[Federal Register: November 5, 2004 (Volume 69, Number 214)]
[Proposed Rules]
[Page 64534-64537]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr05no04-22]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2004-19533; Directorate Identifier 2004-NM-31-AD]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 737-300, -400, and -500
Series Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
-----------------------------------------------------------------------
SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD)
for certain Boeing Model 737-300, -400, and -500 series airplanes. This
proposed AD would require repetitive inspections for cracking of the
crown area of the fuselage skin, and corrective actions, if necessary.
This proposed AD is prompted by a 737 fuselage structure test and
fatigue analysis that indicate fuselage skin cracking could occur
between 21,000 and 42,000 total flight cycles. We are proposing this AD
to detect and correct fatigue cracking of the fuselage skin, which
could cause the fuselage skin to fracture and fail, and could result in
rapid decompression of the airplane.
DATES: We must receive comments on this proposed AD by December 20,
2004.
ADDRESSES: Use one of the following addresses to submit comments on
this proposed AD.
DOT Docket Web Site: Go to http://dms.dot.gov and follow
the instructions for sending your comments electronically.
Government-wide Rulemaking Web Site: Go to http://www.regulations.gov
and follow the instructions for sending your
comments electronically.
Mail: Docket Management Facility, U.S. Department of
Transportation, 400 Seventh Street SW., Nassif Building, room PL-401,
Washington, DC 20590.
By Fax: (202) 493-2251.
Hand Delivery: Room PL-401 on the plaza level of the
Nassif Building, 400 Seventh Street SW., Washington, DC, between 9 a.m.
and 5 p.m., Monday through Friday, except Federal holidays.
For service information identified in this proposed AD, contact
Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-
2207.
You can examine the contents of this AD docket on the Internet at
http://dms.dot.gov, or in person at the Docket Management Facility,
U.S. Department of Transportation, 400 Seventh Street SW., room PL-401,
on the plaza level of the Nassif Building, Washington, DC. This docket
number is FAA-2004-19533; the directorate identifier for this docket is
2004-NM-31-AD.
FOR FURTHER INFORMATION CONTACT:
Technical Information: Sue Lucier, Aerospace Engineer, Airframe
Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind
Avenue, SW., Renton, Washington 98055-4056; telephone (425) 917-6438;
fax (425) 917-6590.
Plain Language Information: Marcia Walters, marcia.walters@faa.gov.
SUPPLEMENTARY INFORMATION:
[[Page 64535]]
Docket Management System (DMS)
The FAA has implemented new procedures for maintaining AD dockets
electronically. As of May 17, 2004, new AD actions are posted on DMS
and assigned a docket number. We track each action and assign a
corresponding directorate identifier. The DMS AD docket number is in
the form ``Docket No. FAA-2004-99999.'' The Transport Airplane
Directorate identifier is in the form ``Directorate Identifier 2004-NM-
999-AD.'' Each DMS AD docket also lists the directorate identifier
(``Old Docket Number'') as a cross-reference for searching purposes.
Comments Invited
We invite you to submit any written relevant data, views, or
arguments regarding this proposed AD. Send your comments to an address
listed under ADDRESSES. Include ``Docket No. FAA-2004-19533;
Directorate Identifier 2004-NM-31-AD'' in the subject line of your
comments. We specifically invite comments on the overall regulatory,
economic, environmental, and energy aspects of the proposed AD. We will
consider all comments submitted by the closing date and may amend the
proposed AD in light of those comments.
We will post all comments we receive, without change, to http://dms.dot.gov
, including any personal information you provide. We will
also post a report summarizing each substantive verbal contact with FAA
personnel concerning this proposed AD. Using the search function of
that Web site, anyone can find and read the comments in any of our
dockets, including the name of the individual who sent the comment (or
signed the comment on behalf of an association, business, labor union,
etc.). You may review DOT's complete Privacy Act Statement in the
Federal Register published on April 11, 2000 (65 FR 19477-78), or you
may visit http://dms.dot.gov.
We are reviewing the writing style we currently use in regulatory
documents. We are interested in your comments on whether the style of
this document is clear, and your suggestions to improve the clarity of
our communications that affect you. You can get more information about
plain language at http://www.faa.gov/language and http://www.plainlanguage.gov.Examining
the Docket
You can examine the AD docket on the Internet at http://dms.dot.gov
, or in person at the Docket Management Facility office
between 9 a.m. and 5 p.m., Monday through Friday, except Federal
holidays. The Docket Management Facility office (telephone (800) 647-
5227) is located on the plaza level of the Nassif Building at the DOT
street address stated in the ADDRESSES section. Comments will be
available in the AD docket shortly after the DMS receives them.
Discussion
We have received the results of a 737 fuselage structure test and
fatigue analysis conducted by the airplane manufacturer. The results
indicate that fatigue cracking is expected to occur between body
station (BS) 360 and BS 1016 common to the chem-milled step of the
upper skin above the S-4 and S-10 lap joints, when the airplane
accumulates between 21,000 to 42,000 total flight cycles. This kind of
cracking is caused by fatigue from high bending stresses at the edge of
the chem-milled step. This condition, if not detected and corrected,
could cause the fuselage skin to fracture and fail, and could result in
rapid decompression of the airplane.
