[Federal Register: April 25, 2003 (Volume 68, Number 80)]
[Rules and Regulations]
[Page 20341-20344]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr25ap03-5]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 2002-NM-329-AD; Amendment 39-13128; AD 2003-08-15]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 737-200, -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 certain Boeing Model 737-200, -200C, -300, -400, and -
500 series airplanes. This action requires a one-time mid-frequency
eddy current (MFEC), a low-frequency eddy current (LFEC), and a
detailed inspection for damage or cracking of stringer S-4L and S-4R
lap joints and stringer clips between body station (BS) 540 and BS 727,
and follow-on inspections and repair if necessary. This action is
necessary to find and fix cracking of the fuselage lap joints, which
could result in sudden decompression of the airplane.
DATES: Effective May 12, 2003.
The incorporation by reference of Boeing Alert Service Bulletin
737-53A1255, dated October 17, 2002, as listed in the regulations, is
approved by the Director of the Federal Register as of May 12, 2003.
The incorporation by reference of Boeing Service Bulletin 737-
53A1177, Revision 6, dated May 31, 2001, as listed in the regulations,
was approved previously by the Director of the Federal Register as of
May 17, 2002 (67 FR 17917, April 12, 2002).
Comments for inclusion in the Rules Docket must be received on or
before June 24, 2003.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-114,
Attention: Rules Docket No. 2002-NM-329-AD, 1601 Lind Avenue, SW.,
Renton, Washington 98055-4056. Comments may be inspected at this
location between 9 a.m. and 3 p.m., Monday through Friday, except
Federal holidays. Comments may be submitted via fax to (425) 227-1232.
Comments may also be sent via the Internet using the following address:
9-anm-iarcomment@faa.gov. Comments sent via fax or the Internet must
contain ``Docket No. 2002-NM-329-AD'' in the subject line and need not
be submitted in triplicate. Comments sent via the Internet as attached
electronic files must be formatted in Microsoft Word 97 for Windows or
ASCII text.
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: Duong Tran, Aerospace Engineer,
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office,
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425)
917-6452; fax (425) 917-6590.
SUPPLEMENTARY INFORMATION:
Related AD
On April 2, 2002, the FAA issued AD 2002-07-08, amendment 39-12702
(67 FR 17917, April 12, 2002), applicable to certain Boeing Model 737
series airplanes. That AD specifies Boeing Service Bulletin (SB) 737-
53A1177, Revision 6, dated May 31, 2001, as an appropriate source of
service information for that AD. That AD requires repetitive
inspections to find cracking of the lower skin at the lower row of
fasteners in the lap joints of the fuselage, and repair of any cracking
found. That AD also requires modification of the fuselage lap joints at
certain locations, which constitutes terminating action for certain
repetitive inspections of the modified areas. Additionally, that AD
requires repetitive inspections and requires replacement of a certain
preventive modification with an improved modification. That AD was
prompted by our determination that, in light of crack findings, certain
modifications of the fuselage lap joints do not provide an adequate
level of safety. The actions specified by that AD are intended to find
and fix cracking of the fuselage lap joints, which could result in
sudden decompression of the airplane.
Since the Issuance of That AD
We have received a report indicating that, during a walk-around
inspection on a Model 737-200 series airplane with 60,333 total flight
cycles, a 23-inch-long crack was found in the lower row of the stringer
S-4L lap joint between body station (BS) 616 and BS 639. The crack was
noticed above the over-wing exit because the lower skin was pushed
outward approximately 1 inch with the crack ends turning downward at
the tear straps. The flight crew did not report any pressurization
problems, and the passengers and cabin crew did not report any abnormal
noise in that area. Further external and internal non-destructive
testing methods for cracking of the lap joint revealed additional
cracking. The possible extent of cracking both forward and aft of the
23-inch-long cracked section is a concern. Cracks were found in between
the tear straps and in the skin locations common to the tear straps.
The intact tear straps were able to turn the cracks as they were
designed to do; however, due to the condition of the skin at the tear
straps forward and aft of the 23-inch crack area, it is likely that
similar crack link-up just forward in an area that had a higher
percentage of cracked fastener holes could have resulted in an
uncontained decompression. Of particular concern is the total number
and length of cracks found at that particular lap joint. The damage
found apparently exceeds all prior in-service crack findings and also
exceeds the
[[Page 20342]]
manufacturer's crack growth predictions based on test and analysis for
an airplane with 60,000 total flight cycles.
