Airworthiness Directives; Boeing Model 767 Series Airplanes Powered by Pratt & Whitney JT9D-7R4 Series Turbofan Engines or General Electric CF6-80A Series Turbofan Engines

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-363-AD; Amendment 39-11363; AD 99-21-18]

RIN 2120-AA64

Airworthiness Directives; Boeing Model 767 Series Airplanes

Powered by Pratt & Whitney JT9D-7R4 Series Turbofan Engines or General

Electric CF6-80A Series Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD),

applicable to certain Boeing Model 767 series airplanes, that requires

repetitive inspections to detect certain discrepancies of the cables,

fittings, and pulleys of the engine thrust control cables; and repair,

if necessary. For certain airplanes, this amendment also requires

replacement of certain pulleys with new pulleys, and re-rigging of the

engine thrust control cable. This amendment is prompted by reports of

engine thrust control cable failures. The actions specified by this AD

are intended to prevent such failures, which could result in a severe

asymmetric thrust condition during landing, and consequent reduced

controllability of the airplane.

DATES: Effective November 22, 1999.

The incorporation by reference of certain publications listed in

the regulations is approved by the Director of the Federal Register as

of November 22, 1999.

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: 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: 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 Boeing Model 767 series

airplanes was published in the Federal Register on April 14, 1999 (64

FR 18386). That action proposed to require modification of the engine

thrust control cable installation; repetitive inspections to detect

certain discrepancies of the cables, pulleys, pulley brackets, and

cable travel; and repair, if necessary. For certain airplanes, that

action also proposed to require replacement of certain pulleys with new

pulleys, and re-rigging of the engine thrust control cable.

Comments

Interested persons have been afforded an opportunity to participate

in the making of this amendment. Due consideration has been given to

the comments received.

Support for the Proposal

One commenter supports the proposed AD.

Request for Clarification on Allowable Part Numbers

One commenter requests clarification on which part numbers of

aluminum pulleys will satisfy the intent of paragraph (b) of the

proposed AD. This commenter states that it has accomplished Boeing

Service Bulletin 767-76-0010, dated April 19, 1985, on its fleet. That

bulletin specifies replacement of the non-metallic pulleys of the

engine thrust control cable that are located in the leading edge of the

wing adjacent to the left and right engine strut, with aluminum pulleys

having the part number 255T1232-1. The proposed AD would require

pulleys to be replaced in accordance with Boeing Service Bulletin 767-

76-0010, Revision 1, dated February 20, 1992. That bulletin specifies

that replacement with aluminum pulleys having the part number 255T1232-

3 is preferred, but use of aluminum pulleys having the part number

255T1232-1 is allowed. The commenter states that, if aluminum pulleys

having the part number 255T1232-3 are the only approved pulleys, the

lack of availability of that pulley may cause unplanned delays in the

accomplishment of the proposed AD.

The FAA intends that paragraph (b) of this AD require replacement

of non-metallic pulleys of the engine thrust control cable that are

located in the leading edge of the wing adjacent to the left and right

engine strut, with aluminum pulleys having the part number 255T1232-1

or -3. Pulleys having the part number 255T1232-3 are preferred because

they use a different bearing that has high temperature grease. After

reviewing Boeing Service Bulletin 767-76-0010, dated April 19, 1985,

the FAA finds that accomplishment of the replacement specified in that

service bulletin is acceptable for compliance with the replacement

required by paragraph (b) of the final rule; therefore, a note stating

this has been added to the final rule.

Request for Information on Other Relevant Rulemaking

One commenter notes that the proposed rule states that the damage

criteria in Appendix 1., ``Thrust Control Cable Inspection Procedure,''

is based on the requirements in the Boeing 757 Maintenance Manual,

which are more stringent than the requirements for the Model 767 series

airplane. The commenter requests information regarding similar

rulemaking for the Boeing Model 757 series airplane. No specific change

to the rule is requested.

