[Federal Register Volume 64, Number 20 (Monday, February 1, 1999)]
[Proposed Rules]
[Pages 4791-4793]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-2271]


 ========================================================================
 Proposed Rules
                                                 Federal Register
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 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.
 
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 

  Federal Register / Vol. 64, No. 20 / Monday, February 1, 1999 / 
Proposed Rules  

[[Page 4791]]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-273-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-200C Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to all Boeing Model 737-200C 
series airplanes, that currently requires a one-time external detailed 
visual inspection to detect cracks of the fuselage skin in the lower 
lobe cargo compartment; repetitive internal detailed visual inspections 
to detect cracks of the frames in the lower lobe cargo compartment; and 
repair of cracked parts. That AD also provides for an optional 
preventative modification that constitutes terminating action for the 
repetitive inspections. This action would require accomplishment of the 
previously optional terminating modification. This proposal is prompted 
by reports of cracking in the body frames between stringers 19 left and 
25 left and at body stations 360 to 500B. The actions specified by the 
proposed AD are intended to prevent opening or loss of the cargo door 
during flight, and consequent rapid decompression of the airplane.

DATES: Comments must be received by March 18, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 98-NM-273-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except 
Federal holidays.
    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: Nenita Odesa, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle 
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-2557; fax (425) 227-1181.

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 notice may be changed in 
light of the comments received.
    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 notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 98-NM-273-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. 98-NM-273-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On June 25, 1993, the FAA issued AD 93-13-02, amendment 39-8615 (58 
FR 36863, July 9, 1993), applicable to all Boeing Model 737-200C series 
airplanes, to require a one-time external detailed visual inspection to 
detect cracks of the fuselage skin in the lower lobe cargo compartment; 
repetitive internal detailed visual inspections to detect cracks of the 
frames in the lower lobe cargo compartment; and repair of cracked 
parts. That AD also provides for an optional preventative modification 
that constitutes terminating action for the repetitive inspections. 
That action was prompted by reports of cracking in the body frames 
between stringers 19 left and 25 left and at body stations 360 to 500B. 
The requirements of that AD are intended to prevent a cargo door from 
opening while the airplane is in flight, which could result in rapid 
decompression of the airplane.

Actions Since Issuance of Previous Rule

    When AD 93-13-02 was issued, it contained a provision for an 
optional preventative modification that involves installation of 
doublers on the frames located between stringers 19 left and 25 left 
and at body stations 360 to 500B, which, if accomplished, constitutes 
terminating action for the required repetitive inspections. This action 
proposes to require accomplishment of the previously optional 
terminating modification in accordance with Boeing Service Bulletin 
737-53A1160, Revision 1, dated April 29, 1993. (That service bulletin 
was referenced as the appropriate source of service information in AD 
93-13-02 for accomplishment of the modification.)

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 93-13-02 to continue to require a one-
time external detailed visual inspection to detect cracks of the 
fuselage skin in the lower lobe cargo compartment; repetitive internal 
detailed visual inspections to detect cracks of the frames in the lower 
lobe cargo compartment; and repair of cracked parts. In addition, the 
proposed

[[Page 4792]]

AD would require accomplishment of the previously optional terminating 
modification.

Differences Between Proposed Rule and Service Bulletin

    Operators should note that this AD proposes to require the 
modification of certain fuselage frames, as described in Boeing Service 
Bulletin 737-53A1160, Revision 1, as terminating action for the 
repetitive inspections. Incorporation of this modification was 
classified as optional in that service bulletin.
    The FAA has determined that long-term continued operational safety 
will be better assured by design changes to remove the source of the 
problem, rather than by repetitive inspections. Long-term inspections 
may not be providing the degree of safety assurance necessary for the 
transport airplane fleet. This, coupled with a better understanding of 
the human factors associated with numerous continual inspections, has 
led the FAA to consider placing less emphasis on inspections and more 
emphasis on design improvements. The proposed modification requirement 
is in consonance with these conditions.

