[Federal Register Volume 64, Number 78 (Friday, April 23, 1999)]
[Rules and Regulations]
[Pages 19879-19881]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-9739]
[[Page 19879]]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 98-NM-337-AD; Amendment 39-11132; AD 99-08-23]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 737-100, -200, -200C, -
300, -400, and -500 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 all Boeing Model 737-100, -200, -200C, -300, -400, and
-500 series airplanes. This action requires repetitive inspections to
detect cracking in the web of the aft pressure bulkhead at body station
1016 at the aft fastener row attachment to the ``Y'' chord; and
corrective actions, if necessary. This amendment is prompted by several
reports of fatigue cracking found at that location on Model 737 series
airplanes. The actions specified in this AD are intended to detect and
correct such fatigue cracking, which could result in rapid
decompression of the fuselage.
DATES: Effective May 10, 1999.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of 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. 98-NM-337-AD, 1601 Lind Avenue, SW.,
Renton, Washington 98055-4056.
FOR FURTHER INFORMATION CONTACT: Nenita Odesa, Aerospace Engineer,
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton,
Washington 98055-4056; telephone (425) 227-2557; fax (425) 227-1181.
SUPPLEMENTARY INFORMATION: The FAA has received reports of fatigue
cracking found on Boeing Model 737-200 series airplanes in the web of
the aft pressure bulkhead at body station 1016 at the aft fastener row
attachment to the ``Y'' chord. An 11-inch crack was found on an
airplane with 40,000 total flight cycles, and a 3.5-inch crack was
found on an airplane with 28,000 total flight cycles. Investigation
revealed 43 fasteners installed in improperly drilled holes at the web-
to-``Y'' chord attachment in the area of the 11-inch crack. Such
fatigue cracking, if not detected and corrected, could result in rapid
decompression of the fuselage.
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 at certain fastener
holes of the aft pressure bulkhead, which could result in rapid
decompression of the fuselage. This AD requires repetitive inspections
of the web of the aft pressure bulkhead at body station 1016 at the aft
fastener row attachment to the ``Y'' chord, and corrective actions, if
necessary. For compliance with this inspection requirement, operators
may perform either a low frequency eddy current (LFEC) inspection from
the aft side of the bulkhead or a detailed visual inspection from the
forward side of the bulkhead. Corrective actions include a high
frequency eddy current inspection to detect cracking of the web at the
``Y'' chord attachment; a detailed visual inspection of the bulkhead,
if necessary; and repair in accordance with a method approved by the
FAA.
Differences Between AD and Relevant Service Information
This AD refers to Boeing 737 Nondestructive Test (NDT) Manual D6-
37239, Part 6, Subject 53-10-54, as the appropriate source of service
information for accomplishment of the LFEC inspection. Operators should
note that, unlike the procedures described in the NDT manual, which
specifies that the web be inspected only from stringer 9 left to
stringer 9 right, this AD expands the area to be inspected. Because of
the safety implications and consequences associated with fatigue
cracking and because of the unknown nature of the source of the subject
cracking, the FAA has determined that an LFEC inspection, if
accomplished, must be performed from stringer 15 left to stringer 15
right of the upper section of the bulkhead at body station 1016.
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 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-337-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.
[[Page 19880]]
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:
99-08-23 Boeing: Amendment 39-11132. Docket 98-NM-337-AD.
Applicability: All Model 737-100, -200, -200C, -300, -400, and -
500 series airplanes; 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 (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 at certain fastener holes
of the aft pressure bulkhead, which could result in rapid
decompresssion of the fuselage, accomplish the following:
Initial Inspection
(a) Perform either inspection specified by paragraph (a)(1) or
(a)(2) of this AD at the time specified in paragraph (b) of this AD.
