03-15336. Airworthiness Directives; Boeing Model 757 Series Airplanes Powered by Pratt & Whitney Engines

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain Boeing Model 757 series airplanes, that currently requires modification of the nacelle strut and wing structure. This action would reduce a certain compliance time in the existing AD. The actions specified by the proposed AD are intended to prevent fatigue cracking in primary strut structure and consequent reduced structural integrity of the strut. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by August 4, 2003.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2001-NM-370-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays. Comments may be submitted via fax to [phone]. Comments may also be sent via the Internet using the following address: [e-mail]. Comments sent via fax or the Internet must contain “Docket No. 2001-NM-370-AD” in the subject line and need not be submitted in triplicate. Comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 for Windows or ASCII text.

The service information referenced in the proposed rule may be obtained from Boeing Commercial Airplane Group, PO Box 3707, Seattle, Washington 98124-2207. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT:

Dennis Stremick, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this action may be changed in light of the comments received.

Submit comments using the following format:

• Organize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues.
• For each issue, state what specific change to the proposed AD is being requested.
• Include justification (e.g., reasons or data) for each request.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2001-NM-370-AD.” The postcard will be date stamped and returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2001-NM-370-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

On September 28, 2000, the FAA issued AD 2000-20-09, amendment 39-11920 (65 FR 59703, October 6, 2000), applicable to certain Boeing Model 757 series airplanes, that requires modification of the nacelle strut and wing structure. The requirements of that AD are intended to prevent fatigue cracking in primary strut structure and consequent reduced structural integrity of the strut.

Actions Since Issuance of Previous Rule

Since the issuance of AD 2000-20-09, the airplane manufacturer has done a new structural reassessment of the upper link of the strut of Boeing Model 757 series airplanes powered by Pratt & Whitney engines. This reassessment indicates that certain design changes are needed on the upper link to ensure that fatigue cracking does not occur on the primary strut structure before an airplane reaches its design service objective of 20 years, or 50,000 flight cycles. Analysis indicates that such cracking, if it were to occur, would grow at a much greater rate than originally expected. Fatigue cracking in primary strut structure would result in reduced structural integrity of the strut.

The compliance time for the modification of the upper link (Boeing Service Bulletin 757-54-0036, dated May 14, 1998) required by paragraph (b) of AD 2000-20-09, has been reduced due to this new structural assessment.

Explanation of New Relevant Service Information

We have reviewed and approved Boeing Service Bulletin 757-54-0034, Revision 1, dated October 11, 2001. (Boeing Service Bulletin 757-54-0034, dated May 14, 1998, was referenced as the appropriate source of service information for the actions required by paragraph (a) of AD 2000-20-09.) We find that the changes incorporated in Revision 1 of the service bulletin are not substantive, meaning that airplanes modified per the original issue of the service bulletin are not subject to any additional work under Revision 1 of the service bulletin. Therefore, we have added Revision 1 of the service bulletin as another source of service information for the accomplishment of the modification required by paragraph (a) of this AD.

Explanation of Requirements of Proposed Rule

Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would supersede AD 2000-20-09 to continue to require modification of the nacelle strut and wing structure. This new action proposes to reduce a certain compliance time in the existing AD. The actions would be required to be accomplished in accordance with the service bulletins described previously, and as discussed below.

Difference Between This Proposed AD and Service Bulletin 757-54-0036

This proposed AD would add a grace period of 2 years to the thresholds recommended in the service bulletin for accomplishment of the modification of the upper link and wire support bracket of the strut, as specified in paragraph (d) of this AD, as follows: Prior to the accumulation of 27,000 total flight cycles (for Model 757-200 series airplanes) or 29,000 total flight cycles (for Model 757-200PF series airplanes), or within 2 years after the effective date of this AD, whichever is later.

Cost Impact

There are approximately 317 airplanes of the affected design in the worldwide fleet. The FAA estimates that 278 airplanes of U.S. registry would be affected by this proposed AD. Since this proposed AD would merely reduce the compliance time for certain actions required by AD 2000-20-09 (Service Bulletin 757-54-0036), it would add no additional costs, and would require no additional work to be performed by affected operators. The current costs associated with AD 2000-20-09 are reiterated in their entirety (as follows) for the convenience of affected operators:

It will take approximately 800 work hours per airplane to accomplish the required modification of the nacelle strut and wing structure described in Boeing Service Bulletin 757-54-0034, at an average labor rate of $60 per work hour. Required parts will be provided at no cost by the airplane manufacturer. Based on these figures, the cost impact of this required modification on U.S. operators is estimated to be $13,344,000, or $48,000 per airplane.