Other Related Rulemaking
On August 26, 2004, we issued AD 2004-18-06, amendment 39-13784 (69
FR 54206, September 8, 2004), applicable to certain Boeing Model 737-
200, -200C, -300, -400, and -500 series airplanes, which requires
repetitive inspections to find fatigue cracking of certain upper and
lower skin panels of the fuselage, and follow-on and corrective
actions, if necessary. That AD was prompted by reports indicating that
cracks were found along the edges of the chem-milled pockets in the
upper skin at stringer S-12, and above the S-4, S-10, and S-14 lap
joints, on several Boeing Model 737 series airplanes. The actions
required by that AD are intended to find and fix fatigue cracking of
the skin panels, which could result in sudden fracture and failure of
the skin panels of the fuselage, and consequent rapid decompression of
the airplane. AD 2004-18-06 does not affect the requirements of this
AD.
Relevant Service Information
We have reviewed Boeing Special Attention Service Bulletin 737-53-
1234, dated June 13, 2002, which describes doing repetitive external
detailed and eddy current inspections for cracking of the crown area of
the fuselage skin just above the S-4 and S-14 lap joints from station
360 to station 1016, and doing either the permanent repair or a time-
limited repair. Doing either repair ends the repetitive inspections for
the repaired area. The service bulletin specifies that the inspections
are not necessary in certain areas and to contact Boeing if certain
repairs are found.
The permanent repair, which is subject to certain limitations,
consists of the following related investigative and corrective actions:
1. Doing eddy current inspections of the fuselage skin for
cracking;
2. Doing detailed inspections of the fastener holes common to the
lower row/remaining rows of fasteners in the lap joint for cracking;
3. Doing general visual, detailed, and eddy current inspections of
the skin and lap joint for cracking, corrosion, or disbonding;
4. Contacting Boeing for repair if any cracking, corrosion, or
disbonding is found or if Hi-locks, lockbolts, or bolts are installed
in the area of a crack; and
5. Reporting any cracking to Boeing.
The time-limited repair, which is subject to certain limitations,
consists of the following related investigative and corrective actions:
1. Doing external detailed inspections of the skin in each adjacent
bay in the area of chem-milled step for cracks;
2. Doing external detailed inspections of the skin and lap joint in
the area of the repair for corrosion or disbonding; and
3. Contacting Boeing for repair if any cracking, corrosion, or
disbonding is found.
If the time-limited repair is done, the service bulletin describes
doing these related investigative and corrective actions at times
varying from 3,000 flight cycles to 10,000 flight cycles after the
time-limited repair is done:
1. Doing repetitive general visual inspections for loose or missing
fasteners;
2. Replacing missing or loose fasteners with new fasteners;
3. Doing one-time inspections of the skin and lap joint of the
repaired area for cracking or corrosion (includes doing a general
visual inspection of the lap joint for corrosion and eddy current
inspections of the skin and the skin under the tear strap for
cracking);
4. Contacting Boeing for repair if any cracking or corrosion is
found; and
5. Doing a permanent modification of the time-limited repair
(includes doing detailed inspections of the fastener holes for
cracking, doing a detailed inspection of the skin for corrosion or
disbonded doublers; and contacting Boeing for any applicable repair).
Doing a permanent modification ends the need for the repetitive general
visual inspections for the repaired area only.
The service bulletin recommends the following approximate
compliance times for the initial detailed and eddy
[[Page 64536]]
current inspections: Within 21,000 to 42,000 total flight cycles,
depending on the applicable site of the fuselage skin; or within 4,500
cycles after release of this service bulletin; whichever is later.
FAA's Determination and Requirements of the Proposed AD
We have evaluated all pertinent information and identified an
unsafe condition that is likely to exist or develop on other airplanes
of this same type design. Therefore, we are proposing this AD, which
would require repetitive inspections for cracking of the crown area of
the fuselage skin, and permanent or time-limited repair if necessary.
The proposed AD would require you to use the service information
described previously to perform these actions, except as discussed
under ``Differences Between the Proposed AD and the Service Bulletin.''
Differences Between the Proposed AD and the Service Bulletin
The service bulletin specifies that you may contact the
manufacturer for instructions on how to repair certain conditions, but
this proposed AD would require you to repair those conditions in one of
the following ways:
Using a method that we approve; or
Using data that meet the type certification basis of the
airplane, and that have been approved by a Boeing Company Designated
Engineering Representative who has been authorized by the FAA to make
such findings.
You should note that, although the service bulletin describes
procedures for reporting information to the manufacturer, this proposed
AD would not require those actions. We do not need this information.
Interim Action
This is considered to be interim action until final action is
identified, at which time we may consider further rulemaking.
Costs of Compliance
There are about 579 airplanes of the affected design in the
worldwide fleet. The following table provides the estimated costs for
U.S. operators to comply with this proposed AD.
