Document ID: FAA-2007-0004-0016
Agency: faa
Document Type: Notice
Title: Airworthiness Directives; Boeing Model 737-200C Series Airplanes
Posted Date: 2007-08-23T04:00Z

[Federal Register: August 23, 2007 (Volume 72, Number 163)]
[Proposed Rules]               
[Page 48243-48246]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr23au07-17]                         

========================================================================
Proposed Rules
                                                Federal Register
________________________________________________________________________

This section of the FEDERAL REGISTER contains notices to the public of 
the proposed issuance of rules and regulations. The purpose of these 
notices is to give interested persons an opportunity to participate in 
the rule making prior to the adoption of the final rules.

========================================================================

[[Page 48243]]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-29029; Directorate Identifier 2007-NM-175-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 adopt a new airworthiness directive (AD) 
for all Boeing Model 737-200C series airplanes. This proposed AD would 
require revising the FAA-approved maintenance inspection program to 
include inspections that will give no less than the required damage 
tolerance rating for each structural significant item (SSI), doing 
repetitive inspections to detect cracks of all SSIs, and repairing 
cracked structure. This proposed AD results from a report of incidents 
involving fatigue cracking and corrosion in transport category 
airplanes that are approaching or have exceeded their design service 
objective. We are proposing this AD to maintain the continued 
structural integrity of the entire fleet of Model 737-200C series 
airplanes.

DATES: We must receive comments on this proposed AD by October 9, 2007.

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: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590.
     Fax: (202) 493-2251.
     Hand Delivery: Room W12-140 on the ground floor of the 
West Building, 1200 New Jersey Avenue, SE., 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 the service information identified in this 
proposed AD.

FOR FURTHER INFORMATION CONTACT: Nancy Marsh, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 
917-6440; 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 ``FAA-2007-
29029; Directorate Identifier 2007-NM-175-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 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.

Examining the Docket

    You may examine the AD docket on the Internet at http://dms.dot.gov
, or in person at the Docket Operations office between 9 

a.m. and 5 p.m., Monday through Friday, except Federal holidays. The 
Docket Operations office (telephone (800) 647-5527) is located on the 
ground level of the West 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

    In the early 1980's, as part of its continuing work to maintain the 
structural integrity of older transport category airplanes, we 
concluded that the incidence of fatigue cracking may increase as these 
airplanes reach or exceed their design service objective (DSO). In 
light of this, and as a result of increased utilization, and longer 
operational lives, we determined that a supplemental structural 
inspection program (SSIP) was necessary to maintain the continued 
structural integrity for all airplanes in the transport fleet.

Issuance of Advisory Circular (AC)

    As a follow-on from that determination, we issued AC No. 91-56, 
``Supplemental Structural Inspection Program for Large Transport 
Category Airplanes,'' dated May 6, 1981. That AC provides guidance 
material to manufacturers and operators for use in developing a 
continuing structural integrity program to ensure safe operation of 
older airplanes throughout their operational lives. This guidance 
material applies to transport airplanes that were certified under the 
fail-safe requirements of part 4b (``Airplane Airworthiness, Transport 
Categories'') of the Civil Air Regulations or damage tolerance 
structural requirements of part 25 (``Airworthiness Standards: 
Transport Category Airplanes'') of the Federal Aviation Regulations 
(FAR) (14 CFR part 25), and that have a maximum gross weight greater 
than 75,000 pounds. The procedures set forth in that AC are applicable 
to transport category airplanes operated under subpart D (``Special 
Flight Operations'') of part 91 of the FAR (14 CFR part 91); part 121 
(``Operating Requirements: Domestic, Flag, and Supplemental 
Operations'');

[[Page 48244]]

part 125 (``Certification and Operations: Airplanes having a Seating 
Capacity of 20 or More Passengers or a Maximum Payload of 6,000 Pounds 
or More''); and part 135 (``Operating Requirements: Commuter and On-
Demand Operations'') of the FAR (14 CFR parts 121, 125, and 135). The 
objective of the SSIP was to establish inspection programs to ensure 
timely detection of fatigue cracking.

