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RULES and REGULATIONS DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR Part 39 [Docket No. 89 -NM- 60 -AD; Amdt. 39 - 6488] Airworthiness Directives; Boeing Model 727 Series Airplanes Wednesday, March 7, 1990 AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 727 series airplanes, which would require incorporation of certain structural mo difications. This amendment is prompted by reports of recent incidents involving fatigue cracking and corrosion in transport category airplanes that are approaching or have exceeded their design life goal. These incidents jeopardized the airworthiness of the affected airplanes. These conditions, if not corrected, could result in a degradation in the structural capabilities of the affected airplanes. This action also reflects the FAA's decision that long term continued operational safety should be assured by actual modification of the airframe rather than repetitive inspection. DATES: Effective April 17, 1990. The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of April 17, 1 990. ADDRESSES: The applicable service information may be obtained from Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124. This information may be examined at the FAA, Northwest Mountain Region, 17900 Pacific Highway South, Seattle, Washington; at the Seattle Aircraft Certification Office, FAA, Northwest Mountain Regin, 9010 East Marginal Way S outh, Seattle, Washington; or at the Office of the Federal Register, 1100 L Street NW., Room 8301, Washington, DC. FOR FURTHER INFORMATION CONTACT:Mr. Stanton R. Wood, Airframe Branch, ANM- 120S; telephone (206) 431 - 1924. Mailing address: FAA, Northwest Mountain Region, 17900 Pacific Highway South, C- 68966, Seattle, Washington 98168. SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal Aviation Regulations to include an airworthiness directive, applicable to Boeing 727 series airplanes, which requires incorporation of certain structural mo difications, was published in the Federal Register on May 23, 1989 ( 54 FR 22302).2

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received. The manufacturer suggested that the latest revision to Boeing Document D6 - 54860 be used to reflect the current service bulletin revision levels. The FAA concurs and the final rule has been revised to reflect Document D6 - 54860, Revision C as the appropriate service document. The changes to Document D6 - 54860 do not add or delete any identified service bulletins, but merely clarify and correct the document. Acceptable service bulletin revision levels that are identified in the document have been increased. Several commenters suggested that the age of the airplane should be made available to the traveling public when the flight reservation is made. The FAA considers this suggestion to be beyond the scope of this rulemaking action. However, the FAA has determined that an airplane properly maintained will be safe beyond its designed economic life goal. Therefore, the FAA does not consider that stating the age of an airplane will do anything to improve the level of safety. The most important thing is to assure that older airplanes are properly maintained, and this is the basis for the actions taken by

the FAA with regard to the modification program mandated by this AD action, and the soon-to -be-proposed mandatory corrosion progam. One commenter proposed that all older airplanes be retired upon reaching 20 years. The FAA does not concur. Airplanes maintained in accordance with the actions required by this final rule, existing AD's, as well as other new actions to be proposed by the FAA based on the recommendations of the Aging Aircraft Task Force, should be able to remain in service indefinitely. One commenter requested that the compliance requirements be clarified, and questioned whether it was necessary to comply with certain service bulletins upon the airplane reaching 20 years of age or within 4 years. The FAA considers the compliance requirements to be clearly stated in paragraph A. of the final rule. In general, however, the modifications must be completed before an airplane reaches 20 years of service or within 4 years after the effective date of the AD, whichever is later. Another commenter requested that FAA Designated Engineering Representatives (DER) at the manufacturer's facility be allowed to approve certain alternate means of compliance to this AD. The FAA does not concur. Airworthiness directives are a primary responsibility of the FAA, and alternate means of com pliance must be approved by the Manager, Seattle Aircraft Certification Office. This function cannot be delegated to a DER. While DER's are authorized to determine whether an alternate design com plies with a specific requirement, they are not authorized to make discretionary determinations as to what the applicable requirement is. Another commenter requested that the rule be revised to allow operators to perform minor deviations from the AD without obtaining FAA approval. The FAA does not concur, because what is “minor” is open to interpretation. The FAA must continue to approve all deviations. An operator of an executive Model 727 stated that low utilization operators were not involved in the Aging Aircraft Task Force working group and, therefore, their concerns were not considered when the mandatory mo dification program was developed. Further, the commenter did not understand the basis for incorporation of certain mo difications on airplanes that are 20 years old. The FAA notes that the working group did have members that were considered3

