[Federal Register: February 8, 2008 (Volume 73, Number 27)]
[Proposed Rules]
[Page 7486-7488]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr08fe08-15]
[[Page 7486]]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2008-0148; Directorate Identifier 2007-NM-299-AD]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 747 Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
-----------------------------------------------------------------------
SUMMARY: We propose to adopt a new airworthiness directive (AD) for all
Boeing Model 747 airplanes. This proposed AD would require a one-time
inspection of certain fuselage skins at section 41 to find any external
doublers that cover the inspection areas and to identify the external
doublers that end on a stringer and those that do not, and related
investigative and corrective actions if necessary. This proposed AD
results from reports of cracks found at fastener locations in the
fuselage skins at section 41. We are proposing this AD to detect and
correct fuselage skin cracks at fastener locations along the skin-to-
stringer attachments, which could join together and become large and
consequently result in rapid decompression of the cabin.
DATES: We must receive comments on this proposed AD by March 24, 2008.
ADDRESSES: You may send comments by any of the following methods:
Federal eRulemaking Portal: Go to http://www.regulations.gov.
Follow the instructions for submitting comments.
Fax: 202-493-2251.
Mail: U.S. Department of Transportation, Docket
Operations, M-30, West Building, Ground Floor, Room W12-140, 1200 New
Jersey Avenue, SE., Washington, DC 20590.
Hand Delivery: U.S. Department of Transportation, Docket
Operations, M-30, West Building, Ground Floor, Room W12-140, 1200 New
Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m.,
Monday through Friday, except Federal holidays.
For service information identified in this AD, contact Boeing
Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.
Examining the AD Docket
You may examine the AD docket on the Internet at http://www.regulations.gov
; or in person at the Docket Management Facility
between 9 a.m. and 5 p.m., Monday through Friday, except Federal
holidays. The AD docket contains this proposed AD, the regulatory
evaluation, any comments received, and other information. The street
address for the Docket Office (telephone 800-647-5527) is in the
ADDRESSES section. Comments will be available in the AD docket shortly
after receipt.
FOR FURTHER INFORMATION CONTACT: Ivan Li, Aerospace Engineer, Airframe
Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind
Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-6437;
fax (425) 917-6590.
SUPPLEMENTARY INFORMATION:
Comments Invited
We invite you to send any written relevant data, views, or
arguments about this proposed AD. Send your comments to an address
listed under the ADDRESSES section. Include ``Docket No. FAA-2008-0148;
Directorate Identifier 2007-NM-299-AD'' at the beginning of your
comments. We specifically invite comments on the overall regulatory,
economic, environmental, and energy aspects of this proposed AD. We
will consider all comments received by the closing date and may amend
this proposed AD because of those comments.
We will post all comments we receive, without change, to http://www.regulations.gov
, including any personal information you provide. We
will also post a report summarizing each substantive verbal contact we
receive about this proposed AD.
Discussion
We have received two reports of cracks found at fastener locations
in the fuselage skins at section 41. One operator reported finding skin
cracks at a fastener location at stringer 5 (S-5) near station (STA)
365, on a Model 747-200F series airplane. These cracks were found
during incorporation of the skin modification specified in Boeing
Service Bulletin 747-53-2272. The cracks were 0.25 inch long and
located on the forward and aft side of the fastener hole. The airplane
had accumulated 13,726 total flight cycles. In the other report,
multiple skin cracks were found during Boeing Model 747-400 series
airplane fatigue testing. That test article had accumulated 40,000 test
cycles. The cracks were found at locations where there are no internal
doublers, at stringers 10 and 13, and between STA 260 and STA 300.
Fuselage skin cracks at fastener locations along the skin-to-stringer
attachments, if not corrected, could join together and become large and
consequently result in rapid decompression of the cabin.
Relevant Service Information
We have reviewed Boeing Alert Service Bulletin 747-53A2704, dated
October 4, 2007. The service bulletin describes procedures for doing a
one-time general visual inspection of certain fuselage skins at section
41 to find any external doublers that cover the inspection area and to
identify the external doublers that end on a stringer and those that do
not; and related investigative and corrective actions if necessary. The
related investigative actions include the following:
Removing any external doubler and doing a one-time
detailed inspection and an open-hole high frequency eddy current (HFEC)
inspection for any crack in the skin at the skin-to-stringer
attachments, for an inspection area where the skin-to-stringer
attachment is covered by an external doubler that ends on a stringer in
the inspection area.
