[Federal Register Volume 70, Number 83 (Monday, May 2, 2005)]
[Proposed Rules]
[Pages 22620-22622]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-8654]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2005-21086; Directorate Identifier 2004-NM-217-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-600, -700, -700C, -
800, and -900 Series Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for all Boeing Model 737-600, -700, -700C, -800, and -900 series 
airplanes. This proposed AD would require repetitive inspections of the 
aft pressure bulkhead web for fatigue cracks, crack indications, 
discrepant holes, and corrosion, and repair if necessary. This proposed 
AD is prompted by reports of fatigue cracks in the aft pressure 
bulkhead web. We are proposing this AD to detect and correct such 
fatigue cracks, which could result in a rapid decompression of the 
airplane.

DATES: We must receive comments on this proposed AD by June 16, 2005.

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.

[[Page 22621]]

This docket number is FAA-2005-21086; the directorate identifier for 
this docket is 2004-NM-217-AD.

FOR FURTHER INFORMATION CONTACT: 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.

SUPPLEMENTARY INFORMATION:

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-2005-21086; 
Directorate Identifier 2004-NM-217-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 
can visit http://dms.dot.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 reports indicating that fatigue cracks were found 
in the aft pressure bulkhead web on Boeing Model 737-200 and -300 
series airplanes. The fatigue cracks ran in the circumferential 
direction along the aft row of fasteners connecting the web assembly to 
the bulkhead ``Y'' chord. Fatigue cracks in the aft pressure bulkhead 
web, if not detected and corrected in a timely manner, could result in 
a rapid decompression of the airplane.
    The aft pressure bulkhead webs on Model 737-600, -700, -700C, -800, 
and -900 series airplanes are identical to those on the affected Model 
737-200 and -300 series airplanes. Therefore, the 737-600, -700, -700C, 
-800, and -900 models may be subject to the same unsafe condition.

Other Relevant Rulemaking

    We have previously issued AD 99-08-23, amendment 39-11132 (64 FR 
19879, April 26, 1999), applicable to Model 737-100, -200, -200C, -300, 
-400, and -500 series airplanes. That AD 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.

Relevant Service Information

    We have reviewed Boeing Alert Service Bulletin 737-53A1248, dated 
September 9, 2004. The service bulletin describes procedures for doing 
inspections (i.e., detailed inspection and either low-or high-frequency 
eddy current inspections) of the aft pressure bulkhead web for fatigue 
cracks, crack indications, discrepant holes, and corrosion, and 
contacting the manufacturer for repair instructions. The inspections 
are in the aft pressure bulkhead web along the aft row of fasteners 
where it attaches to the ``Y'' chord of the body station 1016 bulkhead. 
The service bulletin specifies initial compliance times of 25,000 total 
flight cycles and 66,000 total flight cycles, based on which area is to 
be inspected. Repetitive inspection intervals are every 1,200, 3,800, 
6,000, or 12,000 flight cycles. The repetitive intervals are based on 
which area is inspected and which inspection method is used for that 
area. 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 accomplishing the actions specified in the service 
information described previously, except as discussed under 
``Difference Between the AD and the Service Bulletin.''

Differences Between Proposed Rule 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 certification basis of the 
airplane, and that have been approved by an Authorized Representative 
for the Boeing Delegation Option Authorization Organization who has 
been authorized by the FAA to make those findings.

Costs of Compliance

    There are about 978 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:

[[Page 22622]]



                                                                     Estimated Costs
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                                                                                                                   Number of U.S.-
               Action                  Work hours     Average labor          Parts            Cost per airplane      registered          Fleet cost
                                                      rate per hour                                                   airplanes
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LFEC and detailed inspection per                  8             $65  None.................  $520 per inspection               630  $327,600 inspection
 inspection, cycle.                                                                          cycle.                                 per cycle.
HFEC and detailed inspection (in                  2              65  None.................  130 per inspection                630  81,900 per cycle
 lieu of LFEC and detailed                                                                   cycle.                                 inspection.
 inspection), per inspection cycle.
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Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, Section 106, describes the 
authority of the FAA Administrator. Subtitle VII, Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

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-2005-21086; Directorate Identifier 2004-NM-
217-AD.

Comments Due Date

    (a) The Federal Aviation Administration (FAA) must receive 
comments on this AD action by June 16, 2005.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to all Boeing Model 737-600, -700, -700C, -
800, and -900 series airplanes, certificated in any category.

Unsafe Condition

    (d) This AD was prompted by reports of fatigue cracks in the aft 
pressure bulkhead web. We are issuing this AD to detect and correct 
such fatigue cracks, which 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.

Inspections

    (f) At the applicable ``Inspection Threshold'' in the table in 
Part 1.E. ``Compliance'' of Boeing Alert Service Bulletin 737-
53A1248, dated September 9, 2004, or within 18 months after the 
effective date of this AD, whichever occurs later, and thereafter at 
intervals not to exceed the applicable ``Inspection Repeat 
Interval'' in that table: Do the inspections (i.e., detailed 
inspection and either high-or low-frequency eddy current 
inspections) of the aft pressure bulkhead web for fatigue cracks, 
crack indications, discrepant holes, and corrosion, in accordance 
with the Accomplishment Instructions of the service bulletin.

Corrective Action Difference

    (g) If any fatigue crack, crack indication, discrepant hole, or 
corrosion is found during any inspection required by this AD, before 
further flight, repair the fatigue crack, crack indication, 
discrepant hole, and corrosion according to a method approved by the 
Manager, Seattle Aircraft Certification Office (ACO), FAA; or 
according to data meeting the certification basis of the airplane 
approved by an Authorized Representative (AR) for the Boeing 
Delegation Option Authorization (DOA) Organization who has been 
authorized by the Manager, Seattle ACO, to make those findings. For 
a repair method to be approved, the approval must specifically 
reference this AD.

No Reporting

    (h) Although the service bulletin references a reporting 
requirement in the Accomplishment Instructions, that reporting is 
not required by this AD.

Alternative Methods of Compliance (AMOCs)

    (i)(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 an AR for the 
Boeing DOA Organization who has been authorized by the Manager, 
Seattle ACO, to make those findings. For a repair method to be 
approved, the repair must meet the certification basis of the 
airplane, and the approval must specifically refer to this AD.

    Issued in Renton, Washington, on April 25, 2005.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 05-8654 Filed 4-29-05; 8:45 am]
BILLING CODE 4910-13-P