[Federal Register Volume 63, Number 183 (Tuesday, September 22, 1998)]
[Rules and Regulations]
[Pages 50508-50511]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-25148]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-256-AD; Amendment 39-10791; AD 98-20-25]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747-100 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 series airplanes. This 
action requires repetitive inspections to detect cracking of the outer 
chord of the Body Station (BS) 1480 upper and lower bulkhead and 
longeron splice fitting, and repair, if necessary. Alternatively, this 
action requires other repetitive inspections to detect cracking of the 
BS 1480 upper and lower bulkhead, bulkhead outer chord, web, skin, 
splice components, and lower bulkhead/stringer interface; and 
modification of the skin splice plate, the outer chord splice fitting, 
and the stringer interface of the lower bulkhead, if necessary. This 
amendment is prompted by a report indicating that fatigue cracking was 
found in the outer chord of the BS 1480 bulkhead at the overwing 
longeron splice, and that the longeron splice fitting was completely 
severed. The actions specified in this AD are intended to detect and 
correct fatigue cracking of the BS 1480 bulkhead outer chord and 
longeron splice fitting, which could result in reduced structural 
integrity of the fuselage and the inability to carry limit load.

DATES: Effective October 7, 1998.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of October 7, 1998.

[[Page 50509]]

    Comments for inclusion in the Rules Docket must be received on or 
before November 23, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 98-NM-256-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: Bob Breneman, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle 
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-2776; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION: The FAA has received a report indicating 
that a six-inch fatigue crack was found in the outer chord of the Body 
Station (BS) 1480 bulkhead at the overwing longeron splice on a Boeing 
Model 747-100 series airplane. The report also indicated that the 
longeron splice fitting was completely severed. The effects of such 
fatigue cracking could severely reduce the capability of the overwing 
longeron to carry lateral load. Such fatigue cracking, if not 
corrected, could result in reduced structural integrity of the fuselage 
and the inability to carry limit load.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletin 
747-53A2390, dated July 31, 1997, which describes procedures for 
repetitive inspections to detect cracking of the BS 1480 upper and 
lower bulkhead, bulkhead outer chord, web, skin, splice components, and 
lower bulkhead/stringer interface; and repair, if necessary. The alert 
service bulletin also describes, as part of a certain inspection plan, 
procedures for modification of the skin splice plate, outer chord 
splice fitting, and the stringer interface of the lower bulkhead. 
Accomplishment of the actions specified in the alert service bulletin 
is intended to adequately address the identified unsafe condition.

Explanation of the Requirements of the Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of the same type design, this AD is 
being issued to detect and correct fatigue cracking of the BS 1480 
bulkhead outer chord and longeron splice fitting, which could result in 
reduced structural integrity of the fuselage and the inability to carry 
limit load. This AD requires either repetitive detailed visual 
inspections to detect cracking of the outer chord of the BS 1480 upper 
and lower bulkhead and longeron splice fitting, and repair, if 
necessary; or accomplishment of certain actions specified in the alert 
service bulletin described previously, except as discussed below.

Differences Between Proposed Rule and Alert Service Bulletin

    Operators should note that the alert service bulletin applies to 
all Boeing Model 747-100, -200, and -300 series airplanes. This AD only 
applies to Model 747-100 series airplanes, line positions 1 through 87 
inclusive, which have a different configuration of the longeron splice 
fitting than later Model 747 series airplanes. The severe fatigue 
damage that prompted the FAA to mandate the actions required by this AD 
has only been observed on the longeron splice fitting and outer chord 
of the BS 1480 bulkhead of Model 747-100 series airplanes having line 
positions 1 through 87 inclusive. As discussed below, the FAA is 
currently considering requiring repetitive inspections and modification 
of the upper and lower bulkhead and overwing longeron at BS 1480 for 
all Boeing Model 747-100, -200, and -300 series airplanes.
    In addition, although the alert service bulletin recommends 
accomplishing the inspection prior to the accumulation of 10,000 total 
flight cycles or within 1,000 flight cycles after the release of the 
alert service bulletin, whichever occurs later, the FAA has determined 
that such a compliance time would not address the identified unsafe 
condition in a timely manner. In developing an appropriate compliance 
time for this AD, the FAA considered not only the manufacturer's 
recommendation, but the degree of urgency associated with addressing 
the subject unsafe condition, the average utilization of the affected 
fleet, and the time necessary to perform the inspection. In light of 
all of these factors, the FAA finds a compliance time of 10,000 total 
flight cycles or 45 days after the effective date of this AD, whichever 
occurs later, for initiating the required actions to be warranted, in 
that it represents an appropriate interval of time allowable for 
affected airplanes to continue to operate without compromising safety.
    Operators also should note that, although the alert service 
bulletin specifies that the manufacturer may be contacted for 
disposition of certain repair conditions, this AD requires the repair 
of those conditions to be accomplished in accordance with a method 
approved by the FAA.