Additionally, we received a report of significant cracking on
stringer S-4R of the lap joint between BS 600 and BS 727 on a Model
737-300 series airplane having 52,400 total flight cycles. Although the
individual cracks had not linked up, it was clear that, within a
limited number of flights, the cracking could have linked up with a
length of over 10 inches. Those cracks were detected by performing a
low-frequency eddy current (LFEC) and a medium-frequency eddy current
(MFEC) inspection. Such cracking, if not corrected, could result in
sudden decompression of the airplane.
Explanation of Relevant Service Information
We have reviewed and approved Boeing Alert Service Bulletin (ASB)
737-53A1255, dated October 17, 2002. The ASB describes procedures for
performing an internal detailed inspection, and MFEC and LFEC
inspections for damage and cracking of the stringer S-4L and S-4R lap
joints and stringer clips between BS 540 and BS 727. If no damage or
cracking is found, the ASB advises operators to continue the lap joint
repetitive inspections as specified in Boeing SB 737-53A1177, Revision
6, dated May 31, 2001 (referenced in AD 2002-07-08 as an appropriate
source of service information for that AD). Boeing ASB 737-53A1255 also
describes procedures for performing an external sliding probe
inspection or internal MFEC and LFEC inspections for cracking that is
defined as ``significant'' in the ASB. Boeing ASB 737-53A1255 also
describes an optional open hole non-destructive testing inspection that
may be used in addition to the MFEC, LFEC, and detailed inspections to
confirm crack indications. Additionally, Boeing ASB 737-53A1255
specifies that the repair of any cracked lap joints be done per Boeing
SB 737-53A1177, Revision 6, dated May 31, 2001. Also, Boeing ASB 737-
53A1255 describes procedures for replacing any broken or damaged
stringer clips. Boeing ASB 737-53A1255 also requests that operators
report certain information resulting from the inspection findings, such
as the type of inspection method used and the inspection results, a
description of any damage or cracking found, the airplane serial
number, and the number of current flight cycles and flight hours on the
airplane.
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 find and fix cracking of the fuselage lap joints, which
could result in sudden decompression of the airplane. This AD requires
accomplishment of the actions specified in the service bulletins
described previously, except as discussed below.
Differences Between ASB and This AD
If cracking or damage is found per Boeing ASB 737-53A1255, dated
October 17, 2002, that ASB references Boeing SB 737-53A1177, Revision
6, dated May 31, 2001, for procedures to repair any cracking or damage
that may be found. Operators should note that this AD also will require
repair of cracking or damage that is within the limits specified in
Boeing SB 737-53A1177, Revision 6, dated May 31, 2001, per that service
bulletin. However, this AD requires that, for any damage or cracking
that is found to be outside the limits specified in Boeing SB 737-
53A1177, Revision 6, dated May 31, 2001, repair must be accomplished
per a method approved by the FAA, or per 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.
In addition, Boeing ASB 737-53A1255, dated October 17, 2002,
specifies that, if no cracking or damage is found, operators should
repeat the lap joint inspections specified in Boeing ASB 737-53A1177.
This AD, however, requires only the one-time inspections and, if no
damage or cracking is found, operators need only to accomplish the
reporting requirements of this AD. (Detailed inspections required by
this AD do not replace, but are in addition to the repetitive
inspections required by AD 2002-07-08, amendment 39-12702.)
Operators also should note that Boeing ASB 737-53A1255 does not
recommend the internal mid-frequency MFEC, LFEC, or detailed
inspections described in the ASB for airplanes with less than 45,000
total flight cycles. However, this AD requires those inspections (and
repair if necessary) on airplanes prior to the accumulation of 45,000
total flight cycles or within 90 days after the effective date of this
AD, whichever occurs later. We consider that the identified unsafe
condition must be addressed for all airplanes when 45,000 total flight
cycles have been accumulated. Requiring a specific compliance time for
those airplanes addresses that issue.
Interim Action
This is considered to be interim action. The inspection reports
that are required by this AD will enable the manufacturer to obtain
better insight into the nature, cause, and extent of the cracking, and
eventually to develop final action to address the unsafe condition.
Once final action has been identified, we 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.
Submit comments using the following format:
[sbull] Organize comments issue-by-issue. For example, discuss a
request to change the compliance time and a request to change the
service bulletin reference as two separate issues.
[sbull] For each issue, state what specific change to the AD is
being requested.
[sbull] Include justification (e.g., reasons or data) for each
request.
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
[[Page 20343]]
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 2002-NM-329-AD.'' The postcard will be date stamped
and returned to the commenter.
Regulatory Impact
The regulations adopted herein will not have a substantial direct
effect 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, it
is determined that this final rule does not have federalism
implications under Executive Order 13132.
