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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. 2000-NM-128-AD; Amendment 39-12257; AD 2001-12-02] 
          - RIN 2120-AA64 

# AGENCY:

Federal Aviation Administration, DOT. 

# ACTION:

Final rule. 

# SUMMARY:

                        This amendment adopts a new airworthiness directive (AD), applicable to certain Learjet Model 55 series airplanes and Model 60 airplanes, that requires replacement of the brake valve adjustment screw with a new improved screw, and for certain airplanes, it would also require installation of a new brake valve lever stop. The actions specified by this AD are intended to prevent bottoming of the valve components before contact of the brake valve lever with the stop, which                               ( print page 31838)                            could result in loss of all hydraulic fluid and consequent loss of normal braking. This action is intended to address the identified unsafe condition.                     

# DATES:

Effective July 18, 2001. 

The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of July 18, 2001. 

# ADDRESSES:

The service information referenced in this AD may be obtained from Learjet, Inc., One Learjet Way, Wichita, Kansas 67209-2942. 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 FAA, Wichita Aircraft Certification Office, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. 

# FOR FURTHER INFORMATION CONTACT:

Shane Bertish, Aerospace Engineer, Systems and Propulsion Branch, ACE-116W, FAA, Wichita Aircraft Certification Office, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas 67209; telephone (316) 946-4156; fax (316) 946-4407. 

# SUPPLEMENTARY INFORMATION:

                    A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to certain Learjet Model 55 series airplanes and Model 60 airplanes was published in the                     **Federal Register**                     on March 19, 2001 (66 FR 15362). That action proposed to require replacement of the brake valve adjustment screw with a new improved screw; and for certain airplanes, that action also proposed to require installation of a new brake valve lever stop.                 

## Comments 

Interested persons have been afforded an opportunity to participate in the making of this amendment. No comments were submitted in response to the proposal or the FAA's determination of the cost to the public. 

## Conclusion 

The FAA has determined that air safety and the public interest require the adoption of the rule as proposed. 

## Cost Impact 

There are approximately 331 Model 55 series airplanes and Model 60 airplanes of the affected design in the worldwide fleet. The FAA estimates that 285 airplanes of U.S. registry will be affected by this AD, that it will take approximately 16 work hours per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Required parts will cost approximately $2,368 per airplane. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $948,480, or $3,328 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: 

**2001-12-02 Learjet:**                             Amendment 39-12257. Docket 2000-NM-128-AD.                        

*Applicability:*                            Model 55 series airplanes, serial numbers 55-003 through 55-147 inclusive, and Model 60 airplanes, serial numbers 60-002 through 60-189 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 (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 bottoming of the valve components before contact of the brake valve lever with the stop, which could result in loss of all hydraulic fluid and consequent loss of normal braking; accomplish the following: 

## Replacement of Brake Valve Lever Stop Switch 

(a) Within 300 flight hours or one year after the effective date of this AD, whichever occurs first, accomplish the actions specified in paragraph (a)(1), (a)(2), or (a)(3) of this AD, as applicable. 

(1) For Learjet Model 60 airplanes having serial numbers 60-002 through 60-093 inclusive, and 60-095 through 60-188 inclusive: Replace the existing brake valve lever stop switch with a new brake valve lever stop switch, and replace the brake valve adjustment screws with new improved screws, per Bombardier Service Bulletin 60-32-10, Revision 1, dated June 22, 2000. 

(2) For Learjet Model 60 airplanes having serial number 60-094 or 60-189: Replace the brake valve adjustment screws with new improved screws, per Bombardier Service Bulletin 60-32-10, Revision 1, dated June 22, 2000. 

                            (3) For Learjet Model 55 series airplanes having serial numbers 55-003 through 55-147 inclusive: Replace the existing brake valve lever stop with a new brake valve lever stop, and replace the brake valve adjustment screws with new improved screws, per Bombardier Service Bulletin 55-32-14, dated November 9, 1999.                                   ( print page 31839)    

## 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, Wichita Aircraft Certification Office, FAA. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Wichita ACO. 

# Note 2:

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

## Special Flight Permits 

(c) 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. 

## Incorporation by Reference 

(d) The actions shall be done in accordance with Bombardier Service Bulletin 60-32-10, Revision 1, dated June 22, 2000; and Bombardier Service Bulletin 55-32-14, dated November 9, 1999; as applicable. 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 from Learjet, Inc., One Learjet Way, Wichita, Kansas 67209-2942. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Wichita Aircraft Certification Office, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas; 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 July 18, 2001. 

Issued in Renton, Washington, on June 4, 2001. 

Donald L. Riggin, 

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. 

[FR Doc. 01-14530 Filed 6-12-01; 8:45 am] 

BILLING CODE 4910-13-P