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

[Federal Register Volume 64, Number 71 (Wednesday, April 14, 1999)]
[Proposed Rules]
[Pages 18386-18392]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-9254]


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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]
BILLING CODE 4910-13-P