[Federal Register Volume 64, Number 78 (Friday, April 23, 1999)]
[Rules and Regulations]
[Pages 19883-19885]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-10175]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-49-AD; Amendment 39-11144; AD 99-09-11]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747 Series Airplanes 
Equipped With General Electric Model CF6-45 or -50 Series Engines; or 
Pratt & Whitney Model JT9D-3, -7, or -70 Series Engines; and 747-E4B 
(Military) Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to certain Boeing Model 747 series airplanes and all 747-
E4B (military) airplanes. This action requires repetitive inspections 
to detect cracking or fracture of the steel attachment fittings of the 
diagonal brace to the nacelle struts; and replacement of the attachment 
fittings with new steel fittings, if necessary. This amendment is 
prompted by a report indicating a fractured steel attachment fitting of 
a diagonal brace to the number 2 nacelle strut; such fracture has been 
attributed to fatigue cracking. The actions specified in this AD are 
intended to detect and correct such fatigue cracking, which could 
result in failure of a nacelle strut diagonal brace load path and 
possible separation of the nacelle from the wing.

DATES: Effective May 10, 1999.
    Comments for inclusion in the Rules Docket must be received on or 
before June 22, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 99-NM-49-AD, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056.
    Information pertaining to this amendment may be obtained from or 
examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, 
SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT: Tamara L. Anderson, Aerospace 
Engineer, Airframe Branch, ANM-120S, FAA, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056; telephone (425) 227-2771; fax (425) 227-
1181.

SUPPLEMENTARY INFORMATION: On May 10, 1995, the FAA issued AD 95-10-16, 
amendment 39-9233 (60 FR 27008, May 22, 1995), applicable to certain 
Boeing Model 747 series airplanes equipped with Pratt & Whitney Model 
JT9D series engines (excluding Model JT9D-70 series engines); and on 
June 16, 1995, the FAA issued AD 95-13-07, amendment 39-9287 (60 FR 
33336, June 28, 1995), applicable to certain Boeing Model 747 series 
airplanes equipped with General Electric Model CF6-45 or -50 series 
engines, or Pratt & Whitney Model JT9D-70 series engines. Both of those 
AD's require modification of the nacelle strut and wing structure, 
inspections and checks to detect discrepancies, and correction of 
discrepancies. The requirements of those AD's are intended to prevent 
failure of the nacelle strut and subsequent separation of the nacelle 
from the wing.
    Since issuance of those two AD's, the FAA has received a report 
indicating that a fractured steel attachment fitting of a diagonal 
brace to the number 2 nacelle strut was found during a routine service 
inspection of a Boeing Model 747 series airplane equipped with General 
Electric Model CF6-50 series engines. This is the first report of a 
fractured steel attachment fitting on a Model 747 series airplane that 
was found after the strut and wing were modified in accordance with AD 
95-13-07 or AD 95-10-16. However, the report clarifies that the steel 
fitting had been installed during production rather than during the 
modification required by AD 95-13-07. The FAA points out that the 
replacement of the fitting with a new steel fitting is only part of the 
modification required by the previously referenced AD's. The 
manufacturer reported that the crack initiation, which began at the far 
aft fastener hole on the inboard side of the lower flange of the 
attachment fitting, was attributed to fretting and galling and is 
indicative of fatigue. The airplane had accumulated 54,852 flight hours 
and 11,124 flight cycles, and the strut and wing modification had been 
accomplished in accordance with AD 95-13-07 at 50,357 flight hours and 
10,085 flight cycles.
    While this is the first report of a fitting failure after 
modification in accordance with AD 95-13-07, cracking or fracture of a 
steel attachment fitting of the diagonal brace to the nacelle strut, if 
not corrected, could result in failure of a nacelle strut diagonal 
brace load path and possible separation of the nacelle from the wing.
    The attachment fittings on the Pratt & Whitney series engines are 
similar to the attachment fittings on the General Electric series 
engines that are addressed in this AD. Therefore, all of the attachment 
fittings on either of these engines may be subject to the same unsafe 
condition. However, the configurations of these engines are different 
in that some have enhanced structural capability; therefore, the FAA 
has determined that a somewhat longer repetitive inspection interval 
for those configurations is appropriate.

Explanation of the Requirements of the Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other Boeing Model 747 series airplanes of the same 
type design, this AD is being issued to detect and correct fatigue 
cracking or fracture of the steel attachment fittings of the diagonal 
brace to the nacelle struts, which could result in failure of the 
nacelle strut diagonal brace load path and possible separation of the 
nacelle from the wing. This AD requires repetitive detailed visual 
inspections to detect such cracking or fracture. This AD also requires 
replacement of the attachment fittings with new steel fittings, if 
necessary, in accordance with a method approved by the FAA, or in 
accordance with data meeting the type certification basis of the 
airplane approved by a Boeing Company Designated Engineering 
Representative who has been authorized by the FAA to make such 
findings.

