RULES and REGULATIONS

DEPARTMENT OF TRANSPORTATION 14 CFR Part 39 [Docket No. 84 -NM- 60 -AD; Amdt. 39 -4978] Airworthiness Directives; McDonnell Douglas Model DC - 9 and C - 9 (Military) Series Airplanes Tuesday, January 15, 1985 AGENCY: Federal Aviation Administration (FAA), DO T. ACTION: Final rule. SUMMARY: This action supersedes an existing airworthiness directive (AD) which requires visual, eddy current, and x-ray inspections of the aft pressure bulkhead on McDonnell Douglas DC - 9 series airplanes with an aft passenger entrance door. Cracks, which c ould result in depressurization, have been reported in several new locations on the aft pressure bulkhead. This amendment would increase the inspection requirements on the bulkhead and provide for preventive modification as a terminating action. DATES: Ef

fective February 14, 1985. Com pliance schedule as prescribed in the body of the AD, unless already accomplished. ADDRESSES: The applicable service information may be obtained from McDonnell Douglas Corporation, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Director, Publications and Training, C1 - 750 (54 - 60). This information may also be examined at the FAA, Northwest Mountain Region, 17900 Pacific Highway South, Seattle, Washington, or at 4344 Donald Douglas Drive, Long Beach, California. FOR FURTHER INFORMATION CONTACT: Mr. Michael N. Asahara, Sr., Aerospace Engineer, Airframe Branch, ANM - 122l, FAA, Northwest Mountain Region, Los Angeles Aircraft Certification Office, 4344 Donald Douglas Drive, Long Beach, California 90808; telephone (213) 548 -2826. SUPPLEMENTARY INFORMATION: A proposal to amend Part 39 of the Federal Aviation Regulations to include a new airworthiness directive (AD) to require repetitive inspections of the aft pressure bulkhead on McDonnell Douglas DC - 9 series airplanes with an aft passenger entrance door was published in the Federal Register on August 6, 1984 (49 FR 31295 ). The comment period for the proposal closed September 28, 1984.Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to all comments received. Three comments were received. The first commenter felt that the compliance time for the required inspections be 20,000 cycles instead of the 15,000 cycles as proposed in the NRPM. The com pliance time was based on a num ber of factors: results of operators' inspections, number of inspections performed, crack growth data, total time on aircraft at the time crack(s) were first found, size and location of crack(s), and the manufacturer' s recommendations. Based on this available data, the FAA considers the 15,000 cycles com pliance time appropriate. The second commenter requested that a repetitive inspection program be established as an alternative to the mandatory mo dification and com

p liance schedule of paragraph I. of the proposed rule. The establishment of any repetitive inspection program based on available data would necessitate unusually short repetitive inspection cycles. The FAA considers the modifications and 18 -month compliance time appropriate. The third commenter (the manufacturer) suggested that various paragraphs be revised for clarification and consistency. The FAA concurs and these changes have been incorporated in this AD. Cost Estimate It is estimated that 317 domestic airplanes will be affected by this AD. An average of 245 manhours per airplane will be required to accomplish the required rework and mo difications; 80 manhours per airplane will be required to accomplish the repetitive inspections. Labor cost will be $4 0 per hour. Based on these firgures, the total cost impact of this AD is estimated to be $1,014,400. 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 proposed rule, with the changes previously noted. For the reasons discussed above, the FAA has determined that this regulation is not considered to be major under Executive Order 12291 or significant under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979) and it is further certified under the criteria of the Regulatory Flexibility Act that this rule will not have a significant economic effect on a substantial number of small entitie s because few,i f any, Model DC - 9 airplanes are operated by small entities. A final evaluation has been prepared for this regulation and has been placed in the docket. A copy of it may be obtained by contacting the person identified under the caption “FOR FURTHER INFORMATION CONTACT.” List of Subjects in 14 CFR Part 39 Aviation safety, Aircraft. Adoption of the Amendment Accordingly, pursuant to the authority delegated to me by the Administrator, § 39.13 of Part 39 of the Federal AviationRegulations (1 4 CFR 39.13) is amended by superseding AD 80 - 10 - 03, Amendment 39 - 3769 (45 FR 31052) dated

