[Federal Register Volume 65, Number 196 (Tuesday, October 10, 2000)]
[Proposed Rules]
[Pages 60126-60129]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-25967]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-127-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 767 Series Airplanes 
Powered by General Electric 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 powered by General Electric engines. This proposal would 
require modification of the nacelle strut and wing structure. This 
proposal is prompted by reports indicating that the actual operational 
loads applied to the nacelle are higher than the analytical loads that 
were used during the initial design. Such an increase in loading can 
lead to fatigue cracking in the primary strut structure prior to an 
airplane reaching its design service objective. The actions specified 
by the proposed AD are intended to prevent fatigue cracking in the 
primary strut structure and consequent reduced structural integrity of 
the strut.

DATES: Comments must be received by November 24, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 99-NM-127-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. Comments may be submitted via fax to (425) 227-1232. 
Comments may also be sent via the Internet using the following address: 
[email protected]. Comments sent via fax or the Internet must 
contain ``Docket No. 99-NM-127-AD'' in the subject line and need not be 
submitted in triplicate. Comments sent

[[Page 60127]]

via the Internet as attached electronic files must be formatted in 
Microsoft Word 97 for Windows or ASCII text.
    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: James G. Rehrl, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
227-2783; 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 99-NM-127-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. 99-NM-127-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports indicating that the airplane 
manufacturer has accomplished a structural reassessment of the damage 
tolerance capabilities of the Boeing Model 767 series airplane powered 
by General Electric engines. This reassessment indicates that the 
actual operational loads applied to the nacelle strut and wing 
structure are higher than the analytical loads that were used during 
the initial design. Subsequent analysis and service history, which 
includes numerous reports of fatigue cracking on certain strut and wing 
structure, indicate that fatigue cracking can occur on the primary 
strut structure before an airplane reaches its design service objective 
of 20 years or 50,000 flight cycles. Analysis also indicates that such 
cracking, if it were to occur, would grow at a much greater rate than 
originally expected. Fatigue cracking in the primary strut structure 
would result in reduced structural integrity of the strut.

Explanation of Relevant Service Information

    Boeing recently has developed a modification of the strut-to-wing 
attachment structure installed on Model 767 series airplanes powered by 
General Electric engines. This modification significantly improves the 
load-carrying capability and durability of the strut-to-wing 
attachments. Such improvements also will substantially reduce the 
possibility of fatigue cracking and corrosion developing in the 
attachment assembly.
    The FAA has reviewed and approved Boeing Service Bulletin 767-54-
0081, dated July 29, 1999, which describes procedures for modification 
of the nacelle strut and wing structure. The modification consists of 
replacing many of the significant load-bearing components of the strut 
and wing (e.g., the side link fittings, the midspar fittings, the side 
load fittings, certain fuse pins assemblies, etc.) with improved 
components.
    The service bulletin contains a formula for calculating an optional 
compliance threshold for the specified modification. This formula is 
intended to be used as an alternative to the 20-year calendar threshold 
specified in the service bulletin.
    In addition, Table 2 of the service bulletin also identifies six 
related service bulletin modifications that must be accomplished before 
or at the same time as the modification in Boeing Service Bulletin 767-
54-0081:
     Boeing Service Bulletin 767-29-0057: The FAA has reviewed 
and approved Boeing Service Bulletin 767-29-0057, dated December 16, 
1993, which describes procedures for modification of the electrical 
wiring support of the alternating current motor pump of the main 
hydraulic power system. The modification involves installing new band 
clamps and index-straps, and on certain airplanes, installing new wire 
support brackets on the strut bulkhead.
     Boeing Service Bulletin 767-54-0069: The FAA has reviewed 
and approved Boeing Service Bulletin 767-54-0069, Revision 1, dated 
January 29, 1998, which describes procedures for rework of the side 
load fitting and tension fasteners, as applicable, and replacement of 
midspar fuse pins with new, higher-strength midspar fuse pins. The 
rework involves increasing the size of the tension bolts of the inboard 
and outboard side load fittings. The replacement also involves 
installing new, higher-strength bolts and radius fillers in the side 
load fittings and backup support structure, and installing higher-
strength fasteners common to the front spar and rib number 8 rib post.
     Boeing Service Bulletin 767-54-0083: The FAA has reviewed 
and approved Boeing Service Bulletin 767-54-0083, dated September 17, 
1998, which describes procedures for replacement of the upper link with 
a new, improved part that will increase the strength and durability of 
the upper link installation. That service bulletin also describes 
procedures for modification of the wire support bracket attached to the 
upper link.
     Boeing Service Bulletin 767-54-0088: The FAA has reviewed 
and approved Boeing Service Bulletin 767-54-0088, Revision 1, dated 
July 29, 1999, which describes procedures for replacement of the upper 
link fuse pin and aft pin with new, improved pins that will increase 
the strength and durability of the upper link installation.
     Boeing Service Bulletin 767-54A0094: The FAA has 
previously reviewed and approved Boeing Service Bulletin 767-54A0094, 
Revision 1, dated September 16, 1999. This service bulletin is 
referenced as the appropriate service information for accomplishing the 
actions required in AD 2000-07-05, amendment 39-11659, which was issued 
March 31, 2000 (65 FR 18883, April 10, 2000). This service bulletin 
describes procedures for repetitive detailed visual inspections to 
detect cracking of the one-piece diagonal brace of the forward and aft 
lugs, and corrective actions, if necessary. The corrective actions 
involve installing a new, three-piece diagonal brace, which eliminates 
the need for the repetitive inspections. The service bulletin also 
describes procedures for rework of the three-piece diagonal brace, 
which

