Airworthiness Directives; Boeing Model 747 Series Airplanes

[Federal Register Volume 69, Number 246 (Thursday, December 23, 2004)]
[Rules and Regulations]
[Pages 76839-76841]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-27508]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2001-NM-179-AD; Amendment 39-13911; AD 2004-25-23]
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 Boeing Model 747 series airplanes, that requires 
repetitive inspections for cracking of the top and side panel webs and 
panel stiffeners of the nose wheel well (NWW), and corrective actions 
if necessary. This action is necessary to detect and correct fatigue 
cracks in the top and side panel webs and stiffeners of the NWW, which 
could compromise the structural integrity of the NWW and could lead to 
the rapid depressurization of the airplane. This action is intended to 
address the identified unsafe condition.

DATES: Effective January 27, 2005.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of January 27, 2005.

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: Nick Kusz, 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 Boeing Model 747 series 
airplanes was published in the Federal Register on May 7, 2004 (69 FR 
25519). That notice of proposed rulemaking (NPRM) proposed to require 
repetitive inspections for cracking of the top and side panel webs and 
panel stiffeners of the nose wheel well (NWW), and corrective actions 
if necessary.

Explanation of New Service Information

    Since the issuance of the NPRM, Boeing has issued and we have 
reviewed Revision 2 of Boeing Alert Service Bulletin 747-53A2465, dated 
November 11, 2004 (the NPRM referred to Revision 1 of the service 
bulletin as the appropriate source of service information for 
accomplishing the proposed actions). Revision 2 of the service bulletin 
describes procedures for performing repetitive external detailed 
inspections for cracking of the top and side panel webs of the NWW 
(specified as Area 1 and Area 2 in the service bulletin), as 
applicable; performing repetitive internal detailed and surface high 
frequency eddy current (HFEC) inspections for cracking of the top and 
side panel stiffeners of the NWW (specified as Area 3 in the service 
bulletin); replacing cracked stiffeners with new stiffeners; and 
repairing any cracked panel web.
    We have revised the final rule by adding new paragraph (a)(2) as an 
option to accomplishing the repetitive inspections required by 
paragraph (a)(1) (specified as paragraph (a) of the NPRM). The option 
allows operators to do the repetitive inspections specified in Revision 
2 of the service bulletin. The compliance time intervals for the new, 
optional repetitive inspections are: (1) 1,000 flight cycles for the 
external detailed inspection, and (2) 6,000 flight cycles for the 
internal detailed and suface HFEC inspections, which is less stringent 
than the 1,000 flight-cycle interval for the repetitive inspections

[[Page 76840]]

required by paragraph (a)(1) of this final rule.
    We have also added Revision 2 of the service bulletin to paragraph 
(b) of the final rule to allow repairs to be done according to either 
Revision 1 or Revision 2 of the service bulletin, as applicable.
    Accomplishing the actions specified in either Revision 1 or 
Revision 2 of the service bulletin at the times specified in the final 
rule is intended to adequately address the identified unsafe condition.

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.

Request To Revise or Cancel the NPRM

    Two commenters request that the NPRM be revised or cancelled due to 
the upcoming release of Revision 2 of Boeing Alert Service Bulletin 
747-53A2465. One commenter, the airplane manufacturer, notes that 
Revision 2 of the service bulletin will have different inspections and 
compliance times than what is specified in paragraph (a) of the NPRM. 
The commenter states that the procedures for ultrasonic inspection will 
be removed from the service bulletin and that the repetitive interval 
recommended for the detailed inspection of the NWW sidewall and top 
webs will be changed. The commenter notes that the detailed inspection 
will be performed every 1,000 flight cycles, starting at 16,000 total 
flight cycles, and then, after accumulating 25,000 flight cycles, the 
detailed inspection will be performed every 100 flight cycles for the 
web common to the fore-aft stiffeners at water lines (WL) 150, 160 and 
170 (left and right sides). The commenter suggests that paragraph (a) 
of the NPRM be revised to reflect these changes.
    The other commenter suggests that the NPRM be revised or cancelled 
because of the differences between the NPRM and Revision 2 of the 
service bulletin. The commenter also asks that a new proposal be issued 
that cites the changes specified in Revision 2 of the service bulletin.
    We do not agree with the commenters' requests to revise or cancel 
the NPRM. Revision 2 of the service bulletin does not contain a 25,000 
flight-cycle inspection threshold to reduce the repetitive inspection 
interval. In addition, as stated earlier, we have revised the final 
rule by adding the actions specified in Revision 2 of the service 
bulletin as an option to doing the actions specified in Revision 1 of 
the service bulletin.

Request To Extend Inspection Threshold

    One commenter requests that the second inspection threshold be 
extended from 25,000 flight cycles to 28,000 flight cycles for Model 
747-400D series airplanes. The commenter states that the fatigue cracks 
are caused by cabin pressurization and Model 747-400D series airplanes 
operate with lower cabin differential pressure.
    We do not agree with the commenter. We infer that the commenter is 
referring to Revision 2 of Boeing Alert Service Bulletin 747-53A2465, 
but as stated earlier, Revision 2 does not contain a second inspection 
threshold. No change is made to the final rule in this regard.