Interim Action

    This is considered to be interim action until final action is 
identified, at which time the FAA may consider further rulemaking.

Determination of Rule's Effective Date

    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be

[[Page 19884]]

amended in light of the comments received. Factual information that 
supports the commenter's ideas and suggestions is extremely helpful in 
evaluating the effectiveness of the AD action and determining whether 
additional rulemaking action would be needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the 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 that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 99-NM-49-AD.'' The postcard will be date stamped and 
returned to the commenter.

Regulatory Impact

    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.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and that it is not a ``significant regulatory 
action'' under Executive Order 12866. It has been determined further 
that this action involves an emergency regulation under DOT Regulatory 
Policies and Procedures (44 FR 11034, February 26, 1979). If it is 
determined that this emergency regulation otherwise would be 
significant under DOT Regulatory Policies and Procedures, a final 
regulatory evaluation will be prepared and placed in the Rules Docket. 
A copy of it, if filed, 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, 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. 106(g), 40113, 44701.

Sec. 39.13  [Amended]

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

99-09-11  Boeing: Amendment 39-11144. Docket 99-NM-49-AD.

    Applicability: Model 747 series airplanes equipped with General 
Electric Model CF6-45 or -50 series engines, or Pratt & Whitney 
Model JT9D-3, -7, or -70 series engines, and all 747-E4B (military) 
airplanes, having steel attachment fittings of the diagonal brace to 
the nacelle struts; certificated in any category.

    Note 1: This AD excludes those airplanes that are included in 
the applicability of AD 97-20-01 R1, amendment 39-10982 (64 FR 985, 
January 7, 1999). Those airplanes have aluminum attachment fittings.

    Note 2: 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 detect and correct fatigue cracking or fracture of the steel 
attachment fittings of the diagonal brace to the nacelle struts, 
which could result in failure of a nacelle strut diagonal brace load 
path and possible separation of the nacelle from the wing; 
accomplish the following:

Initial Inspection

    (a) Gain access to the attachment fittings of the diagonal brace 
to the inboard and outboard nacelle struts through the aft fairing 
doors, and perform a detailed visual inspection to detect cracking 
or fracture of the steel attachment fittings of the diagonal brace 
to the inboard and outboard nacelle struts, at the applicable time 
specified in paragraph (a)(1) or (a)(2) of this AD.
    (1) For airplanes on which the strut and wing modification 
required by AD 95-10-16, amendment 39-9233, or AD 95-13-07, 
amendment 39-9287, has not been accomplished: Within 10 days after 
the effective date of this AD, accomplish the detailed visual 
inspection.
    (i) For airplanes equipped with General Electric Model CF6-45 or 
-50 series engines and/or Pratt & Whitney JT9D-3 or -7 series 
engines, repeat the inspection thereafter at intervals not to exceed 
180 flight cycles.
    (ii) For airplanes equipped with Pratt & Whitney JT9D-70 series 
engines, repeat the inspection thereafter at intervals not to exceed 
250 flight cycles.
    (2) For airplanes on which the strut and wing modification 
required by AD 95-10-16, amendment 39-9233, or AD 95-13-07, 
amendment 39-9287, has been accomplished: Within 30 days after the 
effective date of this AD or within 150 flight cycles after 
accomplishment of the modification, whichever occurs later, 
accomplish the detailed visual inspection.
    (i) For airplanes equipped with General Electric Model CF6-45 or 
-50 series engines or Pratt & Whitney JT9D-70 series engines, repeat 
the inspection thereafter at intervals not to exceed 600 flight 
cycles.
    (ii) For airplanes equipped with Pratt & Whitney JT9D-3 or -7 
series engines, repeat the inspection thereafter at intervals not to 
exceed 350 flight cycles.

Corrective Actions

    (b) If any cracking or fracture of any attachment fitting is 
detected during any inspection required by paragraph (a) of this AD, 
prior to further flight, replace the fitting with a new steel 
fitting in accordance with a method approved by the Manager, Seattle 
Aircraft Certification Office (ACO), FAA, Transport Airplane 
Directorate; or in accordance with data meeting the type 
certification of the airplane approved by a Boeing Company 
Designated Engineering Representative who has been authorized by the 
Manager, Seattle ACO, 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

    (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 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 3: 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

    (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.
    (e) This amendment becomes effective on May 10, 1999.


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    Issued in Renton, Washington, on April 16, 1999.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-10175 Filed 4-22-99; 8:45 am]
BILLING CODE 4910-13-U