Interim Action

    This is considered to be interim action. The FAA is currently 
considering further rulemaking action to supersede this AD to require 
inspections and modification of the upper and lower bulkhead and 
overwing longeron at BS 1480 for all Boeing Model 747-100, -200, and -
300 series airplanes. However, the planned compliance time for the 
initial inspection and installation of the modification is sufficiently 
long so that notice and opportunity for prior public comment will be 
practicable.

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,

[[Page 50510]]

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-256-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:

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:

98-20-25 Boeing: Amendment 39-10791. Docket 98-NM-256-AD.

    Applicability: Model 747-100 series airplanes, line positions 1 
through 87 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 (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 of the Body Station (BS) 
1480 bulkhead outer chord and longeron splice fitting, which could 
result in reduced structural integrity of the fuselage and the 
inability to carry limit load, accomplish the following:
    (a) Prior to the accumulation of 10,000 total flight cycles, or 
within 45 days after the effective date of this AD, whichever occurs 
later, accomplish either paragraph (a)(1) or (a)(2) of this AD.
    (1) Perform a detailed visual inspection to detect cracking of 
the longeron splice fitting at BS 1480, the forward side of the 
outer chord of the BS 1480 bulkhead at the longeron splice fitting 
attachment bolts, and the aft side of the outer chord of the BS 1480 
bulkhead within two inches above the outer chord splice fitting, on 
both the left and right sides of the airplane.

    Note 2: Figure 5 of Boeing Alert Service Bulletin 747-53A2390, 
dated July 31, 1997, provides an exploded view of the structural 
components of the splice area for the purpose of parts 
identification. [However, paragraph (a)(1) of this AD does not 
require the inspection described in Figure 5.]

    (i) If any cracking is detected, prior to further flight, repair 
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 basis of the airplane approved by a Boeing Company 
Designated Engineering Representative who has been authorized by the 
Manager, Seattle ACO, to make such findings.
    (ii) Repeat the detailed visual inspection thereafter at 
intervals not to exceed 250 flight cycles, until the initial 
inspection required by paragraph (a)(2) of this AD is accomplished.
    (2) Perform detailed visual and eddy current inspections to 
detect cracking of the upper and lower bulkhead, bulkhead outer 
chord, web, skin, splice components, and lower bulkhead/stringer 
interface, in accordance with Figures 5 and 8 of Boeing Alert 
Service Bulletin 747-53A2390, dated July 31, 1997. Additionally, for 
airplanes on which the inspection in ``Plan B'' of the service 
bulletin is accomplished, modify the skin splice plate, the outer 
chord splice fitting, and the stringer interface of the lower 
bulkhead, in accordance with the Accomplishment Instructions of the 
alert service bulletin. Accomplishment of these actions constitutes 
terminating action for the repetitive inspection requirements of 
paragraph (a)(1) of this AD.
    (i) If any cracking is detected, prior to further flight, repair 
in accordance with the alert service bulletin, except as provided by 
paragraph (b) of this AD.
    (ii) Repeat the inspections thereafter in accordance with the 
flight safety inspection program specified in Figures 1 and 3 of the 
alert service bulletin.
    (b) Where the alert service bulletin specifies that the 
manufacturer may be contacted for disposition of certain repair 
conditions, repair in accordance with a method approved by the 
Manager, Seattle ACO; 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 
Manager, Seattle ACO, to make such findings.
    (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.

    (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) Except as provided by paragraphs (a)(1)(i) and (b) of this 
AD, the actions shall be done in accordance with Boeing Alert 
Service Bulletin 747-53A2390, dated July 31, 1997. 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.
    (f) This amendment becomes effective on October 7, 1998.


[[Page 50511]]


    Issued in Renton, Washington, on September 15, 1998.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-25148 Filed 9-21-98; 8:45 am]
BILLING CODE 4910-13-P