[Federal Register Volume 70, Number 51 (Thursday, March 17, 2005)]
[Proposed Rules]
[Pages 12982-12986]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-5296]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2005-20627; Directorate Identifier 2004-NM-39-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-100, -200, -200C, -
300, -400, and -500 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 certain Boeing Model 737-100, -200, -200C, -300, -400, and -500 
series airplanes. This proposed AD would require the following: 
Repetitive eddy current inspections for cracks of the countersunk rivet 
holes in the lower lobe, adjacent to the radio altimeter cutouts; 
additional inspections, for certain airplanes, for cracks and/or 
corrosion; and further investigative and corrective action if any crack 
is found. This proposed AD also would provide an optional terminating 
action for the repetitive inspections. This proposed AD was prompted by 
reports of cracks in the fuselage skin of the lower lobe. We are 
proposing this AD to detect and correct fatigue cracks of the 
countersunk rivet holes, which could result in cracks of the fuselage 
skin of the lower lobe, and consequent rapid depressurization of the 
cabin.

DATES: We must receive comments on this proposed AD by May 2, 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.

[[Page 12983]]

     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.
    You can get the service information identified in this proposed AD 
from 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. This docket 
number is FAA-2005-20627; the directorate identifier for this docket is 
2004-NM-39-AD.

FOR FURTHER INFORMATION CONTACT: Sue Lucier, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
917-6438; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to submit any written relevant data, views, or 
arguments regarding this proposed AD. Send your comments to an address 
listed under ADDRESSES. Include ``Docket No. FAA-2005-20627; 
Directorate Identifier 2004-NM-39-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 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 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 five operators have found 
seven cracks in the lower lobe fuselage skin on Boeing Model 737-200 
series airplanes. All cracks originated at the countersunk rivet holes 
adjacent to the radio altimeter cutouts at body stations (BSs) 430 and 
450, and were located at buttock line (BL) 0. The cracks were from 
0.375 inch to 5.25 inches in length. One operator reported two cracks 
on the same airplane: a 2-inch crack running aft of BS 431, and a 
2.125-inch crack running forward of BS 449. The two cracks were growing 
toward each other from two adjacent cutouts. The cracks propagate by 
normal fatigue due to operating loads (pressure). Cracking of the 
countersunk rivet holes, if not detected and corrected, could result in 
cracks in the lower lobe fuselage skin reaching critical length for 
residual strength, and consequent rapid depressurization of the cabin.
    The fuselage skin configuration on certain Model 737-200 series 
airplanes is almost identical to that on certain Model 737-100, -200C, 
-300, -400, and -500 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-
1230, dated June 13, 2002. This service bulletin describes procedures 
for doing an eddy current inspection for cracks of the surface area 
around the countersunk rivet holes in the lower lobe, adjacent to the 
radio altimeter cutouts at BL 0, between BS 390 and BS 450. This 
inspection is done with the fasteners installed.
    If no crack is found during the eddy current inspection, the 
service bulletin describes options for repeating the eddy current 
inspection (with fasteners installed), or for doing a preventive 
modification that would eliminate the need for the repetitive 
inspections.
    For operators that choose to do the optional preventive 
modification, the service bulletin describes procedures for an 
additional eddy current inspection for cracks of the satellite holes 
with the fasteners removed.
    If no crack is found during the additional eddy current inspection, 
the service bulletin gives procedures for fabricating and installing 
the preventive modification doublers. The service bulletin states that 
a preventive modification doubler is not needed at BS 390 if the 
doubler has been previously installed in accordance with Boeing Service 
Bulletin 737-53-1117, Revision 1, dated April 6, 1989. For these 
airplanes, the preventive modification is removing the ten fasteners 
around the altimeter cutout at BS 390, doing an eddy current inspection 
of the satellite holes, and installing oversize fasteners.
    If any crack is found during the additional eddy current 
inspection, the service bulletin specifies to discontinue the 
preventive modification and repair the affected area, as described 
below. Repair of the affected area eliminates the need for the 
repetitive inspections.
    If any crack is found during any eddy current inspection, the 
service bulletin describes procedures for repair, which includes 
further investigative and corrective actions. The corrective actions 
included in the repair are cutting out the crack if it is within the 
allowable cutout repair zone, and fabricating and installing a repair 
doubler and spacer ring. The further investigative actions included in 
the repair are an eddy current inspection of the edge of the cutout 
area, an eddy current inspection of the satellite holes (with fasteners 
removed) for additional cracking, and a visual inspection for corrosion 
of the area under the previously repaired area. If any crack is outside 
the allowable cutout repair zone, or if any corrosion is detected, the 
service bulletin specifies to contact Boeing for repair instructions.
    Accomplishing the actions specified in Special Attention Service 
Bulletin 737-53-1230 will address the identified unsafe condition 
adequately.
    This special attention service bulletin refers to Boeing Service 
Bulletin 737-53-1117, Revision 1, dated April 6, 1989, as an additional 
source of service information for repairing certain affected airplanes.

