[Federal Register Volume 67, Number 100 (Thursday, May 23, 2002)]
[Rules and Regulations]
[Pages 36085-36087]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-12634]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-359-AD; Amendment 39-12757; AD 2002-10-11]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-100, -200, -200C, -
300, -400, and -500 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment supersedes an existing airworthiness directive 
(AD), applicable to certain Boeing Model 737 series airplanes, that 
currently requires repetitive inspections for cracking and corrosion of 
the pressure bulkhead at body station (BS) 1016, and follow-on actions. 
This amendment expands the applicability of the existing AD, and 
requires new repetitive inspections to detect cracking and corrosion of 
the aft pressure bulkhead at BS 1016, and follow-on actions. This 
action is necessary to detect and correct corrosion or cracking of the 
aft pressure bulkhead at BS 1016, which could result in loss of the aft 
pressure bulkhead web and stiffeners and consequent rapid decompression 
of the fuselage. This action is intended to address the identified 
unsafe condition.

DATES: Effective June 27, 2002.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of June 27, 2002.

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: Scott Fung, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
227-1221; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) by superseding AD 84-20-03 R1, 
amendment 39-5183 (50 FR 51235, December 16, 1985), which is applicable 
to certain Boeing Model 737 series airplanes, was published in the 
Federal Register on November 19, 2001 (66 FR 57908). The action 
proposed to expand the applicability of the existing AD and require new 
repetitive inspections to detect cracking and corrosion of the aft 
pressure bulkhead at body station 1016, and follow-on actions.

Comments

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received. One commenter has no objection to the proposed 
rule. One commenter agrees with the intent of the proposed rule.

Extend Compliance Time

    One commenter asks that the compliance time specified in paragraph 
(e)(3) of the proposed rule be extended by adding the following, ``Do 
the inspection within 6 years since airplane's date of manufacture, or 
within 4 years after doing tasks C53-701-01.01 and C53-202-01 
(reference Boeing Documents D6-38528 or D6-38278), or within 2 years 
after the effective date of this AD, whichever occurs later.'' The 
compliance time in paragraph (e)(3) now specifies, ``Do the inspection 
within 6 years since the airplane's date of manufacture, or within 2 
years after the effective date of this AD, whichever occurs later.'' 
The commenter states that review of the corrosion reports submitted to 
the manufacturer show very few corrosion findings on the aft pressure 
bulkhead. The commenter notes that this indicates that the Corrosion 
Prevention and Control Program (CPCP) is managing corrosion on the 
bulkhead. The commenter adds that periodic corrosion findings 
necessitate doing specific inspections; so, due to CPCP requirements 
for similar inspections, operators should be able to take credit for 
past inspections per the referenced Boeing documents.
    The same commenter asks that the repetitive inspections specified 
in paragraph (f) of the proposed rule be extended to at least every 
four years, in lieu of every two years. The commenter states that the 
primary difference for the aft pressure bulkhead structure between the 
pre-line number 1043 airplanes and the post-line number 1043 airplanes 
is the lack of application of corrosion inhibiting compound (CIC) on 
the drain holes during manufacture. The commenter adds that because the 
drain hole issue is addressed and CICs are applied per the proposed 
rule, inspections of all affected airplanes should be repeated at the 
same 4-year interval.
    The FAA does not agree with the commenter's requests, as 
insufficient supporting data were provided to us to substantiate those 
requests. In developing an appropriate compliance time for this action, 
we considered not only the degree of urgency associated with addressing 
the subject unsafe condition, but the manufacturer's recommendation as 
to an appropriate compliance time, and the practical aspect of 
accomplishing the required inspections within an interval of time that 
parallels normal scheduled maintenance for the majority of affected 
operators.
    In addition, the comment stating that the primary difference for 
the aft pressure bulkhead structure between the pre-line number 1043 
airplanes and the post-line number 1043 airplanes is the lack of 
application of corrosion inhibiting compound (CIC) on the drain holes 
during manufacture is incorrect. Post-line number airplanes have 
additional drain hole provisions that justify the extended intervals; 
those provisions do not exist for the pre-line number airplanes. 
However, under the provisions of paragraph (h)(1) of the final rule, we 
may approve requests for adjustments to the compliance time if data are 
submitted to substantiate that such an adjustment would provide an 
acceptable level of safety.

