[Federal Register Volume 71, Number 61 (Thursday, March 30, 2006)]
[Proposed Rules]
[Pages 16063-16066]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-4620]


-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-24245; Directorate Identifier 2005-NM-166-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-200C Series Airplanes

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

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: The FAA proposes to supersede an existing airworthiness 
directive (AD) that applies to all Boeing Model 737-200C series 
airplanes. The existing AD currently requires a one-time external 
detailed inspection for cracking of the fuselage skin in the lower lobe 
cargo compartment; repetitive internal detailed inspections for 
cracking of the frames in the lower lobe cargo compartment; repair of 
cracked parts; and terminating action for

[[Page 16064]]

the repetitive internal detailed inspections. This proposed AD restates 
the requirements of the existing AD and adds a requirement to perform 
repetitive detailed inspections of the body station (BS) 360 and BS 500 
fuselage frames, after accomplishing the terminating action, and repair 
if necessary. This proposed AD results from multiple reports that the 
existing AD is not fully effective in preventing cracks in the BS 360 
and BS 500 fuselage frames. We are proposing this AD to detect and 
correct cracking of the fuselage frames from BS 360 to BS 500B, which, 
if not detected, could lead to loss of the cargo door during flight and 
consequent rapid decompression of the airplane.

DATES: We must receive comments on this proposed AD by May 15, 2006.

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.
     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.
    Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, 
Washington 98124-2207, for service information identified in this 
proposed 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 in the ADDRESSES section. Include the docket number ``Docket No. 
FAA-2006-24245; Directorate Identifier 2005-NM-166-AD'' at the 
beginning 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 received 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 the DOT's complete Privacy Act Statement in the 
Federal Register published on April 11, 2000 (65 FR 19477-78), or may 
visit http://dms.dot.gov.

Examining the Docket

    You may 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 Docket Management System 
receives them.

Discussion

    On June 4, 1999, we issued AD 99-12-08, amendment 39-11192 (64 FR 
31488, June 11, 1999), for all Boeing Model 737-200C series airplanes. 
That AD requires a one-time external detailed inspection to detect and 
correct cracking of the fuselage skin in the lower lobe cargo 
compartment; repetitive internal detailed visual inspections for 
cracking of the frames in the lower lobe cargo compartment; repair of 
cracked parts; and a preventative modification that provides 
terminating action for the repetitive internal detailed inspections. 
That AD resulted from reports of cracking of the body frames between 
stringers 19 left and 25 left and at body station (BS) 360 to 500B. We 
issued that AD to prevent opening or loss of the cargo door during 
flight, and consequent rapid decompression of the airplane.

Actions Since Existing AD Was Issued

    AD 99-12-08 states that modifying certain fuselage frames from BS 
360 through BS 500B inclusive constitutes terminating action for the 
repetitive internal detailed inspections required for all specified 
fuselage frames. However, since we issued AD 99-12-08, we have received 
multiple reports indicating that the modification required by AD 99-12-
08 is not fully effective in preventing cracking of the BS 360 and BS 
500 fuselage frames. Consequently, to maintain airplane structural 
integrity, it is necessary to require new internal detailed inspections 
at the BS 360 and BS 500 fuselage frames on airplanes that have been 
modified as required by paragraph (c) of AD 99-12-08, and repair if 
necessary.

Changes to Existing AD

    This proposed AD would retain certain requirements of AD 99-12-08. 
Since AD 99-12-08 was issued, the AD format has been revised; 
therefore, paragraphs (a), (b), and (c) of AD 99-12-08 have been re-
identified as paragraphs (f), (g), and (h) in this proposed AD.
    We have revised paragraph (g)(1) of this proposed AD to include a 
statement that repairs must be performed in accordance with a method 
approved by the Manager, Seattle Aircraft Certification Office (ACO), 
FAA; or in accordance with the procedures specified in paragraph (k)(4) 
of this AD; and that the Boeing 737 Structural Repair Manual is one 
approved source of repair information for accomplishing the 
requirements of paragraph (g)(1) of this proposed AD.
    Operators should be aware that paragraph (c) of AD 99-12-08 states 
that installing doublers on the fuselage frames between BS 360 to 500B 
constitutes terminating action for all inspections required by that AD, 
even though no doublers are installed on the fuselage frames at BS 360 
and BS 500. Therefore, to maintain consistency with AD 99-12-08, 
paragraph (h) of this proposed AD continues to require installing 
doublers on the fuselage frames between BS 360 to 500B, which 
constitutes terminating action for the inspections required for those 
frames, while paragraph (i) of this proposed AD specifies a new 
requirement for repetitive inspections of the fuselage frames at BS 360 
and BS 500 only.
    AD 99-12-08 refers to a ``detailed visual inspection.'' However, 
since the issuance of AD 99-12-08, we have clarified the inspection 
terminology to refer to a ``detailed inspection.'' We have included a 
definition of this type of inspection in Note 1 of this proposed AD.