Concurrent Service Bulletin for Certain Airplanes

    Boeing Service Bulletin 737-53-1117, Revision 1, dated April 6, 
1989, must be accomplished before or at the same time as the repair 
procedures in Boeing Special Attention Service Bulletin 737-53-1230 for 
any airplane that meets all three of the following conditions:

[[Page 12984]]

    1. The airplane is specified as belonging in Group 1, 2, 3, 4, or 5 
as listed in Boeing Special Attention Service Bulletin 737-53-1230;
    2. The airplane has a skin crack at the cutout at BS 390; and
    3. The airplane has not had an external repair doubler installed 
previously in accordance with Boeing Service Bulletin 737-53-1117. The 
repair in Service Bulletin 737-53-1117 includes further investigative 
and corrective actions, which are an additional inspection and repair 
of any crack by stop-drilling the cracks and installing an external 
repair doubler.

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 you to accomplish the actions specified in Special 
Attention Service Bulletin 737-53-1230, except as discussed under 
``Differences Between the Proposed AD and the Service Bulletins.'' This 
proposed AD also would provide for optional terminating action for the 
repetitive inspections.
    This proposed AD would allow repetitive inspections to continue in 
lieu of the terminating action. In making this determination, we 
considered that long-term continued operational safety in this case 
would be adequately ensured by repetitive inspections to detect cracks 
before they represent a hazard to the airplane.

Differences Between the Proposed AD and the Service Bulletins

    For airplanes designated as Groups 1, 2, 3, 4, and 5 that have a 
skin crack at BS 390, Part III of the Accomplishment Instructions of 
Boeing Special Attention Service Bulletin 737-53-1230 specifies 
additional actions in accordance with Boeing Service Bulletin 737-53-
1117. These additional actions are a detailed inspection and repair, if 
necessary, of an adjacent equipment cooling duct cutout just forward of 
BS 390. The repair in Boeing Service Bulletin 737-53-1117 allows for 
repair of any crack by stop-drilling and installing an external repair 
doubler. This repair doubler reinforces the equipment cooling duct 
cutout and the BS 390 cutout. This proposed AD also would allow 
operators the option to do an eddy current inspection and repair in 
accordance with Figure 17 of Boeing Special Attention Service Bulletin 
737-53-1230.
    Special Attention Service Bulletin 737-53-1230 specifies that you 
may contact the manufacturer for instructions for certain repair 
instructions. However, rather than contacting the manufacturer, and for 
instructions for repairing any crack that is 3 inches in length or 
greater that is found during the inspection specified in Service 
Bulletin 737-53-1117, this proposed AD would require you to do these 
repairs in one of the ways listed in the bullets below.
     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.

Clarification of Inspection Language

    Both Boeing Service bulletins request that operators ``visually 
inspect'' for certain conditions. This proposed AD defines this 
inspection in Boeing Service Bulletin 737-53-1117 as a ``detailed 
inspection,'' and in Boeing Special Attention Service Bulletin 737-53-
1230 as a ``general visual inspection.'' These inspections are defined 
in Note 1 and Note 2 of this proposed AD.

Costs of Compliance

    This proposed AD would affect about 3,132 airplanes worldwide. The 
following table provides the estimated costs for U.S. operators to 
comply with this proposed AD.

                                                 Estimated Costs
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                                                                                       Number  of
                                   Work       Average                      Cost per       U.S.-
            Action                 hours    labor rate        Parts        airplane    registered    Fleet cost
                                             per hour                                   airplanes
----------------------------------------------------------------------------------------------------------------
Inspection....................          3         $65   No parts               $195         1,004      $195,780
                                                         required.
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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:

[[Page 12985]]

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-2005-20627; Directorate Identifier 2004-NM-
39-AD.

Comments Due Date

    (a) The Federal Aviation Administration (FAA) must receive 
comments on this AD action by May 2, 2005.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 737-100, -200, -200C, -300, 
-400, and -500 series airplanes, certificated in any category; as 
identified in Boeing Special Attention Service Bulletin 737-53-1230, 
dated June 13, 2002.

Unsafe Condition

    (d) This AD was prompted by reports of cracks in the lower lobe 
fuselage skin of the affected airplanes. We are issuing this AD to 
detect and correct fatigue cracks of the countersunk rivet holes, 
which could result in cracks of the fuselage skin of the lower lobe, 
and consequent rapid depressurization of the cabin.

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 Reference

    (f) The term ``special attention service bulletin,'' as used in 
this AD, means the Accomplishment Instructions of Boeing Special 
Attention Service Bulletin 737-53-1230, dated June 13, 2002.