Estimated Costs
--------------------------------------------------------------------------------------------------------------------------------------------------------
Cost per
Average labor airplane, per Number of U.S.- Fleet cost, per
Action Work hours rate per hour inspection registered inspection
cycle airplanes cycle
--------------------------------------------------------------------------------------------------------------------------------------------------------
Inspections........................................................ 94 $65 $6,110 175 $1,069,250
--------------------------------------------------------------------------------------------------------------------------------------------------------
Regulatory Findings
We have determined that this proposed AD would not have federalism
implications under Executive Order 13132. This proposed AD would 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.
For the reasons discussed above, I certify that the proposed
regulation:
1. Is not a ``significant regulatory action'' under Executive Order
12866;
2. Is not a ``significant rule'' under the DOT Regulatory Policies
and Procedures (44 FR 11034, February 26, 1979); and
3. Will not have a significant economic impact, positive or
negative, on a substantial number of small entities under the criteria
of the Regulatory Flexibility Act.
We prepared a regulatory evaluation of the estimated costs to
comply with this proposed AD. See the ADDRESSES section for a location
to examine the regulatory evaluation.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Safety.
The Proposed Amendment
Accordingly, under the authority delegated to me by the
Administrator, the FAA proposes to amend 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. The FAA amends Sec. 39.13 by adding the following new
airworthiness directive (AD):
Boeing: Docket No. FAA-2004-19533; Directorate Identifier 2004-NM-
31-AD.
Comments Due Date
(a) The Federal Aviation Administration (FAA) must receive
comments on this AD action by December 20, 2004.
Affected ADs
(b) None.
Applicability: (c) This AD applies to Boeing Model 737-300, -
400, and -500 series airplanes, certificated in any category; as
listed in Boeing Special Attention Service Bulletin 737-53-1234,
dated June 13, 2002.
Unsafe Condition
(d) This AD was prompted by a 737 fuselage structure test and
fatigue analysis that indicate fuselage skin cracking could occur
between 21,000 and 42,000 total flight cycles. We are issuing this
AD to detect and correct fatigue cracking of the fuselage skin,
which could cause the fuselage skin to fracture and fail, and could
result in rapid decompression of the airplane.
Compliance: (e) You are responsible for having the actions
required by this AD performed within the compliance times specified,
unless the actions have already been done.
Service Bulletin References
(f) The term ``service bulletin,'' as used in this AD, means
Boeing Special Attention Service Bulletin 737-53-1234, dated June
13, 2002.
Initial and Repetitive Inspections
(g) At the later of the times specified in paragraphs (g)(1) and
(g)(2) of this AD, perform detailed and eddy current inspections for
cracking of the crown area of the fuselage skin in accordance with
Part 1, including the ``Note,'' of the Work Instructions of the
service bulletin, except as provided by paragraph (j) of this AD.
(1) Before the accumulation of the applicable total flight
cycles specified in the ``Threshold'' column of Table 1 of Figure 1
of the service bulletin.
(2) Within 4,500 flight cycles after the effective date of this
AD.
(h) Repeat either the detailed or eddy current inspections
specified in paragraph (g) of this AD at the applicable intervals
specified in paragraph (h)(1) or (h)(2) of this AD until paragraph
(i)(1) or (i)(2) of this AD has been done, as applicable.
(1) Repeat the detailed inspections thereafter at intervals not
to exceed 1,200 flight cycles.
(2) Repeat the eddy current inspections thereafter at intervals
not to exceed 3,000 flight cycles.
Permanent or Time-Limited Repair
(i) If any cracking is found during any inspection required by
paragraph (g) or (h) of this AD, do the actions specified in
paragraph (i)(1) or (i)(2) of this AD in accordance with the service
bulletin, except as provided by paragraphs (j) and (k) of this AD.
[[Page 64537]]
(1) Before further flight, do a permanent repair (including
related investigative actions and applicable corrective actions) in
accordance with Part 2, including the ``Note,'' of the Work
Instructions of the service bulletin. Doing a permanent repair ends
the repetitive inspections required by paragraph (h) of this AD for
the repaired area only.
(2) Do the actions specified in paragraphs (i)(2)(i) and
(i)(2)(ii) of this AD at the time specified in the applicable
paragraph. Doing a time-limited repair ends the repetitive
inspections required by paragraph (h) of this AD for the repaired
area only.
(i) Before further flight, do a time-limited repair (including
related investigative actions and applicable corrective actions) in
accordance with Part 3, including the ``Note,'' of the Work
Instructions of the service bulletin.
(ii) At the times specified in Figure 8 of the service bulletin,
do the related investigative and corrective actions in accordance
with Part 3, including the ``Note,'' of the Work Instructions of the
service bulletin.
Contact the FAA
(j) Where the service bulletin specifies to contact Boeing for
appropriateaction: 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 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.
No Reporting
(k) Although the service bulletin specifies reporting certain
information to Boeing, this AD does not require that action.
Alternative Methods of Compliance (AMOCs)
(l) The Manager, Seattle ACO, FAA, has the authority to approve
AMOCs for this AD, if requested using the procedures found in 14 CFR
39.19.
Issued in Renton, Washington, on October 26, 2004.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 04-24721 Filed 11-4-04; 8:45 am]
BILLING CODE 4910-13-P