AD 2006-10-14

The FAA is adopting a new airworthiness directive (AD) for certain McDonnell Douglas transport category airplanes. This AD requires an inspection to determine the part number of the upper and lower stop pad support fittings of all the lower cargo doors, repetitive inspections of all early configuration stop pad support fittings, and corrective action if necessary. This AD also provides an optional terminating action for the repetitive inspections. This AD results from a report of cracks found in the area of the upper and lower stop pad support fittings of the cargo door pan on numerous airplanes. We are issuing this AD to prevent cracks in the cargo door pan, which could result in the inability to fully pressurize an airplane, possible pressure loss, or possible rapid decompression of the airplane.

Final rule.

2006-10-14 McDonnell Douglas: Amendment 39-14598. Docket No. FAA- 2005-22254; Directorate Identifier 2005-NM-001-AD. \n\nEffective Date \n\n\t(a) This AD becomes effective June 21, 2006. \n\nAffected ADs \n\n\t(b) Accomplishing paragraph (g) or (h), as applicable, of this AD terminates certain requirements of AD 96-10-11, amendment 39- 9618, as specified in McDonnell Douglas DC-9 Service Bulletin 52-89, Revision 5, dated February 26, 1991. \n\nApplicability \n\n\t(c) This AD applies to the airplanes specified in paragraphs (c)(1) and (c)(2) of this AD, certificated in any category. \n\n\t(1) All McDonnell Douglas Model DC-9-11, DC-9-12, DC-9-13, DC-9- 14, DC-9-15, DC-9-15F, DC-9-21, DC-9-31, DC-9-32, DC-9-32 (VC-9C), DC-9-32F, DC-9-33F, DC-9-34, DC-9-34F, DC-9-32F (C-9A, C-9B), DC-9- 41, and DC-9-51 airplanes; Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), DC-9-87 (MD-87) airplanes; Model MD-88 airplanes; and Model MD-90-30 airplanes; and \n\n\t(2) Model 717-200 airplanes, as identified in Boeing Service Bulletin 717-52-0007, Revision 1, dated March 2, 2006. \n\nUnsafe Condition \n\n\t(d) This AD was prompted by a report of cracks found in the area of the upper and lower stop pad support fittings of the cargo door pan on numerous airplanes. We are issuing this AD to prevent cracks in the cargo door pan, which could result in the inability to fully pressurize an airplane, possible pressure loss, or possible rapid decompression of the airplane. \n\nCompliance \n\n\t(e) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done. \n\nService Bulletin References \n\n\t(f) The term "service bulletin," as used in this AD, means the following service bulletins, as applicable: \n\n\t(1) For Model DC-9-11, DC-9-12, DC-9-13, DC-9-14, DC-9-15, DC-9- 15F, DC-9-21, DC-9-31, DC-9-32, DC-9-32 (VC-9C), DC-9-32F, DC-9-33F, DC-9-34, DC-9-34F, DC-9-32F (C-9A, C-9B), DC-9-41, and DC-9-51 airplanes; Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), DC-9-87 (MD-87) airplanes; and Model MD-88 airplanes: Boeing Service Bulletin DC9-52-189, Revision 2, dated December 20, 2005; \n\n\t(2) For Model MD-90-30 airplanes: Boeing Service Bulletin MD90- 52-014, Revision 1, dated March 22, 2006; and \n\n\t(3) For Model 717-200 airplanes: Boeing Service Bulletin 717-52- 0007, Revision 1, dated March 2, 2006. \n\nDetermine Part Numbers (P/Ns) and Inspect if Necessary \n\n\t(g) For the airplanes identified in Table 1 of this AD: At the compliance time specified in Table 1 of this AD, inspect to determine the part number of the upper and lower stop pad support fittings of the lower cargo doors, in accordance with the Accomplishment Instructions of the service bulletin, as applicable. If new configuration or new upper and lower stop pad support fittings, as identified in the applicable service bulletin, are found installed on all lower cargo doors, then no further action is required by this paragraph. If any early configuration stop pad support fitting is found installed on any lower cargo door, at the applicable compliance time specified in Table 1 of this AD, do the inspection specified in either paragraph (g)(1) or (g)(2) of this AD, in accordance with the Accomplishment Instructions of the service bulletin, until the replacement specified in paragraph (k) of this AD is accomplished. \n\n\t(1) Do a general