May 15, 1980, with the following new airworthiness directive (AD): McDonnell Douglas: Applies to McDonnell Douglas Model DC - 9 and C - 9 (Military) series airplanes, certificated in all categories, with ventral aft pressure bulkhead. Compliance required as indicated, unless previously accomplished. To detect fatigue cracks and prevent structural failure of the fuselage cabin aft ventral pressure bulkhead, P/N 5910130 (and rework drawing numbers 5924597 and 5924350), accomplish the following: A. For airplanes with 15,000 or more landings on or after the effective date of this AD, within the next 700 additional landings or, for airplanes which have been inspected in accordance with AD 80 - 10 - 03, at the next inspection scheduled in accordance with AD 80 - 10 - 03 after the effective date of this AD, conduct visual and x-ray inspections in accordance with the instructions contained in Service Sketch 2934C, of McDonnell Douglas Service Bulletin 53 - 137, Revision 3, dated August 4, 1983. Note.

—McDonnell Douglas Service Bulletin 53 - 137, Revision 3, dated August 4, 1983, is herein referred to as SB 53 - 137, R3. B. If no cracks are found in the bulkhead web and doublers, in the areas of the doorjam b upper LH and RH corners, identified in Figure 1 of Service Sketch 2934C of SB 53 - 137, R3, for those corner areas: 1. At intervals not to exceed 2,000 landings from last inspection, repeat the visual inspections required by paragraph A., above; and 2. At intervals not to exceed 4,000 landings from last inspection, repeat the x-ray inspections required by paragraph A., above. 3. Repetitive inspections must be continued until terminating action in accordance with paragraph K., below, has been accomplished. C. If cracks are found in the bulkhead web and doublers, for both Group I and II airplanes (as defined in SB 53 - 137, R) accomplish the following: 1. For cracks found in the upper left and/or right bend radius, with no radial cracks, modify and inspect upper corners of bulkhead in accordance with paragraph 2.C. (Accomplishment Instructions) of SB 53 - 137, R3. 2. For new

cracks found in the upper left bend radius, with no radial cracks and with Condition II mo dification installed, modify and inspect corners of bulkhead per paragraph 2.D. of SB 53 - 137, R3. 3. For new cracks found in the upper right bend radius, with no radial cracks and with Condition I mo dification installed, modify and inspect upper corners of bulkhead in accordance with paragraph 2.E. of SB 53 - 137, R3.4. For radial crack(s) found in any or all members of u pper right corner, with or without bend radius cracks, modify and inspect corners of bulkhead in accordance with paragraph 2.I. of SB 53 - 137, R3. 5. For radial and/or bend radius crack(s), found in upper left and/or right corner(s) or portion of upper left and/or right bulkhead skin which exceeds the repairable limits of Conditions I through XVII, XX, or XXII through XXXIV (any noted conditions), or at operator's option for replacement of cracked parts that are within repairable limits, in lieu of repair mo dification, replace cracked parts in accordance with paragraph 2.J. of SB 53 - 137, R3. Reinstate repetitive inspections of

the upper corners within 15,000 landings and at intervals noted in paragraphs B.1., B.2., and B.3., above. 6. For radial crack(s) found in any or all members of lower left and/or right corner radius (except P/N 5910130 - 9/- 11 side channel), with or without cracks in the lower inboard tab portion of the P/N 5910130 - 3/- 5 bulkhead skin, modify and inspect corners of bulkhead in accordance with paragraph 2.L. of SB 53 - 137, R3. 7. For crack(s) found in any or all memb ers which extends below the lower edge of the P/N 5910130 - 37 channel forward vertical leg; replace cracked parts, and inspect corners in accordance with paragraph 2.N. of SB 53 - 137, R3. Reinstate repetitive inspections within 15,0 00 landings and at intervals noted in paragraphs B.1., B.2., and B.3., above. 8. For radial crack(s) found in P/N 5910130 - 3/- 5 side bulkhead skin at one or more of the five lower inboard fasteners through the P/N 5910130 - 9/- 11 side channel, install doublers and inspect lower corners in accordance with paragraph 2.0. of SB 53 - 137, R3. 9. For new

