AD Amdt-39-10464

[Federal Register Volume 63, Number 70 (Monday, April 13, 1998)]
[Rules and Regulations]
[Pages 17932-17934]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 98-9589]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-83-AD; Amendment 39-10464; AD 98-08-15]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747-100, -200, and -300 
Series 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 747-100, -200, and -300 series 
airplanes. This action requires repetitive detailed visual and/or 
borescope inspections to detect discrepancies of certain areas of the 
wing strut. This amendment also provides for an optional terminating 
action for the repetitive inspections. This amendment is prompted by 
reports that fatigue cracking was found in the vertical chords, midspar 
webs, and canted closure webs. The actions specified in this AD are 
intended to detect and correct fatigue cracking and stress corrosion of 
the wing strut, which could result in failure of the strut-to-wing 
interface, and consequent separation of the engine and strut from the 
airplane.

DATES: Effective April 28, 1998.
    The incorporation by reference of Boeing Alert Service Bulletin 
747-54A2179, Revision 2, dated December 4, 1997, as listed in the 
regulations, is approved by the Director of the Federal Register as of 
April 28, 1998.
    The incorporation by reference of certain other publications, as 
listed in the regulations, was approved previously by the Director of 
the Federal Register as of January 22, 1997 (61 FR 66201, December 17, 
1996).
    Comments for inclusion in the Rules Docket must be received on or 
before June 12, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 98-NM-83-AD, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056.
    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 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.

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

SUPPLEMENTARY INFORMATION: The FAA has received several reports of 
cracking of the vertical chords, midspar webs, and canted closure webs 
on the inboard and outboard struts of certain Boeing Model 747 series 
airplanes. Investigation has revealed that the cracking in the vertical 
chords was due to fatigue and stress corrosion. Additionally, the 
investigation revealed that the cracking in the midspar webs was due to 
fatigue. Such fatigue cracking and stress corrosion, if not corrected, 
could result in failure of the strut-to-wing interface, and consequent 
separation of the engine and strut from the airplane.

Other Relevant Rulemaking

    AD 97-12-03, amendment 39-10045 (62 FR 31331, June 9, 1997) 
currently requires inspections for cracking, corrosion, and fracturing 
of the lower and upper horizontal clevis of the strut midspar fittings; 
and replacement of discrepant parts with new parts, or rework, if 
necessary. Boeing Alert Service Bulletin 747-54A2179, Revision 1, dated 
November 27, 1996, is cited in AD 97-12-03 as the appropriate service 
information.

[[Page 17933]]

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletin 
747-54A2179, Revision 2, dated December 4, 1997, which describes, among 
other actions, procedures for performing repetitive detailed visual 
and/or borescope inspections to detect fatigue cracking, stress 
corrosion, and fracturing of certain parts of the wing spar (the 
midspar fitting vertical legs, aft torque bulkhead vertical chords, 
midspar webs, and midspar canted closure webs). The alert service 
bulletin also describes procedures for certain repair, rework, and 
replacement actions. The initial inspection and repetitive intervals 
recommended in the alert service bulletin will detect fatigue cracking, 
stress corrosion, and fracturing of the subject area in a timely 
manner.

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 747-100, -200, and -300 series 
airplanes of the same type design, this AD is being issued to detect 
and correct fatigue cracking, stress corrosion, or fracturing of 
certain areas of the wing spar (the midspar fitting vertical legs, aft 
torque bulkhead vertical chords, midspar webs, and midspar canted 
closure webs), which could cause failure of the strut-to-wing 
interface, and consequent separation of the engine and strut from the 
airplane. This AD requires repetitive inspections to detect fatigue 
cracking, stress corrosion, or fracturing of certain areas of the wing 
spar (the midspar fitting vertical legs, aft torque bulkhead vertical 
chords, midspar webs, and midspar canted closure webs) to be 
accomplished in accordance with the alert service bulletin described 
previously. Also, if any fatigue cracking, stress corrosion, or 
fracturing is detected that is within the limits specified by the alert 
service bulletin, certain corrective actions (repair) shall be 
accomplished in accordance with the alert service bulletin. Certain 
other corrective actions that are outside the limits specified by the 
alert service bulletin shall be accomplished in accordance with a 
method approved by the FAA.

Differences Between the Rule and the Relevant Service Information

    Operators should note the following differences between the rule 
and the relevant alert service bulletin:
    1. If any fatigue cracking, stress corrosion, or fracturing is 
detected during any inspections required by this AD that is outside the 
limits specified in the alert service bulletin, corrective actions must 
be accomplished in accordance with a method approved by the FAA.
    2. Additionally, operators should note that, while this AD cites 
Boeing Alert Service Bulletin 747-54A2179, Revision 2, dated December 
4, 1997, as the appropriate service information for this AD, this AD 
does not supersede the requirements of AD 97-12-03, which cites 
Revision 1 of the same alert service bulletin as the appropriate 
service information.
    3. Although the alert service bulletin referenced in this AD 
provides procedures to detect and correct fatigue cracking, stress 
corrosion, or fracturing of the midspar fitting vertical legs, aft 
torque bulkhead vertical chords, midspar webs, and midspar canted 
closure webs for certain airplanes identified as Group 5 airplanes, 
this AD does not require any action for those airplanes. At this time, 
the FAA has not received any reports of cracked structure on the 
airplanes designated as Group 5 airplanes. However, the FAA may 
consider further rulemaking if additional information indicates that 
the identified unsafe condition is found on Group 5 airplanes.