FAA's Determination and Requirements of the Proposed AD

    We have evaluated all pertinent information and identified an 
unsafe condition that is likely to develop on other airplanes of the 
same type design.

[[Page 16065]]

For this reason, we are proposing this AD, which would supersede AD 99-
12-08 and retain the requirements of the existing AD. This proposed AD 
would also require repetitive internal detailed inspections for 
cracking of the BS 360 and BS 500 fuselage frames and repair if 
necessary. These inspections would be required to be done in accordance 
with Boeing Alert Service Bulletin 737-53A1160, dated October 24, 1991; 
or Boeing Service Bulletin 737-53A1160, Revision 1, dated April 29, 
1993; which were referenced as appropriate sources of service 
information by AD 99-12-08. That service information specifies to 
contact the manufacturer for instructions on how to repair certain 
conditions, but this proposed AD would require repairing 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 Commercial Airplanes Delegation Option Authorization 
Organization whom we have authorized to make those findings.

Clarification of Alternative Method of Compliance (AMOC) Paragraph

    We have revised this action to clarify the appropriate procedure 
for notifying the principal inspector before using any approved AMOC on 
any airplane to which the AMOC applies.

Costs of Compliance

    There are about 90 airplanes of the affected design in the 
worldwide fleet. This proposed AD would affect about 18 airplanes of 
U.S. registry.
    The modification required by AD 99-12-08, and retained in this 
proposed AD, takes approximately 160 work hours per airplane to 
accomplish, at an average labor rate of $80 per work hour. Required 
parts cost about $5,500 per airplane. Based on these figures, the 
estimated cost of the currently required modification for U.S. 
operators is $329,400, or $18,300 per airplane.
    The new proposed inspections would take about 3 work hours per 
airplane, at an average labor rate of $80 per work hour. Based on these 
figures, the estimated cost of the new inspections specified in this 
proposed AD for U.S. operators is $4,320, or $240 per airplane, per 
inspection cycle.

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 and placed it in the AD docket. 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 Federal Aviation Administration (FAA) amends Sec.  39.13 by 
removing amendment 39-11192 (64 FR 31488, June 11, 1999), and adding 
the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2006-24245; Directorate Identifier 2005-NM-
166-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by May 15, 
2006.

Affected ADs

    (b) This AD supersedes AD 99-12-08.

Applicability

    (c) This AD applies to all Boeing Model 737-200C series 
airplanes, certificated in any category.

Unsafe Condition

    (d) This AD results from multiple reports that the modification 
required by AD 99-12-08 is not fully effective in preventing cracks 
in the BS 360 and BS 500 fuselage frames. We are issuing this AD to 
detect and correct cracking of the fuselage frames from BS 360 to BS 
500B, which, if not detected, could lead to loss of the cargo door 
during flight 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.

Restatement of Requirements of AD 99-12-08

One-Time External Detailed Inspection

    (f) Prior to the accumulation of 29,000 total flight cycles or 
within 250 flight cycles after August 9, 1993 (the effective date AD 
93-13-02, amendment 39-8615, which was superseded by AD 99-12-08), 
whichever occurs later, accomplish an external detailed inspection 
to detect cracks of the fuselage skin between stringers 19 left and 
25 left and at body stations 360 to 540, in accordance with Boeing 
Alert Service Bulletin 737-53A1160, dated October 24, 1991; or 
Boeing Service Bulletin 737-53A1160, Revision 1, dated April 29, 
1993. If any crack is found, prior to further flight, accomplish the 
requirements of paragraphs (f)(1) and (f)(2) of this AD.
    (1) Perform an internal detailed inspection to detect cracks of 
the frames between stringers 19 left and 25 left and at body 
stations 360 to 500B, in accordance with either service bulletin.
    (2) Repair all cracks in accordance with a method approved by 
the Manager, Seattle Aircraft Certification Office (ACO), FAA, 
Transport Airplane Directorate.

