[Federal Register Volume 60, Number 124 (Wednesday, June 28, 1995)]
[Rules and Regulations]
[Pages 33336-33338]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-15299]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 94-NM-208-AD; Amendment 39-9287; AD 95-13-07]


Airworthiness Directives; Boeing Model 747 Series Airplanes 
Equipped with General Electric Model CF6-45 or -50 Series Engines, or 
Pratt & Whitney Model JT9D-70 Series Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain Boeing Model 747 series airplanes, that requires 
modification of the nacelle strut and wing structure, inspections and 
checks to detect discrepancies, and correction of discrepancies. This 
amendment is prompted by the development of a modification of the strut 
and wing structure that improves the damage tolerance capability and 
durability of the strut-to-wing attachments, and reduces reliance on 
non-routine inspections of those attachments. The actions specified by 
this AD are intended to prevent failure of the strut and subsequent 
loss of the engine.

DATES: Effective July 28, 1995.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of July 28, 1995.

ADDRESSES: The service information referenced in this AD may be 
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, 
Washington 98124-2207. This information may be examined at the Federal 
Aviation Administration (FAA), Transport Airplane Directorate, Rules 
Docket, 1601 Lind Avenue SW., Renton, Washington; or at the Office of 
the Federal Register, 800 North Capitol Street, NW., suite 700, 
Washington, DC.

FOR FURTHER INFORMATION CONTACT: Tim Backman, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle 
Aircraft Certification Office, 1601 Lind Avenue SW., Renton, Washington 
98055-4056; telephone (206) 227-2776; fax (206) 227-1181.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD) that is applicable to certain Boeing Model 747 series 
airplanes was published in the Federal Register on January 3, 1995 (60 
FR 66). That action proposed to require modification of the nacelle 
strut and wing structure, inspections and checks to detect 
discrepancies in the adjacent structure, and correction of 
discrepancies.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.
    Two commenters support the proposed rule.
    One commenter notes that the description of the unsafe condition 
that appeared in the Discussion section of the preamble to the notice 
refers to ``the structural fail-safe capability of the strut-to-wing 
attachment.'' The commenter states that this description is inaccurate 
since it implies that the strut-to-wing attachment is inadequate. The 
commenter suggests that a more accurate description would be ``damage 
tolerance capability of the strut-to-wing attachment.'' The FAA 
acknowledges that the commenter's wording is more accurate. The 
pertinent wording in the preamble to the final rule has been revised to 
reflect this change. Furthermore, the FAA considers that the new 
structure of the strut meets the damage tolerance requirements of 
amendment 45 of section 25.571, ``Damage--tolerance and fatigue 
evaluation of structure,'' of the Federal Aviation Regulations (14 CFR 
25.571, amendment 45), which provides an even higher level of safety 
than simply fail-safe requirements.
    This same commenter provides further information to describe the 
purpose of the proposed modification of the nacelle strut and wing 
structure. This commenter suggests that the rule should specify that 
the modification not only significantly improves the load-carrying and 
durability of the strut-to-wing attachments, but ``reduces the reliance 
on non-routine inspections,'' as well. The FAA concurs with this 
suggestion and has revised the Summary section of the preamble to the 
final rule to include relevant wording.
    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule with the changes previously 
described. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD. [[Page 33337]] 
    There are approximately 145 Model 747 series airplanes equipped 
with General Electric Model CF6-45 or -50 series engines or Pratt & 
Whitney Model JT9D-70 series engines of the affected design in the 
worldwide fleet. The FAA estimates that 12 airplanes of U.S. registry 
will be affected by this AD.
    The full strut modification required by this AD will take as many 
as 6,600 to 7,151 work hours to accomplish, depending upon the 
configuration of the airplane. The manufacturer will incur the cost of 
labor, on a pro-rated basis, with 20 years being the expected life of 
these airplanes. The total cost impact of this AD on U.S. operators is 
based on the median age for the fleet of Model 747 series airplanes 
equipped with General Electric Model CF6-45 or -50 series engines or 
Pratt & Whitney Model JT9D-70 series engines, which is estimated to be 
15 years. The average labor rate is estimated to be $60 per work hour. 
Required parts will be supplied by the manufacturer at no cost to the 
operator. Based on these figures, the cost impact of this AD on U.S. 
operators is estimated to be between $3,564,000 ($297,000 per airplane) 
and $3,861,540 ($321,795 per airplane).
    This cost impact figure does not reflect the cost of the 
terminating actions described in the service bulletins listed in 
paragraph I.C., Table 2, ``Prior or Concurrent Service Bulletins,'' on 
page 7 of Boeing Alert Service Bulletin 747-54A2158, dated November 30, 
1994, that are required to be accomplished prior to or concurrently 
with the modification of the nacelle strut and wing structure. Since 
some operators may have accomplished certain modifications on some or 
all of the airplanes in its fleet, while other operators may not have 
accomplished any of the modifications on any of the airplanes in its 
fleet, the FAA is unable to provide a reasonable estimate of the cost 
of accomplishing the terminating actions described in the service 
bulletins listed in Table 2 of the Boeing alert service bulletin.
    The cost impact figure discussed above is based on assumptions that 
no operator has yet accomplished any of the requirements of this AD 
action, and that no operator would accomplish those actions in the 
future if this AD were not adopted. However, the FAA is aware that some 
operators have already installed the strut modification that is 
required by this AD; therefore, the future economic cost impact of this 
rule on U.S. operators is reduced by that amount.
    The FAA recognizes that the obligation to maintain aircraft in an 
airworthy condition is vital, but sometimes expensive. Because AD's 
require specific actions to address specific unsafe conditions, they 
appear to impose costs that would not otherwise be borne by operators. 
However, because of the general obligation of operators to maintain 
aircraft in an airworthy condition, this appearance is deceptive. 
Attributing those costs solely to the issuance of this AD is 
unrealistic because, in the interest of maintaining safe aircraft, 
prudent operators would accomplish the required actions even if they 
were not required to do so by the AD.
    A full cost-benefit analysis has not been accomplished for this AD. 
As a matter of law, in order to be airworthy, an aircraft must conform 
to its type design and be in a condition for safe operation. The type 
design is approved only after the FAA makes a determination that it 
complies with all applicable airworthiness requirements. In adopting 
and maintaining those requirements, the FAA has already made the 
determination that they establish a level of safety that is cost-
beneficial. When the FAA, as in this AD, makes a finding of an unsafe 
condition, this means that the original cost-beneficial level of safety 
is no longer being achieved and that the required actions are necessary 
to restore that level of safety. Because this level of safety has 
already been determined to be cost-beneficial, a full cost-benefit 
analysis for this AD would be redundant and unnecessary.
    The regulations adopted herein will 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 final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it may be obtained 
from the Rules Docket at the location provided under the caption 
ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends 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. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR 11.89.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