Repetitive Inspections

    (g) Before the airplane accumulates 20,000 total flight cycles, 
or within 4,500 flight cycles after the effective date of this AD, 
whichever occurs later: Do an eddy current inspection for cracks of 
the surface area around the satellite holes of the radio altimeter 
cutouts at buttock line 0, between body station (BS) 390 and BS 450. 
Do the inspection with the fasteners installed. Repeat the 
inspection at intervals not to exceed 4,500 flight cycles. Do all 
inspections in accordance with the special attention service 
bulletin.

Repair

    (h) If any crack is found during any eddy current inspection 
required by this AD: Before further flight, repair the area by doing 
all applicable corrective and further investigative actions in 
accordance with the special attention service bulletin. 
Accomplishment of the repair terminates the repetitive inspection 
requirements of paragraph (g) of this AD for the repaired area. 
Where the special attention service bulletin specifies to contact 
Boeing for appropriate action or for instructions about how to 
repair certain conditions: Before further flight, repair in 
accordance with 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 for the Boeing 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 
approval must specifically reference this AD.

Additional Inspection and Repair for Certain Airplanes

    (i) For the following airplanes, before or at the same time as 
the repair in paragraph (h) of this AD, inspect in accordance with 
Table 1 of this AD: Any airplane in Group 1, 2, 3, 4, or 5 of the 
special attention service bulletin; any airplane that has a skin 
crack at the cutout at BS 390 found during any inspection required 
by paragraphs (g) and (h) of this AD; and any airplane that has not 
had an external repair doubler installed in accordance with Boeing 
Service Bulletin 737-53-1117, Revision 1, dated April 6, 1989.

                      Table 1.--Service Information
------------------------------------------------------------------------
                   Inspect in accordance with either--
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   The Accomplishment Instructions of
  Boeing Service Bulletin 737-53-1117,       Figure 17 of the special
   Revision 1, dated April 6, 1989--       attention service bulletin--
------------------------------------------------------------------------
A detailed inspection for cracks in the  An eddy current inspection for
 fuselage lower skin in the area of the   cracks of the exhaust port
 electronics bay cooling duct cutout.     duct cutout edge and the 6
                                          fastener locations;
                                         An eddy current and open-hole
                                          probe inspection for cracks of
                                          the satellite holes; and
                                         A general visual inspection for
                                          corrosion of the area under
                                          the repair.
------------------------------------------------------------------------

    (1) If any crack at the equipment cooling duct cutout is found 
that is less than 3 inches in length: Before further flight, stop-
drill the crack or cracks and install an external repair doubler in 
accordance with the Accomplishment Instructions of Boeing Service 
Bulletin 737-53-1117, Revision 1, dated April 6, 1989; or repair in 
accordance with Part III of the special attention service bulletin. 
Accomplishment of the repair terminates the repetitive inspection 
requirements of paragraph (g) of this AD for the repaired area.
    (2) If any corrosion is found, or if any crack is found that is 
3 inches in length or greater: Before further flight, repair in 
accordance with a method approved by the Manager, Seattle Aircraft 
Certification Office (ACO), FAA; or in accordance with data meeting 
the certification basis of the airplane approved by an Authorized 
Representative for the Boeing 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 
approval must specifically reference this AD.

    Note 1: For the purposes of this AD, a general visual inspection 
is: ``A visual examination of an interior or exterior area, 
installation, or assembly to detect obvious damage, failure, or 
irregularity. This level of inspection is made from within touching 
distance unless otherwise specified. A mirror may be necessary to 
enhance visual access to all exposed surfaces in the inspection 
area. This level of inspection is made under normally available 
lighting conditions such as daylight, hangar lighting, flashlight, 
or droplight and may require removal or opening of access panels or 
doors. Stands, ladders, or platforms may be required to gain 
proximity to the area being checked.''


    Note 2: 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 
mirrors magnifying lenses, etc. may be necessary. Surface cleaning 
and elaborate procedures may be required.''

Optional Terminating Action

    (j) Installing preventive modification doublers in accordance 
with the special attention service bulletin, including the 
additional eddy current inspection with the fasteners removed (with 
no crack finding), terminates the repetitive inspection requirements 
of paragraph (g) of this AD. If any crack is found during the eddy 
current inspection specified by this paragraph: Before further 
flight, discontinue the preventive modification and do the 
applicable actions in paragraph (h) of this AD.

[[Page 12986]]

Alternative Methods of Compliance

    (k)(1) In accordance with 14 CFR 39.19, the Manager, Seattle 
Aircraft Certification Office (SACO), is authorized to approve 
alternative methods of compliance (AMOCs) for this AD.
    (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 Delegation Option 
Authorization Organization who has been authorized by the Manager, 
Seattle ACO, to make those findings.

    Issued in Renton, Washington, on March 8, 2005.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 05-5296 Filed 3-16-05; 8:45 am]
BILLING CODE 4910-13-P