[[Page 60128]]

increases the inspection intervals of the three-piece diagonal brace.
     Boeing Service Bulletin 767-57-0053: Boeing Service 
Bulletin 767-54-0081 lists Boeing Service Bulletin 767-57-0053, 
Revision 1, however, the FAA has previously reviewed and approved 
Boeing Service Bulletin 767-57-0053, Revision 2, dated September 23, 
1999. This service bulletin is referenced as the appropriate source of 
service information for accomplishing the actions required in AD 2000-
12-17, amendment 39-11795, which was issued June 9, 2000 (65 FR 37843, 
June 19, 2000). Revision 1 also is acceptable for compliance with the 
requirements in that AD. Revision 2 of the service bulletin describes 
procedures for repetitive ultrasonic and eddy current inspections of 
the pitch load fitting lugs of the wing front spar for cracking, and 
rework of the fitting, if necessary.
    Accomplishment of the actions specified in the service bulletins 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 accomplishment of the actions specified in 
the service bulletins described previously, except as discussed below.

Differences Between Proposed Rule and Service Bulletin

    Operators should note that, although Boeing Service Bulletin 767-
54-0081 specifies that the manufacturer may be contacted for 
disposition of certain damage conditions that may be detected during 
accomplishment of the modification, this proposal would require the 
repair of those conditions to be accomplished in accordance with a 
method approved by the FAA.

Cost Impact

    There are approximately 381 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 159 airplanes of U.S. registry 
would be affected by this proposed AD, that it would take approximately 
1,006 work hours, including time for gaining access and closing up, per 
airplane to accomplish the proposed modification in Boeing Service 
Bulletin 767-54-0081, and that the average labor rate is $60 per work 
hour. Based on these figures, the cost impact of the proposed AD on 
U.S. operators is estimated to be $9,597,240, or $60,360 per airplane.
    It would take approximately 16 work hours per airplane to 
accomplish the proposed actions described in Boeing Service Bulletin 
767-29-0057, at an average labor rate of $60 per work hour. Required 
parts would be provided at no cost by the airplane manufacturer. Based 
on these figures, the cost impact of these proposed actions on U.S. 
operators is estimated to be $152,640, or $960 per airplane.
    It would take approximately 106 work hours per airplane to 
accomplish the actions described in Boeing Service Bulletin 767-53-
0069, Revision 1, at an average labor rate of $60 per work hour. 
Required parts would be provided at no cost by the airplane 
manufacturer. Based on these figures, the cost impact of these proposed 
actions on U.S. operators is estimated to be $1,011,240, or $6,360 per 
airplane.
    It would take approximately 1 work hour per airplane to accomplish 
the actions described in Boeing Service Bulletin 767-54-0083, at an 
average labor rate of $60 per work hour. Required parts would be 
provided at no cost by the airplane manufacturer. Based on these 
figures, the cost impact of these proposed actions on U.S. operators is 
estimated to be $9,540, or $60 per airplane.
    It would take approximately 4 work hours per airplane to accomplish 
the actions described in Boeing Service Bulletin 767-54-0088, Revision 
1, at an average labor rate of $60 per work hour. Required parts would 
be provided at no cost by the airplane manufacturer. Based on these 
figures, the cost impact of these proposed actions on U.S. operators is 
estimated to be $38,160, or $240 per airplane.
    It would take approximately 20 work hours per airplane to 
accomplish the proposed actions described in Boeing Service Bulletin 
767-54A0094, Revision 1, at an average labor rate of $60 per work hour. 
Required parts would be provided at no cost by the airplane 
manufacturer. Based on these figures, the cost impact of these proposed 
actions on U.S. operators is estimated to be $190,800, or $1,200 per 
airplane. Because the actions described in this service bulletin are 
already required by another AD action, this proposed requirement would 
add no new costs for affected operators.
    It would take approximately 5 work hours per airplane to accomplish 
the proposed actions described in Boeing Service Bulletin 767-57-0053, 
Revision 2, at an average labor rate of $60 per work hour. Based on 
these figures, the cost impact of these proposed actions on U.S. 
operators is estimated to be $47,700, or $300 per airplane. Because the 
actions described in this service bulletin are already required by 
another AD action, this proposed requirement would add no new costs for 
affected operators.
    Some operators may have accomplished certain modifications on some 
or all of the airplanes in their fleets, while other operators may not 
have accomplished any of the modifications on any of the airplanes in 
their fleets. As indicated earlier in this preamble, the FAA invites 
comments specifically on the overall economic aspects of this proposed 
rule.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the current or proposed 
requirements of this AD action, and that no operator would accomplish 
those actions in the future if this AD were not adopted. The cost 
impact figures discussed in AD rulemaking actions represent only the 
time necessary to perform the specific actions actually required by the 
AD. These figures typically do not include incidental costs, such as 
the time required to gain access and close up, planning time, or time 
necessitated by other administrative actions.

