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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. 2000-NM-94-AD; Amendment 39-11712; AD 2000-09-04] 
          - RIN 2120-AA64 

# AGENCY:

Federal Aviation Administration, DOT. 

# ACTION:

Final rule; request for comments. 

# SUMMARY:

This amendment supersedes an existing airworthiness directive (AD), applicable to certain Boeing Model 767 series airplanes, that currently requires tests, inspections, and adjustments of the thrust reverser system. That AD also requires installation of a terminating modification, and repetitive follow-on actions. This amendment revises certain actions in the existing AD. This amendment is prompted by a report indicating that certain instructions referenced in the existing AD for accomplishment of the cone brake test of the center drive unit are not accurate for certain airplanes. The actions specified in this AD are intended to ensure the integrity of the fail safe features of the thrust reverser system by preventing possible failure modes in the thrust reverser control system that can result in inadvertent deployment of a thrust reverser during flight. 

# DATES:

Effective May 19, 2000. 

The incorporation by reference of Boeing Service Bulletin 767-78A0081, Revision 1, dated October 9, 1997, was previously approved by the Director of the Federal Register, as of March 9, 2000 (65 FR 5229, February 3, 2000). 

The incorporation by reference of Boeing Service Bulletin 767-78-0047, Revision 3, dated July 28, 1994; and Boeing Service Bulletin 767-78-0063, Revision 2, dated April 28, 1994; was previously approved by the Director of the Federal Register, as of August 18, 1995 (60 FR 36976, July 19, 1995). 

Comments for inclusion in the Rules Docket must be received on or before July 3, 2000. 

# ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-94-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. 

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 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. 

# FOR FURTHER INFORMATION CONTACT:

Holly Thorson, Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-1357; fax (425) 227-1181. 

# SUPPLEMENTARY INFORMATION:

On January 24, 2000, the FAA issued AD 2000-02-20, amendment 39-11538 (65 FR 5229, February 3, 2000), applicable to certain Boeing Model 767 series airplanes, to require tests, inspections, and adjustments of the thrust reverser system. That action also requires installation of a terminating modification, and repetitive follow-on actions. That action was prompted by reports indicating that several center drive units (CDU's) of the thrust reverser system were returned to the manufacturer of the CDU's because of low holding torque of the CDU cone brake. The actions required by that AD are intended to ensure the integrity of the fail safe features of the thrust reverser system by preventing possible failure modes in the thrust reverser control system that can result in inadvertent deployment of a thrust reverser during flight. 

## Actions Since Issuance of Previous Rule 

Since the issuance of AD 2000-02-20, the FAA has received information indicating that the functional test that is described in Boeing Service Bulletin 767-78A0081, Revision 1, is not applicable to Model 767 series airplanes having a third locking system installed on the thrust reversers. For those airplanes, an additional step is necessary in order to unlock the electro-mechanical brake, prior to accomplishment of the functional test, as described in Appendix 1 (including Figure 1) of the existing AD. If the test is performed on airplanes with the third locking system installed, in accordance with the service bulletin, the system will always pass the test, even if the cone brake has failed. Paragraph (d) of the existing AD does not specifically list which airplanes are required to do the functional test of the cone brake of the CDU, in accordance with Boeing Service Bulletin 767-78A0081, Revision 1; and which are required to do the test in accordance with Appendix 1 (including Figure 1) of the AD. Therefore, paragraph (d) of this AD has been revised to separate the service information requirements for accurate accomplishment of the functional test. 

In addition, the grace period of 650 flight hours to accomplish the functional test of the cone brake of the CDU is expected to expire for most airplanes by May or June 2000. For airplanes that have been modified to incorporate the third locking system, this would allow accomplishment of an invalid test with potentially misleading results. The valid functional test as described in Appendix 1 (including Figure 1) of this AD imposes no additional burden. 

## Explanation of Requirements of Rule 

Since an unsafe condition has been identified that is likely to exist or develop on other airplanes of this same type design, this AD supersedes AD 2000-02-20 to continue to require tests, inspections, and adjustments of the thrust reverser system. The AD also continues to require installation of a terminating modification, and repetitive follow-on actions. In addition, this AD revises certain actions in the existing AD. 

## Determination of Rule's Effective Date 

Since a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days. 

## Comments Invited 

                    Although this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this 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 under the caption                     **ADDRESSES.**                     All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments                           ( print page 25834)                        received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.                 

