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]

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: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness

directive (AD) that is applicable to certain Boeing Model 767 series

airplanes. This proposal would 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, this

proposal also would require replacement of certain pulleys with new

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

proposal is prompted by reports of engine thrust control cable

failures. The actions specified by the proposed 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: Comments must be received by June 1, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Transport Airplane Directorate, ANM-114,

Attention: Rules Docket No. 98-NM-363-AD, 1601 Lind Avenue, SW.,

Renton, Washington 98055-4056. Comments may be inspected at this

location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except

Federal holidays.

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: 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:

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 in this notice may be changed in

light of the comments received.

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

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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 notice must submit a self-addressed,

stamped postcard on which the following statement is made: ``Comments

to Docket Number 98-NM-363-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. 98-NM-363-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

In December 1985, the FAA received a report indicating that a

Boeing Model 747-100 series airplane had experienced a thrust control

`B' cable failure following application of reverse thrust during

landing. This failure caused engine number 1 to go full forward thrust

with engine numbers 2, 3, and 4 in full reverse thrust. The airplane

exited the runway and eventually slid to a stop with consequent hull

damage.

In December 1992, a broken thrust control `B' cable was found on a

Boeing Model 767-200 series airplane following an uncommanded

acceleration of the number two engine during engine start. The broken

cable was located adjacent to the right-hand wing.

In April 1997, during a review of the certification plan for the

Boeing Model 757-300 series airplane, Boeing informed the FAA that the

thrust control cable installation on Boeing Model 757-200, -200PF, and

-200CB series airplanes equipped with Rolls Royce engines, and on Model

767 series airplanes equipped with Pratt & Whitney Model JT9D-7R4

series engines and General Electric CF6-80A series turbofan engines, is

similar to the thrust control cable installation on the Boeing Model

747-100 series airplane, and that a similar failure could result in

subsequent runway departure.

The FAA has recently received a report of uncommanded advancement

of the right thrust lever on a Boeing Model 757-200 series airplane

during flight. Subsequently, the engine power began steadily

increasing. In order to reduce the engine power, the flight crew set

the lever to the idle stop position; however, the engine power

continued to increase. The flight crew then used the cut-off lever to

stop the engine as it approached the maximum speed. After the airplane

landed, a close visual inspection revealed that the thrust control

cable had broken due to continuous chafing against the adjacent wire

bundle that supplies power to the right window heater.

In addition, failure of a pulley could result in insufficient

support or improper positioning of the thrust control cable and may

lead to cable chafing on adjacent structure or airplane system

components and subsequent failure of the thrust control cable. Such

failure of a thrust control cable could result in a severe asymmetric

thrust condition during landing, and consequent reduced controllability

of the airplane.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing Service Bulletin 767-76-

0010,

Revision 1, dated February 20, 1992, which describes procedures for

replacement of 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. The service bulletin also

describes procedures for re-rigging of the thrust control cable after

replacement of the pulleys.

Accomplishment of the actions specified in the service bulletin

described previously, and the repetitive inspection mandated by this

AD, is intended to adequately address the identified unsafe condition.

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 modification of the engine thrust control

cable installation and repetitive inspections to detect certain

discrepancies of the engine thrust control cables, pulleys, pulley

brackets, and cable travel; and repair, if necessary. The actions would

be required to be accomplished in accordance with the procedure

included in Appendix 1 of this AD.

For certain airplanes, this proposed AD would require replacement

of the non-metallic pulleys of the two thrust control cables that are

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

engine strut with aluminum pulleys. The proposed AD also would require

re-rigging of the thrust control cable after replacement of the

pulleys. These actions would be required to be accomplished in

accordance with the service bulletin described previously.

Justification of Compliance Time

This proposed AD includes a procedure to inspect the engine thrust

control cables, pulleys, pulley brackets, and cable travel, which is

similar to the inspection for control cables contained in Chapter 20-

20-02 of the Boeing 767 Maintenance Manual. The Boeing Maintenance

Planning Document recommends that an inspection of the engine thrust

control cables be conducted in accordance with Chapter 20-20-02 at

every ``2C'' check. The FAA has no evidence that indicates that the

Model 747, 757, and 767 series airplanes that experienced the thrust

control cable failures were not adhering to those recommendations;

therefore, the FAA has determined that the repetitive inspections of

the thrust control cables, pulleys, pulley brackets, and cable travel

must be done at every ``C'' check, which corresponds with 18 months or

4,500 flight hours, whichever occurs first.

Explanation of Inspection Procedure

The inspection procedure identified for the thrust control cables

was derived from the Boeing 747, 757, and 767 Maintenance Manuals. The

thrust control cable designs are similar among these airplane models.

However, the damage tolerance criteria for replacement of the thrust

control cables are more stringent for Model 757 than for the Model 767.