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The FAA has issued two proposed rules to address the unsafe

condition on other Boeing airplane models that have an engine thrust

control cable installation similar to the Model 767 series airplane:

FAA Rules Docket No. 98-NM-323-AD (64 FR 49105, September

10, 1999), which applies to certain Model 757-200 series airplanes; and

FAA Rules Docket No. 99-NM-22-AD (64 FR 53275, October 1,

1999), which applies to certain Model 747 series airplanes.

No change to the final rule is necessary in this regard.

Request for Extension of the Compliance Time

Two commenters request that the compliance time for the repetitive

inspections specified in paragraph (a) of the proposed AD be extended.

One commenter suggests that its inspection program, which specifies

inspection of different sections of the engine thrust control cable

installation at intervals from 2,600 flight hours to 9,000 flight

hours, including inspections of certain sections to be performed only

on a sampling of airplanes in an operator's fleet, is adequate.

Therefore, reducing the interval by 50 percent, as specified in the

proposed AD, is unnecessary. The other commenter suggests that the

engine thrust control cables be inspected at every ``2C'' check, with

certain sections of the cable run to be inspected at every ``C'' check.

(This commenter considers a ``C'' check interval to be 456 days.) This

commenter states that it will have to modify its maintenance program to

accomplish the proposed repetitive inspections every 18 months or 4,500

flight hours.

The FAA does not concur with the commenters' request to extend the

compliance time. There has been one engine thrust control cable failure

on a Model 767 series airplane, and two failures on Model 757 series

airplanes. (The engine thrust control cable installation on certain

Model 757 series airplanes is similar to that on certain Model 767

series airplanes.) There was no evidence in these events that the

operators were not following the Boeing maintenance planning document

recommendations for the engine thrust control cable inspections. Given

this experience and the possibly catastrophic effect of a thrust

control cable failure, the FAA has determined that it is necessary to

conduct more frequent inspections of the cable installations.

Therefore, this AD requires the engine thrust control cable inspections

to be accomplished every 18 months or 4,500 flight hours, whichever

occurs first. No change to the final rule is necessary in this regard.

Request for Clarification of Applicability

One commenter requests clarification of the applicability of the

proposed AD. The commenter states that this proposed AD affects Model

767 series airplanes powered by Pratt & Whitney JT9D series turbofan

engines, and Model 767 series airplanes powered by General Electric CF6

series turbofan engines that do not use full authority digital

electronic controls (FADEC).

The FAA concurs partially. This AD only affects certain Model 767

series airplanes powered by General Electric CF6 series turbofan

engines that do not use FADEC (as well as Model 767 series airplanes

powered by Pratt & Whitney JT9D series turbofan engines). Specifically,

this AD affects Model 767 series airplanes powered by CF6-80A series

turbofan engines. The engine thrust control cable installation is

different on airplanes powered by other General Electric CF6 series

turbofan engines that do not use FADEC, and the unsafe condition

discussed previously does not exist on those airplanes. Therefore, no

change to the final rule is necessary in this regard.

Explanation of Changes Made to the Cost Impact

The FAA has been advised that the replacement of pulleys required

by paragraph (b) of this AD has been accomplished on 23 airplanes of

U.S. registry. Accordingly, the FAA has revised the cost impact, below,

to reflect this information.

Explanation of Changes Made to Appendix 1

Prompted by two comments received to FAA Rules Docket No. 98-NM-

323-AD (64 FR 7822, February 17, 1999), which proposed actions similar

to those required by this AD for the Model 757 series airplane, the FAA

reviewed Appendix 1., ``Thrust Control Cable Inspection Procedure,'' of

the proposed AD. One commenter to FAA Rules Docket No. 98-NM-323-AD

stated that the proposed procedure would require disassembly of the

engine thrust control cable installation. The other commenter suggested

that the procedure be revised to eliminate all steps that do not

contribute to the intent of the AD.

