AD 2003-07-13 Airworthiness Directives; Boeing Model 757-200, -200CB, and -200PF Series Airplanes

Models named: 757-200, -200CB, -200PF series. Read the applicability below — it usually turns on serial or part numbers too.

Model 757-200, -200CB, and -200PF series airplanes; line numbers (L/Ns) 1 through 979 inclusive; 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 (i)(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.

Required as indicated, unless accomplished previously,” which appears in every AD. As the commenter states, the next inspection must be done within 3,000 flight cycles or 24 months after the most recent inspection, whichever is first. No change is necessary in this regard. (Since we have revised this final rule to refer to Revision 2 of the service bulletin, credit for inspections per Revision 1 of the service bulletin is given in paragraph (h) of this AD.) Request To Clarify Definition of Wear One commenter requests that we more clearly define excessive wear of the torque tube assemblies, as it pertains to the requirement for measurements in paragraph (d) of the proposed AD. The commenter states that normal, worn, and excessively worn areas are subject to interpretation, and different individuals could interpret wear differently. We note that paragraph (d) of the proposed AD would require measurements “if any wear is found during any inspection required by paragraph (b) or (c) of this AD. * * *.” If wear is found during an inspection per paragraph (b) or (c) of this AD, the follow-on measurement required by paragraph (d) of this AD should provide adequate guidance as to the necessary course of action. However, we find that it may be helpful to provide examples of some types of wear that may be found. Therefore, paragraphs (b), (c), and (d) of this AD have been revised to include examples of wear that may be found. Request To Revise Compliance Threshold for Paragraph (e) of Proposed AD One commenter expresses concern over the inspections that would be required by paragraph (e) of the proposed AD and the requirement to replace the gearbox assembly and drive shaft assembly with new components if certain measurements are outside the limits specified in the service bulletin. The commenter is concerned about the potential cost of replacement parts, which it states may be as high as $108,000. A second commenter, the Air Transport Association of America, on behalf of its members, requests that these costs be specified in the AD. The first commenter is also concerned about the availability of necessary parts within the compliance time specified in the proposed AD, and it requests that we revise the initial compliance time to correspond with spares availability. The commenter also requests that we allow repetitive inspections of the gearbox assemblies and U-joints, as allowed for the torque tubes elsewhere in the proposed AD, so that the gearboxes or drive shaft assemblies do not have to be replaced before further flight if the measurements are outside the specified limits. We do not concur. The compliance times specified in this final rule represent an acceptable interval of time wherein affected airplanes may be allowed to operate without jeopardizing safety. Further, we find that allowing repetitive inspections in lieu of requiring replacement of discrepant parts with new parts would not ensure that the unsafe condition is addressed in a timely manner. The measurement criteria identified in paragraphs (e)(1) and (e)(2) of this AD represent the maximum wear limits for the gearboxes and U-joints. To allow continued use of these components, even with repetitive inspections, would greatly increase the potential for a trailing edge flap skew. With regard to the commenter's concern about parts availability, we have reviewed available data and find that an adequate supply of parts should be available. We have made no change to this final rule in this regard. We also do not concur with the other commenter's request that we include the cost associated with replacing the gearboxes or U-joints in the AD. The economic analysis included in AD actions is limited only to the cost of actions actually required by the rule. It does not consider the costs of “on-condition” actions, such as replacing a part if a discrepancy is detected during a required inspection. Such “on-condition” actions would be required to be accomplished—regardless of AD direction—to correct an unsafe condition identified in an airplane and to ensure operation of that airplane in an airworthy condition, as required by the Federal Aviation Regulations. Request To Revise Repetitive Interval for Paragraph (e) of Proposed AD One commenter requests that we increase the repetitive interval for the inspections of the gearbox assemblies and U-joints that would be required by paragraph (e) of the proposed AD. The proposed AD states a repetitive interval of 3,000 flight cycles or 24 months, whichever is first; the commenter requests an interval of 4,500 flight cycles or 48 months, whichever is later. To justify its request, the commenter presents data from three airplanes in its fleet. These data show that no discrepancies were found on two of the airplanes, and only minor wear of one torque tube was found on the third. The commenter also contends that calendar time is not useful for gauging wear, as wear is a function of flight cycles. We do not concur. Three airplanes do not constitute an adequate statistical sample size to determine that extension of the repetitive interval would provide an acceptable level of safety. While in general the number of flight cycles is a large contributor to wear on components, the intent of this AD is to protect against all types of wear. This includes wear accelerated by corrosion, which is a function of calendar time. We have made no change to the final rule in this regard. Explanation of Additional Change to Proposed AD We have added paragraph (i)(2) to this final rule to give credit for accomplishment of certain alternative methods of compliance that were approved previously in accordance with AD 92-25-01, amendment 39-8416. Also, throughout this final rule, we have changed the citation for Boeing Service Bulletin 757-27-0107, dated June 16, 1994, to exclude the Evaluation Form. The form is intended to be completed by operators and submitted to the airplane manufacturer to provide input on the quality of the service bulletin; however, this AD does not include such a requirement. 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 979 Model 757-200, -200CB, and -200PF series airplanes of the affected design in the worldwide fleet. In AD 92-25-01, we estimated that approximately 279 U.S.-registered airplanes would be subject to the inspections in that AD. For these airplanes, the currently required inspections take approximately 2 work hours per airplane, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the currently required actions on U.S. operators is estimated to be $33,480, or $120 per airplane, per inspection cycle. We estimate that approximately 283 U.S.-registered airplanes (Group 1 of Boeing Service Bulletin 757-27A0125, Revision 2) will be subject to the required inspection of torque tube assemblies 3 and 6. This inspection will take approximately 2 work hours per airplane, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of this new inspection required for U.S. operators of Group 1 airplanes is estimated to be $33,960, or $120 per airplane, per inspection cycle. We estimate that approximately 376 U.S.-registered airplanes (Groups 1 and 2 of Boeing Service Bulletin 757-27A0125, Revision 2) will be subject to the required inspection of torque tube assemblies 4 and 5. This inspection will take approximately 2 work hours per airplane, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of these new inspections required for U.S. operators of Groups 1 and 2 airplanes is estimated to be $45,120, or $120 per airplane, per inspection cycle. We estimate that 643 U.S.-registered airplanes (Groups 1, 2, and 3 of Boeing Service Bulletin 757-27A0125, Revision 2) will be subject to the new required inspections of the gear box assemblies and U-joints of the drive shaft assembly. These inspections will take approximately 4 work hours per airplane, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of these new inspections required for U.S. operators is estimated to be $154,320, or $240 per airplane, per inspection cycle. 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. Should an operator elect to accomplish the modification that involves replacement of torque tube assemblies 3 and 6, this modification will take approximately 5 work hours per airplane, at an average labor rate of $60 per work hour. Required parts will cost approximately $4,550. Based on these figures, the cost impact of this optional modification is estimated to be $4,850 per airplane. Should an operator elect to accomplish the modification that involves replacement of torque tube assemblies 4 and 5, this modification will take approximately 5 work hours per airplane, at an average labor rate of $60 per work hour. Required parts will cost approximately $4,550. Based on these figures, the cost impact of this optional modification is estimated to be $4,850 per airplane. 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 [Amended] 2. Section 39.13 is amended by removing amendment 39-8416 (57 FR 54298, November 18, 1992), and by adding a new airworthiness directive (AD), amendment 39-13109, to read as follows: 2003-07-13 Boeing: Amendment 39-13109. Docket 2001-NM-329-AD. Supersedes AD 92-25-01, Amendment 39-8416.