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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. 99-NM-373-AD; Amendment 39-11993; AD 2000-23-20] 
          - RIN 2120-AA64 

# AGENCY:

Federal Aviation Administration, DOT. 

# ACTION:

Final rule. 

# SUMMARY:

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 777-200 series airplanes, that requires replacement of certain components. The actions specified by this AD are intended to prevent corrosion of the axle of the main landing gear, which could result in cracking and failure of one or more axles, loss of the wheels on the axle, and loss of controllability of the airplane on the ground. This action is intended to address the identified unsafe condition. 

# DATES:

Effective December 26, 2000. 

The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of December 26, 2000. 

# ADDRESSES:

The service information referenced in this AD may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. This information may be examined at the Federal Aviation Administration (FAA), Transport Airplane Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. 

# 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:

                    A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD)                           ( print page 69860)                        that is applicable to certain Boeing Model 777-200 series airplanes was published in the                     **Federal Register**                     on July 31, 2000 (65 FR 46666). That action proposed to require replacement of certain components.                 

## Comments 

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comment received. 

The commenter states that the unsafe condition in the Discussion section of the proposed rule is understated. The commenter also states that failure of more than one axle on one main landing gear (MLG) can equal two axles or even all three axles, which would increase the potential hazard. The commenter further states that there is potential for a “cascade failure scenario.” From this comment, the FAA infers that the commenter is requesting that the unsafe condition be revised to include the failure scenario suggested by the commenter. The FAA agrees with the commenter that there is always a possibility of additional failures (i.e., “cascade failure scenario”) resulting from the initial failure. 

The FAA has revised the unsafe condition of the final rule to read, “which could result in cracking and failure of one or more axles, loss of the wheels on the axle, and loss of controllability of the airplane on the ground.” 

## Conclusion 

After careful review of the available data, including the comment 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 neither increase the economic burden on any operator nor increase the scope of the AD. 

## Cost Impact 

There are approximately 8 airplanes of the affected design in the worldwide fleet. The FAA estimates that 4 airplanes of U.S. registry will be affected by this AD. It will take between 56 and 93 work hours per airplane (depending on which, and how many, of the airplane's MLG axles are affected) to accomplish the required replacement, at an average labor rate of $60 per work hour. Required parts will be provided by the manufacturer at no cost to the operator. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be between $3,360 and $5,580 per airplane. 

The cost impact figure discussed above is 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. 

## 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 

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

**2000-23-20 Boeing:**                                 Amendment 39-11993. Docket 99-NM-373-AD.                             

*Applicability:*                                Model 777-200 series airplanes; line numbers 7 through 11 inclusive, 26, 28, and 33; 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 (b) 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 corrosion of the axle of the main landing gear, which could result in cracking and failure of one or more axles, loss of the wheels on the axle, and loss of controllability of the airplane on the ground, accomplish the following: 

## Replacement 

(a) Within 12 months after the effective date of this AD, replace specified axles of the main landing gear with new axles, in accordance with Boeing Alert Service Bulletin 777-32A0024, dated August 12, 1999. 

## Alternative Methods of Compliance 

(b) 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 Aircraft Certification Office (ACO), FAA. 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 

(c) 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. 

## Incorporation by Reference 

                                (d) The replacement shall be done in accordance with Boeing Alert Service Bulletin 777-32A0024, dated August 12, 1999. This incorporation by reference 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                                       ( print page 69861)                                    from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.                             

## Effective Date 

(e) This amendment becomes effective on December 26, 2000. 

Issued in Renton, Washington, on November 9, 2000. 

Donald L. Riggin, 

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. 

[FR Doc. 00-29376 Filed 11-20-00; 8:45 am] 

BILLING CODE 4910-13-P