Development of the SSIP

    In order to evaluate the effect of increased fatigue cracking with 
respect to maintaining fail-safe design and damage tolerance of the 
structure of Boeing Model 737-200C series airplanes, Boeing conducted a 
structural reassessment of those airplanes, using damage tolerance 
evaluation techniques. Boeing accomplished this reassessment using the 
criteria contained in AC No. 91-56, as well as Amendment 25-45 of 
section 25.571 (``Damage-tolerance and fatigue evaluation of 
structure'') of the FAR (14 CFR 25.571). During the reassessment, 
members of the airline industry participated with Boeing in working 
group sessions and developed the SSIP for Model 737-200C series 
airplanes. Engineers and maintenance specialists from the FAA also 
supported these sessions. Subsequently, based on the working group's 
recommendations, Boeing developed the Supplemental Structural 
Inspection Document (SSID).

Other Related Rulemaking

    We previously issued AD 98-11-04 R1, amendment 39-10984 (64 FR 987, 
January 7, 1999), applicable to all Boeing Model 737-100, -200, and -
200C series airplanes (which refers to Boeing Document No. D6-37089, 
``Supplemental Structural Inspection Document'' (SSID), Revision D, 
dated June 1995, as the appropriate source of service information for 
doing the required actions). That AD requires the FAA-approved 
maintenance inspection program be revised to include inspections that 
will give no less than the required damage tolerance rating (DTR) for 
each structural significant item (SSI), and repair of cracked 
structure. The affected SSIs include, but are not limited to, the wing, 
fuselage, empennage, and strut. For Model 737-200C series airplanes, 
that AD requires inspecting SSIs affected by cargo configuration 
changes only. For Model 737-100 and -200 series airplanes, that AD 
requires inspecting all affected SSIs.

Relevant Service Information

    We have reviewed Boeing Document No. D6-37089, ``Supplemental 
Structural Inspection Document for Model 737-100/200/200C Airplanes,'' 
Revision E, dated May 2007 (hereafter ``Revision E''). Revision E 
describes procedures for revising the FAA-approved maintenance 
inspection program to include inspections that will give no less than 
the required damage tolerance rating (DTR) for each SSI, doing 
repetitive inspections to detect cracks of all SSIs, and repairing 
cracked structure. The inspections specified in Revision E are 
essentially identical to those in Revision D. The applicability of 
Revision E has been updated, among other editorial changes, to show 
that for the Model 737-200C, SSIs not affected by cargo configuration 
changes are subject to the same inspections as Model 737-100 and -200 
series airplanes. Accomplishing the actions specified in Revision E 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. For this reason, we are proposing this AD, 
which would require the following actions:
    Paragraph (g) of the proposed AD would require incorporation of a 
revision into the FAA-approved maintenance inspection program that 
provides no less than the required DTR for each SSI listed in Revision 
E.
    Paragraph (h) of the proposed AD would require repetitive 
inspections to detect cracks of all SSIs.
    Paragraph (i) of the proposed AD would require repairing any 
cracked structure in accordance with a method approved by the FAA or an 
Authorized Representative (AR) for the Boeing Commercial Airplanes 
Delegation Option Authorization Organization who has been authorized by 
the FAA to make those findings.
    Paragraph (j) of the proposed AD specifies the requirements of the 
inspection program for transferred airplanes. Before any airplane that 
is subject to this proposed AD can be added to an air carrier's 
operations specifications, a program for doing the inspections required 
by this proposed AD must be established.
    Accomplishing the actions required by paragraphs (g) and (h) of 
this AD ends the requirements of AD 98-11-04 R1 for Model 737-200C 
series airplanes only. Operators of Model 737-100 and -200 series 
airplanes must continue to do the actions required by AD 98-11-04 R1.

