[Federal Register Volume 68, Number 139 (Monday, July 21, 2003)]
[Proposed Rules]
[Pages 43045-43047]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-18420]


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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2002-NM-150-AD]
RIN 2120-AA64


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

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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

SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to certain Boeing Model 737-
100, -200, and -200C series airplanes, that currently requires 
repetitive inspections to detect discrepancies in the upper and lower 
skins of the fuselage lap joint, and repair if necessary. This action 
would add new inspections, reduce the repetitive inspection intervals 
for certain airplanes, and mandate a terminating modification. The 
actions specified by the proposed AD are intended to detect and correct 
discrepancies in the upper and lower skins of the fuselage lap joint 
and circumferential joint, which could result in sudden fracture and 
failure of a lap joint or circumferential joint and rapid decompression 
of the airplane fuselage.

DATES: Comments must be received by September 4, 2003.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2002-NM-150-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9 a.m. and 3 p.m., Monday through Friday, except 
Federal holidays. Comments may be submitted via fax to (425) 227-1232. 
Comments may also be sent via the Internet using the following address: 
[email protected]. Comments sent via fax or the Internet must 
contain ``Docket No. 2002-NM-150-AD'' in the subject line and need not 
be submitted in triplicate. Comments sent via the Internet as attached 
electronic files must be formatted in Microsoft Word 97 or 2000 or 
ASCII text.
    The service information referenced in the proposed rule may be 
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, 
Washington 98124-2207. This information may be examined at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington.

FOR FURTHER INFORMATION CONTACT: Duong Tran, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle 
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 917-6452; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed rule by submitting such written data, views, or arguments as 
they may desire. Communications shall identify the Rules Docket number 
and be submitted in triplicate to the address specified above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this action may be changed in 
light of the comments received.
    Submit comments using the following format:
    [sbull] Organize comments issue-by-issue. For example, discuss a 
request to change the compliance time and a request to change the 
service bulletin reference as two separate issues.
    [sbull] For each issue, state what specific change to the proposed 
AD is being requested.
    [sbull] Include justification (e.g., reasons or data) for each 
request.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed rule. All 
comments submitted will be available, both before and after the closing 
date for comments, in the Rules Docket for examination by interested 
persons. A report summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this action must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2002-NM-150-AD.'' The postcard will be date stamped 
and returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules 
Docket No. 2002-NM-150-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On August 18, 2000, the FAA issued AD 2000-17-04, amendment 39-
11878 (65 FR 51750, August 25, 2000), applicable to certain Boeing 
Model 737-100, -200, and -200C series airplanes, to require repetitive 
inspections to detect discrepancies in the upper and lower skins of the 
fuselage lap joint, and repair if necessary. That action was prompted 
by a report indicating in-flight rapid decompression of a Boeing Model 
737 series airplane. The requirements of that AD are intended to detect 
and correct such discrepancies, which could result in sudden fracture 
and failure of a lap joint and rapid decompression of the airplane 
fuselage.

Actions Since Issuance of Previous Rule

    In the preamble to AD 2000-17-04, we indicated that the actions 
required by that AD were considered ``interim action'' and that the 
manufacturer was developing a modification to address the unsafe 
condition. The manufacturer now has developed such a modification, and 
we have determined that further rulemaking action is indeed necessary; 
this proposed AD follows from that determination.
    Additionally, we have determined that the inspections for cracking 
as specified in paragraph (a) of the existing AD do not provide the 
crack detection necessary to support the compliance time for the 
repetitive inspection intervals. Therefore, we are proposing to reduce 
the compliance time for the

[[Page 43046]]

repetitive inspections for airplanes with more than 70,000 total flight 
cycles.
    Also, since the issuance of AD 2000-17-04, we have received damage 
reports on 75 percent of the airplanes on which the inspections 
required by that AD had been done, and almost half of the reports 
indicated that damage was found. The reports indicate that 18 airplanes 
had cracking damage on the upper and lower rows of the lap joint, and 
19 airplanes had corrosion damage with some of the corrosion extending 
the entire length of the lap joint. On one airplane, a 25-inch section 
of the lap joint was very corroded. Other corrosion damage of the lap 
joints, which was due to improper repairs, was also reported. Skin 
corrosion of the circumferential joints was also found. Such 
conditions, if not detected and corrected, could result in sudden 
fracture and failure of a lap joint or circumferential joint and rapid 
decompression of the airplane fuselage.