visual inspection for cracks in any lower cargo door having an early configuration stop pad support fitting. Repeat the general visual inspection thereafter at intervals not to exceed 1,700 flight cycles. \n\n\t(2) Do an eddy current inspection for cracks in any lower cargo door having an early configuration stop pad support fitting. Repeat the eddy current inspection thereafter at intervals not to exceed 3,900 flight cycles. \n\n\tNote 1: For the purposes of this AD, a general visual inspection is: "A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity. This level of inspection is made from within touching distance unless otherwise specified. A mirror may be necessary to ensure visual access to all surfaces in the inspection area. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or droplight and may require removal or opening of access panels or doors. Stands, ladders, or platforms may be required to gain proximity to the area being checked." \n\n\tTable 1.--Compliance Times for Certain Airplanes \n\t\n\n\nApplicable airplanes \n\nInspection to determine P/N \nInitial inspection of early configuration stop pad support fitting, if applicable \n\n\n\n\n\n\n\n\n\nAirplanes identified as Group 2, 3, and 4 in paragraph 1.A. of Boeing Service Bulletin DC9-52-189, Revision 2, dated December 20, 2005. \nWithin 18 months after the effective date of this AD. \nBefore further flight. \n\n\n\n\n\n\nModel MD-90-30 airplanes and Model 717-200 airplanes. \nBefore the accumulation of 25,000 total flight cycles, or within 3,900 flight cycles after the effective date of this AD, whichever is later. \nWithin 300 flight hours. \n\nRepetitive Inspections for Certain Airplanes \n\n\t(h) For the airplanes identified as Group 1 in paragraph 1.A. of Boeing Service Bulletin DC9-52-189, Revision 2, dated December 20, 2005: At the applicable compliance time specified in Table 2 of this AD, do the inspection specified in either paragraph (g)(1) or (g)(2) of this AD, in accordance with the Accomplishment Instructions of the applicable service bulletin. Repeat the inspection thereafter at the interval specified in paragraph (g)(1) or (g)(2), as applicable, until the replacement specified in paragraph (k) of this AD is accomplished. Inspections also may be done in accordance with the Accomplishment Instructions of McDonnell Douglas DC-9 Service Bulletin 52-89, Revision 5, dated February 26, 1991; or Revision 6, dated January 11, 1993. \n\n\tTable 2.--Compliance Times for Initial Inspection of Certain Other Airplanes\n\n\nFor airplanes that have-\nCompliance time \n\n\n\n\n\n\nBeen inspected before the effective date of this AD in accordance with paragraph (b) of AD 96-10-11 as specified in Phase I of the Accomplishment Instructions of McDonnell Douglas DC-9 Service Bulletin 52-89, Revision 5, dated February 26, 1991; or Revision 6, dated January 11, 1993. \nWithin 1,700 flight cycles after the last general visual inspection, or within 3,900 flight cycles after the last eddy current inspection, as applicable. \n\n\n\n\n\n\nNot been inspected before the effective date of this AD in accordance with paragraph (b) of AD 96-10-11 as specified in Phase I of the Accomplishment Instructions of McDonnell Douglas DC-9 Service Bulletin 52-89, Revision 5, dated February 26, 1991; or Revision 6, dated January 11, 1993. \nWithin 18 months after the effective date of this AD. \n\nCorrective Actions for Certain Airplanes \n\n\t(i) For Model MD-90-30 airplanes and Model 717-200 airplanes: If any crack is found in the door jamb or jamb structure of a lower cargo door during any inspection required by paragraph (g)(1) or (g)(2) of this AD, and the service bulletin specifies contacting Boeing for appropriate action, before further flight, repair the crack using a method in accordance with the procedures specified in paragraph (o) of this AD. \n\nCorrective Actions for Certain Other Airplanes \n\n\t(j) For Model DC-9-11, DC-9-12, DC-9-13, DC-9-14, DC-9-15, DC-9- 15F, DC-9-21, DC-9-31, DC-9-32, DC-9-32 (VC-9C), DC-9-32F, DC-9-33F, DC-9-34, DC-9-34F, DC-9-32F (C-9A, C-9B), DC-9-41, DC-9-51 airplanes; Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), and