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
0
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
0
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]
0
2. Section 39.13 is amended by adding the following new airworthiness
directive:
2003-08-15 Boeing: Amendment 39-13128. Docket 2002-NM-329-AD.
Applicability: Model 737-200, -200C, -300, -400, and -500 series
airplanes, having line numbers 292 through 2552 inclusive, and on
which the modification specified in Boeing Service Bulletin (SB)
737-53A1177, Revision 6, dated May 31, 2001, has not been
accomplished; certificated in any category.
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 (h) 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 find and fix cracking of the fuselage lap joints, which could
result in sudden decompression of the airplane, accomplish the
following:
Note 2: Detailed inspections required by this AD do not replace,
but are in addition to the repetitive inspections required by AD
2002-07-08, amendment 39-12702.
One-Time Inspections
(a) With the exception of any area of any lap joints that are
specified in this paragraph that have previously been repaired or
modified per Boeing SB 737-53A1177, Revision 4, dated September 2,
1999; Revision 5, dated February 15, 2001; and Revision 6, dated May
31, 2001: Perform an internal mid-frequency eddy current (MFEC), a
low-frequency eddy current (LFEC), and a detailed inspection for
damage or cracking on stringers S-4L and S-4R lap joints between
body station (BS) 540 and BS 727; and perform a detailed inspection
for damage of the stringer clips at all frame locations at stringers
S-4L and S-4R between BS 540 and BS 727 at the applicable time
specified in paragraph (a)(1), (a)(2), or (a)(3) of this AD; per the
Accomplishment Instructions of Boeing Alert Service Bulletin (ASB)
737-53A1255, dated October 17, 2002. If no damage or cracking is
found, no further action is required by this paragraph.
Note 3: For the purposes of this AD, a detailed inspection is
defined as: ``An intensive visual examination of a specific
structural area, system, installation, or assembly to detect damage,
failure, or irregularity. Available lighting is normally
supplemented with a direct source of good lighting at intensity
deemed appropriate by the inspector. Inspection aids such as mirror,
magnifying lenses, etc., may be used. Surface cleaning and elaborate
access procedures may be required.''
(1) For airplanes that have accumulated less than 45,000 total
flight cycles as of the effective date of this AD: Perform the
inspections prior to the accumulation of 45,000 total flight cycles
or within 90 days after the effective date of this AD, whichever
occurs later.
(2) For airplanes that have accumulated 45,000 total flight
cycles but not more than 49,999 total flight cycles as of the
effective date of this AD: Perform the inspections within 90 days
after the effective date of this AD.
(3) For airplanes that have accumulated 50,000 total flight
cycles or more as of the effective date of this AD: Perform the
inspections within 45 days after the effective date of this AD.
(b) The optional accomplishment of an open-hole non-destructive
testing (NDT) inspection per Boeing ASB 737-53A1255, dated October
17, 2002, is acceptable as a method of verification of any cracking
of the fastener holes found during the inspections required by
paragraph (a) of this AD.
(c) If any damage or cracking is found during the inspections
required by paragraph (a), (b), (d), or (e) of this AD that is not
``significant,'' as defined in Boeing ASB 737-53A1255, dated October
17, 2002, repair per paragraph (c)(1) or (c)(2) of this AD, as
applicable.
(1) For cracking that is within the limits specified by Boeing
SB 737-53A1177, Revision 6, dated May 31, 2001: Before further
flight, repair per the Accomplishment Instructions of Boeing SB 737-
53A1177, Revision 6, dated May 31, 2001; and before further flight,
replace any damaged stringer clips with a new part, per Boeing ASB
737-53A1255, dated October 17, 2002.
(2) For any cracking that exceeds the limits specified in Boeing
SB 737-53A1177, Revision 6, dated May 31, 2001: Before further
flight, repair per a method approved by the Manager, Seattle
Aircraft Certification Office (ACO), FAA; or per data meeting the
type certification basis of the airplane approved by a Boeing
Company Designated Engineering Representative (DER) who has been
authorized by the Manager, Seattle ACO, to make such findings. For a
repair method to be approved, the approval must specifically
reference this AD.
(d) If any damage or cracking is found during the inspections
required by paragraphs (a), (b), (d), or (e) of this AD that is
``significant,'' as defined in Boeing ASB 737-53A1255, dated October
17, 2002: Before further flight, accomplish the actions specified by
paragraph (d)(1) or (d)(2) of this AD, per the Accomplishment
Instructions of the ASB.
