02-208. Airworthiness Directives; Boeing Model 757 Series Airplanes Equipped with Rolls Royce RB211 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 equipped with Rolls Royce RB211 engines, that currently requires modification of the nacelle strut and wing structure. This action would add a one-time inspection of the middle gusset of the inboard side load fitting for proper alignment, and a one-time inspection of certain fastener holes in the lower spar fitting of the nacelle strut and wing structure for cracking, and corrective actions, if necessary. For certain airplanes, this action would require installation of new fasteners. 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. These actions are intended to address the identified unsafe condition.

DATES:

Comments must be received by February 19, 2002.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-376-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. 2000-NM-376-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, P.O. 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 2000-NM-376-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. 2000-NM-376-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

On November 17, 1999, the FAA issued AD 99-24-07, amendment 39-11431 (64 FR 66370, November 26, 1999), applicable to certain Boeing Model 757 series airplanes equipped with Rolls Royce RB211 engines, to require modification of the nacelle strut and wing structure. That action was prompted by reports indicating that the actual operational loads applied to the nacelle are higher than the analytical loads that were used during the initial design. Such an increase in loading can lead to fatigue cracking in primary strut structure prior to an airplane's reaching its design service objective. 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 99-24-07, the FAA has reviewed and approved Boeing Service Bulletin 757-54-0035, Revision 1, dated April 15, 1999. The procedures in this service bulletin are similar to those in Boeing Service Bulletin 757-54-0035, dated July 17, 1997, which was referenced as the appropriate source of service information for the modification of the nacelle strut and wing structure required by the existing AD. However, Revision 1 describes new procedures for an examination of the middle gusset of the inboard side load fitting to determine if the angle between the middle gusset and the outboard face of the lug is out of alignment. If the angle is out of alignment, the corrective action involves machining the middle gusset to the specified angle.

Revision 1 also describes procedures for removing and discarding the midchord and aft bulkhead fasteners of the lower spar fitting, and doing a one-time eddy current inspection of those fastener holes for cracking. If any indication of a crack is found, the service bulletin specifies contacting the airplane manufacturer for repair instructions. The service bulletin also describes procedures to increase the diameter of the fastener holes and install new, improved fasteners. For airplanes modified per the original issue of the service bulletin, these new procedures are described separately in Part V of Revision 1. Accomplishment of the actions specified in the service bulletin is intended to adequately address the identified unsafe condition.

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 99-24-07 to continue to require modification of the nacelle strut and wing structure. This action would add a one-time inspection of the middle gusset of the inboard side load fitting for proper alignment, and corrective action, if necessary; and a one-time inspection of the lower spar fitting of the nacelle strut and wing structure for cracking, and enlargement of the holes and replacement of certain fasteners with new, improved fasteners. The actions would be required to be accomplished according to the service bulletin described previously, except as discussed below.

Differences Between Proposed AD and Service Bulletin

Although the service bulletin specifies that the manufacturer may be contacted for disposition of certain repairs, this proposed AD would require such repairs to be accomplished per a method approved by the FAA, or per data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the Manager, Seattle Aircraft Certification Office, to make such findings.

This proposed AD requires accomplishment of the inspections within 3 years after accomplishment of the modification of the nacelle strut and wing structure, or 3 years after the effective date of this AD, whichever is later. The service bulletin recommends that operators accomplish the actions in the bulletin “at a maintenance time when the engines are removed, but before the airplane gets 50,000 total flight cycles.” In developing an appropriate compliance time for this AD, the FAA considered not only the manufacturer's recommendation, but the degree of urgency associated with addressing the subject unsafe condition, the average utilization of the affected fleet, and the time necessary to perform the inspections (1 hour for detailed visual/8 hours for fastener removal/eddy current). In light of all of these factors, the FAA finds a 3-year compliance time for initiating the inspections to be warranted, in that it represents an appropriate interval of time allowable for affected airplanes to continue to operate without compromising safety.

Although the service bulletin specifies an examination of the middle gusset of the inboard side load fitting for proper alignment, this proposed AD would require a detailed visual inspection for accomplishment of that action. A note has been included in this proposed rule to define that inspection.

Cost Impact

There are approximately 394 airplanes of the affected design in the worldwide fleet. The FAA estimates that 176 airplanes of U.S. registry would be affected by this proposed AD.