It will take approximately 26 work hours per airplane to accomplish the actions described in Boeing Service Bulletin 757-54-0027, Revision 1, at an average labor rate of $60 per work hour. Required parts will be provided at no cost by the airplane manufacturer. Based on these figures, the cost impact of these required actions on U.S. operators is estimated to be $433,680, or $1,560 per airplane.

It will take approximately 90 work hours per airplane to accomplish the actions described in Boeing Service Bulletin 757-54-0036, at an average labor rate of $60 per work hour. Required parts will be provided at no cost by the airplane manufacturer. Based on these figures, the cost impact of these required actions on U.S. operators is estimated to be $1,501,200, or $5,400 per airplane.

The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the current or proposed 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 proposed herein would 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 proposal would not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that this proposed regulation (1) is not a “significant regulatory action” under Executive Order 12866; (2) is not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, 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 copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend 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 39-11920 (65 FR 59703, October 6, 2000), and by adding a new airworthiness directive (AD), to read as follows:

Boeing: Docket 2001-NM-370-AD. Supersedes AD 2000-20-09, Amendment 39-11920.

Applicability: Model 757 series airplanes powered by Pratt & Whitney engines, line numbers 1 through 735 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 (e) 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 prevent fatigue cracking in primary strut structure and consequent reduced structural integrity of the strut, accomplish the following:

Restatement of Requirements of AD 2000-20-09:

Modifications

(a) Modify the nacelle strut and wing structure on both the left and right sides of the airplane, in accordance with Boeing Service Bulletin 757-54-0034, dated May 14, 1998; or Revision 1, dated October 11, 2001; at the later of the times specified in paragraph (a)(1) or (a)(2) of this AD.

(1) Prior to the accumulation of 37,500 total flight cycles, or within 20 years since the date of manufacture, whichever occurs first. Use of the optional threshold formula described in paragraph I.D. of the service bulletin is an acceptable alternative to the 20-year threshold.

(2) Within 3,000 flight cycles after November 13, 2000 (the effective date of AD 2000-20-09, amendment 39-11920).

(b) Except as provided by paragraph (d) of this AD: Prior to or concurrently with the accomplishment of the modification of the nacelle strut and wing structure required by paragraph (a) of this AD; as specified in paragraph I.D., Table I, “Strut Improvement Bulletins,” on page 5 of Boeing Service Bulletin 757-54-0034, dated May 14, 1998; accomplish the actions specified in Boeing Service Bulletin 757-54-0027, Revision 1, dated October 27, 1994; and Boeing Service Bulletin 757-54-0036, dated May 14, 1998, as applicable, in accordance with those service bulletins.

Repair

(c) If any damage to airplane structure is found during the accomplishment of the modification required by paragraph (a) of this AD; and the service bulletin specifies to contact Boeing for appropriate action: Prior to further flight, repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or in accordance with data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative (DER) who has been authorized by the Manager, Seattle ACO, to make such findings. For a repair method to be approved by the Manager, Seattle ACO, as required by this paragraph, the approval letter must specifically reference this AD.

New Requirements of this AD:

Modification

(d) Modify the nacelle strut (includes replacing the upper link with a new, improved part and modifying the wire support bracket attached to the upper link) in accordance with Boeing Service Bulletin 757-54-0036, dated May 14, 1998, at the earlier of the times specified in paragraph (d)(1) or (d)(2) of this AD.

(1) Prior to or concurrently with accomplishment of the modification of the nacelle strut and wing structure required by paragraph (a) of this AD.

(2) Prior to the accumulation of 27,000 total flight cycles (for Model 757-200 series airplanes) or 29,000 total flight cycles (for Model 757-200PF series airplanes), or within 2 years after the effective date of this AD, whichever is later.

Alternative Methods of Compliance

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

Note 2:

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

Special Flight Permits

(f) 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.

Issued in Renton, Washington, on June 12, 2003.

Kalene C. Yanamura,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.