In FAA Rules Docket No. 98-NM-323-AD (the FAA issued a supplemental

NPRM for reasons other than the inspection procedure), the FAA

concurred with the commenters' request to revise the inspection

procedure. The FAA's intent was to define a thorough inspection of the

engine thrust control cable installation while minimizing the amount of

disruptive maintenance to the installation. With technical input from

the airplane manufacturer, an improved and simplified inspection

procedure has been developed, and Appendix 1. of this AD has been

revised accordingly. Figure 2 of Appendix 1. has been removed because

it is no longer needed for the inspection. The FAA has determined that

the revision, although extensive, does not change the intent of the

proposed procedure and actually decreases the scope of the inspection.

In addition, the FAA has revised certain language in the preamble of

this AD to reflect the changes to Appendix 1.

In addition, the FAA has corrected the summary of the final rule.

The summary of the proposed AD stated a modification of the engine

thrust control cable installation would be required on all affected

airplanes. No such requirement was included in the proposed AD.

Conclusion

After careful review of the available data, including the comments

noted above, the FAA has determined that air safety and the public

interest require the adoption of the rule with the changes previously

described. The FAA has determined that these changes will neither

increase the economic burden on any operator nor increase the scope of

the AD.

Cost Impact

There are approximately 211 airplanes of the affected design in the

worldwide fleet. The FAA estimates that 100 airplanes of U.S. registry

will be affected by this AD.

For all airplanes (100 U.S.-registered airplanes), it will take

approximately 3 work hours per airplane to accomplish the required

inspection, at an average labor rate of $60 per work hour. Based on

these figures, the cost impact of the inspection required by this AD on

U.S. operators is estimated to be $18,000, or $180 per airplane, per

inspection cycle.

For airplanes identified in Boeing Service Bulletin 767-76-0010,

Revision 1 (52 U.S.-registered airplanes), it will take approximately 9

work hours per airplane to accomplish the required replacement and re-

rigging, at an average labor rate of $60 per work hour. Required parts

will cost $484 per airplane. Based on these figures, the cost impact of

the replacement and re-rigging required by this AD on U.S. operators is

estimated to be $53,248, or $1,024 per airplane. The cost impact

figures

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discussed above are 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. However, the FAA has been advised that 23 airplanes of

U.S. registry have been modified in accordance with Boeing Service

Bulletin 767-76-0010, Revision 1, as required by paragraph (b) of this

AD. Therefore, the future economic cost impact of the required

replacement and re-rigging on U.S. operators is now only $29,696, or

$1,024 per airplane.

Regulatory Impact

The regulations adopted herein will not have substantial direct

effects 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, in

accordance with Executive Order 12612, it is determined that this final

rule does not have sufficient federalism implications to warrant the

preparation of a Federalism Assessment.

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.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new

airworthiness directive:

99-21-18 Boeing: Amendment 39-11363. Docket 98-NM-363-AD.

Applicability: Model 767 series airplanes powered by Pratt &

Whitney JT9D-7R4 series turbofan engines or General Electric CF6-80A

series turbofan 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 (c) 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 engine thrust control cable failure, which could

result in a severe asymmetric thrust condition during landing, and

consequent reduced controllability of the airplane, accomplish the

following:

(a) For all airplanes: Within 18 months or 4,500 flight hours

after the effective date of this AD, whichever occurs first,

accomplish the ``Thrust Control Cable Inspection Procedure''

specified in Appendix 1 (including Figure 1) of this AD to verify

the integrity of the thrust control cables. Prior to further flight,

repair any discrepancy found, in accordance with the procedures

described in the Boeing 767 Maintenance Manual. Repeat the

inspection thereafter at intervals not to exceed 18 months or 4,500

flight hours, whichever occurs first.