to be low utilization operators. The working group selected certain service bulletins for incorporation on airplanes that were 20 years old. The procedures described in those service bulletins address problems associated with corrosion and/or stress corrosion that are time -dependent; as such, these problems are more appropriately corrected by mo dification of the airplane prior to reaching 20 years of age, rather than 60,000 flight cycles. This commenter further stated that if the 20 -year com pliance time was selected because of corrosion, the em

phasis should be placed upon a corrosion control program. The FAA concurs that corrosion control is important, and has initiated rulemaking to propose a corrosion program that will affect Model 727 airplanes. A Notice of Proposed Rulemaking is being issued concurrently with this amendment. However, the actions required by this final rule, prior to an aircraft reaching 20 years of age, are all related to known, frequent problems related to corrosion that can be alleviated after the modifications described in the service bulletins are incorporated. Finally, this commenter stated that the FAA appears to be relying upon the mandatory modification program while reducing reliance on non-destructive testing. The FAA does not agree. This mandatory modification program will not replace the diligent, continuing inspection of the airplane fleet for defects, as required by the FAA-approved maintenance programs and other existing AD' s. Another Model 727 executive operator stated that it has not experienced the problems associated with corrosion, cracking, or delamination. Therefore, the commenter proposed that only inspections be required for low-utilization aircraft. The FAA does not concur with this suggestion for the reasons noted in the above paragraph as well as in the preamble to the Notice. Several commenters expressed concern regarding the ability of the manufacturer to supply the parts necessary to complete the modifications . The FAA considered this concern during the development of the compliance time for this AD action. The manufacturer has confirmed that ample parts will be available to meet the schedule mandated by this final rule. Various foreign airworthiness authorities stated that (1) compliance times were arbitrarily chosen, independent of any fatigue history; (2) no mandatory inspections were required for all areas not affected by an existing AD; and (3) no post-mo dification inspections were proposed. As for item (1), the FAA does not concur with the suggestion that the com pliance times for the mo difications were arbitrarily chosen. On the contrary, in developing the appropriate compliance times for this AD action, the FAA, with input from the aviation industry/community, considered not only the degree of urgency associated with addressing the identified unsafe condition, but the practical aspects of the availability of required parts, the time necessary to install the required mo difications, and the availability of overhaul facilities to perform the necessary work. Further, fatigue history is always considered when assessing inspection thresholds for problems caused by f atigue. Likewise, repetitive inspection intervals are based on damage tolerance asses sments when appropriate. As for item (2), the FAA does not fully agree. While several of the service bulletins included in Boeing Document D6 - 54860 are the subject of currently existing AD's (which require inspections and optional mo difications), other service bulletins and their related inspections are under consideration for mandatory action, and will be handled on a case-by-case basis. As was explained in detail in the preamble to the Notice, safety will continue to be maintained by various means currently in place that are considered satisfactory to detect damage prior to the occurrence of an unsafe4