Explanation of Relevant Service Information

    We have reviewed and approved Boeing Alert Service Bulletin 737-
53A1224, Revision 1, dated March 14, 2002, which describes procedures 
for inspections (eddy current, nondestructive test, and detailed) to 
detect discrepancies (i.e., cracks, pillowing, corrosion, delamination, 
or loose or missing fasteners) in the upper and lower skins of the 
fuselage lap joint and circumferential joint, and repair of any 
discrepancies. The service bulletin also describes procedures for a 
terminating modification, which includes removal of the upper and lower 
skins along the full length of the three-row lap joint and repair of 
the production joint. To ensure that the lap joint repair is 
structurally sound, the service bulletin describes procedures to 
inspect to find any additional existing skin damage and repair damage 
(corrosion, cracking, excessive blendouts, disbonding). The terminating 
modification involves repair of the entire length of all lap joints 
between body stations 259.5 and 1016. Accomplishment of the actions 
specified in the service bulletin is intended to adequately address the 
identified unsafe condition.

Explanation of Requirements of Proposed Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, the 
proposed AD would supersede AD 2000-17-04 to continue to require 
inspections to detect discrepancies in the upper and lower skins of the 
fuselage lap joint, and repair if necessary. This new action would add 
new inspections, reduce the repetitive inspection intervals for certain 
airplanes, and mandate a terminating modification. The actions would be 
required to be accomplished in accordance with the service bulletin 
described previously, except as discussed below.

Difference Between Alert Service Bulletin and This AD

    Although the service bulletin specifies that the manufacturer may 
be contacted for disposition of certain repair conditions, this AD 
requires the repair of those conditions to be accomplished in 
accordance with a method approved by the FAA, or in accordance with 
data meeting the type certification basis of the airplane approved by a 
Boeing Company Designated Engineering Representative who has been 
authorized by the FAA to make such findings.

Changes to 14 CFR Part 39/Effect on the Proposed AD

    On July 10, 2002, the FAA issued a new version of 14 CFR part 39 
(67 FR 47997, July 22, 2002), which governs the FAA's airworthiness 
directives system. The regulation now includes material that relates to 
altered products, special flight permits, and alternative methods of 
compliance. Because we have now included this material in part 39, we 
no longer need to include it in each individual AD; therefore, 
paragraph (d) and Note 1 of AD 2000-17-04 are not included in this 
proposed AD. However, this proposed AD identifies the office authorized 
to approve alternative methods of compliance.

Cost Impact

    There are approximately 291 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 60 airplanes of U.S. registry 
would be affected by this proposed AD.
    The inspections that are currently required by AD 2000-17-04 take 
approximately 575 work hours per airplane to accomplish, at an average 
labor rate of $60 per work hour. Based on these figures, the cost 
impact of the currently required inspections on U.S. operators is 
estimated to be $2,070,000, or $34,500 per airplane.
    The new inspections that are proposed in this AD action would take 
approximately 341 work hours per airplane to accomplish, at an average 
labor rate of $60 per work hour. Based on these figures, the cost 
impact of the proposed inspections on U.S. operators is estimated to be 
$1,227,600, or $20,460 per airplane.
    The terminating modification that is proposed in this AD action 
would take approximately 15,000 work hours per airplane to accomplish, 
at an average labor rate of $60 per work hour. Based on these figures, 
the cost impact of the proposed modification on U.S. operators is 
estimated to be $54,000,000, or $900,000 per airplane.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the current or proposed 
requirements of this AD action, and that no operator would accomplish 
those actions in the future if this AD were not adopted. The cost 
impact figures discussed in AD rulemaking actions represent only the 
time necessary to perform the specific actions actually required by the 
AD. These figures typically do not include incidental costs, such as 
the time required to gain access and close up, planning time, or time 
necessitated by other administrative actions.

Regulatory Impact

    The regulations proposed herein 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. Therefore, it 
is determined that this proposal would not have federalism implications 
under Executive Order 13132.
    For the reasons discussed above, I certify that this 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) if promulgated, 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. A copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting the Rules 
Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
part 39 of the Federal Aviation Regulations (14 CFR part 39) as 
follows:

[[Page 43047]]

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. Section 39.13 is amended by removing amendment 39-11878 (65 FR 
51750, August 25, 2000), and by adding a new airworthiness directive 
(AD), to read as follows:

Boeing: Docket 2002-NM-150-AD. Supersedes AD 2000-17-04, Amendment 
39-11878.
    Applicability: Model 737-100, -200, and -200C series airplanes; 
line numbers 1 through 291 inclusive; certificated in any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To detect and correct discrepancies in the upper and lower skins 
of the fuselage lap joint and circumferential joint, which could 
result in sudden fracture and failure of a lap joint or 
circumferential joint and rapid decompression of the airplane 
fuselage, accomplish the following:

Requirements of AD 2000-17-04

Initial and Repetitive Inspections

    (a) Perform the applicable (initial and repetitive) inspections 
as specified in Figures 1 through 4 of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1224, dated 
August 17, 2000, to detect discrepancies (i.e., cracks, pillowing, 
corrosion, delamination, or loose or missing fasteners) in the upper 
and lower skins of the fuselage lap joint. Perform the inspections 
at the applicable times specified in Tables 1 and 2 of Section 1.E. 
``Compliance'' of the alert service bulletin, in accordance with the 
alert service bulletin; except that where Table 1 specifies a 
compliance time of ``airplane flight cycles at time of service 
bulletin release,'' this AD requires a compliance time of ``airplane 
flight cycles as of September 11, 2000 (the effective date of AD 
2000-17-04, amendment 39-11878).''

Repair

    (b) Prior to further flight: Repair any discrepancies detected 
during any inspection required by paragraph (a) of this AD in 
accordance with Boeing Alert Service Bulletin 737-53A1224, dated 
August 17, 2000; repair any discrepancies detected during any 
inspection required by paragraph (c) of this AD in accordance with 
Boeing Alert Service Bulletin 737-53A1224, Revision 1, dated March 
14, 2002. If any discrepancy is detected and the alert service 
bulletin specifies that the manufacturer may be contacted for 
disposition of certain repairs, prior to 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 type certification basis of the airplane approved by a Boeing 
Company Designated Engineering Representative who has been 
authorized by the Manager, Seattle ACO, to make such findings.

New Requirements of This AD

Compliance Times

    (c) Where the compliance times in Section 1.E. ``Compliance'' of 
Boeing Alert Service Bulletin 737-53A1224, Revision 1, dated March 
14, 2002, specify a compliance time interval calculated ``from 
release of service bulletin,'' this AD requires compliance within 
the interval specified in the service bulletin ``after the effective 
date of this AD.'' In addition, where the compliance time for the 
initial and repetitive inspections in Tables 1 through 3 of Section 
1.E. ``Compliance'' of the service bulletin specifies ``airplane 
flight cycles at time of service bulletin release,'' this AD 
requires a compliance time of ``airplane flight cycles as of the 
effective date of this AD.''

Initial and Repetitive Inspections

    (d) Except as provided by paragraph (e) of this AD: Perform the 
applicable (initial and repetitive) inspections as specified in 
Figures 1 through 9 of the Accomplishment Instructions of Boeing 
Alert Service Bulletin 737-53A1224, Revision 1, dated March 14, 
2002, to detect discrepancies (i.e., cracks, pillowing, corrosion, 
delamination, or loose or missing fasteners) in the upper and lower 
skins of the fuselage lap joint and circumferential joint. Perform 
the inspections at the applicable times specified in Tables 1 and 2 
of Section 1.E. ``Compliance'' of the alert service bulletin, in 
accordance with the alert service bulletin, until accomplishment of 
paragraph (f) of this AD. Accomplishment of this paragraph 
terminates the inspections required by paragraph (a) of this AD.
    (e) For airplanes that have accumulated more than 70,000 total 
flight cycles as of the effective date of this AD: Do the first 
repeat inspection at the earlier of the times specified in paragraph 
(e)(1) or (e)(2) of this AD, and repeat the inspection thereafter at 
intervals not to exceed 1,000 flight cycles.
    (1) Within 2,000 flight cycles after the last inspection done 
per AD 2000-17-04.
    (2) Within 1,000 flight cycles after the last inspection done 
per AD 2000-17-04, or within 500 flight cycles after the effective 
date of this AD, whichever is later.

Terminating Modification

    (f) Perform the modification of the skin of all fuselage lap 
joints between body stations 259.5 and 1016 per Part IV of the Work 
Instructions of Boeing Alert Service Bulletin 737-53A1224, Revision 
1, dated March 14, 2002; at the applicable times specified in Table 
3 of Section 1.E. ``Compliance'' of the alert service bulletin; in 
accordance with the alert service bulletin. Accomplishment of this 
paragraph terminates the repetitive inspection requirements of this 
AD.

Alternative Methods of Compliance

    (g)(1) In accordance with 14 CFR 39.19, the Manager, Seattle 
ACO, is authorized to approve alternative methods of compliance 
(AMOC) 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 a 
Boeing Company Designated Engineering Representative who has been 
authorized by the Manager, Seattle ACO, to make such findings.

    Issued in Renton, Washington, on July 15, 2003.
Ali Bahrami,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 03-18420 Filed 7-18-03; 8:45 am]
BILLING CODE 4910-13-P