[Federal Register Volume 69, Number 151 (Friday, August 6, 2004)]
[Proposed Rules]
[Pages 47808-47811]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-17988]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2004-18788; Directorate Identifier 2003-NM-203-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-100, -200, -200C, -
300, -400, and -500 Series Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain Boeing Model 737-100, -200, -200C, -300, -400, and -500 
series airplanes. This proposed AD would require repetitive inspections 
of the intercostal webs, attachment clips, and stringer splice channels 
for cracks; and corrective action if necessary. This proposed AD is 
prompted by reports of fatigue cracks on several Boeing Model 737-200 
series airplanes. We are proposing this AD to detect and correct 
fatigue cracking of the intercostals on the forward and aft sides of 
the forward entry door, which could result in loss of the forward entry 
door and rapid decompression of the airplane.

DATES: We must receive comments on this proposed AD by September 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 at the Docket Management Facility, U.S. 
Department

[[Page 47809]]

of Transportation, 400 Seventh Street SW., room PL-401, on the plaza 
level of the Nassif Building, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Technical Information: Howard Hall, 
Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft 
Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-
4056; telephone (425) 917-6430; fax (425) 917-6590.
    Plain Language Information: Marcia Walters, [email protected].

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 relevant written data, views, or 
arguments regarding this proposed AD. Send your comments to an address 
listed under ADDRESSES. Include ``Docket No. FAA-2004-18788; 
Directorate Identifier 2003-NM-203-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 can 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 a report indicating that eleven operators have 
found fatigue cracks in the intercostal web at body station (BS) 358.5 
and stringer (S) S-16L on several Boeing Model 737-200 series 
airplanes. The cracks extended from the inboard edge of the intercostal 
through tooling or fastener holes and terminated at the two-inch 
diameter lightening hole. Three operators have also reported four 
airplanes with cracks in the intercostals at S-11L, S-12L, and S-13L on 
the forward and aft sides of the forward entry door. All additional 
cracks are in the radius of return flanges of the webs and attachment 
clips. One operator has reported one airplane with cracks in the 
stringer splice channels at S-14L and S-15L on the aft side of the 
forward entry door. The cracks were in the intercostal web attachment 
flange at the aft end of the intercostal. Such fatigue cracking, if not 
detected and corrected in a timely manner, could result in loss of the 
forward entry door and rapid decompression of the airplane.
    The intercostal webs, attachment clips, and stringer splice 
channels on certain Boeing Model 737-100, -200C, -300, -400, and -500 
series airplanes are identical to those on the affected Boeing Model 
737-200 series airplanes. Therefore, all of these models may be subject 
to the same unsafe condition.

Relevant Service Information

    We have reviewed Boeing Special Attention Service Bulletin 737-53-
1204, dated June 19, 2003. The service bulletin describes procedures 
for detailed and high frequency eddy current inspections (as 
applicable) of the intercostal webs, attachment clips, and stringer 
splice channels for cracks; and corrective actions if necessary. The 
corrective actions include repairing cracks and contacting Boeing for 
certain repair instructions.

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 of the intercostal webs, 
attachment clips, and stringer splice channels for cracks; and 
corrective action 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

    Although the service bulletin specifies that operators may contact 
the manufacturer for disposition of certain repair conditions, this 
proposed AD would require operators to repair those conditions 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.
    The service bulletin specifies to repair any crack found at the S-
16L intercostal (BS 348.2-360) on Boeing Model 737-400 series airplanes 
per 737-400 Structural Repair Manual (SRM) 53-10-04, Figure 202. Figure 
202 does not exist; the correct figure is 737-400 SRM 53-10-04, Figure 
201. Note 2 of this proposed AD points out this error in the service 
bulletin.
    Paragraphs 3. and 4. of the ``Part 1 for Group 1 passenger 
airplanes'' section of the Work Instructions of the service bulletin do 
not give instructions for repairing cracks found in the attachment clip 
or stringer splice channel during the inspections. Other paragraphs of 
the service bulletin give instructions for similar attachment clips and 
stringer splice channels. This proposed AD would require operators to 
contact the FAA or an FAA-authorized Boeing Delegated Engineer 
Representative (DER) for repair instructions and do the repair before 
further flight if any crack is found in the attachment clip or stringer 
splice channel during the inspections specified in ``Part 1 for Group 1 
passenger airplanes.'' If no crack is found in the attachment clip or

[[Page 47810]]

stringer splice channel during the inspections, this proposed AD would 
require the repetitive inspections.
    The differences discussed above have been coordinated with Boeing.

Costs of Compliance

    This proposed AD would affect about 3,113 airplanes worldwide and 
876 airplanes of U.S. registry. The proposed actions would take about 2 
work hours per airplane, at an average labor rate of $65 per work hour. 
Based on these figures, the estimated cost of the proposed AD for U.S. 
operators is $113,880, or $130 per airplane, per inspection cycle.

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-2004-18788; Directorate Identifier 2003-NM-
203-AD.

Comments Due Date

    (a) The Federal Aviation Administration (FAA) must receive 
comments on this AD action by September 20, 2004.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Model 737-100, -200, -200C, -300, -400, 
and -500 series airplanes, as listed in Boeing Special Attention 
Service Bulletin 737-53-1204, dated June 19, 2003; certificated in 
any category.

Unsafe Condition

    (d) This AD was prompted by reports of fatigue cracks on several 
Boeing Model 737-200 series airplanes. We are issuing this AD to 
detect and correct fatigue cracking of the intercostals on the 
forward and aft sides of the forward entry door, which could result 
in loss of the forward entry door and 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 Definition

    (f) The term ``service bulletin,'' as used in this AD, means 
Boeing Special Attention Service Bulletin 737-53-1204, dated June 
19, 2003.