DC-9-87 (MD-87) airplanes; and Model MD-88 airplanes: If any crack is found during any inspection required by paragraph (g)(1), (g)(2), or (h) of this AD, do the corrective action at the applicable compliance time specified in paragraph 1.E.of the service bulletin, in accordance with the Accomplishment Instructions of the service bulletin, as applicable. \n\nOptional Replacement of Stop Pad Support Fittings \n\n\t(k) For all airplanes: Replacement of all early configuration stop pad support fittings installed on a lower cargo door with new configuration or new stop pad support fittings, as identified in the applicable service bulletin; and reidentification of the applicable lower cargo door; in accordance with the Accomplishment Instructions of the applicable service bulletin; terminates the repetitive inspections required by paragraphs (g)(1), (g)(2), and (h) of this AD, as applicable, for that lower cargo door only. \n\nParts Installation \n\n\t(l) For all airplanes: As of the effective date of this AD, no person may install an early configuration stop pad support fitting having P/N 3925046-1, -501, -505, -507, or -509, or P/N 3926046-1 or -501, on any airplane. \n\nCredit for Previous Service Bulletin \n\n\t(m) Actions done before the effective date of this AD in accordance with the applicable service bulletin specified in paragraph (m)(1), (m)(2), or (m)(3) of this AD, are acceptable for compliance with the corresponding requirements of this AD. \n\n\t(1) Boeing Service Bulletin DC9-52-189, dated August 10, 2001; or Revision 01, dated March 20, 2003. \n\n\t(2) Boeing Service Bulletin MD90-52-014, dated December 14, 2004. \n\n\t(3) Boeing Service Bulletin 717-52-0007, dated December 14, 2004, except where the service bulletin refers to Chapter 52-31-00 of the Boeing 717 Aircraft Maintenance Manual for instructions on adjusting the forward and aft lower cargo doors, instead refer to Chapter 52-31-01 for those instructions. \n\nTerminating Action for Certain Requirements of AD 96-10-11 \n\n\t(n) For Model DC-9-11, DC-9-12, DC-9-13, DC-9-14, DC-9-15, DC-9- 15F, DC-9-21, DC-9-31, DC-9-32, DC-9-32 (VC-9C), DC-9-32F, DC-9-33F, DC-9-34, DC-9-34F, DC-9-32F (C-9A, C-9B), DC-9-41, and DC-9-51 airplanes: Accomplishing the replacement specified in paragraph (k) of this AD for the forward and aft lower cargo doors terminates the repetitive inspections of the forward and aft lower cargo doors for cracks required by paragraph (b) of AD 96- 10-11 as specified in McDonnell Douglas DC-9 Service Bulletin 52-89, Revision 5, dated February 26, 1991. \n\nAlternative Methods of Compliance (AMOCs) \n\n\t(o)(1) The Manager, Los Angeles Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19. \n\n\t(2) Before using any AMOC approved in accordance with 14 CFR 39.19 on any airplane to which the AMOC applies, notify the appropriate principal inspector in the FAA Flight Standards Certificate Holding District Office. \n\n\t(3) An AMOC that provides an acceptable level of safety may be used for any repair required by this AD, if it is approved by an Authorized Representative for the Boeing Commercial Airplanes Delegation Option Authorization Organization who has been authorized by the Manager, Los Angeles ACO, to make those findings. For a repair method to be approved, the repair must meet the certification basis of the airplane, and the approval must specifically refer to this AD. For McDonnell Douglas Model DC-9-10, DC-9-20, DC-9-30, DC- 9-40, and DC-9-50 series airplanes; Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), and DC-9-87 (MD-87) airplanes; and Model MD-88 airplanes: The repair also must meet 14 CFR 25.571, Amendment 45. \n\nMaterial Incorporated by Reference \n\n\t(p) You must use the service information specified in Table 3 of this AD to perform the actions that are required by this AD, unless the AD specifies otherwise. The Director of the Federal Register approved the incorporation by reference of these documents in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Contact Boeing Commercial Airplanes, Long Beach Division, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Data and Service Management, Dept. C1-L5A (D800-0024), for a copy of this service information. You may review copies at the Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street, SW., room PL-401, Nassif Building, Washington, DC; on the Internet at http://dms.dot.gov; or at the National Archives and Records Administration (NARA). For information on the availability of this material at the NARA, call (202) 741-6030, or go to http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html . \n\n\t\tTable 3.