(1) With the exception of BS 540 through 727 inclusive: Perform
an external sliding probe inspection for damage or cracking, per
Figure 2 of Boeing ASB 737-53A1255, dated October 17, 2002, for each
model (Model 737-200, -200C, -300, -400, and -500 series airplanes)
at the applicable locations specified in the Compliance Section of
Boeing SB 737-53A1177, Revision 6, dated May 31, 2001.
(2) With the exception of BS 540 through 727 inclusive: Perform
internal MFEC, LFEC, and detailed inspections for damage or
cracking, per Figure 1 of Boeing ASB 737-53A1255, dated October 17,
2002, for each model (Model 737-200, -200C, -300, -400,
[[Page 20344]]
and -500 series airplanes) at the applicable locations specified in
the Compliance Section of Boeing SB 737-53A1177, Revision 6, dated
May 31, 2001.
(e) If any ``significant'' cracking, as defined in Boeing ASB
737-53A1255, dated October 17, 2002, is found in any lap joint
during the external inspection required by paragraph (d) of this AD:
Before further flight, accomplish the actions required by paragraphs
(e)(1) and (e)(2) of this AD.
(1) Perform internal MFEC, LFEC, and detailed inspections for
cracking of the entire affected section of the lap joint, specified
in the Compliance Section and Inspection Zone Figures of Boeing SB
737-53A1177, Revision 6, dated May 31, 2001; per Boeing ASB 737-
53A1255, dated October 17, 2002.
(2) Perform a detailed inspection for damage of the stringer
clips and replace any damaged stringer clip with a new part, per
Boeing ASB 737-53A1255, dated October 17, 2002.
(f) If any cracking, ``significant'' (as defined in Boeing ASB
737-53A1255, dated October 17, 2002) or otherwise, is found during
the inspections required by paragraphs (a), (b), (d), or (e) of this
AD: Before further flight, accomplish the actions specified by
paragraph (f)(1) or (f)(2) of this AD, as applicable.
(1) For cracking that is within the limits specified in Boeing
SB 737-53A1177, Revision 6, dated May 31, 2001: Repair per the
Accomplishment Instructions of that ASB; and replace any damaged
stringer clips with a new part per Boeing ASB 737-53A1255, dated
October 17, 2002.
(2) For any cracking that exceeds the limits specified in Boeing
SB 737-53A1177, Revision 6, dated May 31, 2001, repair per a method
approved by the Manager, Seattle ACO; or per data meeting the type
certification basis of the airplane approved by a Boeing Company DER
who has been authorized by the Manager, Seattle ACO, to make such
findings. For a repair method to be approved, the approval must
specifically reference this AD.
Reporting Requirements
(g) Submit a report of inspection findings (both positive and
negative) to the Boeing Commercial Airplane Group, P.O. Box 3707,
Seattle, Washington 98124-2207, as specified in paragraph B.10 of
the Accomplishment Instructions of Boeing ASB 737-53A1255, dated
October 17, 2002, at the applicable time specified by paragraph
(g)(1) or (g)(2) of this AD. Information collection requirements
contained in this AD have been approved by the Office of Management
and Budget (OMB) under the provisions of the Paperwork Reduction Act
of 1980 (44 U.S.C. 3501 et seq.) and have been assigned OMB Control
Number 2120-0056.
(1) For airplanes on which the inspection required by paragraph
(a) of this AD is accomplished after the effective date of this AD:
Submit the report within 10 days after performing the inspection
required by paragraph (a) of this AD.
(2) For airplanes on which the inspection required by paragraph
(a) of this AD has been accomplished prior to the effective date of
this AD: Submit the report within 10 days after the effective date
of this AD.
Alternative Methods of Compliance
(h) 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, ACO, FAA. 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 4: 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
(i) 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.
Incorporation by Reference
(j) Unless otherwise specified by this AD, the actions shall be
done in accordance with Boeing Alert Service Bulletin 737-53A1255,
dated October 17, 2002; and Boeing Service Bulletin 737-53A1177,
Revision 6, dated May 31, 2001; as applicable.
(1) This incorporation by reference of Boeing Alert Service
Bulletin 737-53A1255, dated October 17, 2002, is approved by the
Director of the Federal Register in accordance with 5 U.S.C. 552(a)
and 1 CFR part 51.
(2) The incorporation by reference of Boeing Service Bulletin
737-53A1177, Revision 6, dated May 31, 2001, was approved previously
by the Director of the Federal Register as of May 17, 2002 (67 FR
17917, April 12, 2002).
(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.
Effective Date
(k) This amendment becomes effective on May 12, 2003.
Issued in Renton, Washington, on April 18, 2003.
Ali Bahrami,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 03-10115 Filed 4-24-03; 8:45 am]
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