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the 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 that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket. 

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2000-NM-94-AD.” The postcard will be date stamped and returned to the commenter. 

## 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. 

                    The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a “significant regulatory action” under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, 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 removing amendment 39-11538 ( 65 FR 5229, February 3, 2000), and by adding a new airworthiness directive (AD), amendment 39-11712, to read as follows: 

**2000-09-04 Boeing:**                             Amendment 39-11712. Docket 2000-NM-94-AD. Supersedes AD 2000-02-20, Amendment 39-11538.                         

*Applicability:*                             Model 767 series airplanes equipped with General Electric Model CF6-80C2 series engines, 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 (i)(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 ensure the integrity of the fail safe features of the thrust reverser system by preventing possible failure modes in the thrust reverser control system that can result in inadvertent deployment of a thrust reverser during flight, accomplish the following: 

## Repetitive Tests, Inspections, and Adjustments 

(a) Within 30 days after August 18, 1995 (the effective date of AD 95-13-12 R1, amendment 39-9528), perform tests, inspections, and adjustments of the thrust reverser system in accordance with Boeing Service Bulletin 767-78-0047, Revision 3, dated July 28, 1994. 

(1) Except as provided by paragraph (a)(2) of this AD, repeat all tests and inspections thereafter at intervals not to exceed 3,000 flight hours until the modification required by paragraph (c) of this AD is accomplished. 

(2) Repeat the check of the grounding wire for the Directional Pilot Valve (DPV) of the thrust reverser in accordance with the service bulletin at intervals not to exceed 1,500 flight hours, and whenever maintenance action is taken that would disturb the DPV grounding circuit, until the modification required by paragraph (c) of this AD is accomplished. 

## Repair 

(b) If any of the tests and/or inspections required by paragraph (a) of this AD cannot be successfully performed, or if those tests and/or inspections result in findings that are unacceptable in accordance with Boeing Service Bulletin 767-78-0047, Revision 3, dated July 28, 1994; accomplish paragraphs (b)(1) and (b)(2) of this AD. 

(1) Prior to further flight, deactivate the associated thrust reverser in accordance with Section 78-31-1 of Boeing Document D630T002, “Boeing 767 Dispatch Deviation Guide,” Revision 9, dated May 1, 1991; or Revision 10, dated September 1, 1992. After August 18, 1995, this action shall be accomplished only in accordance with Revision 10 of the Boeing document. No more than one reverser on any airplane may be deactivated under the provisions of this paragraph. 

(2) Within 10 days after deactivation of any thrust reverser in accordance with this paragraph, the thrust reverser must be repaired in accordance with Boeing Service Bulletin 767-78-0047, Revision 3, dated July 28, 1994. Additionally, the tests and/or inspections required by paragraph (a) of this AD must be successfully accomplished; once this is accomplished, the thrust reverser must then be reactivated. 

## Modification 

(c) For airplanes having line numbers 1 through 474 inclusive: Within 3 years after August 18, 1995, install a third locking system on the left- and right-hand engine thrust reversers in accordance with Boeing Service Bulletin 767-78-0063, Revision 2, dated April 28, 1994. 

# Note 2:

Model 767 series airplanes equipped with General Electric Model CF6-80C2 series engines and having line numbers 475 and subsequent, on which Production Revision Record (PRR) B11481-70 (which installs a third locking system on the left- and right-hand engine thrust reversers) has been incorporated, need NOT be modified in accordance with Boeing Service Bulletin 767-78-0063, Revision 2. 

# Note 3:

Boeing Service Bulletin 767-78-0063, references General Electric (GE) Service Bulletin 78-135 as an additional source of service information for accomplishment of the third locking system on the thrust reversers. However, the Boeing service bulletin does not specify the appropriate revision level, and the GE service bulletin has a new Lockheed Martin title for the same service bulletin: Lockheed Martin Service Bulletin 78-135, Revision 4, dated September 30, 1996. The appropriate revision level for the GE Service Bulletin is Revision 3, dated August 2, 1994. The GE and Lockheed Martin service bulletins are identical, and either may be used for accomplishment of the action described previously. 

