[Federal Register: May 7, 2004 (Volume 69, Number 89)]
[Proposed Rules]
[Page 25519-25521]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr07my04-18]
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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:
9-anm-nprmcomment@faa.gov. 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]
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