radial crack(s) found in P/N 5910130 - 3/- 5 side bulkhead skin at one or more of the five inboard fasteners through the P/N 5910130 - 9/- 11 side channel, and preventive corner repair modification in accordance with Condition XIII has been installed, modify and inspect in accordance with paragraph 2.P. of SB 53 - 137, R3. 10. For new

radial crack(s) found in any or all memb ers of upper right corner, with or without bend radius cracks in P/N 5910130 - 13 doubler, and with Condition I mo dification installed, mo dify and inspect upper corners in accordance with paragraph 2.Y. of SB 53 - 137, R3. D. If no crack(s) are found in the lower corners of the bulkhead web and doublers, for both Groups I and II airplanes (as defined in SB 53 - 137, R3); install preventive repair modification and repetitively inspect lower corners at 15,000 landing intervals in accordance with paragraph 2.M. of SB 53 - 137, R3. If preventive repair is not installed, repetitively inspect at intervals in accordance with paragraph B., above. E. If cracks are found in the bulkhead web and doublers in Group I airplanes, accomplish the following: 1. For radial crack(s) found in any or all members of upper left or both upper left/right corners, with or without bend radius cracks, modify and inspect corners of bulkhead in accordance with paragraph 2.F. of SB 53 - 137, R3. 2. For new radial crack(s) found in any or all members of upper right corners, with or without bend radius cracks, andwith Condition XXII mo dification installed, mo dify and inspect corners of bulkhead in accordance with paragraph 2.Q. of SB 53 - 137, R3. 3. For radial crack(s) found in P/N 5910130 - 13 doubler at upper left and/or right corner running along heel line of P/N 5910130 - 95 left and/or - 96 right door stop angle, with or without radial cracks in any or all member of upper left and/or right corners, and with or without crack(s) in upper left and/or right bend radius of the forward flange of P/N 5910130 - 13 doubler, modify and inspect upper corners of bulkhead in accordance with paragraph 2.T. of SB 53 - 137, R3. 4. For new

radial crack(s) found in any or all members of upper left corner, with or without bend radius cracks, and with Condition V modification installed, modify and inspect upper corners of bulkhead in accordance with paragraph 2.V. of SB 53 - 137, R3. 5. For new

radial crack(s) found in any or all members of upper left corner, with or without bend radius cracks in P/N 5910130 - 13 doubler, and with Condition II mo dification installed, mo dify and inspect upper corners in accordance with paragraph 2.W. of SB 53 - 137, R3. F. If no crack(s) are found in the bulkhead web and doublers in Group I airplanes, the interim crack preventative repair mo dification may be installed and the upper corners repetitively inspected at 15,000 landing intervals in accordance with paragraph 2.G. of SB 53 - 137, R3. If preventive repair mo dification is not installed, repetitively inspect at intervals specified in accordance with paragraph B., above. G. If cracks are found in the bulkhead web and doublers for Group II airplanes, accomplish the following: 1. For radial crack(s) found in any or all members of upper left or both upper left/right corners, with or without bend radius cracks, modify and inspect corners of bulkhead in accordance with paragraph 2.H. of SB 53 - 137, R3. 2. For new radial crack(s) found in any or all members of upper right corner, with or without bend radius cracks, and with Condition IV modification installed, accomplish paragraph 2.R. of SB 53 - 137, R3. 3. For new

radial crack(s) found in any or all members of upper left corner, with or without bend radius cracks, and with Condition V modification installed, accomplish paragraph 2.S. of SB 53 - 137, R3. 4. For radial crack(s) found in P/N 5910130 - 13 doubler, at upper left and/or right corner running along heel line of P/N 5910130 - 95/- 96, side door stop angle, with or without radial cracks in any or all members of upper left and/or right corners, and with or without crack(s) in upper left and/or right bend radius of forward flange of P/N 5910130 - 13, doubler, modify and inspect corners of bulkhead in accordance with paragraph 2.U. of SB 53 - 137, R3. 5. For radial crack(s) found in any or all members of upper left corner, with or without bend radius cracks in 5910130 - 13 doubler, and with Condition II mo dification installed, mo dify and inspect upper corners in accordance with paragraph 2.X. of SB 53 - 137, R3.H. If no crack(s) are found in the bulkhead web and doublers in Group II airplanes, the interim crack preventive

