[Federal Register Volume 69, Number 152 (Monday, August 9, 2004)]
[Rules and Regulations]
[Pages 48133-48135]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-17979]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2003-NM-107-AD; Amendment 39-13765; AD 2004-16-09]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747 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 all Model 747 series airplanes, that requires repetitive 
detailed inspections of the aft pressure bulkhead for indications of 
``oil cans'' and previous oil can repairs, and corrective actions, if 
necessary. An oil can is an area on a pressure dome web that moves when 
pushed from the

[[Page 48134]]

forward side. This action is necessary to detect and correct the 
propagation of fatigue cracks in the vicinity of oil cans on the web of 
the aft pressure bulkhead, which could result in rapid decompression 
and overpressurization of the tail section, and consequent loss of 
control of the airplane. This action is intended to address the 
identified unsafe condition.

DATES: Effective September 13, 2004.
    The incorporation by reference of a certain publication listed in 
the regulations is approved by the Director of the Federal Register as 
of September 13, 2004.

ADDRESSES: The service information referenced in this AD may be 
obtained from Boeing Commercial Airplanes, 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 National 
Archives and Records Administration (NARA). For information on the 
availability of this material at NARA, call (202) 741-6030, or go to: 
http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.

FOR FURTHER INFORMATION CONTACT: Nicholas Kusz, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
917-6432; fax (425) 917-6590.

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 all Model 747 series airplanes was 
published in the Federal Register on February 6, 2004 (69 FR 5765). 
That action proposed to require a repetitive detailed inspection of the 
aft pressure bulkhead for indications of ``oil cans'' and previous oil 
can repairs, and corrective actions, if necessary. An oil can is an 
area on a pressure dome web that moves when pushed from the forward 
side.

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.

Agreement With Proposed Rule

    Two commenters agree with the proposed rule.

Request To Change Inspection Intervals

    One commenter requests that the repetitive inspection intervals be 
changed. The commenter notes that the initial compliance time of 30,000 
total flight cycles specified in paragraph (b) of the proposed rule 
would impact its fleet within six to seven years. The commenter 
suggests that the repetitive inspection interval for webs with 
allowable oil can damage, specified in paragraph (e)(1) of the proposed 
rule, be changed from 1,000 flight cycles to 1,200 flight cycles. The 
commenter also suggests that the repetitive inspection interval for 
webs with no oil can damage, specified in paragraph (c) of the proposed 
rule, be changed from 2,000 flight cycles to 2,400 flight cycles. The 
commenter contends that these changes would allow the repetitive 
inspections to occur during scheduled heavy maintenance C-check level 
visits.
    The FAA does not agree with changing the repetitive inspection 
intervals. In developing appropriate compliance times for this action, 
we considered the safety implications, the manufacturer's 
recommendations, and the practical aspect of accomplishing the 
inspections within an interval of time that corresponds to the normal 
maintenance schedules of most affected operators. The manufacturer 
determined through tests and analysis that existing inspection programs 
would not have found a crack in the web of the aft pressure bulkhead 
prior to the crack reaching critical length. The repetitive inspection 
intervals are based on the manufacturer's analysis of crack growth in 
the web of the aft pressure bulkhead.
    In light of all these factors, we consider the repetitive 
inspection intervals required by paragraphs (c) and (e)(1) of the final 
rule to be appropriate. Therefore, no change to the final rule is 
necessary in this regard. However, according to the provisions of 
paragraph (h) of the final rule, we may approve a request to adjust the 
inspection intervals if the request includes data that prove that the 
new inspection intervals would provide an acceptable level of safety.

Editorial Changes

    We have reformatted paragraphs (f)(2) and (f)(3) of the proposed AD 
by combining the paragraphs. Paragraph (f)(2) of the final rule 
contains the actions that were specified in paragraphs (f)(2) and 
(f)(3) of the proposed AD. We have also removed the reference to 
paragraph (f)(2) from paragraph (e) of the final rule.

Conclusion

    After careful review of the available data, including the comments 
noted above, we have determined that air safety and the public interest 
require the adoption of the rule with the changes previously described. 
We have determined that these changes will neither increase the 
economic burden on any operator nor increase the scope of the AD.

Cost Impact

    There are approximately 1,140 airplanes of the affected design in 
the worldwide fleet. The FAA estimates that 254 airplanes of U.S. 
registry will be affected by this AD, that it will take approximately 6 
work hours per airplane to accomplish the required actions, and that 
the average labor rate is $65 per work hour. Based on these figures, 
the cost impact of the AD on U.S. operators is estimated to be $99,060, 
or $390 per airplane, per inspection cycle.
    The cost impact figure discussed above is 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.