Initial Compliance Time

    (g) Before the accumulation of 15,000 total flight cycles, or 
within 4,500 flight cycles after the effective date of this AD, 
whichever occurs later: Do the inspections specified in paragraph 
(h) or (i) of this AD, as applicable.

Inspection for Passenger Configuration Airplanes

    (h) For Group 1 passenger airplanes identified in the service 
bulletin: Perform a detailed inspection of the intercostal web, 
attachment clips, and stringer splice channels for cracks; and a 
high frequency eddy current inspection of the stringer splice 
channels, located forward and aft of the forward entry door, for 
cracks; per Parts 1 and 2 of the Work Instructions of the service 
bulletin.

Inspection for Cargo Configuration Airplanes

    (i) For Group 2 cargo airplanes identified in the service 
bulletin: Perform a detailed inspection of the intercostal webs and 
attachment clips located forward of the forward entry door for 
cracks, per Part 3 of the Work Instructions of the service bulletin.

Repetitive Inspections

    (j) If no crack is found during any inspection required by 
paragraph (h) or (i) of this AD, repeat the inspections at the 
applicable time specified in Table 1 of this AD, except as provided 
by paragraph (k) of this AD.

                                    Table 1.--Repetitive Inspection Interval
----------------------------------------------------------------------------------------------------------------
   Airplane group number in Service                                      Repeat inspections at intervals not to
               Bulletin                   For intercostal location--                    exceed--
----------------------------------------------------------------------------------------------------------------
Group 1...............................  S-16L, from BS 348.2 to BS 360  4,500 flight cycles.
                                         (aft of door).
---------------------------------------
Group 1...............................  S-7L through S-15L, from BS     25,000 flight cycles.
                                         348.2 to BS 360 (aft of door).
---------------------------------------
Group 1 and 2.........................  S-7L through S-16L, from BS     25,000 flight cycles.
                                         294.5 to BS 303.9 (forward of
                                         door).
----------------------------------------------------------------------------------------------------------------

Deferral of Certain Repetitive Inspections

    (k) For intercostal webs at S-16L from BS 348.2 to BS 360: 
Installation of the repair as a preventative modification or 
corrective action per Part 1 of the Work Instructions of the service 
bulletin defers the repetitive inspections to intervals not to 
exceed 25,000 flight cycles. Use 737-400 SRM 53-10-04, Figure 201 
instead of Figure 202, as applicable.

Corrective Actions

    (l) If any crack is found during any inspection required by 
paragraph (h) or (i) of this AD, perform the actions specified in 
paragraphs (l)(1) through (l)(3) of Table 2 of this AD, as 
applicable. Repeat the inspections at the applicable time specified 
in Table 1 of this AD, except as provided by paragraph (k) of this 
AD.

[[Page 47811]]



                                          Table 2.--Corrective Actions
----------------------------------------------------------------------------------------------------------------
During any inspection specified in--  If any crack is found      At intercostal
                                              in--                 location--          Before further flight--
----------------------------------------------------------------------------------------------------------------
(1) Part 1 of the Work Instructions  (i) The intercostal     Stringer (S)-16L, from  Repair per Part 1 of the
 of the service bulletin.             web.                    body station (BS)       the Work Instructions of
                                                              348.2 to BS 360 (aft    the service bulletin,
                                                              of door).               except where the service
                                                                                      bulletin specifies to
                                                                                      contact Boeing for repair
                                                                                      instructions, before
                                                                                      further flight, do the
                                                                                      repair specified in
                                                                                      paragraph (m) of this AD.
                                                                                      Use 737-400 Structural
                                                                                      Repair Manual (SRM) 53-10-
                                                                                      04, Figure 201 instead of
                                                                                      Figure 202, as applicable
                                                                                      (see note 2).
                                    -------------------------
                                     (ii) An attachment      S-16L, from BS 348.2    Do the repair specified in
                                      clip or stringer        to BS 360 (aft of       paragraph (m) of this AD.
                                      splice channel.         door).
------------------------------------
(2) Part 2 of the Work Instructions  An intercostal web,     S-7L through S-16L,     Do the repair specified in
 of the service bulletin.             attachment clip, or     from BS 294.5 to BS     paragraph (m) of this AD.
                                      stringer splice         303.9 (forward of
                                      channel.                door); and S-7L
                                                              through S-15L, from
                                                              BS 348.2 to BS 360
                                                              (aft of door).
------------------------------------
(3) Part 3 of the Work Instructions  An intercostal web or   S-7L through S-16L,     Do the repair specified in
 of the service bulletin.             attachment clip.        from BS 294.5 to BS     paragraph (m) of this AD.
                                                              303.9 (forward of
                                                              door).
----------------------------------------------------------------------------------------------------------------


    Note 2: The service bulletin specifies to repair any crack found 
at the S-16L intercostal (BS 348.2-360) on Boeing Model 737-400 
series airplanes per 737-400 SRM 53-10-04, Figure 202. Figure 202 
does not exist; the correct figure is 737-400 SRM 53-10-04, Figure 
201.

Repair

    (m) At the time specified in Table 2 of this AD, 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.

Alternative Methods of Compliance (AMOCs)

    (n)(1) The Manager, Seattle 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 corrective actions, if it is approved by a Boeing Company 
Designated Engineering Representative who has been authorized by the 
Manager, Seattle ACO, to make those findings.

    Issued in Renton, Washington, on July 30, 2004.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 04-17988 Filed 8-5-04; 8:45 am]
BILLING CODE 4910-13-P