Regulatory Impact

    The regulations proposed herein would not have a substantial direct 
effect 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, it 
is determined that this proposal would not have federalism implications 
under Executive Order 13132.
    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

[[Page 60129]]

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 99-NM-127-AD.

    Applicability: Model 767 series airplanes powered by General 
Electric engines, line numbers 1 through 663 inclusive, 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 (d) 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 fatigue cracking in the primary strut structure and 
consequent reduced structural integrity of the strut, accomplish the 
following:

Modification

    (a) Modify the nacelle strut and wing structure on both the left 
and right sides of the airplane, in accordance with Boeing Service 
Bulletin 767-54-0081, dated July 29, 1999, at the later of the times 
specified in paragraphs (a)(1) and (a)(2) of this AD.
    (1) Prior to the accumulation of 37,500 total flight cycles, or 
within 20 years since date of manufacture, whichever occurs first. 
Use of the optional threshold formula described in Figure 1 on page 
54 of the service bulletin is an acceptable alternative to the 20-
year threshold provided that the conditions specified in Figure 1 of 
the service bulletin are met.
    (2) Within 3,000 flight cycles after the effective date of this 
AD.
    (b) Prior to or concurrently with the accomplishment of the 
modification of the nacelle strut and wing structure required by 
paragraph (a) of this AD; as specified in paragraph 1.D., Table 2, 
``Prior or Concurrent Service Bulletins,'' on page 8 of Boeing 
Service Bulletin 767-54-0081, dated July 29, 1999; accomplish the 
actions specified in Boeing Service Bulletin 767-29-0057, dated 
December 16, 1993; Boeing Service Bulletin 767-54-0069, Revision 1, 
dated January 29, 1998; Boeing Service Bulletin 767-54-0083, dated 
September 17, 1998; Boeing Service Bulletin 767-54-0088, Revision 1, 
dated July 29, 1999; Boeing Service Bulletin 767-54A0094, Revision 
1, dated September 16, 1999; and Boeing Service Bulletin 767-57-
0053, Revision 2, dated September 23, 1999; as applicable, in 
accordance with those service bulletins.

    Note 2: AD 2000-12-17, amendment 39-11795, requires 
accomplishment of Boeing Service Bulletin 767-57-0053, Revision 2, 
dated September 23, 1999. However, inspections and rework 
accomplished in accordance with Boeing Service Bulletin 767-57-0053, 
Revision 1, dated October 31, 1996, are acceptable for compliance 
with the applicable actions required by paragraph (b) of this AD.


    Note 3: AD 2000-07-05, amendment 39-11659, requires 
accomplishment of Boeing Service Bulletin 767-54A0094, dated May 22, 
1998. However, inspections and rework accomplished in accordance 
with Boeing Service Bulletin 767-54A0094, dated May 22, 1998, are 
acceptable for compliance with the applicable actions required by 
paragraph (b) of this AD.

    (c) If any damage to the airplane structure is found during the 
accomplishment of the modification required by paragraph (a) of this 
AD, and the service bulletin specifies to contact Boeing for 
appropriate action: Prior to further flight, repair in accordance 
with a method approved by the Manager, Seattle Aircraft 
Certification Office (ACO), FAA, or a Boeing Company Designated 
Engineering Representative who has been authorized by the FAA to 
make such findings. For a repair method to be approved by the 
Manager, Seattle ACO, as required by this paragraph, the Manager's 
approval letter must specifically reference this AD.

Alternative Methods of Compliance

    (d) 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 ACO. 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 4: 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

    (e) 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 October 3, 2000.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-25967 Filed 10-6-00; 8:45 am]
BILLING CODE 4910-13-U