[Federal Register Volume 66, Number 16 (Wednesday, January 24, 2001)]
[Rules and Regulations]
[Pages 7576-7577]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-1660]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-380-AD; Amendment 39-12085; AD 2001-02-01]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-300, -400, and -500 
Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain Boeing Model 737-300, -400, and -500 series 
airplanes, that requires repetitive inspections to detect cracking of 
certain areas of the forward pressure bulkhead, and repair, if 
necessary. This amendment also requires certain preventive 
modifications, which, when accomplished, terminate the repetitive 
inspections for the affected areas.
This action is necessary to prevent fatigue cracking on critical areas 
of the forward pressure bulkhead, which could result in rapid 
decompression of the airplane fuselage. This action is intended to 
address the identified unsafe condition.

DATES: Effective February 28, 2001.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of February 28, 2001.

ADDRESSES: The service information referenced in this AD may be 
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, 
Washington 98124-2207. This information may be examined at the Federal 
Aviation Administration (FAA), Transport Airplane Directorate, Rules 
Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of 
the Federal Register, 800 North Capitol Street, NW., suite 700, 
Washington, DC.

FOR FURTHER INFORMATION CONTACT: Nenita K. Odesa, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
227-2557; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD) that is applicable to certain Boeing Model 737-300, -
400, and -500 series airplanes was published in the Federal Register on 
October 18, 2000 (65 FR 62313). That action proposed to require 
repetitive inspections to detect cracking of certain areas of the 
forward pressure bulkhead, and repair, if necessary. That action also 
proposed to require certain preventive modifications, which, when 
accomplished, would terminate the repetitive inspections for the 
affected areas.

Comments

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. No comments were submitted in response 
to the proposal or the FAA's determination of the cost to the public.

Conclusion

    The FAA has determined that air safety and the public interest 
require the adoption of the rule as proposed.

Cost Impact

    There are approximately 330 Model 737 series airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 115 
airplanes of U.S. registry will be affected by this AD.
    It will take approximately 2 work hours per airplane to accomplish 
the required inspection, at an average labor rate of $60 per work hour. 
Based on these figures, the cost impact of the AD on U.S. operators is 
estimated to be $13,800, or $120 per airplane, per inspection cycle.
    It will take approximately 38 work hours per airplane to accomplish 
the required modification of the vertical chords, at an average labor 
rate of $60 per work hour. Required parts will cost approximately 
$2,789 per airplane. Based on these figures, the cost impact of the AD 
on U.S. operators is estimated to be $582,935, or $5,069 per airplane.
    It will take approximately 274 work hours per airplane to 
accomplish the required modification of the side chord areas, at an 
average labor rate of $60 per work hour. Required parts will cost 
approximately $6,629 per airplane. Based on these figures, the cost 
impact of the AD on U.S. operators is estimated to be $2,652,935, or 
$23,069 per airplane.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the 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 adopted herein will 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 final rule does not

[[Page 7577]]

have federalism implications under Executive Order 13132.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under 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. A final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it may be obtained 
from the Rules Docket at the location provided under the caption 
ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends 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 adding the following new 
airworthiness directive:

2001-02-01  Boeing: Amendment 39-12085. Docket 99-NM-380-AD.

    Applicability: Model 737-300, -400, and -500 series airplanes, 
certificated in any category; as listed in Boeing Alert Service 
Bulletin 737-53A1208, dated May 6, 1999.

    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) 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 detect fatigue cracking of the forward pressure bulkhead, 
which could result in rapid decompression of the airplane fuselage, 
accomplish the following:

Initial and Repetitive Inspections

    (a) Before the accumulation of 20,000 total flight cycles, or 
within 3,000 flight cycles after the effective date of this AD, 
whichever occurs later: Perform the applicable inspections of the 
vertical and side chord areas of the forward pressure bulkhead to 
detect cracking, in accordance with the Accomplishment Instructions 
of Boeing Alert Service Bulletin 737-53A1208, dated May 6, 1999. 
Thereafter, repeat the inspections at intervals not to exceed 6,000 
flight cycles until the preventive modifications required by 
paragraph (c) of this AD have been accomplished.

Repair

    (b) If any cracking is detected during any inspection required 
by paragraph (a) of this AD, before further flight, repair the area 
in accordance with the Accomplishment Instructions of Boeing Alert 
Service Bulletin 737-53A1208, dated May 6, 1999.

Terminating Action

    (c) Before the accumulation of 75,000 total flight cycles, or 
within 12,000 flight cycles after the effective date of this AD, 
whichever occurs later: Accomplish preventive modifications of the 
vertical and side chord areas of the forward pressure bulkhead, in 
accordance with the Accomplishment Instructions of Boeing Alert 
Service Bulletin 737-53A1208, dated May 6, 1999. Accomplishment of 
these modifications constitutes terminating action for the 
repetitive inspections required by paragraph (a) of this AD.

Alternative Methods of Compliance

    (d) 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 Aircraft Certification 
Office (ACO), FAA. 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.

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

Special Flight Permit

    (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.

Incorporation by Reference

    (f) The actions shall be done in accordance with Boeing Alert 
Service Bulletin 737-53A1208, dated May 6, 1999. This incorporation 
by reference was approved by the Director of the Federal Register in 
accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be 
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, 
Seattle, Washington 98124-2207. Copies may be inspected at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington; or at the Office of the Federal Register, 800 North 
Capitol Street, NW., suite 700, Washington, DC.

Effective Date

    (g) This amendment becomes effective on February 28, 2001.

    Issued in Renton, Washington, on January 12, 2001.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-1660 Filed 1-23-01; 8:45 am]
BILLING CODE 4910-13-P