(1) Perform a low frequency eddy current inspection from the aft
side of the aft pressure bulkhead to detect discrepancies (including
cracking, misdrilled fastener holes, and corrosion) of the web of
the upper section of the aft pressure bulkhead at body station 1016
at the aft fastener row attachment to the ``Y'' chord, from stringer
15 left to stringer 15 right, in accordance with Boeing 737
Nondestructive Test Manual D6-37239, Part 6, Section 53-10-54, dated
December 5, 1998.
(2) Perform a detailed visual inspection of the aft fastener row
attachment to the ``Y'' chord from the forward side of the aft
pressure bulkhead to detect discrepancies (including cracking,
misdrilled fastener holes, and corrosion) of the entire web of the
aft pressure bulkhead at body station 1016.
(b) Perform the inspection required by paragraph (a) of this AD
at the time specified by paragraph (b)(1), (b)(2), or (b)(3) of this
AD, as applicable.
(1) For airplanes that have accumulated 40,000 or more total
flight cycles as of the effective date of this AD: Inspect within
375 flight cycles or 60 days after the effective date of this AD,
whichever occurs later.
(2) For airplanes that have accumulated 25,000 or more total
flight cycles and fewer than 40,000 total flight cycles as of the
effective date of this AD: Inspect within 750 flight cycles or 90
days after the effective date of this AD, whichever occurs later.
(3) For airplanes that have accumulated fewer than 25,000 total
flight cycles as of the effective date of this AD: Inspect prior to
the accumulation of 25,750 total flight cycles.
Repetitive Inspections
(c) Within 1,200 flight cycles after performing the initial
inspection required by paragraph (a) of this AD, and thereafter at
intervals not to exceed 1,200 flight cycles: Perform either
inspection specified by paragraph (a)(1) or (a)(2) of this AD.
Corrective Actions
(d) If any discrepancy is detected during any inspection
required by this AD: Prior to further flight, accomplish the actions
specified by paragraphs (d)(1) and (d)(3), and paragraph (d)(2) if
applicable, of this AD.
(1) Perform a high frequency eddy current inspection from the
forward side of the bulkhead to detect cracking of the web at the
``Y'' chord attachment, around the entire periphery of the ``Y''
chord, in accordance with Boeing 737 Nondestructive Test Manual D6-
37239, Part 6, Section 51-00-00, Figure 23, dated November 5, 1997.
(2) If the most recent inspection performed in accordance with
paragraph (a) of this AD was not a detailed visual inspection:
Accomplish the actions specified by paragraph (a)(2) of this AD. If
the inspection was a detailed visual inspection, it is not necessary
to repeat that inspection prior to further flight.
(3) Repair any discrepancy such as cracking or corrosion or
misdrilled fastener holes 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.
Alternative Methods of Compliance
(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.
Special Flight Permits
(f) Special flight permits may be issued in accordance with
Secs. 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.
Incorporation by Reference
(g) The eddy current inspections shall be done in accordance
with Boeing 737 Nondestructive Test Manual D6-37239, Part 6, Section
53-10-54, dated December 5, 1998; or Boeing 737 Nondestructive Test
Manual D6-37239, Part 6, Section 51-00-00, Figure 23, dated November
5, 1995; as applicable. These references contain the specified list
of effective pages:
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Page No. Revision level shown on page Date shown on page
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Title Page............................. Not Shown.......................... February 5, 1995.
List of Effective Pages--Pages 1, 6-12. Not Shown.......................... December 5, 1998.
List of Effective Pages--Page 2........ Not Shown.......................... August 5, 1998.
List of Effective Pages--Pages 2A, 3... Not Shown.......................... November 5, 1997.
List of Effective Pages--Page 4........ Not Shown.......................... November 5, 1995.
[[Page 19881]]
List of Effective Pages--Page 5........ Not Shown.......................... May 5, 1997.
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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.
(h) This amendment becomes effective on May 10, 1999. .
Issued in Renton, Washington, on April 9, 1999.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 99-9739 Filed 4-22-99; 8:45 am]
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