Conclusion

    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule as proposed.

[[Page 36086]]

Cost Impact

    There are approximately 2,920 airplanes of the affected design in 
the worldwide fleet.
    We estimate that 337 airplanes of U.S. registry are subject to the 
existing AD. The inspections that are currently required by AD 84-20-03 
R1 take approximately 2 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 $40,440, or $120 per airplane, per inspection cycle.
    The drain hole enlargement that is currently required by AD 84-20-
03 R1 takes approximately 2 work hours per airplane to accomplish, at 
an average labor rate of $60 per work hour. Based on these figures, the 
cost impact of this currently required action on U.S. operators is 
estimated to be $40,440, or $120 per airplane.
    We estimate that 1,143 airplanes of U.S. registry will be affected 
by this AD. The new inspections that are required in this AD action 
will take approximately 4 work hours per airplane to accomplish, at an 
average labor rate of $60 per work hour. Based on these figures, the 
cost impact of these new requirements on U.S. operators is estimated to 
be $274,320, or $240 per airplane, per inspection cycle.
    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 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.


 39.13  [Amended]

    2. Section 39.13 is amended by removing amendment 39-5183 (50 FR 
51235, December 16, 1985), and by adding a new airworthiness directive 
(AD), amendment 39-12757, to read as follows:

2002-10-11  Boeing: Amendment 39-12757. Docket 2000-NM-359-AD. 
Supersedes AD 84-20-03 R1, Amendment 39-5183.

    Applicability: Model 737-100, -200, -200C, -300, -400, and -500 
series airplanes; line numbers (L/N) 1 through 3132 inclusive; 
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 (h)(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 detect and correct corrosion or cracking of the aft pressure 
bulkhead at Body Station (BS) 1016, which could result in loss of 
the aft pressure bulkhead web and stiffeners and consequent rapid 
decompression of the fuselage, accomplish the following:

Restatement of Requirements of AD 84-20-03 R1

Initial Inspection

    (a) For Model 737 series airplanes with L/N 1 through 929 
inclusive, with more than 20,000 hours time-in-service or 7 years 
since date of manufacture, whichever occurs first: Within 120 days 
after January 20, 1986 (the effective date of AD 84-20-03 R1, 
amendment 39-5183), unless already accomplished within the 21 months 
before January 20, 1986, visually inspect the BS 1016 pressure 
bulkhead for cracking and corrosion; according to Boeing Alert 
Service Bulletin 737-53A1075, Revision 1, dated September 2, 1983; 
Revision 2, dated July 13, 1984; or Revision 3, dated June 8, 2000. 
Remove any obstruction to the drain hole in the frame chord and 
replace any deteriorated leveling compound as noted in the service 
bulletin. Treat the area of inspection with corrosion inhibitor BMS 
3-23, or equivalent.

Drain Hole Enlargement

    (b) For airplanes identified in paragraph (a) of this AD: Within 
1 year after January 20, 1986, accomplish the drain hole enlargement 
as shown in Boeing Alert Service Bulletin 737-53A1075, Revision 1, 
dated September 2, 1983; Revision 2, dated July 13, 1984; or 
Revision 3, dated June 8, 2000.

Corrective Action

    (c) If cracking or corrosion is found during any inspection 
required by paragraph (a) or (d) of this AD, before further flight, 
repair according to paragraph (c)(1) or (c)(2) of this AD.
    (1) According to Boeing Alert Service Bulletin 737-53A1075, 
Revision 1, dated September 2, 1983; Revision 2, dated July 13, 
1984; or Revision 3, dated June 8, 2000.
    (2) According to a method approved by the Manager, Seattle 
Aircraft Certification Office (ACO), FAA; or per data meeting the 
type certification basis of the airplane approved by a Boeing 
Company Designated Engineering Representative (DER) who has been 
authorized by the Manager, Seattle ACO, to make such findings. For a 
repair method to be approved by the Manager, Seattle ACO, as 
required by this paragraph, the Manager's approval letter must 
specifically reference this AD.

Repetitive Inspections

    (d) For airplanes identified in paragraph (a) of this AD: Repeat 
the visual inspections and corrosion inhibitor treatment in 
paragraph (a) at intervals not to exceed 2 years, until paragraph 
(e) of this AD has been done.