(b) For airplanes identified in Boeing Service Bulletin 767-76-

0010, Revision 1, dated February 20, 1992: Within 18 months or 4,500

flight hours after the effective date of this AD, whichever occurs

first, replace the two non-metallic pulleys of the thrust control

cable that are located in the leading edge of the wing adjacent to

the left and right engine strut with aluminum pulleys; and re-rig

the thrust control cables; in accordance with the service bulletin.

Note 2: Accomplishment of the replacement specified in Boeing

Service Bulletin 767-76-0010, dated April 19, 1985, is acceptable

for compliance with the replacement required by paragraph (b) of

this AD.

Alternative Methods of Compliance

(c) 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.

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.

Incorporation by Reference

(e) The replacement and re-rigging specified in paragraph (b) of

this AD shall be done in accordance with Boeing Service Bulletin

767-76-0010, Revision 1, dated February 20, 1992. 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 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.

(f) This amendment becomes effective on November 22, 1999.

Appendix 1.--Thrust Control Cable Inspection Procedure

1. General

A. Clean the cables, if necessary, for the inspection, in

accordance with Boeing 767 Maintenance Manual 12-21-31.

B. Use these procedures to verify the integrity of the thrust

control cable system. The procedures must be performed along the

entire cable run for each engine. To ensure verification of the

portions of the cables which are in contact with pulleys and

quadrants, the thrust control must be moved by operation of the

thrust and/or the reverse thrust levers to expose those portions of

the cables.

C. The first task is an inspection of the control cable wire

rope. The second task is an inspection of the control cable

fittings. The third task is an inspection of the pulleys.

Note: These three tasks may be performed concurrently at one

location of the cable system on the airplane, if desired, for

convenience.

Note: For the purposes of this procedure, 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. Inspection of the Control Cable Wire Rope

A. Perform a detailed visual inspection to ensure that the cable

does not contact parts

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other than pulleys, quadrants, cable seals, or grommets installed to

control the cable routing. Look for evidence of contact with other

parts. Correct the condition if evidence of contact is found.

B. Perform a detailed visual inspection of the cable runs to

detect incorrect routing, kinks in the wire rope, or other damage.

Replace the cable assembly if:

(1) One cable strand had worn wires where one wire cross section

is decreased by more than 40 percent (see Figure 1),

(2) A kink is found, or

(3) Corrosion is found.

C. Perform a detailed visual inspection of the cable: To check

for broken wires, rub a cloth along the length of the cable. The

cloth catches on broken wires.

(1) Replace the 7x7 cable assembly if there are two or more

broken wires in 12 continuous inches of cable or there are three or

more broken wires anywhere in the total cable assembly.

(2) Replace the 7x19 cable assembly if there are four or more

broken wires in 12 continuous inches of cable or there are six or

more broken wires anywhere in the total cable assembly.

3. Inspection of the Control Cable Fittings

A. Perform a detailed visual inspection to ensure that the means

of locking the joints are intact (wire locking, cotter pins,

turnbuckle clips, etc.). Install any missing parts.

B. Perform a detailed visual inspection of the swaged portions

of swaged end fitting to detect surface cracks or corrosion. Replace

the cable assembly if cracks or corrosion are found.

C. Perform a detailed visual inspection of the unswaged portion

of the end fitting. Replace the cable assembly if a crack is

visible, if corrosion is present, or if the end fitting is bent more

than 2 degrees.

D. Perform a detailed visual inspection of the turnbuckle.

Replace the turnbuckle if a crack is visible or if corrosion is

present.

4. Inspection of Pulleys

A. Perform a detailed visual inspection to ensure that pulleys

are free to rotate. Replace pulleys which are not free to rotate.

BILLING CODE 4910-13-P

[[Page 56155]]

[GRAPHIC] [TIFF OMITTED] TR18OC99.000

Issued in Renton, Washington, on October 4, 1999.

D.L. Riggin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 99-26568 Filed 10-15-99; 8:45 am]

BILLING CODE 4910-13-C