# Note 4:

                                The actions specified in Lockheed Martin Service Bulletin 78-1007, Revision 1, dated March 18, 1997; and Lockheed Martin Service Bulletin 78-1020, Revision 2, dated March 20, 1997; may be accomplished                                       ( print page 25835)                                    simultaneously in conjunction with Boeing Service Bulletin 767-78-0063 for accomplishment of the installation of the thrust reverser bracket and the thrust reverser lock. (Accomplishment of these two service bulletins together achieves the same results as Lockheed Martin Service Bulletin 78-135, Revision 4, and is acceptable for compliance with Boeing Service Bulletin 767-78-0063.)                             

## Repetitive Tests and Checks 

(d) Perform a functional test to detect discrepancies of the cone brake of the center drive unit (CDU) on each thrust reverser, as specified in paragraph (d)(1) or (d)(2) of this AD, as applicable. 

(1) For airplanes on which the modification required by paragraph (c) of this AD or a production equivalent has NOT been accomplished: Within 650 flight hours after the effective date of this AD, perform the test in accordance with Boeing Service Bulletin 767-78A0081, Revision 1, dated October 9, 1997. 

(2) For airplanes on which the modification required by paragraph (c) of this AD or a production equivalent has been accomplished: Perform the test in accordance with Appendix 1 (including Figure 1), sections 1.A.(2), 2.A., 2.C., and 2.D; of this AD. Accomplish the test at the time specified in paragraph (d)(2)(i) or (d)(2)(ii) of this AD, as applicable. 

(i) For airplanes on which the test required by paragraph (d) of AD 95-13-12 R1 HAS been accomplished prior to the effective date of this AD: Accomplish the functional test within 1,000 flight hours after the most recent test of the CDU cone brake performed in accordance with paragraph (d) of AD 95-13-12 R1, or within 650 flight hours after the effective date of this AD, whichever occurs later. 

(ii) For airplanes on which the test required by paragraph (d) of AD 95-13-12 R1 has NOT been accomplished prior to the effective date of this AD: Accomplish the functional test within 1,000 flight hours since the date of manufacture, or within 650 flight hours after the effective date of this AD, whichever occurs later. 

(e) Repeat the functional test of the CDU cone brake specified in paragraph (d) of this AD at the time specified in paragraph (e)(1) or (e)(2) of this AD, as applicable. 

(1) For Model 767 series airplanes, line numbers up to and including 474, equipped with thrust reversers that have not been modified in accordance with Boeing Service Bulletin 767-78-0063: Repeat the functional test of the CDU cone brake thereafter at intervals not to exceed 650 flight hours. 

(2) For Model 767 series airplanes, line numbers 475 and subsequent; and Model 767 series airplanes equipped with thrust reversers that have been modified in accordance with Boeing Service Bulletin 767-78-0063, or a production equivalent: Repeat the functional test of the CDU cone brake thereafter at intervals not to exceed 1,000 flight hours. 

(f) Within 1,000 flight hours after accomplishing the modification required by paragraph (c) of this AD or after the equivalent modification (Production Revision Record B11481-70) is incorporated in production, or within  1,000 flight hours after March 9, 2000, whichever occurs later: Perform operational checks of the electro-mechanical brake in accordance with Appendix 1 (including Figure 1); sections 1.A.(1), 2.A., 2.B., and 2.D; of this AD. Repeat the operational checks thereafter at intervals not to exceed 1,000 flight hours. 

## Repair 

(g) If any functional test or operational check required by paragraph (d), (e), or (f) of this AD cannot be successfully performed, prior to further flight, repair in accordance with Boeing Service Bulletin 767-78A0081, Revision 1, dated October 9, 1997; or Appendix 1, section 2.B. and 2.C., of this AD; as applicable; and repeat the applicable test or check until successfully accomplished. 

## Terminating Action 

(h) Accomplishment of the modification required by paragraph (c) or installation of an equivalent modification (Production Revision Record B11481-70) in production, and accomplishment of the periodic functional tests and operational checks required by paragraphs (d), (e), and (f) of this AD, constitutes terminating action for the tests, inspections, and adjustments required by paragraph (a) of this AD. 

## Alternative Methods of Compliance 

(i)(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 Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. 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 95-13-12, amendment 39-9292, are approved as alternative methods of compliance with this AD. 

# Note 5:

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 

(j) 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 

(k) Except as provided by paragraphs (b)(1), (d)(2), and (f) of this AD, the actions shall be done in accordance with Boeing Service Bulletin 767-78-0047, Revision 3, dated July 28, 1994; Boeing Service Bulletin 767-78-0063, Revision 2, dated April 28, 1994; and Boeing Service Bulletin 767-78A0081, Revision 1, dated October 9, 1997; as applicable. 

