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

[Federal Register Volume 70, Number 66 (Thursday, April 7, 2005)]
[Rules and Regulations]
[Pages 17600-17603]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-6763]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2004-19003; Directorate Identifier 2003-NM-245-AD; 
Amendment 39-14044; AD 2005-07-19]
RIN 2120-AA64


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

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

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for all 
Boeing Model 737-100, -200, -200C, -300, -400, and -500 series 
airplanes. This AD requires repetitive inspections for cracks in the 
fuselage skin, doubler, bearstrap, and frames surrounding the main, 
forward, and aft cargo doors; and repair of any cracking. This AD also 
requires inspections of certain existing repairs for cracking, and 
related corrective action if cracking is found. This AD is prompted by 
reports of multiple fatigue cracks in the fuselage skin and bonded skin 
doubler, bearstrap, and doorway frames surrounding the forward and aft 
cargo doors. We are issuing this AD to find and fix fatigue cracking in 
the fuselage skin, doubler, bearstrap, and frames, which could result 
in reduced structural integrity of the frames, possible loss of a cargo 
door, and consequent rapid decompression of the fuselage.

DATES: This AD becomes effective May 12, 2005.
    The incorporation by reference of a certain publication listed in 
the AD is approved by the Director of the Federal Register as of May 
12, 2005.

ADDRESSES: For service information identified in this AD, contact 
Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-
2207. You can examine this information at the National Archives and 
Records Administration (NARA). For information on the availability of 
this material at NARA, call (202) 741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.
    Docket: The AD docket contains the proposed AD, comments, and any 
final disposition. 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 U.S. 
Department of Transportation, 400 Seventh Street, SW., room PL-401, 
Washington, DC. This docket number is FAA-2004-19003; the directorate 
identifier for this docket is 2003-NM-245-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: The FAA proposed to amend 14 CFR Part 39 
with an AD for all Boeing Model 737-100, -200, -200C, -300, -400, and -
500 series airplanes. That action, published in the Federal Register on 
September 7, 2004 (69 FR 54058), proposed to require repetitive 
inspections for cracks in the fuselage skin, doubler, bearstrap, and 
frames surrounding the main, forward, and aft cargo doors; and repair 
of any cracking. That action also proposed to require inspections of 
certain existing repairs for cracking, and related corrective action if 
cracking is found.

Comments

    We provided the public the opportunity to participate in the 
development of this AD. We have considered the comments that have been 
submitted on the proposed AD.

Supportive Comment

    One commenter states that the proposed AD will affect only its 737-
200C and -400 fleets, and adds that the proposed detailed inspections 
and compliance intervals will allow compliance at heavy check 
maintenance visits. The commenter stipulates that these requirements 
are acceptable provided there are adequate replacement parts available 
if discrepancies are found.

[[Page 17601]]

    We have discussed the issue of obtaining replacement parts with the 
airplane manufacturer and we anticipate no difficulty in getting the 
parts to accomplish repairs.

Request for Credit for Accomplishing AD 93-14-10

    One commenter, the airplane manufacturer, asks that we add a 
sentence to paragraph (f) of the proposed AD that gives credit for 
accomplishing the inspections and repairs required by AD 93-14-10, 
amendment 39-8634 (58 FR 43547, August 17, 1993). The commenter states 
that the requirements of the proposed AD are equivalent to, or more 
conservative than, the requirements in AD 93-14-10.
    We agree with the commenter that accomplishing the requirements in 
paragraph (f) of the proposed AD ends the requirements in AD 93-14-10 
(referenced as related rulemaking in the preamble of the proposed AD). 
As specified in the preamble of the proposed AD, during structural 
inspections, cracks were found in the bearstrap under the fuselage 
frame flanges at the edges of the forward cargo door. In two cases, 
cracks were found in the fuselage frames of the aft cargo door where 
steel repair doublers had been installed using the requirements of AD 
93-14-10; therefore, the requirements in this AD exceed the 
requirements of AD 93-14-10. We have changed paragraph (f) of this AD 
by adding credit for previously accomplishing AD 93-14-10.

Request To Add Inspection Type to Paragraph (f) of the Proposed AD

    The same commenter states that the first sentence in paragraph (f) 
specifies, in part, ``Do the applicable detailed, general visual, and 
low and high frequency eddy current inspections for cracks * * *'' The 
commenter asks that a reference to the mid-frequency eddy current 
(MFEC) inspection be added to paragraph (f). The commenter notes that 
this inspection is specified in the referenced service bulletin.
    We agree with the commenter that the MFEC inspection should be 
added to paragraph (f), for clarification. An internal MFEC inspection 
is specified in the referenced service bulletin as an option to 
accomplishing the detailed visual inspections, and would extend the 
compliance time for the repetitive inspections, but was not identified 
in the proposed AD. Paragraph (f) of the proposed AD specified doing 
the ``applicable'' inspections for cracks as specified in the 
referenced tables. However, to clarify the type of inspection, we have 
changed paragraph (f) of this final rule to include the MFEC 
inspection.

