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###### Department of Transportation

###### Federal Aviation Administration

          - 14 CFR Part 39
          - [Docket No. 2000-NM-334-AD]
          - RIN 2120-AA64

# AGENCY:

Federal Aviation Administration, DOT.

# ACTION:

Notice of proposed rulemaking (NPRM).

# SUMMARY:

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 777-200 series airplanes. This proposal would require inspections for cracking of the web of the horizontal and sloping pressure decks of the fuselage and certain stiffener splice angles and stiffener end fittings, and repair, if necessary. This proposal would also provide an optional preventative modification, which ends the repetitive inspections. This action is necessary to find and fix cracking of the web of the horizontal and sloping pressure decks, which could result in rapid in-flight decompression of the airplane. This action is intended to address the identified unsafe condition.

# DATES:

Comments must be received by August 13, 2001.

# ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-334-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 (425) 227-1232. Comments may also be sent via the Internet using the following address: 9-anm-nprmcomment@faa.gov. Comments sent via fax or the Internet must contain “Docket No. 2000-NM-334-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:

Stan Wood, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2772; fax (425) 227-1181.

# 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                           ( print page 34131)                        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-334-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-334-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

## Discussion

The FAA has received a report indicating that, during fatigue testing of a Boeing Model 777-200 series airplane, fatigue cracking was found in the web of the horizontal and sloping pressure decks of the fuselage. Stiffener splice angles at body station (BS) 1287 and stiffener end fittings at BS 1245 were also found cracked. The cracks in the web were found in the radius of the milled pockets of the horizontal and sloping pressure decks. Analysis revealed that the cracks initiated at the upper surface of the web and propagated down through the web to the tangent point of the machined fillet radius of the milled pockets. Such cracks, if not found and fixed, could result in a rapid in-flight decompression of the airplane.

## Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing Special Attention Service Bulletin 777-53-0004, dated May 11, 2000, which describes procedures for inspections for cracking of the web of the horizontal and sloping pressure decks of the fuselage and certain stiffener splice angles and stiffener end fittings, and repair or modification, if necessary. The subject area has been divided into three inspection areas, and the service bulletin recommends a different compliance threshold for each inspection area, based on when cracks were found on the test airplane during the fatigue test. The three areas are subject to the following inspections:
    - Area 1: Repetitive internal high frequency eddy current (HFEC) inspections or, alternatively, external low frequency eddy current (LFEC) inspections, of the horizontal pressure deck web.
    - Area 2: Repetitive internal HFEC inspections or, alternatively, repetitive external LFEC inspections of the horizontal pressure deck web, repetitive internal HFEC inspections of the sloping pressure deck, and repetitive detailed visual inspections of the stiffener splice angles at BS 1287 and the stiffener end fittings at BS 1245.
    - Area 3: Repetitive internal HFEC inspections or, alternatively, repetitive external LFEC inspections of the horizontal pressure deck web, and repetitive internal HFEC inspections of the sloping pressure deck.

The service bulletin also describes procedures for repair of cracks, as well as a preventative modification, which would eliminate the need for the repetitive inspections for the repaired or modified areas. The preventative modification described in the service bulletin is an option for ending the repetitive inspections on airplanes with no cracking. Accomplishment of the actions specified in the service bulletin is intended to adequately address the identified unsafe condition.

The effectivity listing of the service bulletin includes Model 777-200 series airplanes with line numbers 001 through 093. The structure of the area subject to this proposed AD has been redesigned on airplanes with line numbers 094 and subsequent, so these airplanes are not subject to the actions described in the service bulletin.

## 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 require accomplishment of the actions specified in the service bulletin described previously, except as discussed below.

## Difference Between Proposed Rule and Service Bulletin

Although the service bulletin specifies that the manufacturer may be contacted for disposition of certain repair conditions, this proposal would require the repair of those conditions 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.

## Cost Impact

There are approximately 93 airplanes of the affected design in the worldwide fleet. The FAA estimates that 27 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 36 work hours per airplane to accomplish the proposed inspections, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the proposed AD on U.S. operators is estimated to be $58,320, or $2,160 per airplane, per inspection cycle.

The cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this proposed 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                           ( print page 34132)                        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 

2. Section 39.13 is amended by adding the following new airworthiness directive:

**Boeing:**                                 Docket 2000-NM-334-AD.                            

*Applicability:*                                 Model 777-200 series airplanes, line numbers 001 through 093 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 find and fix cracking of the web of the horizontal and sloping pressure decks, which could result in rapid in-flight decompression of the airplane, accomplish the following:

## Initial Inspections

(a) Do the inspections in paragraphs (a)(1), (a)(2), and (a)(3) of this AD at the compliance times specified in those paragraphs. Do the inspections according to the Accomplishment Instructions of Boeing Special Attention Service Bulletin 777-53-0004, dated May 11, 2000.

(1) Area 1: Prior to the accumulation of 16,000 total flight cycles, do an internal high frequency eddy current (HFEC) inspection or an external low frequency eddy current (LFEC) inspection of the horizontal pressure deck web in Inspection Area 1, as defined in the service bulletin.

(2) Area 2: Prior to the accumulation of 31,000 total flight cycles, do an internal HFEC inspection or an external LFEC inspection of the horizontal pressure deck web, an internal HFEC inspection of the sloping pressure deck, and a detailed visual inspection of the stiffener end fittings at body station (BS) 1245 and the stiffener splice angles at BS 1287, in Inspection Area 2, as defined in 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.”

(3) Area 3: Prior to the accumulation of 46,000 total flight cycles, do an internal HFEC inspection or an external LFEC inspection of the horizontal pressure deck web, and an internal HFEC inspection of the sloping pressure deck, in Inspection Area 3, as defined in the service bulletin.

## Repetitive Inspections

(b) Repeat the inspections in paragraph (a) of this AD at least every 2,500 flight cycles for areas inspected using the HFEC or detailed visual inspection method, or at least every 1,000 flight cycles for areas inspected using the LFEC inspection method, until paragraph (d) of this AD is done.

## Corrective Actions

(c) If any cracking is found during any inspection required by paragraph (a) or (b) of this AD: Before further flight, repair the affected area according to Boeing Special Attention Service Bulletin 777-53-0004, dated May 11, 2000; except, where the service bulletin says to contact Boeing for repairs, 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. Repair according to this paragraph ends the repetitive inspections required by paragraph (b) of this AD for the repaired area.

## Optional Preventative Modification

(d) Modification of Inspection Areas 1, 2, and 3, according to Boeing Special Attention Service Bulletin 777-53-0004, dated May 11, 2000, ends the repetitive inspections required by paragraph (b) of this AD for the modified area.

## 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 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

(f) Special flight permits may be issued in accordance with §§ 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 20, 2001.

Kalene C. Yanamura,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.

[FR Doc. 01-16054 Filed 6-26-01; 8:45 am]

BILLING CODE 4910-13-U