New Requirements of This AD

Initial Inspection

    (e) Do a detailed inspection for cracking or corrosion of the 
aft pressure bulkhead at BS 1016 (including the forward and aft 
sides of the pressure web, forward and aft sides of the pressure 
chord, pressure chord radius, forward and aft sides of the angle 
stiffener, forward and aft chord, stringer end fitting, system 
penetration doublers, channel stiffeners and fasteners, ``Z'' 
stiffeners and fasteners, and fasteners common to the pressure chord 
and pressure web), according

[[Page 36087]]

to Boeing Alert Service Bulletin 737-53A1075, Revision 3, dated June 
8, 2000. Do this inspection at the applicable time shown in 
paragraph (e)(1), (e)(2), or (e)(3) of this AD.

    Note 2: For the purposes of this AD, a detailed inspection is 
defined as: ``An intensive visual examination of a specific 
structural area, system, installation, or assembly to detect damage, 
failure, or irregularity. Available lighting is normally 
supplemented with a direct source of good lighting at intensity 
deemed appropriate by the inspector. Inspection aids such as mirror, 
magnifying lenses, etc., may be used. Surface cleaning and elaborate 
access procedures may be required.''

    (1) For airplanes on which an inspection has previously been 
done according to the requirements of paragraph (a) of this AD: Do 
the inspection within 2 years since the most recent inspection 
according to paragraph (a) or (d) of this AD, as applicable. 
Inspection according to paragraph (e) of this AD ends the 
requirement for inspections according to paragraph (d) of this AD.
    (2) For airplanes having L/N 930 through 1042 inclusive, on 
which an inspection has not previously been done according to 
paragraph (a) of this AD: Do the inspection within 2 years after the 
effective date of this AD.
    (3) For airplanes having L/N 1043 through 3132 inclusive, on 
which an inspection has not previously been done according to 
paragraph (a) of this AD: Do the inspection within 6 years since the 
airplane's date of manufacture, or within 2 years after the 
effective date of this AD, whichever occurs later.

Repetitive Inspections

    (f) Repeat the inspection in paragraph (e) of this AD at the 
applicable time shown in paragraph (f)(1) or (f)(2) of this AD.
    (1) For airplanes having L/N 1 through 1042 inclusive: Repeat 
the inspection at least every 2 years.
    (2) For airplanes having L/N 1043 through 3132 inclusive: Repeat 
the inspection at least every 4 years.

Repair

    (g) If any corrosion or cracking is found during any inspection 
according to paragraph (e) or (f) of this AD: Before further flight, 
repair according to Boeing Alert Service Bulletin 737-53A1075, 
Revision 3, dated June 8, 2000. Exception: If corrosion or cracking 
of the web and stiffeners is outside the limits specified in the 
service bulletin, or if corrosion or cracking is found in any 
structure not covered by the repair instructions in the service 
bulletin, before further flight, repair according to a method 
approved by the Manager, Seattle ACO, or per data meeting the type 
certification basis of the airplane approved by a Boeing Company DER 
who has been authorized by the Manager, Seattle ACO, to make such 
findings. For a repair method to be approved by the Manager, Seattle 
ACO, as required by this paragraph, the Manager's approval letter 
must specifically reference this AD.

Alternative Methods of Compliance

    (h)(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.
    (2) Alternative methods of compliance, approved previously in 
accordance with AD 84-20-03 R1, amendment 39-5183, are approved as 
alternative methods of compliance with this AD.

    Note 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

Special Flight Permits

    (i) Special flight permits may be issued in accordance with 
 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

    (j) Except as provided by paragraphs (c)(2) and (g) of this AD, 
the actions shall be done in accordance with Boeing Alert Service 
Bulletin 737-53A1075, Revision 1, dated September 2, 1983; Boeing 
Alert Service Bulletin 737-53A1075, Revision 2, dated July 13, 1984; 
or Boeing Alert Service Bulletin 737-53A1075, Revision 3, dated June 
8, 2000, as applicable. 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

    (k) This amendment becomes effective on June 27, 2002.

    Issued in Renton, Washington, on May 14, 2002.
Vi L. Lipski,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 02-12634 Filed 5-22-02; 8:45 am]
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