Request for Clarification of Location of Inspections for Existing 
Repairs

    One commenter asks for clarification regarding accomplishing 
inspections of existing repairs around the cargo doors in accordance 
with the referenced service bulletin. The commenter states that it is 
unclear which inspection is required if repairs are of a different 
configuration than those referenced in the figures in the service 
bulletin. The commenter notes, for example, that a repair of the cargo 
door lower corner per Boeing Structural Repair Manual 737-100/200, 
Figure 46, Detail IV, does not match the Figure 8 repair in the service 
bulletin. The commenter adds that verbiage needs to be added clarifying 
whether the ``intent'' of the service bulletin is to accomplish a MFEC 
inspection of all outer row fasteners of the repair doubler, no matter 
what the configuration.
    We agree that clarification is necessary. The repairs shown in 
Figures 8, 9, and 10 of the referenced service bulletin are conceptual 
illustrations of typical doubler/tripler type repairs. These figures 
are intended to indicate that the location of the detailed visual or 
MFEC inspections for cracking is the skin or bearstrap at the outer row 
fasteners common to the outer edge of the repair. We have added a note 
after paragraph (f) of the final rule for further clarification.

Request for Certain Repair Instructions

    One commenter states that repair instructions that are similar to 
those currently available for Model 737-100 and -200 series airplanes 
for damaged skin, doubler, and bearstrap around the cargo doors should 
also be available for Model 737-300, -400, and -500 series airplanes. 
The commenter adds that it is crucial to limit downtime of aircraft as 
much as possible, an coordinating repair procedures with Boeing extends 
the out-of-service time for affected airplanes.
    We agree that repair instructions should be made available for 
Model 737-300, -400 and -500 series airplanes. However, until repair 
instructions are published for Model 737-300, -400 and -500 series 
airplanes, the repair must be accomplished according to a method 
approved by the Manager, Settle Aircraft Certification Office or an 
Authorized Representative for the Boeing Delegation Option 
Authorization (DOA) Organization. Repair procedures have been developed 
for incorporation into the next revision of the 737-300/400/500 SRM and 
will be submitted to us by Boeing soon. As provided by paragraph (i) of 
this AD, we will consider approving these repairs as an alternative 
method of compliance for paragraph (g) of this AD. We have made no 
change to the final rule in this regard.

Clarification of Applicability

    One commenter asks why the proposed AD isn't applicable to Model 
737-300C series airplanes with a main cargo door installed by PEMCO. 
The commenter notes that the proposed AD includes Model 737-200C series 
airplanes with a main cargo door, and asks if excluding the 737-300C is 
normal.
    We acknowledge the commenter's concern and offer clarification. The 
proposed AD is applicable to Model 737-100, -200, -200C, -300, -400, -
500 series airplanes, including airplanes modified to include a main 
cargo door. We infer that the commenter's reference to a ``Model 737-
300C'' is an informal designation for a Model 737-300 series airplane 
that has been modified to include a main cargo door per a supplemental 
type certificate. However, no model 737-300C series airplane is 
identified in the type certificate data sheet. Thus, an airplane with 
that configuration would be subject to the AD requirements for Model 
737-300 series airplanes. In comparison, the Model 737-200C series 
airplane is identified in the type certificate data sheet.

Explanation of Changer to Proposed AD

    Boeing has received a DOA. We have revised paragraph (i)(2) of this 
final rule to delegate the authority to approve an alternative method 
of compliance for any repair required by this AD to the Authorized 
Representative for the Boeing DOA Organization rather than the 
Designated Engineering Representative.

Conclusion

    We have carefully reviewed the available data, including the 
comments that have been submitted, and determined that air safety and 
the public interest require adopting the AD with the change described 
previously. We have determined that these changes will neither increase 
the economic burden on any operator nor increase the scope of the AD.

Costs of Compliance

    There are about 3,132 airplanes of the affected design in the 
worldwide fleet. We estimate that 870 airplanes of U.S. registry will 
be affected by this AD. We provide the following cost estimates to

[[Page 17602]]

comply with this AD, per inspection cycle:

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                                                                             Hourly                  Cost per
                           Group                              Work hours   labor rate    Parts       airplane
----------------------------------------------------------------------------------------------------------------
1..........................................................           24          $65         $0          $1,560
2 and 4....................................................           28           65          0           1,820
3 and 5....................................................           30           65          0           1,950
6 and 7....................................................           28           65          0           1,820
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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 AD will not have federalism 
implications under Executive Order 13132. This AD 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.
    For the reasons discussed above, I certify that this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866;
    (2) Is not a ``significant rule'' under 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 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, Incorporated by 
reference, Safety.

