[Federal Register Volume 69, Number 171 (Friday, September 3, 2004)]
[Proposed Rules]
[Pages 53855-53858]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-20124]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2004-18996; Directorate Identifier 2004-NM-40-AD]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 737-700 and -800 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 737-700 and -800 series airplanes. This
proposed AD would require doing an initial inspection for pitting and
cracks of the lower skin panel at the lap joint; trimming the inner
skin; installing exterior doublers; replacing the fuselage skin
assembly; doing repetitive supplemental inspections; and repairing if
necessary; as applicable. This proposed AD is prompted by a report
indicating that localized pitting in the lower skin panels was found
during production on a limited number of airplanes. We are proposing
this AD to detect and correct premature fatigue cracking at certain lap
splice locations and consequent rapid decompression of the airplane.
DATES: We must receive comments on this proposed AD by October 18,
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://
[[Page 53856]]
dms.dot.gov, or 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.
FOR FURTHER INFORMATION CONTACT: 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.
SUPPLEMENTARY INFORMATION:
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-2004-18996;
Directorate Identifier 2004-NM-40-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 website, 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 can review DOT's complete Privacy Act Statement in the
Federal Register published on April 11, 2000 (65 FR 19477-78), or you
can 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 9:00 a.m. and 5:00 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 a report indicating that localized pitting in the
lower skin panels was found during production on a limited number of
Boeing Model 737-700 and -800 series airplanes. The pitting was caused
by chemical milling solution leaking through sealer at a maskant line.
The leakage caused local pits to form on the surface of the skin.
Testing and analysis revealed that the chemical mill pitting does not
reduce the ultimate strength of the effected skin panels, but chemical
mill pitting greater than the allowable limit may reduce the fatigue
performance and damage tolerance capability of the lower skin panels.
This condition, if not corrected, could result in premature fatigue
cracking at certain lap splice locations and consequent rapid
decompression of the airplane.
Relevant Service Information
We have reviewed Boeing Service Bulletin 737-53-1256, dated
September 18, 2003, which describes the following procedures depending
on the airplane configuration:
Doing an initial external ultrasonic inspection for
pitting and cracks of the lower skin panel at the lap joint;
Trimming the inner skin and installing two exterior
doublers (including an internal high frequency eddy current inspection
of the edge of the trim for cracks) or installing three exterior
doublers, as applicable;
Replacing the fuselage skin assembly with a new assembly;
Doing supplemental repetitive inspections; and
Contacting Boeing for repair of discrepancies.
The service bulletin recommends compliance times at the following
approximate intervals, depending on the lap splice location:
Table--Service Bulletin Recommended Compliance Times
----------------------------------------------------------------------------------------------------------------
Action Recommended compliance time
----------------------------------------------------------------------------------------------------------------
Initial inspection.................. Ranging from 28,000 to 75,000 total flight cycles.
Initial supplemental inspection..... 56,000 flight cycles after repair incorporation.
Repetitive supplemental inspections. Ranging from 5,000 to 7,500 flight cycles.
----------------------------------------------------------------------------------------------------------------
Accomplishing the actions specified in the service information is
intended to adequately address the unsafe condition.
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 you to use the service information described previously
to perform the required actions, except as discussed under ``Difference
Between the Proposed AD and Service Bulletin.''
Difference Between the Proposed AD and 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
[[Page 53857]]
that have been approved by a Boeing Company Designated Engineering
Representative who has been authorized by the FAA to make those
findings.
Costs of Compliance
This proposed AD would affect about 4 airplanes worldwide and 2
airplanes of U.S. registry. The following table provides the estimated
costs to comply with this proposed AD.
The average labor rate is $65 per work hour. The cost impact of the
proposed AD on U.S. operators is estimated to be $83,855.
Table--Cost Impact
----------------------------------------------------------------------------------------------------------------
For airplanes listed in the referenced service Per airplane
bulletin as group-- Work hours Parts cost cost
----------------------------------------------------------------------------------------------------------------
1............................................. Inspection: 2................... None $130
Modification: 38................ $105 2,575
2............................................. Inspection: 2................... None 130
Modification: 30................ 104 2,054
3............................................. Inspection: 2................... None 130
Modification: 42................ 106 2,836
4............................................. Repair: 920..................... 16,200 76,000
----------------------------------------------------------------------------------------------------------------
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-2004-18996; Directorate Identifier 2004-NM-
40-AD.
Comments Due Date
(a) The Federal Aviation Administration (FAA) must receive
comments on this AD action by October 18, 2004.
Affected ADs
(b) None.
Applicability
(c) This AD applies to Boeing Model 737-700 and -800 series
airplanes, certificated in any category; having variable and serial
numbers listed in Table 1 of this AD.
Table 1.--Applicable Variable and Serial Numbers
------------------------------------------------------------------------
Variable No.-- Serial No.-- Group--
------------------------------------------------------------------------
YA004................................... 27837 1
YA005................................... 27836 2
YA201................................... 28004 4
YC003................................... 27977 3
------------------------------------------------------------------------
Unsafe Condition
(d) This AD was prompted by a report indicating that localized
pitting in the lower skin panels was found during production on a
limited number of airplanes. We are issuing this AD to detect and
correct premature fatigue cracking at certain lap splice locations
and consequent 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.
Initial Inspection and/or Repair
(f) At the applicable times specified in Table 1 of paragraph
1.E., ``Compliance'' of Boeing Service Bulletin 737-53-1256, dated
September 18, 2003, do the applicable actions specified in Table 2
of this AD in accordance with the Accomplishment Instructions of the
service bulletin.
Table 2.--Initial Inspection and/or Repair
------------------------------------------------------------------------
For airplanes identified in
the service bulletin as-- Requirements--
------------------------------------------------------------------------
(1) Groups 1, 2, and 3....... Do an external ultrasonic inspection for
pitting and cracks of the lower skin
panel at the lap joint.
(2) Groups 1 and 2........... Trim the inner skin and install two
exterior doublers (including related
investigative actions).
[[Page 53858]]
(3) Group 3.................. Install three exterior doublers.
(4) Group 4.................. Replace the fuselage skin assembly with a
new assembly.
------------------------------------------------------------------------
Repetitive Inspections
(g) For Groups 1, 2, and 3 airplanes identified in Boeing
Service Bulletin 737-53-1256, dated September 18, 2003: At the
applicable times specified in Table 2 of paragraph 1.E.,
``Compliance'' of the service bulletin, do the repetitive
supplemental inspections of the lower skins and external doublers
for discrepancies in accordance with the Accomplishment Instructions
of the service bulletin.
Corrective Action
(h) If any discrepancy is found during any action required by
this AD, 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.
Alternative Methods of Compliance (AMOCs)
(i)(1) The Manager, Seattle Aircraft Certification Office (ACO),
FAA, has the authority to approve AMOCs for this AD, if requested in
accordance with the procedures found in 14 CFR 39.19.
(2) An AMOC that provides an acceptable level of safety may be
used for any repair required by this AD, if it is approved by a
Boeing Company DER who has been authorized by the Manager, Seattle
ACO, to make those findings. For a repair method to be approved, the
approval must specifically refer to this AD.
Issued in Renton, Washington, on August 20, 2004.
Kevin M. Mullin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 04-20124 Filed 9-2-04; 8:45 am]
BILLING CODE 4910-13-P