Airworthiness Directives; Boeing Model 757-200, -200PF, and - 200CB Series Airplanes Powered by Rolls-Royce RB211-535C/E4/E4B Turbofan Engines

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-323-AD]

RIN 2120-AA64

Airworthiness Directives; Boeing Model 757-200, -200PF, and -

200CB Series Airplanes Powered by Rolls-Royce RB211-535C/E4/E4B

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 757-200, -

200PF, and -200CB series airplanes. This proposal would require

modification of the engine thrust control cable installation, and

repetitive inspections to detect certain discrepancies of the cables,

pulleys, pulley brackets, and cable travel; and repair, if necessary.

This proposal is prompted by reports of failure of certain engine

thrust control cables. 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 April 5, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 98-NM-323-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: Kathrine Rask, Aerospace Engineer,

Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate,

Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton,

Washington 98055-4056; telephone (425) 227-1547; 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 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-323-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-323-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

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

Model 757-300 series airplanes, 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, 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. Such a failure mode was examined during the type

certification of the Boeing Model 757-200 series airplane and, at that

time, the consensus was that the airplane would be controllable

following a thrust control `B' cable failure. The 1985 report and

subsequent testing of a Model 757-200 series airplane contradicted this

assumption.

The FAA recently has 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. Such failure of

a thrust control cable could result in a severe asymmetric thrust

condition during landing, and consequent reduced controllability of the

airplane.

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Explanation of Relevant Service Information

The FAA has reviewed and approved the following service bulletins:

Boeing Service Bulletin 757-76-1, dated May 18, 1984,

which describes procedures for removal of the guide bracket of the

engine thrust control cable that is located on the front spar of the

right wing.

Boeing Service Bulletin 757-76-0005, dated May 5, 1988,

which describes procedures for replacement of sections of the engine

thrust control cables with smaller diameter cables, and removal of the

engine cable breakaway stop assemblies.

Boeing Alert Service Bulletin 757-30A0018, Revision 1,

dated September 17, 1998, which describes procedures for installation

of a support bracket assembly between the window heat wire bundle and

the engine thrust control cable, and adjustment of the wire bundle, if

necessary, to maintain necessary clearance.

Accomplishment of the actions specified in the service bulletins

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 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 paragraph (a)

of this AD, the service bulletins described previously, and the

airplane maintenance manual.

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 757 Maintenance Manual. Although the Boeing Maintenance

Planning Document (MPD) recommends that an inspection of the engine

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

at every ``2C'' check, this proposed AD requires repetitive inspections

at intervals of 18 months or 6,000 flight hours (whichever occurs

first), which corresponds with a ``C'' check interval. The FAA has no

evidence that indicates that the Model 757 series airplane that

experienced the thrust control cable failure was 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 on a more frequent basis than that specified

in the MPD.

Cost Impact

There are approximately 450 airplanes of the affected design in the

worldwide fleet. The FAA estimates that 228 airplanes of U.S. registry

would be affected by this proposed AD.

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 $41,040, or $180 per

airplane, per inspection cycle.

For airplanes identified in Boeing Service Bulletin 757-76-1 (8

U.S.-registered airplanes), it would take approximately 2 work hours

per airplane to accomplish the proposed guide bracket removal, at an

average labor rate of $60 per work hour. Based on these figures, the

cost impact of the proposed AD on U.S. operators is estimated to be

$960, or $120 per airplane.

For airplanes identified in Boeing Service Bulletin 757-76-0005 (14

U.S.-registered airplanes), it would take approximately 14 work hours

per airplane to accomplish the proposed replacement, at an average

labor rate of $60 per work hour. Required parts would be provided by

the manufacturer at no cost to the operators. Based on these figures,

the cost impact of the proposed AD on U.S. operators is estimated to be

$11,760, or $840 per airplane.

For airplanes identified in Boeing Alert Service Bulletin 757-

30A0018, Revision 1 (167 U.S.-registered airplanes), it would take

approximately 2 work hours per airplane to accomplish the proposed

installation and adjustment, at an average labor rate of $60 per work

hour. Required parts would be provided by the manufacturer at no cost

to the operators. Based on these figures, the cost impact of the

proposed AD on U.S. operators is estimated to be $20,040, or $120 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-323-AD.

Applicability: Model 757-200, -200PF, and -200CB series

airplanes powered by Rolls-Royce RB211-535C/E4/E4B 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

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requirements of this AD is affected, the owner/operator must request

approval for an alternative method of compliance in accordance with

paragraph (e) 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) Within 18 months or 6,000 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 757 Maintenance Manual. Repeat the inspection thereafter at

intervals not to exceed 18 months or 6,000 flight hours, whichever

occurs first.

(b) For airplanes identified in Boeing Service Bulletin 757-76-

1, dated May 18, 1984: Within 18 months or 6,000 flight hours after

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

guide bracket of the engine thrust control cable located on the

front spar of the right wing in accordance with the service

bulletin.

(c) For airplanes identified in Boeing Service Bulletin 757-76-

0005, dated May 5, 1988: Within 18 months or 6,000 flight hours

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

the engine thrust control cable breakaway stop assemblies, and

replace sections of the engine thrust control cables with smaller

diameter cables in accordance with the service bulletin.

(d) For airplanes identified in Boeing Alert Service Bulletin

757-30A0018, Revision 1, dated September 17, 1998: Within 60 days

after the effective date of this AD, install a support bracket

assembly between the window heat wire bundle and the engine thrust

control cable; and adjust the wire bundle clearance, as necessary,

to parallel the minimum clearance specified in the alert service

bulletin.

(e) 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.

(f) 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.

Appendix 1.--Thrust Control Cable Inspection Procedure

1. General

A. Use these procedures to test 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 757 Maintenance Manual 12-12-31.

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 or around pulleys. Examine these areas carefully.

C. Remove the control cable from the airplane when you find one

of these conditions:

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

section is decreased by 40 percent or more in an area that goes over

a pulley, through a pressure seal, or through a fairlead (see Figure

1).

(2) 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 agree with the other specifications of this section.

(3) Two or more broken wires.

(4) A nick or cut.

(5) Rust or corrosion.

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

accordance with 757 Maintenance Manual 12-12-31.

Note: Do not apply grease to CRES cables.

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. Remove the pulley from the airplane 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.

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

does not contact structure, wire bundles, or tubing.

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Issued in Renton, Washington, on February 9, 1999.

John J. Hickey,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 99-3736 Filed 2-16-99; 8:45 am]

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