condition. These include on- going basic maintenance programs, inspections/modifications required by existing AD's, Supplemental Structural Inspection Document programs, and the like. As for item (3), the FAA has determined that there is no need to stipulate special “post-modification inspections” since the operators' existing on- going inspection programs include such inspections and are acceptable to monitor the affected area. Accordingly, the FAA has determined that no change to the final rule is warranted based on these comments made by the foreign airworthiness authorities. Several commenters requested that the FAA accept alternate means of com pliance involving inspections if required mo dification parts cannot be obtained. The FAA will review each case individually to consider alternate means of compliance, as provided for in paragraph B of the final rule. One commenter questioned whether there is adequate maintenance capability to com ply with this rule and similar rules affecting other aging airplanes. As discussed above, the FAA considered this aspect when developing the compliance times for this action. At this point, the FAA considers there to be adequate facilities for accom plishing the requirements of this rule in a timely manner. Finally, a commenter questioned the accuracy of the number of aircraft affected by the proposed rule and the estimated costs. This commenter, however, provided no new figures to contradict those reflected in the Notice. The FAA based the number of airplanes and cost estimates upon the best data that was currently available. The cost estimates represent the average costs and rates based on overall industry standards. 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 change previously described. The FAA has determined that this change will not increase the economic burden on any operator nor increase the scope of the AD. There are approximately 1,710 Model 727 series airplanes of the affected design in the worldwide fleet. It is estimated that 67 airplanes of U.S. registry will be affected by this AD within the initial threshold of 4 years. The cost to modify each airplane is estimated to be $1,057,212. This cost includes the price of mo dification kits, which is $362,932 per airplane, and the estimated num ber of manhours to accomplish the modifications, which is approximately 17,357 manhours at $40 per manhour. It does not include the cost of dow ntime, planning, set up, familiarization, or tool acquisition costs. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $70,833,204 within the initial threshold of 4 years. Additional airplanes will be affected as they accumulate time-in- service and reach the threshold for modification. The regulations adopted herein will not have substantial direct effects on the States, on the relationship between the national government and the States, or on the distribution of p ower and responsibilities among the various levels of government. Therefore, in accordance with Executive Order 12612 , it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.5

For the reasons discussed above, I certify that this action (1) is not a “major rule” under Executive Order 12291 ; (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 im pact, 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 is contained in the regulatory docket. A copy of it may be obtained from the Rules Docket. List of Subjects in 14 CFR part 39 Air transportation, Aircraft, Aviation safety, Safety, Incorporation by reference. Adoption of the Amendment Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends 14 CFR part 39 of the Federal Aviation Regulations as follows: PART 39

—[AMENDED]1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. 1354(a), 1421 and 1423; 49 U.S.C. 106(g)(Revised) Pub. L. 97 -449, January 12, 1983); and 14 CFR 11.89 . § 3 9.13 [Amended] 2. By adding the following new airworthiness directive: Boeing: Applies to Model 727 series airplanes, listed in Boeing Document No. D6 - 54860, Revision C, dated D ecem ber 11, 1989, certificated in any category. Compliance required as indicated, unless previously accomplished. To prevent structural failure, accomplish the following: A. Except as provided below, prior to reaching the incorporation thresholds listed in Boeing Document No. D6 - 54860, Revision C, dated December 11, 1989, “Aging Airplane Service Bulletin Structural Modification Program

—Model 727” (hereinafter called “the Document”), or within the next 4 years after the effective date of this AD, whichever occurs later, accomplish the structural modifications listed in section 3 of the Document. Modifications for w hich the incorporation threshold is identified in the Document as a specific date must be accom plished by that date in lieu of the 4 years specified in this paragraph. Note: The mo difications required by this paragraph do not terminate the inspection requirements of any other AD unless that AD specified that any such modification constitutes terminating action of the inspection requirements. B. An alternate means of com pliance or adjustment of

the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region.6

Note: The request should be forwarded through an FAA Principal Maintenance Inspector (PMI), who will either concur or comment, and then send it to the Manager, Seattle Aircraft Certification Office. C. Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base in order to comply with the requirements of this AD. The mo difications shall be done in accordance with Boeing Document D6 - 54860, Revision C, dated December 11, 1989, “Aging Airplane Service Bulletin Structural Modification Program

—Model 727.”This incorporation by re ference 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 Airplanes, P.O. Box 3707, Seattle, Washington 98124. Copies may be inspected at the FAA, Northwest Mountain Region, 17900 Pacific Highway South, Seattle, Washington; or at the Seattle Aircraft Certification Office, FAA, Northwest Mountain Region, 9010 East Marginal Way S outh, Seattle, Washington; or at the Office of the Federal Register, 1100 L Street NW., Room 830 1, Washington, DC. This amendment becomes effective April 17, 1990. Issued in Seattle, Washington, on January 16, 1990. Leroy A. Keith, Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 90 - 5131 Filed 3 - 6 -90; 11:59 am] B ILLING CODE 4910 - 13 -M 55 FR 8370