Internal Detailed Inspections

    (g) Within 3,000 flight cycles after completing the requirements 
of paragraph (f) of this AD, unless accomplished within the last 
6,000 flight cycles prior to August 9, 1993, perform an internal 
detailed inspection to detect cracks of the frames between stringers 
19 left and 25 left and at body stations 360 to 500B, in accordance 
with Boeing Alert Service Bulletin 737-53A1160,

[[Page 16066]]

dated October 24, 1991; or Boeing Service Bulletin 737-53A1160, 
Revision 1, dated April 29, 1993. Thereafter, repeat the internal 
detailed inspection at intervals not to exceed 9,000 flight cycles. 
If any crack is found during any inspection required by this 
paragraph, before further flight, repair as specified in paragraph 
(g)(1) or (g)(2) of this AD, as applicable.
    (1) If any crack is found that does not exceed the limits 
specified in the Boeing 737 Structural Repair Manual (SRM), repair 
the crack in accordance with a method approved by the Manager, 
Seattle Aircraft Certification Office (ACO), FAA; or in accordance 
with the procedures specified in paragraph (k)(4) of this AD. The 
SRM is one approved source of information for accomplishing the 
requirements of this paragraph. Repeat the internal detailed 
inspection thereafter at intervals not to exceed 9,000 flight 
cycles.
    (2) If any crack is found that exceeds the limits specified in 
the SRM, repair the crack in accordance with a method approved by 
the Manager, Seattle ACO; or in accordance with the procedures 
specified in paragraph (k)(4) of this AD. Repeat the internal 
detailed visual inspection thereafter at intervals not to exceed 
9,000 flight cycles.

Install Doublers

    (h) Prior to the accumulation of 75,000 total flight cycles, or 
within 3,000 flight cycles after July 16, 1999 (the effective date 
of AD 99-12-08), whichever occurs later, install doublers on the 
specified frames located between stringers 19 left and 25 left from 
BS 360 to BS 500B, in accordance with Boeing Service Bulletin 737-
53A1160, Revision 1, dated April 29, 1993. Installing these doublers 
on the specified fuselage frames ends the repetitive inspections 
required by paragraphs (f) and (g) of this AD.

New Requirements of This AD

Repetitive Inspection of Certain Frames

    (i) Within 9,000 flight cycles after accomplishing the 
modification required by paragraph (h) of this AD, or within 4,500 
flight cycles after the effective date of this AD, whichever occurs 
later, perform an internal detailed inspection to detect cracking in 
the fuselage frame at BS 360 and the fuselage frame at BS 500, 
between stringers 19 left and 25 left, in accordance with Boeing 
Alert Service Bulletin 737-53A1160, dated October 24, 1991; or 
Boeing Service Bulletin 737-53A1160, Revision 1, dated April 29, 
1993. Thereafter, repeat the internal detailed inspection of the BS 
360 and BS 500 frames at intervals not to exceed 9,000 flight 
cycles.
    (j) If any crack is found during any inspection required by 
paragraph (i) of this AD, before further flight, repair the crack 
using a method approved in accordance with the procedures specified 
in paragraph (k) of this AD.


    Note 1: For the purposes of this AD, a detailed inspection is: 
``An intensive examination of a specific item, installation, or 
assembly to detect damage, failure, or irregularity. Available 
lighting is normally supplemented with a direct source of good 
lighting at an intensity deemed appropriate. Inspection aids such as 
mirror, magnifying lenses, etc., may be necessary. Surface cleaning 
and elaborate procedures may be required.''

Alternative Methods of Compliance (AMOCs)

    (k)(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) Before using any AMOC approved in accordance with 14 CFR 
39.19 on any airplane to which the AMOC applies, notify the 
appropriate principal inspector in the FAA Flight Standards 
Certificate Holding District Office.
    (3) AMOCs approved previously in accordance with AD 99-12-08, 
including AMOCs approved previously in accordance with AD 93-13-02, 
are approved as AMOCs for the corresponding provisions specified in 
paragraphs (f), (g), and (h) of this AD.
    (4) 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 Commercial Airplanes 
Delegation Option Authorization 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 March 17, 2006.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E6-4620 Filed 3-29-06; 8:45 am]
BILLING CODE 4910-13-P