--Material Incorporated by Reference \n\n\nService bulletin \nRevision level \nDate \nBoeing Service Bulletin Revision 717-52-0007\nRevision 1 \nMarch 2, 2006. \nBoeing Service Bulletin DC9-52-189 \nRevision 2 \nDecember 20, 2005. \nBoeing Service Bulletin MD90-52-014 \nRevision 1 \nMarch 22, 2006.

Examining the Docket \n\n\tYou may examine the airworthiness directive (AD) docket on the Internet at http://dms.dot.gov or in person at the Docket Management Facility office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Management Facility office (telephone (800) 647-5227) is located on the plaza level of the Nassif Building at the street address stated in the ADDRESSES section. \n\nDiscussion \n\n\tThe FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an AD that would apply to certain McDonnell Douglas Model DC-9-10, DC-9-20, DC-9-30, DC-9-40, and DC-9-50 series airplanes; Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), and DC-9-87 (MD-87) airplanes (hereafter referred to as Model DC-9 airplanes); Model MD-88 airplanes; Model MD-90-30 airplanes; and Model 717-200 airplanes. That NPRM was published in the Federal Register on September 1, 2005 (70 FR 52046). That NPRM proposed to require an inspection to determine the part number (P/N) of the upper and lower stop pad support fittings of all the lower cargo doors, repetitive inspections of all early configuration stop pad support fittings, and corrective action if necessary. That NPRM also proposed to provide an optional terminating action for the repetitive inspections. \n\nComments \n\n\n\tWe provided the public the opportunity to participate in the development of this AD. We have considered the comments received. \n\nRequest To Use New Service Information \n\n\tBoeing requests that we reference Boeing Service Bulletin DC9-52- 189, Revision 2, dated December 20, 2005, in paragraph (f)(1) of the NPRM as the appropriate source of service information for certain airplanes. (We referenced Revision 01, dated March 20, 2003, as an appropriate source of service information in the NPRM.) \n\n\tWe agree. We have reviewed Revision 2 of Boeing Service Bulletin DC9-52-189, which contains procedures identical to those in Revision 01. We, therefore, have revised paragraphs (f)(1) and (h) and Table 1 of this AD to reference Revision 2 of the service bulletin. \n\n\tAlso since issuance of the NPRM, Boeing has published Boeing Service Bulletin 717-52-0007, Revision 1, dated March 2, 2006; and Boeing Service Bulletin MD90-52-014, Revision 1, dated March 22, 2006. For certain airplanes, we referenced the original issues of these service bulletins, both dated December 14, 2004, as appropriate sources of service information in the NPRM. The procedures in Revision 1 of Boeing Service Bulletin 717-52-0007 are identical to those in the original issue of that service bulletin, except that Revision 1 recommends inspecting only the aft lower cargo door, whereas the original issue recommends inspecting both the forward and aft lower cargo doors. Boeing, however, has verified that the unsafe condition of this AD has been corrected on the forward cargo doors for all the affected Model 717-200 airplanes. Therefore, wehave revised paragraph (f)(3) of this AD to reference Revision 1 of Boeing Service Bulletin 717-52-0007. \n\n\tThe procedures in Revision 1 of Boeing Service Bulletin MD90-52-014 are identical to those in the original issue of that service bulletin. We, therefore, have revised paragraph (f)(2) of this AD to reference Revision 1 of Boeing Service Bulletin MD90-52-014. Consequently, we have also revised paragraph (m) of this AD to give credit for actions done previously in accordance with