Therefore, in recognition that the cable designs are similar and the

fact that there is no readily apparent reason for the differences in

damage tolerance criteria, the more stringent Model 757 requirements

are stated in the thrust control cable procedure described in this

proposed rule.

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

would be affected by this proposed AD.

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

approximately 3 work hours per airplane to accomplish the proposed

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

these figures, the cost impact of the inspection proposed 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 would take approximately

9 work hours per airplane to accomplish the proposed

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replacement and re-rigging, at an average labor rate of $60 per work

hour. Required parts would cost $484 per airplane. Based on these

figures, the cost impact of the replacement and re-rigging proposed by

this AD on U.S. operators is estimated to be $53,248, or $1,024 per

airplane.

The cost impact figures discussed above are 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 AD were not adopted.

Regulatory Impact

The regulations proposed herein would 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

proposal would not have sufficient federalism implications to warrant

the preparation of a Federalism Assessment.

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

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.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new

airworthiness directive:

Boeing: 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 figures 1 and 2) 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.

Appendix 1.--Thrust Control Cable Inspection Procedure

1. General

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

control cables. The procedures must be performed along the entire

cable run for each engine.

B. The first task is an inspection of the control cable. The

second task is an inspection of the control cable pulley. The third

task is an inspection of the control cable pulley bracket. The

fourth task is an inspection of control cable travel.

2. Inspection of the Control Cables

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

accordance with 767 Maintenance Manual 12-21-31.

B. Examine the cables:

(1) To do a check for broken wires, rub a cloth along the length

of the cable. The cloth catches broken wires.

(2) To aid in the visual inspection, remove the tension and bend

the cable.

Broken wire ends frequently move apart from the cable surface.

Use large bend radius to prevent kinks.

Note: Wires break most frequently where cables go through

fairleads, seals, or around drums, quadrants, or pulleys. Examine

these areas carefully, paying close attention to cable runs outside

the pressurized areas. Use a flashlight and mirror to aid inspection

in places that are difficult to access.

C. Replace the control cable when you find one of these

conditions:

(1) Two or more broken wires.

(2) If one cable strand has worn wires where one wire cross

section is decreased by 40 percent or more (see Figure 1).

(3) For cables not in the pressurized area, replace a worn cable

where you cannot identify the wire strands on the worn side.

(4) A broken wire in the area that goes over a pulley, through a

pressure seal, or through a fairlead.

Note: A cable assembly can have one broken wire if the broken

wire is in a straight part of the cable assembly. The broken wire

must not go over a pulley or through a pressure seal or fairlead.

The cable must comply with the other specifications of this section.

(5) A nick or cut.

(6) Rust or corrosion.

D. Lubricate the cable (if you removed the lubricant), in

accordance with 767 Maintenance Manual 12-21-31.

Note: Do not apply grease or corrosion preventative agents on

corrosion resistant cables (CRES) because accumulation of grit

increases the wear rate on CRES cables. CRES cables should not be

lubricated.

3. Inspection of the Control Cable Pulley

A. Visually examine the pulleys for roughness, sharp edges, and

unwanted material in the grooves.

B. Visually examine the pulley wear pattern (see Figure 2).

C. Do these steps at the same time to examine the pulley for

wobble:

(1) Push on the side of the pulley at the outer edge with a 2-

pound force, perpendicular to control cable travel.

(2) Make sure the movement of the outer edge is no more than:

(a) 0.10 inch for 8-inch diameter pulleys

(b) 0.09 inch for 6-inch diameter pulleys

(c) 0.08 inch for 5-inch diameter pulleys

(d) 0.07 inch for 4-inch diameter pulleys

(e) 0.06 inch for 3-inch diameter pulleys

D. Make sure the pulley bearings have lubrication and turn

smoothly.

E. Examine the pulley bolts for wear.

F. Replace the pulley when you find one of these conditions:

(1) An unusual pulley wear pattern.

(2) Too much pulley wobble.

(3) The pulley does not turn freely and smoothly.

4. Inspection of the Control Cable Pulley Bracket

A. Examine the brackets and the support structure for cracks or

other damage.

B. Replace or repair all brackets or structure that have damage.

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5. Inspection of the Cable Travel

A. Make sure the cable guides and fairleads have no worn or

broken parts and that the parts are aligned, clean, and attached

correctly.

B. Make sure the deflection angle at each fairlead is not more

than 3 degrees.

C. Visually examine the cable runs for incorrect routing or

twists in the cable.

D. The minimum clearance between the cable and the adjacent

structure shall be 0.20 inches. At pulley bracket locations, the

minimum clearance is 0.10 inches for a 10 inch distance, beginning

at the cable breakpoint and extending along the cable run in both

directions.

E. Make sure the cable moves freely through its full travel, and

does not contact structure, wire bundles, or tubing.

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(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.

(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 2: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be

obtained from the Seattle ACO.

(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.

Issued in Renton, Washington, on April 7, 1999.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 99-9254 Filed 4-13-99; 8:45 am]

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