mo dification may be installed and the upper corners repetitively inspected at 15,000 landing interval in accordance with paragraph 2.K. of SB 53 - 137, R3. If preventive repair mo dif ication is not installed, repetitively inspect at intervals specified in accordance with paragraph B., above. I. McDonnell Douglas DC - 9 Service Bulletin A53 - 144, or later FAA approved revisions, must be accomplished within 18 months after the effective date of this AD. J. For aircraft mo dified per DC - 9 Service Bulletin 53 - 139 (basic), or production equivalent, accom plish McDonnell Douglas DC - 9 Service Bulletin 53 - 157 within 18 months after effective date of this AD. K. The following constitutes terminating action compliance for this AD: 1. For aircraft previously mo dified in accordance with DC - 9 Service Bulletin 53 - 139 (basic and Revision 1), or production equivalent, rework the aft pressure bulkhead in accordance with Part 2 of the Ac complishment Instructions in McDonnell Douglas DC - 9 Service Bulletin 53 - 165, dated January 31, 1983, or later FAA approved revisions. 2. For aircraft not previously mo dified in accordance with DC - 9 Service Bulletin 53 - 139 (basic and Revision 1), or production equivalent; mo dify in accordance with DC - 9 Service Bulletin 53 - 166, R1, or later FAA approved revisions. L. Previous accom

plishment of any rework or inspection(s), or portion(s) thereof, which is outlined in McDonnell Douglas DC - 9 Service Bulletin 53 - 137, Revision 1, dated December 6, 1979, required by AD 80 - 10 - 03 Amendment 39 - 3769, effective May

1 5, 1980, which is also outlined in McDonnell Douglas DC - 9 Service Bulletin 53 - 137, Revision 2, or SB 53 - 137, R3, provided for in AD 80 - 10 - 03, may be considered an equivalent to that requirement of this AD. M. The inspections and modifications required by this AD need not be accomplished if, after the effective date of this AD, the aircraft is operated without cabin pressurization and a placard is installed in the cockpit, in full view of the pilots, stating: “Operation With Cabin Pressurization is Prohibited” N. Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to base for the accomplishment of modifications required by this AD. O. Upon the request of an operator, an FAA Maintenance Inspector, subject to prior approval by the Manager, Los Angeles Aircraft Certification Office, FAA, Northwest Mountain Region, may adjust the repetitive inspection intervals of the operator if the request contains substantiating data to justify the increase for that operator.P. Alternate means of com pliance which provide an equivalent level of safety may be used when approved by the Manager, Los Angeles Aircraft Certification Office, FAA, Northwest Mountain Region. All persons affected by

this proposal who have not already received these documents from the manufacturer may obtain copies upon request to the McDonnell Douglas Corporation, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Director, Publications and Training, C1 - 750 (54 - 60). These documents also may be examined at the FAA, Northwest Mountain Region, 17900 Pacific Highway South, Seattle, Washington, the Los Angeles Aircraft Certification Office, or 4344 Donald Douglas Drive, Long Beach, California. This Amendment becomes effective February 14, 1985. This supersedes AD 80 - 10 - 03, Amendment 39 - 3769 (45 FR 31052; May 15, 1980). Secs. 313(a), 314(a), 601 through 610, and 1102 of the Federal Aviation Act of 1958 (49 U.S.C. 1354(a), 1421 through 1430, and 1502); 49 U.S.C. 106(g) (Revised, Pub. L. 97 -449, January 12, 1983); and 14 CFR 11.89 ) Issued in Seattle, Washington, on December 31, 1985. Wayne J. Barlow, Acting Director, Northwest Mountain Region. [FR Doc. 85 - 1071 Filed 1 - 15 - 85; 8:45 am] BILLING CODE 4910 - 13 -M 5 0 FR 2043