Differences Between the Proposed AD and Service Information

    For Model 737-200C series airplanes, Section 3.0, ``Structural 
Significant Items (SSIs),'' of Revision E specifies a threshold of 
66,000 or 46,000 flight cycles for accomplishing the initial 
inspections, depending on the airplane configuration; however, it does 
not specify a grace period for airplanes that are near or have passed 
that threshold. This proposed AD would allow a grace period of 12 
months after the effective date of the AD to incorporate Revision E 
into the FAA-approved maintenance inspection program. This proposed AD 
also would allow a grace period of 4,000 flight cycles measured from 12 
months after the effective date of the AD to initiate the applicable 
inspections to detect cracks of all SSIs.
    Revision E does not specify instructions on how to repair certain 
conditions. This proposed AD would require repairing those conditions 
in one of the following ways:
     Using a method that we approve; or
     Using data that have been approved by an AR for the Boeing 
Commercial Airplanes Delegation Option Authorization Organization whom 
we have authorized to make those findings.

Costs of Compliance

    There are about 49 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.

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                 Number of U.S.-
            Action                Work hours     Average labor        Cost         registered       Fleet cost
                                                 rate per hour                      airplanes
----------------------------------------------------------------------------------------------------------------
Revision of maintenance        1,000, per                  $80  $80,000 per                   9  $240,000.
 inspection program.            operator (3                      operator.
                                U.S.
                                operators).

[[Page 48245]]

Inspections..................  500 per                      80  $40,000, per                  9  $360,000, per
                                airplane.                        airplane, per                    inspection
                                                                 inspection                       cycle.
                                                                 cycle.
----------------------------------------------------------------------------------------------------------------

    The number of work hours, as indicated above, is presented as if 
the accomplishment of the actions in this proposed AD is to be 
conducted as ``stand alone'' actions. However, in actual practice, 
these actions for the most part will be done coincidentally or in 
combination with normally scheduled airplane inspections and other 
maintenance program tasks. Therefore, the actual number of necessary 
additional work hours will be minimal in many instances. Additionally, 
any costs associated with special airplane scheduling will be minimal.
    Further, compliance with this proposed AD would be a means of 
compliance with the aging airplane safety final rule (AASFR) for the 
baseline structure of Model 737-200C series airplanes. The AASFR final 
rule requires certain operators to incorporate damage tolerance 
inspections into their maintenance inspection programs. These 
requirements are described in 14 CFR 121.370(a) and 129.16. 
Accomplishment of the actions required by this proposed AD will meet 
the requirements of these CFR sections for the baseline structure. The 
costs for accomplishing the inspection portion of this proposed AD were 
accounted for in the regulatory evaluation of the AASFR final rule.

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 
adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2007-29029; Directorate Identifier 2007-NM-
175-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by October 
9, 2007.

Affected ADs

    (b) Accomplishing the actions required by paragraph (g) and the 
initial inspections required by paragraph (h) of this AD ends the 
requirements of AD 98-11-04 R1, amendment 39-10984, for Model 737-
200C series airplanes only. Operators of Model 737-100 and -200 
series airplanes must continue to do the actions required by AD 98-
11-04 R1.

Applicability

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

Unsafe Condition

    (d) This AD results from a report of incidents involving fatigue 
cracking and corrosion in transport category airplanes that are 
approaching or have exceeded their design service objective. We are 
issuing this AD to maintain the continued structural integrity of 
the entire fleet of Model 737-200C series airplanes.

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 Information

    (f) The term ``Revision E,'' as used in this AD, means Boeing 
Document No. D6-37089, ``Supplemental Structural Inspection Document 
for Model 737-100/200/200C Airplanes,'' Revision E, dated May 2007.

Revision of the FAA-Approved Maintenance Inspection Program

    (g) At the applicable time specified in Table 1 of this AD, 
incorporate a revision into the FAA-approved maintenance inspection 
program that provides no less than the required damage tolerance 
rating (DTR) for each structural significant item (SSI) listed in 
Revision E. (The required DTR value for each SSI is listed in 
Revision E.) The revision to the maintenance inspection program must 
include and must be implemented in accordance with the procedures in 
Section 5.0, ``Damage Tolerance Rating (DTR) System Application,'' 
and Section 6.0, ``SSI Discrepancy Reporting'' of Revision E. Under 
the provisions of the Paperwork Reduction Act of 1980 (44 U.S.C. 
3501 et seq.), the Office of Management and Budget (OMB) has 
approved the information collection requirements contained in this 
AD and has assigned OMB Control Number 2120-0056.