(1) The incorporation by reference of Boeing Service Bulletin 767-78A0081, Revision 1, dated October 9, 1997, was previously approved by the Director of the Federal Register, as of March 9, 2000 (65 FR 5229, February 3, 2000). 

(2) The incorporation by reference of Boeing Service Bulletin 767-78-0047, Revision 3, dated July 28, 1994; and Boeing Service Bulletin 767-78-0063, Revision 2, dated April 28, 1994; was previously approved by the Director of the Federal Register, as of August 18, 1995 (60 FR 36976, July 19, 1995). 

(3) Copies may be obtained 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. 

(l) This amendment becomes effective on May 19, 2000. 

## Appendix 1.—Thrust Reverser Electro-Mechanical Brake and CDU Cone Brake Test 

### 1. General 

A. This procedure contains steps to do two checks: 

(1) A check of the holding torque of the electro-mechanical brake. 

(2) A check of the holding torque of the CDU cone brake. 

2. Electro-Mechanical Brake and CDU Cone Brake Torque Check (Fig. 1) 

A. Prepare to do the checks: 

(1) Open the fan cowl panels. 

B. Do a check of the torque of the electro-mechanical brake: 

(1) Do a check of the running torque of the thrust reverser system: 

(a) Manually extend the thrust reverser six inches and measure the running torque. 

(1) Make sure the torque is less than 10 pound-inches. 

(2) Do a check of the electro-mechanical brake holding torque: 

(a) Make sure the thrust reverser translating cowl is extended at least one inch. 

(b) Make sure the CDU lock handle is released. 

(c) Pull down on the manual release handle on the electro-mechanical brake until the handle fully engages the retaining clip. 

# Note:

This will lock the electro-mechanical brake.

                            (d) With the manual drive lockout cover removed from the CDU, install a                             1/4                            -inch extension tool and dial-type torque wrench into the drive pad.                         

# Note:

You will need a 24-inch extension to provide adequate clearance for the torque wrench.

(e) Apply 90 pound-inches of torque to the system. 

                            (1) The electro-mechanical brake system is working correctly if the torque is reached before you turn the wrench 450 degrees (1                            1/4                             turns).                         

(2) If the flexshaft turns more than 450 degrees before you reach the specified torque, you must replace the long flexshaft between the CDU and the upper angle gearbox. 

(3) If you do not get 90 pound-inches of torque, you must replace the electro-mechanical brake. 

(f) Release the torque by turning the wrench in the opposite direction until you read zero pound-inches. 

                            (1) If the wrench does not return to within 30 degrees of initial starting point, you must                                   ( print page 25836)                                replace the long flexshaft between the CDU and upper angle gearbox.                         

(3) Fully retract the thrust reverser. 

C. Do a check of the CDU cone brake: 

(1) Pull up on the manual release handle to unlock the electro-mechanical brake. 

(2) Pull the manual brake release lever on the CDU to release the cone brake. 

# Note:

This will release the pre-load tension that may occur during a stow cycle.

(3) Return the manual brake release lever to the locked position to engage the cone brake. 

(4) Remove the two bolts that hold the lockout plate to the CDU and remove the lockout plate. 

                            (5) Install a                             1/4                            -inch drive and a dial type torque wrench into the CDU drive pad.                         

**CAUTION:**                             DO NOT USE MORE THAN 100 POUND-INCHES OF TORQUE WHEN YOU DO THIS CHECK. EXCESSIVE TORQUE WILL DAMAGE THE CDU.                         

(6) Turn the torque wrench to try to manually extend the translating cowl until you get at lease 15-pound inches. 

# Note:

The cone brake prevents movement in the extend direction only. If you try to measure the holding torque in the retract direction, you will get a false reading.

(a) If the torque is less than 15-pound-inches, you must replace the CDU. 

D. Return the airplane to its usual condition: 

(1) Fully retract the thrust reverser (unless already accomplished). 

(2) Pull down on the manual release handle on the electro-mechanical brake until the handle fully engages the retaining clip (unless already accomplished). 

# Note:

This will lock the electro-mechanical brake.

(3) Close the fan cowl panels. 
      ( print page 25837)    
      ( print page 25838)    
Issued in Renton, Washington, on April 26, 2000. 

Donald L. Riggin, 

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. 

[FR Doc. 00-11061 Filed 5-3-00; 8:45 am] 

BILLING CODE 4910-13-P