Conclusion

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

Cost Impact

    There are approximately 1,127 airplanes of the affected design in 
the worldwide fleet. We estimate that 255 airplanes of U.S. registry 
will be affected by this AD.
    It will take approximately 42 work hours per airplane to accomplish 
the required inspections specified in Boeing Service Bulletin 747-
53A2465, Revision 1, dated October 16, 2003, and that the average labor 
rate is $65 per work hour. Based on these figures, the cost impact of 
the required inspections on U.S. operators is estimated to be $2,730 
per airplane, per inspection cycle.
    In lieu of the inspections specified in Revision 1 of Boeing 
Service Bulletin 747-53A2465, it will take approximately 87 or 97 work 
hours per airplane (depending on the airplane configuration) to 
accomplish the required inspections specified in Boeing Alert Service 
Bulletin 747-53A2465, Revision 2, dated November 11, 2004, and that the 
average labor rate is $65 per work hour. Based on these figures, the 
cost impact of the required inspections on U.S. operators is estimated 
to be $5,655 or $6,305 per airplane, per inspection cycle (depending on 
the airplane configuration).
    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.

Authority for This Rulemaking

    The FAA's authority to issue rules regarding aviation safety is 
found in Title 49 of the United States Code. Subtitle I, Section 106 
describes the authority of the FAA Administrator. Subtitle VII, 
Aviation Programs, describes in more detail the scope of the agency's 
authority.
    This rulemaking is promulgated under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701, ``General 
requirements.'' Under that section, the FAA is charged with promoting 
safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this AD.

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 76841]]

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:

2004-25-23 Boeing: Amendment 39-13911. Docket 2001-NM-179-AD.

    Applicability: All Model 747 series airplanes, certificated in 
any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To detect and correct fatigue cracks in the top and side panel 
webs and stiffeners of the nose wheel well (NWW), which could 
compromise the structural integrity of the NWW and could lead to the 
rapid depressurization of the airplane, accomplish the following:

Initial and Repetitive Inspections

    (a) Prior to the accumulation of 16,000 total flight cycles, or 
within 1,000 flight cycles after the effective date of this AD, 
whichever is later, do the inspections specified in either paragraph 
(a)(1) or (a)(2) of this AD.
    (1) Do the inspections specified in paragraphs (a)(1)(i) and 
(a)(1)(ii) of this AD in accordance with the Accomplishment 
Instructions of Boeing Service Bulletin 747-53A2465, Revision 1, 
dated October 16, 2003. Repeat the inspections thereafter at 
intervals not to exceed 1,000 flight cycles.
    (i) Do detailed and ultrasonic inspections of the top and side 
panel webs of the NWW for cracks.
    (ii) Do detailed and surface high frequency eddy current (HFEC) 
inspections of the top and side panel stiffeners of the NWW for 
cracks.
    (2) Do the inspections specified in paragraphs (a)(2)(i) and 
(a)(2)(ii) of this AD in accordance with the Accomplishment 
Instructions of Boeing Alert Service Bulletin 747-53A2465, Revision 
2, dated November 11, 2004. Repeat the inspections thereafter at the 
intervals specified in paragraphs (a)(2)(i) and (a)(2)(ii) of this 
AD.
    (i) Do external detailed inspections of the top and side panel 
webs of the NWW (specified as Area 1 and Area 2 in the service 
bulletin), as applicable, for cracks. Repeat the inspections 
thereafter at intervals not to exceed 1,000 flight cycles.
    (ii) Do internal detailed and surface HFEC inspections of the 
top and side panel stiffeners of the NWW (specified as Area 3 in the 
service bulletin) for cracks. Repeat the inspections thereafter at 
intervals not to exceed 6,000 flight cycles.

    Note 1: 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 
mirrors, magnifying lenses, etc., may be used. Surface cleaning and 
elaborate access procedures may be required.''

Corrective Actions

    (b) If any crack is found during any inspection required by 
paragraph (a) of this AD: Prior to further flight, do the applicable 
corrective actions specified in paragraphs (b)(1) and (b)(2) of this 
AD, in accordance with the Accomplishment Instructions of Boeing 
Service Bulletin 747-53A2465, Revision 1, dated October 16, 2003; or 
Boeing Alert Service Bulletin 747-53A2465, Revision 2, dated 
November 11, 2004; as applicable. Thereafter, repeat the inspections 
required by paragraph (a) of this AD at the time specified in 
paragraph (a)(1) or (a)(2) of this AD, as applicable.
    (1) Repair web cracks.
    (2) Replace cracked stiffeners with new stiffeners.

Inspections Accomplished per Previous Issue of Service Bulletin

    (c) Inspections accomplished before the effective date of this 
AD in accordance with Boeing Alert Service Bulletin 747-53A2465, 
dated April 5, 2001, are considered acceptable for compliance with 
the corresponding inspections specified in paragraph (a) of this AD.

Alternative Methods of Compliance

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

Incorporation by Reference

    (e) Unless otherwise specified in this AD, the actions shall be 
done in accordance with Boeing Service Bulletin 747-53A2465, 
Revision 1, dated October 16, 2003; or Boeing Alert Service Bulletin 
747-53A2465, Revision 2, dated November 11, 2004. 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

    (f) This amendment becomes effective on January 27, 2005.

    Issued in Renton, Washington, on December 7, 2004.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 04-27508 Filed 12-22-04; 8:45 am]
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