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 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 98-NM-83-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, 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:

[[Page 17934]]

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:

98-08-15 Boeing: Amendment 39-10464. Docket 98-NM-83-AD.

    Applicability: Model 747-100, -200, and -300 series airplanes 
having line positions 1 through 886 inclusive, certificated in any 
category; excluding airplanes on which the strut/wing modification 
has been accomplished in accordance with AD 95-13-07, amendment 39-
9287; or AD 95-10-16, amendment 39-9233; and excluding airplanes 
designated as Group 5 in Boeing Service Bulletin 747-54A2179, 
Revision 2, dated December 4, 1997.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
otherwise 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 (e) 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 stress corrosion of 
certain areas of the wing strut (the midspar fitting vertical leg, 
aft bulkhead vertical chords, the midspar webs, and the canted 
closure webs), which could cause failure of the strut-to-wing 
interface, and consequent separation of the engine and strut from 
the airplane; accomplish the following:
    (a) Perform detailed visual and/or borescope inspections to 
detect fatigue cracking, stress corrosion, or fracture of the 
midspar fitting vertical legs, the aft torque bulkhead vertical 
chords, the midspar webs and the midspar canted closure webs at the 
time specified in paragraph (a)(1), (a)(2), or (a)(3) of this AD, as 
applicable; in accordance with Part III of Section III of the 
Accomplishment Instructions of Boeing Alert Service Bulletin 747-
54A2179, Revision 2, dated December 4, 1997. Thereafter, repeat the 
inspections in accordance with and at the times specified in the 
alert service bulletin.
    (1) For airplanes identified as Group 1 in the alert service 
bulletin: Perform the inspections on the inboard struts and the 
outboard struts, prior to the accumulation of 5,000 total landings, 
or within 90 days after the effective date of this AD, whichever 
occurs later.
    (2) For airplanes identified as Group 6 in the alert service 
bulletin: Perform the inspections on the inboard struts, prior to 
the accumulation of 5,000 total landings or within 90 days after the 
effective date of this AD, whichever occurs later.
    (3) For airplanes identified as Groups 2, 3, and 4 in the alert 
service bulletin: Perform the inspections on the inboard struts, 
prior to the accumulation of 12,000 total landings, or within 90 
days after the effective date of this AD, whichever occurs later.
    (b) If any fatigue cracking, stress corrosion, or fracturing is 
detected during any inspection required by paragraph (a) of this AD 
that is within the limits specified in Boeing Alert Service Bulletin 
747-54A2179, Revision 2, dated December 4, 1997, prior to further 
flight, repair in accordance with the alert service bulletin.
    (c) If any fatigue cracking, stress corrosion, or fracturing is 
detected during any inspection required by paragraph (a) of this AD 
that is beyond the limits specified in Boeing Alert Service Bulletin 
747-54A2179, Revision 2, dated December 4, 1997, prior to further 
flight, accomplish corrective actions in accordance with a method 
approved by the Manager, FAA, Transport Airplane Directorate, 
Seattle Aircraft Certification Office (ACO), Seattle, Washington.
    (d) Accomplishment of the strut/wing modification specified in 
paragraph (d)(1) or (d)(2) of this AD, as applicable, constitutes 
terminating action for the requirements of this AD.
    (1) For airplanes equipped with General Electric Model CF6-45 or 
-50 series engines, or Pratt & Whitney Model JT9D-70 series engines: 
Accomplish the strut/wing modification in accordance with Boeing 
Alert Service Bulletin 747-54A2158, Revision 2, dated August 15, 
1996.
    (2) For airplanes equipped with Pratt & Whitney Model JT9D 
series engines (excluding Model JT9D-70 engines): Accomplish the 
strut/wing modification in accordance with Boeing Alert Service 
Bulletin 747-54A2159, Revision 2, dated March 14, 1996.
    (e) 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 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

    (f) 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.
    (g) Except as provided by the requirements of paragraph (c) of 
this AD, the actions and the terminating modifications shall be done 
in accordance with Boeing Alert Service Bulletin 747-54A2179, 
Revision 2, dated December 4, 1997; Boeing Service Bulletin 747-
54A2158, Revision 2, dated August 15, 1996; and Boeing Service 
Bulletin 747-54A2159, Revision 2, dated March 14, 1996.
    (1) The detailed visual and borescope inspections shall be done 
in accordance with Boeing Alert Service Bulletin 747-54A2179, 
Revision 2, dated December 4, 1997. The incorporation by reference 
of that service bulletin was approved by the Director of the Federal 
Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) The strut/wing modification, if accomplished, shall be done 
in accordance with the Boeing Alert Service Bulletins listed in the 
following table. The incorporation by reference of those documents 
was approved previously by the Director of the Federal Register on 
January 22, 1997 (61 FR 66201, December 17, 1996):

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                                     Revision                           
    Referenced service bulletin       level               Date          
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747-54A2158.......................          2  Aug. 15, 1996.           
747-54A2159.......................          2  March 14, 1996.          
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    (3) 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.
    (h) This amendment becomes effective on April 28, 1998.

    Issued in Renton, Washington, on April 6, 1998.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-9589 Filed 4-10-98; 8:45 am]
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