[Federal Register Volume 69, Number 89 (Friday, May 7, 2004)]
[Proposed Rules]
[Pages 25519-25521]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-10433]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2001-NM-179-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to all Boeing Model 747 series 
airplanes. This proposal would 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. 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: Comments must be received by June 21, 2004.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2001-NM-179-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9 a.m. and 3 p.m., Monday through Friday, except 
Federal holidays. Comments may be submitted via fax to (425) 227-1232. 
Comments may also be sent via the Internet using the following address: 
[email protected]. Comments sent via fax or the Internet must 
contain ``Docket No. 2001-NM-179-AD'' in the subject line and need not 
be submitted in triplicate. Comments sent via the Internet as attached 
electronic files must be formatted in Microsoft Word 97 or 2000 or 
ASCII text.
    The service information referenced in the proposed rule may be 
obtained from Boeing Commercial Airplanes, PO Box 3707, Seattle, 
Washington 98124-2207. This information may be examined at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton.

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:

[[Page 25520]]

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 action may be changed in 
light of the comments received.
    Submit comments using the following format:
     Organize comments issue-by-issue. For example, discuss a 
request to change the compliance time and a request to change the 
service bulletin reference as two separate issues.
     For each issue, state what specific change to the proposed 
AD is being requested.
     Include justification (e.g., reasons or data) for each 
request.
    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 action must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2001-NM-179-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. 2001-NM-179-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports indicating that cracks have been found 
on the top and side panel webs and side panel horizontal stiffeners of 
the nose wheel well (NWW) on Boeing Model 747 series airplanes. The 
cause of the cracking is fatigue. If left undetected, fatigue cracks in 
the top and side panel webs and stiffeners could become large. This 
condition, if not detected and corrected, could compromise the 
structural integrity of the NWW and could lead to rapid 
depressurization of the airplane.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Service Bulletin 747-
53A2465, Revision 1, dated October 16, 2003. The service bulletin 
describes procedures for performing repetitive detailed and ultrasonic 
inspections for cracking of the top and side panel webs of the NWW and 
for performing repetitive detailed and surface high frequency eddy 
current inspections for cracking of the top and side panel stiffeners 
of the NWW; replacing cracked stiffeners with new stiffeners; and 
repair of any cracked panel web. Accomplishment of the actions 
specified in the service bulletin is intended to adequately address the 
identified unsafe condition.

New Reports Since Issuance of Service Bulletin

    Since issuance of the service bulletin, there have been several new 
reports of cracking in the nose wheel well panels. The reported 
cracking was as long as 12 inches and, in one case, was discovered 
within less than 1,200 flight cycles since the previous inspection per 
the service bulletin.

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 require accomplishment of the actions specified in 
the service bulletin described previously, except as described below.

Differences Between Proposed Rule and Service Bulletin

    Operators should note that while the service bulletin, ``Planning 
Information'' 1.D. Note 2., specifies that flight cycles with a cabin 
differential pressure of 2.0 psi or less do not need to be counted as 
part of the compliance time, this proposed AD counts all flight cycles 
as part of the compliance time. We have determined that an adjustment 
of flight cycles due to a lower cabin differential pressure is not 
substantiated and will not be allowed for use in determining the flight 
cycle threshold.
    It should also be noted that, although the repeat interval listed 
in Figure 1 of the service bulletin is listed as 6,000 flight cycles, 
this proposal would require repeat inspections at 1,000 flight cycle 
intervals due to the severity of the new reports and the relatively 
short interval since the previous inspection that they were found. This 
reduced interval has been coordinated with the manufacturer.

Clarification of Service Bulletin

    Operators should note that, although the ``Action'' paragraph in 
the Summary and paragraph D., ``Description,'' in the Planning 
Information of the service bulletin specify that operators may contact 
the manufacturer for disposition of certain repair conditions, the 
Accomplishment Instructions of the service bulletin specify to repair 
web cracks as shown in the Structural Repair Manual. This proposed AD 
would require the repairs be done per the Accomplishment Instructions 
of the service bulletin.

Cost Impact

    There are approximately 1,127 airplanes of the affected design in 
the worldwide fleet. The FAA estimates that 255 airplanes of U.S. 
registry would be affected by this proposed AD, that it would take 
approximately 42 work hours per airplane to accomplish the proposed 
inspection, and that the average labor rate is $65 per work hour. Based 
on these figures, the cost impact of the proposed AD on U.S. operators 
is estimated to be $696,150, or $2,730 per airplane, per inspection 
cycle.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the proposed requirements 
of this AD action, and that no operator would accomplish those actions 
in the future if this proposed 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 proposed herein would 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 proposal would not have federalism implications 
under Executive Order 13132.
    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

[[Page 25521]]

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 adding the following new 
airworthiness directive:

Boeing: 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 paragraphs 
(a)(1) and (a)(2) of this AD, per 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.
    (1) Do detailed and ultrasonic inspections of the top and side 
panel webs of the NWW for cracks.
    (2) Do detailed and surface high frequency eddy current 
inspections of the top and side panel stiffeners of the NWW for 
cracks.

    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 repair 
specified in paragraph (b)(1) and/or (b)(2) of this AD, as 
applicable, in accordance with the Accomplishment Instructions of 
Boeing Service Bulletin 747-53A2465, Revision 1, dated October 16, 
2003. Thereafter, repeat the inspections required by paragraph (a) 
of this AD.
    (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 per Boeing Alert Service Bulletin 747-53A2465, dated April 5, 
2001, are considered acceptable for compliance with the 
corresponding inspection specified in 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.

    Issued in Renton, Washington, on April 29, 2004.
Kevin M. Mullin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 04-10433 Filed 5-6-04; 8:45 am]
BILLING CODE 4910-13-P