Revision 01 of Boeing Service Bulletin DC9-52-189, the original issue of Boeing Service Bulletin 717- 52-0007, and the original issue of Boeing Service Bulletin MD90-52-014, as applicable. \n\nRequest To Revise Certain Compliance Times \n\n\tBoeing and Northwest Airlines (NWA) request that we revise certain compliance times to match those specified in Revision 2 of Boeing Service Bulletin DC9-52-189. NWA would like the compliance times for the repetitive inspections of early configuration stop pad fittings changed from units of flight hours to landings. We infer NWA is referring to the inspections in paragraphs (g)(1) and (g)(2) of the NPRM. NWA further requests that, for Group 2 airplanes, we extend the compliance time for inspecting to determine the P/N of the stop pad fittings from 300 flight hours to within 3,900 landings from the last general visual inspection. We infer that NWA is referring to the compliance time specified in the first row of Table 1 of the NPRM. As justification, NWA states Revision 2 of Boeing Service Bulletin DC9-52- 189 (which was published after issuance of the NPRM) recommends a compliance time of 18 months. Based on its maintenance program for Model DC-9 airplanes, NWA states that 18 months is approximately equivalent to 3,900 landings. Boeing specifically requests the following: \n\t\n\tFor the inspection to determine the P/N of the stop pad fittings, specified in Table 1 of the NPRM: For Group 2, 3, and 4 airplanes, extend the compliance time from 300 flight hours to within 18 months after the effective date of the AD. For Model MD-90-30 and Model 717-200 airplanes, change the compliance times from flight hours to flight cycles. \n\n\tFor repetitive inspections of early configuration stop pad fittings for cracking on certain airplanes, specified in Table 2 of the NPRM: For airplanes that have been inspected before the effective date of this AD in accordance with paragraph (b) of AD 96-10-11, change the compliance times from flight hours to flight cycles. For airplanes that have not been inspected before the effective date of this AD in accordance with paragraph (b) of AD 96-10-11, extend the compliance time from 300 flight hours to within 18 months after the effective date of the AD. \n\n\tFor the initial inspection of early configuration stop pad fittings for cracking on other certain airplanes if applicable, specified in paragraph (g) of the NPRM: Delete the compliance time of 300 flight hours. \n\n\tAs justification, Boeing states thatthe service issue is driven by flight cycles, not flight hours. Boeing further states that the new compliance times of 18 months better correspond with a C-check, and that its analysis supports extending the compliance time. \n\n\tWe agree to revise the compliance times in paragraphs (g)(1) and (g)(2) and in Tables 1 and 2 of this AD, as proposed by the commenters. These changes agree with compliance times recommended in Revision 2 of Boeing Service Bulletin DC9-52-189, Revision 1 of Boeing Service Bulletin 717-52-0007, and Revision 1 of Boeing Service Bulletin MD90- 52-014, as applicable. \n\n\tHowever, we do not agree to delete the compliance time of 300 flight hours from paragraph (g) of this AD for the initial inspection of any early configuration stop pad support fitting for cracking if applicable. For certain Model DC-9 airplanes and Model MD-88 airplanes, we have added a third column to Table 1 of this AD to require accomplishing the initial inspection for cracking "before furtherflight" after the inspection to determine the P/N of the stop pad support fittings. We have determined that we no longer need to provide a grace period of 300 flight hours for certain Model DC-9 airplanes and Model MD-88 airplanes because we extended the compliance time for inspecting to determine the P/N from 300 flight hours to 18 months. \n\n\tFor Model MD-90-30 airplanes and Model 717-200 airplanes, this AD does allow a grace period of 300 flight hours to accomplish the initial inspection for cracking, as proposed by the NPRM. We have moved the compliance time for these airplanes to the third column of Table 1 of this AD. To reduce the compliance time