[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]
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