The modification that is currently required by AD 99-24-07 takes approximately 1,049 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. This work hour figure includes the time it will take to remove and reinstall the struts from the airplane as well as the time to gain and close access to the adjacent wing structure. Based on these figures, the cost impact of the currently required modification on U.S. operators is estimated to be $11,077,440, or $62,940 per airplane.

This cost impact figure does not reflect the cost of the terminating actions described in the service bulletins listed in paragraph I.C., Table I, “Strut Improvement Bulletins,” on page 6 of Boeing Service Bulletin 757-54-0035, that are required to be accomplished prior to, or concurrently with, the modification of the nacelle strut and wing structure. Since some operators may have accomplished certain modifications on some or all of the airplanes in its fleet, while other operators may not have accomplished any of the modifications on any of the airplanes in its fleet, the FAA is unable to provide a reasonable estimate of the cost of accomplishing the terminating actions described in the service bulletins listed in Table I of the service bulletin.

It would take approximately 1 work hour per airplane to accomplish the new detailed visual inspection of the middle gusset, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the inspection proposed by this AD on U.S. operators is estimated to be $60 per airplane.

It would take approximately 8 work hours per airplane to accomplish the new fastener removal and eddy current inspection, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the removal and inspection proposed by this AD on U.S. operators is estimated to be $480 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 39-11431 (64 FR 66370, November 26, 1999), and by adding a new airworthiness directive (AD), to read as follows:

Boeing: Docket 2000-NM-376-AD. Supersedes AD 99-24-07, Amendment 39-11431.

Applicability: Model 757 series airplanes equipped with Rolls Royce 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 (c)(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.

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 99-24-07

Modification

(a) Modify the nacelle strut and wing structure according to Boeing Service Bulletin 757-54-0035, dated July 17, 1997, or Revision 1, dated April 15, 1999, at the later of the times specified in paragraph (a)(1) or (a)(2) of this AD. All of the terminating actions described in the service bulletins listed in paragraph I.C., Table I, “Strut Improvement Bulletins,” on page 6 of Boeing Service Bulletin 757-54-0035, or on page 7 of Revision 1 of the service bulletin, as applicable, must be accomplished according to those service bulletins prior to, or concurrently with, the accomplishment of the modification of the nacelle strut and wing structure required by this paragraph. After the effective date of this AD, use only Revision 1 of the service bulletin.

(1) Prior to the accumulation of 37,500 total flight cycles, or prior to 20 years since the date of manufacture of the airplane, whichever occurs first.

(2) Within 3,000 flight cycles after January 3, 2000 (the effective date of AD 99-24-07, amendment 39-11431).

New Requirements of This AD

One-Time Inspections/Corrective Actions

(b) For airplanes that have done the modification required by paragraph (a) of this AD according to Boeing Service Bulletin 757-54-0035, dated July 17, 1997: Within 3 years after doing the modification required by paragraph (a) of this AD, or 3 years after the effective date of this AD, whichever is later, do the requirements specified in paragraphs (b)(1) and (b)(2) of this AD.

(1) Do a one-time detailed visual inspection of the middle gusset of the inboard side load fitting for proper alignment according to Part II of the Accomplishment Instructions of Boeing Service Bulletin 757-54-0035, Revision 1, dated April 15, 1999. If the gusset is not aligned properly, before further flight, machine the gusset to the specified angle, according to the service bulletin.

Note 2:

For the purposes of this AD, a detailed visual inspection is defined as: “An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required.”

(2) Remove and discard the midchord and aft bulkhead fasteners of the lower spar fitting and do a one-time eddy current inspection of those fastener holes for cracking according to Part V of the Accomplishment Instructions of Boeing Service Bulletin 757-54-0035, Revision 1, dated April 15, 1999.

(i) If any cracking is found during the inspection required by paragraph (b)(2) of this AD: Before further flight, repair per a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or per data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative 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 Manager's approval letter must specifically reference this AD. Then do paragraph (b)(2)(ii) of this AD.

(ii) If no cracking is found during the inspection required by paragraph (b)(2) of this AD, or after repair of cracking as required by paragraph (b)(2)(i) of this AD: Before further flight, increase the diameter of the fastener holes and install new fasteners, according to the service bulletin.

Alternative Methods of Compliance

(c)(1) 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.

(2) Alternative methods of compliance, approved previously in accordance with AD 99-24-07, amendment 39-11431, are approved as alternative methods of compliance with paragraph (a) of this AD.

Note 3:

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

(d) 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 December 28, 2001.

Vi L. Lipski,

Manager, Transport Airplane Directorate, Aircraft Certification Service.