[[Page 48135]]

List of Subjects in 14 CFR Part 39

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

Adoption of the Amendment

0
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

0
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]

0
2. Section 39.13 is amended by adding the following new airworthiness 
directive:

2004-16-09 Boeing: Amendment 39-13765. Docket 2003-NM-107-AD.

    Applicability: All Model 747 series airplanes; certificated in 
any category.
    Compliance: Required as indicated, unless accomplished 
previously.

    Note 1: This AD refers to certain portions of a Boeing service 
bulletin for inspections and repair information. In addition, this 
AD specifies requirements beyond those included in the service 
bulletin. Where the AD and the service bulletin differ, the AD 
prevails.


    To detect and correct the propagation of fatigue cracks in the 
vicinity of ``oil cans'' on the web of the aft pressure bulkhead, 
which could result in rapid decompression and overpressurization of 
the tail section, and consequent loss of control of the airplane, 
accomplish the following:

Service Bulletin References

    (a) The term ``service bulletin,'' as used in this AD, means the 
Accomplishment Instructions of Boeing Alert Service Bulletin 747-
53A2482, dated October 3, 2002.

Initial and Repetitive Inspections

    (b) Prior to the accumulation of 30,000 total flight cycles, or 
within 1,000 flight cycles after the effective date of this AD, 
whichever is later, perform a detailed inspection of the aft 
pressure bulkhead for indications of oil cans and previous oil can 
repairs, in accordance with the service bulletin.

    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.''


    (c) If no indication of an oil can is found and no indication of 
a previous oil can repair is found during the detailed inspection 
required by paragraph (b) of this AD, repeat the detailed inspection 
thereafter at intervals not to exceed 2,000 flight cycles.

Indication of Oil Can

    (d) If any indication of an oil can is found during the detailed 
inspection required by paragraph (b) or (c) of this AD, before 
further flight, perform an eddy current inspection of the web around 
the periphery of the oil can indication for cracks, as shown in 
Figure 3 of the service bulletin.
    (e) If no crack is found during the eddy current inspection 
required by paragraph (d) of this AD, do the actions specified in 
paragraph (e)(1) or (e)(2) of this AD, as applicable.
    (1) For the oil can that meets the allowable limits specified in 
the service bulletin: Repeat the eddy current inspection specified 
in paragraph (d) of this AD thereafter at intervals not to exceed 
1,000 flight cycles. As an option, repair the oil can in accordance 
with paragraph (e)(2) of this AD.
    (2) For the oil can that does not meet the allowable limits 
specified in the service bulletin: Before further flight, repair the 
oil can in accordance with the service bulletin. If the repair 
eliminates the oil can, accomplishment of this repair constitutes 
terminating action for the repetitive eddy current inspection 
requirements of paragraph (e)(1) of this AD for that location only. 
However, the repetitive detailed inspection required by paragraph 
(c) of this AD is still required. If any oil can remains after the 
repair, repeat the eddy current inspection specified in paragraph 
(d) of this AD thereafter at intervals not to exceed 1,000 flight 
cycles.

Indication of Previous Oil Can Repairs

    (f) If any previous oil can repair is found during the detailed 
inspection required by paragraph (b) or (c) of this AD, before 
further flight, do a detailed inspection of the web for cracks and 
oil cans, as shown in Figure 4 or Figure 5 of the service bulletin, 
as applicable.
    (1) If no crack and no oil can are found, repeat the detailed 
inspection in accordance with paragraph (c) of this AD.
    (2) If any oil can is found, before further flight, do the eddy 
current inspection for cracks, as shown in Figure 3 of the service 
bulletin. If no crack is found during the eddy current inspection 
required by this paragraph, do the actions specified in paragraph 
(e)(1) or (e)(2) of this AD, as applicable, at the time specified in 
the applicable paragraph.

Repair of Cracks

    (g) If any crack is found during any inspection required by this 
AD, before further flight, repair in accordance with the service 
bulletin. If any crack or damage exceeds limits specified in the 
service bulletin and the service bulletin specifies to contact 
Boeing for appropriate action: Before further flight, repair per 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 who has been authorized by the Manager, Seattle ACO, 
to make such findings. For a repair method to be approved, the 
approval must specifically reference this AD.

Alternative Methods of Compliance

    (h) In accordance with 14 CFR 39.19, the Manager, Seattle ACO, 
FAA, is authorized to approve alternative methods of compliance for 
this AD.

Incorporation by Reference

    (i) Unless otherwise specified in this AD, the actions shall be 
done in accordance with Boeing Alert Service Bulletin 747-53A2482, 
dated October 3, 2002. 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 Airplanes, 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 National 
Archives and Records Administration (NARA). For information on the 
availability of this material at NARA, call (202) 741-6030, or go 
to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.

Effective Date

    (j) This amendment becomes effective on September 13, 2004.

    Issued in Renton, Washington, on July 30, 2004.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 04-17979 Filed 8-6-04; 8:45 am]
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