of the NPRM for these airplanes would necessitate (under the provisions of the Administrative Procedure Act) reissuing the notice, reopening the period for public comment, considering additional comments subsequently received, and eventually issuing a final rule. That procedure could take as long as 4 months. In comparing the compliance date of the final rule after completing such a procedure with the compliance date of this final rule as issued, we find the increment in time minimal. In light of this, and in consideration of the amount of time that has already elapsed since issuance of the NPRM, we have determined that further delay of this final rule is not appropriate. \n\nRequest To Revise End-Level Effect \n\n\tBoeing requests that we revise the end-level effect of the unsafe condition on the affected airplanes in the Summary, Discussion, and paragraph (d) of the NPRM. The commenter states that cracks in the cargo door pan could result in the inability to fully pressurize an airplane "or possible pressure loss," instead of "and possible rapid decompression of the airplane" as we stated in the NPRM. Boeing states that the possibility of rapid decompression is remote because cracking in the surrounding area would mostly likely prevent pressurization of the airplane prior to reaching altitude. Boeing further states that if a leak were to occur while the airplane is pressurized, the cabin pressurization system may be able to overcome the leak, or at worst, may result in pressure reduction to a point that the cabin pressurization system could sustain. \n\n\tWe agree that the inability to pressurize the airplane or pressure loss in-flight are both more likely to occur than rapid decompression of the airplane. However, we do not agree that the possibility of rapid decompression should be excluded from the end-level effect of the unsafe condition. Therefore, we have revised the Summary section and paragraph (d) of this AD to include possible pressure loss as one end- level effect. We point out that the Discussion section of the NPRM is not retained in the AD. \n\nRequest To Correct Alternative Method of Compliance (AMOC) Paragraph \n\n\tBoeing requests that we delete citation of 14 CFR 25.571, Amendment 45, from the AMOC paragraph for McDonnell Model MD-90-30 airplanes and Model 717-200 airplanes. Boeing states that paragraph (o)(2) of the NPRM should cite 14 CFR 25.571, Amendment 25-45, for McDonnell Douglas Model DC-9-10, DC-9-20, DC-9-30, DC-9-40, and DC-9-50 series airplanes; Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), and DC-9-87 (MD-87) airplanes; and Model MD-88 airplanes. \n\n\tWe agree that we do not need to cite 14 CFR 25.571, Amendment 45, for Model MD-90-30 airplanes and Model 717-200 airplanes, since damage tolerance requirements are included in the certification basis of those airplanes. We have revised the AMOC paragraph of this AD accordingly. \n\nRequest To Correct Reference to Aircraft Maintenance Manual (AMM) \n\n\tAirTran Airways states that Boeing Service Bulletin 717-52-0007, dated December 14, 2004, references the incorrect chapter of the Boeing 717 AMM for adjustment of the forward and aft lower cargo doors. According to the commenter, the correct reference is Chapter 52-31-01 of the Boeing 717 AMM. We infer AirTran Airways requests that we correct this reference in the AD. \n\tWe agree. Boeing has confirmed that the original issue of the service bulletin should have referenced Chapter 52-31-01 of the Boeing 717 AMM. Boeing has corrected the reference in Revision 1 of the service bulletin, which we reference as an appropriate source of service information in paragraph (f)(3) of this AD. As stated previously, the original issue of the service bulletin is now referenced in paragraph (m)(3) of this AD to give credit for previous actions done in accordance with the original issue of the service bulletin; that paragraph refers operators to the correct chapter of the AMM. \n\nRequest To Identify the Method for Repairing Cracking on Model 717-200 Airplanes \n\n\tAirTran Airways also requests that we identify the FAA-approved method for repairing cracking found on the cargo door