[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
[[Page 18387]]
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.
[[Page 18389]]
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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Figure 1
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Figure 2
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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