Adoption of the Amendment

0
Accordingly, under the authority delegated to me by the Administrator, 
the FAA amends 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. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive (AD):

2005-07-19 Boeing: Amendment 39-14044. Docket No. FAA-2004-19003; 
Directorate Identifier 2003-NM-245-AD.

Effective Date

    (a) This AD becomes effective May 12, 2005.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to all Model 737-100, -200, -200C, -300, -
400, and -500 series airplanes; certified in any category.

Unsafe Condition

    (d) This AD was prompted by reports of multiple fatigue cracks 
in the fuselage skin and bonded skin doubler, bearstrap, and doorway 
frames surrounding the forward and aft cargo doors. We are issuing 
this AD to find and fix fatigue cracking in the fuselage skin, 
doubler, bearstrap, and frames, which could result in reduced 
structural integrity of the frames, possible loss of a cargo door, 
and consequent rapid decompression of the fuselage.

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 and Repetitive Inspections/Corrective Action

    (f) Do the applicable detailed, general visual, and low-, mid-, 
and high-frequency eddy current inspections for cracks in the 
fuselage skin, doubler, bearstrap, and frames surrounding the main, 
forward, and aft cargo doors, and for cracks in existing repairs, as 
specified in Tables 1, 2, and 3, as applicable, of paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1228, dated 
July 10, 2003. Do the inspections at the initial compliance times 
listed in Tables 1, 2, and 3, as applicable, of paragraph 1.E., 
``Compliance,'' of the service bulletin; except, where the service 
bulletin specifies a compliance time after the service bulletin 
date, this AD requires compliance within the specified compliance 
time after the effective date of this AD. Do the inspections in 
accordance with the Accomplishment Instructions of the service 
bulletin. Repeat the inspections within the repetitive inspection 
intervals listed in Tables 1, 2, 3 of paragraph 1.E., 
``Compliance,'' of the service bulletin. Accomplishing the 
requirements in this paragraph ends the requirements in AD 93-14-10, 
amendment 39-8634 (58 FR 43547. August 17, 1993).

    Note 1: At existing repairs around the forward and aft cargo 
door cutouts: The location for the specified detailed or mid-
frequency eddy current inspections for cracking of the skin or 
bearstrap is at the outer row of fasteners common to the repair, as 
illustrated in Figures 8, 9, and 10 of Boeing Alert Service Bulletin 
737-53A1228, dated July 10, 2003.

    (g) If any crack is found during any inspection: Repair before 
further flight in accordance with the Accomplishment Instructions of 
Boeing Alert Service Bulletin 737-53A1228, dated July 10, 2003. 
Where the service bulletin specifies contacting the manufacturer for 
disposition of certain repair conditions, repair before further 
flight in accordance with a method approved by the Manager, Seattle 
Aircraft Certification Office (ACO), FAA; or an Authorized 
Representative for the Boeing Delegation Option Authorization (DOA) 
Organization who has been authorized by the Manager, Seattle ACO, to 
make such findings. For a repair method to be approved, the approval 
must specifically refer to this AD.

No Reporting Required

    (h) Although the service bulletin referenced in this AD 
recommends reporting any discrepancies to the manufacturer, this AD 
does not include that requirement.

Alternative Methods of Compliance (AMOCs)

    (i)(1) The Manager, Seattle ACO, 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 an 
Authorized Representative for the Boeing

[[Page 17603]]

DOA Organization who has been authorized by the Manager, Seattle 
ACO, to make those findings.

Material Incorporated by Reference

    (j) You must use Boeing Alert Service Bulletin 737-53A1228, 
dated July 10, 2003, to perform the actions that are required by 
this AD, unless the AD specifies otherwise. The Director of the 
Federal Register approves the incorporation by reference of this 
document in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. For 
copies of the service information, contact Boeing Commercial 
Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207. For 
information on the availability of this material at the National 
Archives and Records Administration (NARA), call (202) 741-6030, or 
go to http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html. You may view the AD docket at the 
Docket Management Facility, U.S. Department of Transportation, 400 
Seventh Street, SW., room PL-401, Nassif Building, Washington, DC.

    Issued in Renton, Washington, on March 30, 2005.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 05-6763 Filed 4-6-05; 8:45 am]
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