pans of Model 717-200 airplanes. The commenter would like us to make this method available before the initial threshold of the first inspection, in order to reduce airplane downtime. We infer AirTran Airways would like the repair added to paragraph (i) of this AD. \n\n\tWe do not agree, at this time, to identify the FAA-approved method for repairing cracking found on Model 717-200 airplanes. It is unlikely that cracking will be found immediately on the cargo door pans for these airplanes, since the airplane fleet of Model 717-200 airplanes has accumulated fewer total flight cycles, as compared to when cracking was found on the cargo door pans of Model DC-9 airplanes. Operators should be able to locate and replace any early configuration stop pad fittings before cracking initiates in a cargo door pan. Furthermore, the cargo doors on the Model 717-200 airplanes are similar to those on the Model DC-9 airplanes. Should cracking be found on the cargo door pan of a Model 717-200 airplane, it is likely that an operator will be able to use one of the existing repair configurations developed and approved previously for a Model DC-9 airplane. Therefore,no change to this AD is necessary in this regard. \n\nClarification of AMOC Paragraph \n\n\tWe have revised this action to clarify the appropriate procedure for notifying the principal inspector before using any approved AMOC on any airplane to which the AMOC applies. \n\nConclusion \n\n\tWe have carefully reviewed the available data, including the comments received, and determined that air safety and the public interest require adopting the AD with the changes described previously. We have determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD. \n\nCosts of Compliance \n\n\tThere are about 2,016 airplanes of the affected design in the worldwide fleet. This AD affects about 1,586 airplanes of U.S. registry. The following table provides the estimated costs for U.S. operators, at an average labor rate of $65 per hour, to comply with this AD. \n\n\t\t\t\t\t\tEstimated Costs\n\t\n\n\nAction \n\nWork hours \n\nCost per airplane \nNumber of U.S.-registered airplanes \n\nFleet cost \n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\nInspection to determine P/N for Group 2, 3, and 4 airplanes identified in Boeing Service Bulletin DC9-52-189; Model MD-90-30 airplanes; and Model 717-200 airplanes. \n1 \n$65\n1,218\n $79,170. \n\n\n\n\n\n\n\n\n\n\nInspection for cracks for Group 1 airplanes identified in Boeing Service Bulletin DC9-52-189, per inspection cycle. \n4 \n$260, per inspection cycle \n368 \n $95,680, per inspection cycle. \n\nAuthority for This Rulemaking \n\n\tTitle 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the Agency's authority. \n\n\tWe are issuing this rulemaking under the authority described in subtitle VII, part A, subpart III, section 44701, "General requirements." Under that section, Congress charges the FAA with promoting safeflight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action. \n\nRegulatory Findings \n\n\tWe have determined that this AD will not have federalism implications under Executive Order 13132. This AD 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. \n\n\tFor the reasons discussed above, I certify that this AD: \n\n\t(1) Is not a "significant regulatory action" under Executive Order 12866; \n\n\t(2) Is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and \n\n\t(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. \n\n\tWe prepared a regulatory evaluation of the estimated costs to comply with this AD and placed it in the AD docket. See the ADDRESSES section for a location to examine the regulatory evaluation. \n\nList of Subjects in 14 CFR Part 39 \n\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. \n\nAdoption of the Amendment \n\nAccordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows: \n\nPART 39--AIRWORTHINESS DIRECTIVES \n\n1. The authority citation for part 39 continues to read as follows: \n\n\tAuthority: 49 U.S.C. 106(g), 40113, 44701. \n\nSec. 39.13 (Amended) \n\n2. The Federal Aviation Administration (FAA) amends Sec. 39.13 by adding the following new airworthiness directive (AD):