[[Page 48246]]

  Table 1.--Compliance Time for Revising Maintenance Inspection Program
------------------------------------------------------------------------
         For airplanes with SSIs--                 Compliance time
------------------------------------------------------------------------
(1) Affected by the cargo configuration...  Before the accumulation of
                                             46,000 total flight cycles,
                                             or within 12 months after
                                             the effective date of this
                                             AD, whichever occurs later.
(2) Not affected by the cargo               Before the accumulation of
 configuration.                              66,000 total flight cycles,
                                             or within 12 months after
                                             the effective date of this
                                             AD, whichever occurs later.
------------------------------------------------------------------------

Initial and Repetitive Inspections

    (h) At the applicable time specified in Table 2 of this AD, do 
the applicable initial inspections to detect cracks of all SSIs, in 
accordance with Revision E. Repeat the applicable inspections 
thereafter at the intervals specified in Section 3.0, 
``Implementation'' of Revision E.

            Table 2.--Compliance Time for Initial Inspections
------------------------------------------------------------------------
         For airplanes with SSIs--                 Compliance time
------------------------------------------------------------------------
(1) Affected by the cargo configuration...  Before the accumulation of
                                             46,000 total flight cycles,
                                             or within 4,000 flight
                                             cycles measured from 12
                                             months after the effective
                                             date of this AD, whichever
                                             occurs later.
(2) Not affected by the cargo               Before the accumulation of
 configuration.                              66,000 total flight cycles,
                                             or within 4,000 flight
                                             cycles measured from 12
                                             months after the effective
                                             date of this AD, whichever
                                             occurs later.
------------------------------------------------------------------------

Repair

    (i) If any cracked structure is found during any inspection 
required by paragraph (h) of this AD, before further flight, repair 
the cracked structure using a method approved in accordance with the 
procedures specified in paragraph (k) of this AD.

Inspection Program for Transferred Airplanes

    (j) Before any airplane that is subject to this AD and that has 
exceeded the applicable compliance times specified in paragraph (h) 
of this AD can be added to an air carrier's operations 
specifications, a program for the accomplishment of the inspections 
required by this AD must be established in accordance with paragraph 
(j)(1) or (j)(2) of this AD, as applicable.
    (1) For airplanes that have been inspected in accordance with 
this AD: The inspection of each SSI must be done by the new operator 
in accordance with the previous operator's schedule and inspection 
method, or the new operator's schedule and inspection method, at 
whichever time would result in the earlier accomplishment for that 
SSI inspection. The compliance time for accomplishment of this 
inspection must be measured from the last inspection accomplished by 
the previous operator. After each inspection has been done once, 
each subsequent inspection must be performed in accordance with the 
new operator's schedule and inspection method.
    (2) For airplanes that have not been inspected in accordance 
with this AD: The inspection of each SSI required by this AD must be 
done either before adding the airplane to the air carrier's 
operations specification, or in accordance with a schedule and an 
inspection method approved by the Manager, Seattle Aircraft 
Certification Office (ACO), FAA. After each inspection has been done 
once, each subsequent inspection must be done in accordance with the 
new operator's schedule.

Alternative Methods of Compliance (AMOCs)

    (k)(1) The Manager, Seattle Aircraft Certification Office (ACO) 
has the authority to approve AMOCs for this AD, if requested in 
accordance with the procedures found in 14 CFR 39.19.
    (2) To request a different method of compliance or a different 
compliance time for this AD, follow the procedures in 14 CFR 39.19. 
Before using any approved AMOC on any airplane to which the AMOC 
applies, notify your appropriate principal inspector (PI) in the FAA 
Flight Standards District Office (FSDO), or lacking a PI, your local 
FSDO.
    (3) 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 approval must specifically refer 
to this AD.

    Issued in Renton, Washington, on August 12, 2007.
Stephen P. Boyd,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E7-16656 Filed 8-22-07; 8:45 am]

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