACO.                         

## Group 2, Inspection of Modified Doorstops and Corners With Steel Doublers 

                            (c)                             *Group 2, Condition 1.*                             For airplanes identified as Group 2 in McDonnell Douglas Service Bulletin DC9-53-280, Revision 01, dated July 30, 1998: If the visual inspection required by paragraph (a) of this AD reveals that the doorstops and corners of the forward passenger door doorjamb have been modified previously in accordance with the McDonnell Douglas DC-9 Structural Repair Manual (SRM), using a steel doubler, accomplish either paragraph (c)(1) or (c)(2) of this AD in accordance with McDonnell Douglas Service Bulletin DC9-53-280, dated December 1, 1997, Revision 01, dated July 30, 1998, or Revision 02, dated July 26, 1999.                         

                            (1)                             *Option 1.*                             Prior to the accumulation of 6,000 landings after accomplishment of the modification, prior to the accumulation of 48,000 total landings, within 3,575 landings after January 22, 1999, or within 2,000 landings after the effective date of this AD, whichever occurs latest: Perform an eddy current inspection to detect cracks on the skin adjacent to the modification, in accordance with the service bulletin.                         

(i) If no crack is detected on the skin adjacent to the modification during any eddy current inspection required by paragraph (c)(1) of this AD, repeat the eddy current inspection thereafter at intervals not to exceed 3,000 landings. 

(ii) If any crack is detected on the skin adjacent to the modification during any eddy current inspection required by paragraph (c)(1) of this AD, prior to further flight, repair it in accordance with a method approved by the Manager, Los Angeles ACO. 

                            (2)                             *Option 2.*                             Prior to further flight, modify the doorstops and corners of the forward passenger door doorjamb in accordance with the service bulletin. Prior to the accumulation of 28,000 landings after the accomplishment of the modification, perform a eddy current inspection to detect cracks on the skin adjacent to the modification, in accordance with the service bulletin.                         

(i) If no crack is detected on the skin adjacent to the modification during any eddy current inspection required by paragraph (c)(2) of this AD, repeat the eddy current inspection thereafter at intervals not to exceed 20,000 landings. 

(ii) If any crack is detected on the skin adjacent to the modification during any eddy current inspection required by paragraph (c)(2) of this AD, prior to further flight, repair it in accordance with a method approved by the Manager, Los Angeles ACO. 

## Group 2, Inspection of Modified Doorstops and Corners With Aluminum Doublers 

                            (d)                             *Group 2, Condition 2.*                             For airplanes identified as Group 2 in McDonnell Douglas Service Bulletin DC9-53-280, Revision 01, dated July 30, 1998: If the visual inspection required by paragraph (a) of this AD reveals that the doorstops and corners of the forward passenger door doorjamb have been modified previously in accordance with McDonnell Douglas DC-9 SRM or Service Rework Drawing, using an aluminum doubler, prior to the accumulation of 28,000 landings after the accomplishment of the modification, prior to the accumulation of 48,000 total landings, or within 3,575 landings after January 22, 1999, whichever occurs latest, perform an eddy current inspection to detect cracks on the skin adjacent to the modification, in accordance with McDonnell Douglas Service Bulletin DC9-53-280, dated December 1, 1997, Revision 01, dated July 30, 1998, or Revision 02, dated July 26, 1999.                         

(1) If no crack is detected on the skin adjacent to the modification during any eddy current inspection required by paragraph (d) of this AD, repeat the eddy current inspection thereafter at intervals not to exceed 20,000 landings. 

(2) If any crack is detected on the skin adjacent to the modification during any eddy current inspection required by paragraph (d) of this AD, prior to further flight, repair it in accordance with a method approved by the Manager, Los Angeles ACO. 

## Group 2, Inspection of Modified Doorstops and Corners Not Per SRM or Service Rework Drawing 

                            (e)                             *Group 2, Condition 3.*                             For airplanes identified as Group 2 in McDonnell Douglas Service Bulletin DC9-53-280, Revision 02, dated July 26, 1999: If the visual inspection required by paragraph (a) of this AD reveals that the doorstops and corners of the forward passenger door doorjamb have been modified previously, but not in accordance with McDonnell Douglas DC9 SRM or the Service Rework Drawing, prior to further flight, repair it in accordance with a method approved by the Manager, Los Angeles ACO.                         

## Terminating Action for Supplemental Inspection Document, AD 96-13-03 

(f) Accomplishment of the actions required by this AD constitutes terminating action for inspections of Principal Structural Element (PSE) 53.09.031 (reference McDonnell Douglas Model DC-9 Supplemental Inspection Document) required by AD 96-13-03, amendment 39-9671. 

## Alternative Methods of Compliance 

(g)(1) 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, Los Angeles ACO. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Los Angeles ACO. 

(2) Alternative methods of compliance, approved previously in accordance with AD 98-26-09, amendment 39-10949, or AD 96-13-03, amendment 39-9671, are approved as alternative methods of compliance with this AD. 

# Note 4:

Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Los Angeles ACO.

## Special Flight Permits 

(h) 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 

(i) Except as provided by paragraphs (b)(1)(ii)(B), (b)(2)(ii), (b)(3), (c)(1)(ii), (c)(2)(ii), (d)(2), and (e) of this AD, the actions shall be done in accordance with McDonnell Douglas Service Bulletin DC9-53-280, dated December 1, 1997; McDonnell Douglas Service Bulletin DC9-53-280, Revision 01, dated July 30, 1998; or McDonnell Douglas Service Bulletin DC9-53-280, Revision 02, dated July 26, 1999. 

(1) The incorporation by reference of McDonnell Douglas Service Bulletin DC9-53-280, Revision 02, dated July 26, 1999, is approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. 

(2) The incorporation by reference of the remaining publications was approved previously by the Director of the Federal Register as of January 22, 1999 (63 FR 70005, December 18, 1998). 

(3) Copies may be obtained from Boeing Commercial Aircraft Group, Long Beach Division, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Technical Publications Business Administration, Dept. C1-L51 (2-60). Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. 

## Effective Date 

(j) This amendment becomes effective on January 2, 2001.

Issued in Renton, Washington, on November 13, 2000. 

Dorenda D. Baker, 

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. 

[FR Doc. 00-29497 Filed 11-24-00; 8:45 am] 

BILLING CODE 4910-13-U