Cost Impact

    There are approximately 90 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 18 airplanes of U.S. registry 
would be affected by this proposed AD.
    The inspections that are currently required by AD 93-13-02, and 
retained in this proposed AD, take approximately 12 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 $12,960, or $720 per 
airplane, per inspection cycle.
    The new modification that is proposed in this AD action would take 
approximately 160 work hours per airplane to accomplish, at an average 
labor rate of $60 per work hour. Required parts would cost 
approximately $5,500 per airplane. Based on these figures, the cost 
impact of the modification proposed by this AD on U.S. operators is 
estimated to be $271,800, or $15,100 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.

Regulatory Impact

    The regulations proposed herein would not have substantial direct 
effects 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, in 
accordance with Executive Order 12612, it is determined that this 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.
    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:

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 39-8615 (58 FR 
36863, July 9, 1993), and by adding a new airworthiness directive (AD), 
to read as follows:

Boeing: Docket 98-NM-273-AD. Supersedes AD 93-13-02, Amendment 39-
8615.

    Applicability: All Model 737-200C series airplanes, certificated 
in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
modified, altered, or repaired in the area subject to the 
requirements of this AD. For airplanes that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (d)(1) 
of this AD. The request should include an assessment of the effect 
of the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent opening or loss of the cargo door during flight, and 
consequent rapid decompression of the airplane, accomplish the 
following:

Restatement of Requirements of AD 93-13-02

    (a) Prior to the accumulation of 29,000 flight cycles or within 
250 flight cycles after August 9, 1993 (the effective date AD 93-13-
02, amendment 39-8615), whichever occurs later, accomplish an 
external detailed visual 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 
(a)(1) and (a)(2) of this AD.
    (1) Perform an internal detailed visual 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.
    (b) Within 3,000 flight cycles after completing the requirements 
of paragraph (a) of this AD, unless accomplished within the last 
6,000 flight cycles prior to August 9, 1993, perform an internal 
detailed visual 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, dated 
October 24, 1991; or Boeing Service Bulletin 737-53A1160, Revision 
1, dated April 29, 1993. Thereafter, repeat the internal detailed 
visual inspection at intervals not to exceed 9,000 flight cycles. If 
any crack is found, prior to further flight, accomplish the 
requirements of paragraph (b)(1) or (b)(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 the Boeing 737 SRM. Repeat the internal 
detailed visual inspection thereafter at intervals not to exceed 
9,000 flight cycles.
    (2) If any crack is found that exceeds the limits specified in 
the Boeing 737 SRM, repair the crack in accordance with a method 
approved by the Manager, Seattle ACO. Repeat the internal detailed 
visual inspection thereafter at intervals not to exceed 9,000 flight 
cycles.

New Requirements of This AD

    (c) Prior to the accumulation of 75,000 total flight cycles, or 
within 3,000 flight cycles after the effective date of this AD, 
whichever occurs later, install doublers on the frames located 
between stringers 19 left and 25 left

[[Page 4793]]

and at body stations 360 to 500B, in accordance with Boeing Service 
Bulletin 737-53A1160, Revision 1, dated April 29, 1993. 
Accomplishment of this modification constitutes terminating action 
for the requirements of this AD.
    (d)(1) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if approved by the Manager, Seattle ACO. Operators shall submit 
their requests through an appropriate FAA Principal Maintenance 
Inspector, who may add comments and then send it to the Manager, 
Seattle ACO.
    (d)(2) Alternative methods of compliance approved previously in 
accordance with AD 93-13-02, amendment 39-8615, are approved as 
alternative methods of compliance with this AD.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

    (e) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the airplane to a location where 
the requirements of this AD can be accomplished.

    Issued in Renton, Washington, on January 26, 1999.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-2271 Filed 1-29-99; 8:45 am]
BILLING CODE 4910-13-P