95-13-07  Boeing: Amendment 39-9287. Docket 94-NM-208-AD.

    Applicability: Model 747 series airplanes, equipped with General 
Electric Model CF6-45 or -50 series engines, or Pratt & Whitney 
Model JT9D-70 series 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 use the authority 
provided in paragraph (d) of this AD to request approval from the 
FAA. This approval may address either no action, if the current 
configuration eliminates the unsafe condition; or different actions 
necessary to address the unsafe condition described in this AD. Such 
a request should include an assessment of the effect of the changed 
configuration on the unsafe condition addressed by this AD.

    In no case does the presence of any modification, alteration, or 
repair remove any airplane from the applicability of this AD.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent failure of the strut and subsequent loss of the 
engine, accomplish the following:
    (a) Accomplish the modification of the nacelle strut and wing 
structure in accordance with Boeing Alert Service Bulletin 747-
54A2158, dated November 30, 1994, within 56 months after the 
effective date of this AD. All of the terminating actions described 
in the service bulletins listed in paragraph I.C., Table 2, ``Prior 
or Concurrent Service Bulletins,'' on page 7 of Boeing Alert Service 
Bulletin 747-54A2158, dated November 30, 1994, must be accomplished 
in accordance with those service bulletins prior to, or concurrently 
with, the accomplishment [[Page 33338]] of the modification of the 
nacelle strut and wing structure required by this paragraph.
    (b) Perform the inspections and checks specified in paragraph 
III, NOTES 8, 9, 10, and 11 of the Accomplishment Instructions on 
page 129 of Boeing Alert Service Bulletin 747-54A2158, dated 
November 30, 1994, concurrently with the modification of the nacelle 
strut and wing structure required by paragraph (a) of this AD. Prior 
to further flight, correct any discrepancies found in accordance 
with the alert service bulletin.
    (c) Accomplishment of the modification of the nacelle strut and 
wing structure in accordance with Boeing Alert Service Bulletin 747-
54A2158, dated November 30, 1994, constitutes terminating action for 
the inspections required by the following AD's:

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                                       Federal                          
        AD No.          Amendment      Register      Date of publication
                           No.         citation                         
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94-22-08                 39-9057-  59 FR 58761      Nov. 15, 1994.      
93-17-07                 39-8678-  58 FR 45827-     Aug. 31, 1993.      
93-03-14                 39-8518-  58 FR 14513-     Mar. 18, 1993.      
92-24-51                 39-8439-  57 FR 60118-     Dec. 18, 1992.      
90-20-20                 39-6725-  55 FR 37859-     Sept. 14, 1990.     
89-07-15                 39-6167-  54 FR 11693-     Mar. 22, 1989.      
87-04-13 R1-              39-5836  53 FR 2005-      Jan. 26, 1988.      
86-23-01                 39-5450-  51 FR 37712-     Oct. 24, 1986.      
86-08-03                 39-5289-  51 FR 12836-     Apr. 16, 1986.      
86-07-06                 39-5270-  51 FR 10821-     Mar. 31, 1986.      
86-05-11 R1-              39-5334  51 FR 21900-     June 17, 1986.      
80-08-02                 39-3738-  45 FR 24450-     Apr. 10, 1980.      
79-17-07                 39-3533-  44 FR 50033-     Aug. 27, 1979.      
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    (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 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.

    (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.
    (f) The modification, inspections, checks, and correction of 
discrepancies shall be done in accordance with Boeing Alert Service 
Bulletin 747-54A2158, dated November 30, 1994. This incorporation by 
reference was approved by the Director of the Federal Register in 
accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be 
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, 
Seattle, Washington 98124-2207. Copies may be inspected at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington; or at the Office of the Federal Register, 800 North 
Capitol Street, NW., suite 700, Washington, DC.
    (g) This amendment becomes effective on July 28, 1995.

    Issued in Renton, Washington, on June 16, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 95-15299 Filed 6-27-95; 8:45 am]
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