Doing repetitive external HFEC inspections for any crack
in the skin at the skin-to-stringer attachments, for an inspection area
where the skin-to-stringer attachment is not covered by an external
doubler.
For the one-time general visual inspection, one-time detailed
inspection, one-time open-hole HFEC inspection, and the initial
external HFEC inspection, the service bulletin specifies a compliance
time of 16,000 or 25,000 total flight cycles depending on the airplane
configuration, or 2,000 flight cycles after the date on the service
bulletin, whichever occurs later. The service bulletin also specifies
that if a skin panel was replaced, the inspection threshold for the
affected area can be calculated from the time it was replaced. For the
repetitive external HFEC inspections, the service bulletin specifies a
repeat interval of 3,000 flight cycles.
The corrective actions include repairing any crack found in an
inspection area, and installing a new external doubler where any
external doubler has been removed from the inspection area. The service
bulletin specifies accomplishing the corrective actions before further
flight.
FAA's Determination and Requirements of This Proposed AD
We are proposing this AD because we evaluated all relevant
information and determined the unsafe condition described previously is
likely to exist or develop in other products of the(se) same type
design(s). This proposed AD would require accomplishing the actions
specified in the service
[[Page 7487]]
information described previously, except as discussed under
``Differences Between the Proposed AD and Service Bulletin.''
Differences Between Proposed AD and Service Bulletin
Although Figure 19 of the service bulletin specifies doing a
``detailed visual inspection'' of the fastener holes, this proposed AD
would require doing a ``detailed inspection.''
This proposed AD expands the inspection area at certain skin-to-
stringer attachments. In Figure 3 of the service bulletin, S-5 and S-5A
from STA 340 to STA 360 should be bold in the illustration to include
those areas as part of the recommended inspection (similar to Figure 8
for the right side). Also, in Figure 15 of the service bulletin, S-14A
from STA 200 to STA 220 should be bold in the illustration to include
that area as part of the recommended inspection (similar to Figure 17
for the right side). Boeing is aware of these discrepancies, concurs
with the changes, and has issued Information Notice (IN) 747-53A2704 IN
01, dated December 19, 2007, to inform operators of the errors. We have
included this information in paragraph (g) of this proposed AD.
Clarification of Proposed Requirements
The service bulletin notes that, at locations where external
doublers exist that do not end on a stringer in the inspection area,
repetitive inspections of the skin for cracking at critical rows of
fasteners are required in accordance with Boeing Document Number D6-
36181, ``Repair Assessment Guidelines--Model 747.'' These inspections
would not be required by this AD, since compliance is already required
by sections 91.410, 121.370, 125.248, and 129.32 of the Federal
Aviation Regulations (14 CFR 91.410, 121.370, 125.248, and 129.32).
Costs of Compliance
We estimate that this proposed AD would affect 165 airplanes of
U.S. registry. We also estimate that it would take up to 64 work-hours
per product to comply with this proposed AD. The average labor rate is
$80 per work-hour. Based on these figures, we estimate the cost of this
proposed AD to the U.S. operators to be $844,800 or $5,120 per product.
Authority for This Rulemaking
Title 49 of the United States Code specifies the FAA's authority to
issue rules on aviation safety. 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.
We are issuing this rulemaking under the authority described in
``Subtitle VII, Part A, Subpart III, Section 44701: General
requirements.'' Under that section, Congress charges the FAA 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
rulemaking action.
Regulatory Findings
We determined that this proposed AD would not have federalism
implications under Executive Order 13132. This proposed AD 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.
For the reasons discussed above, I certify 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 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.
You can find our regulatory evaluation and the estimated costs of
compliance in the AD Docket.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Safety.
The Proposed Amendment
Accordingly, under the authority delegated to me by the
Administrator, the FAA proposes to amend 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. The FAA amends Sec. 39.13 by adding the following new AD:
Boeing: Docket No. FAA-2008-0148; Directorate Identifier 2007-NM-
299-AD.
Comments Due Date
(a) We must receive comments by March 24, 2008.
Affected ADs
(b) None.
Applicability
(c) This AD applies to all Boeing Model 747-100, 747-100B, 747-
100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D,
747-400F, 747SR, and 747SP series airplanes, certificated in any
category.
Unsafe Condition
(d) This AD results from reports of cracks found at fastener
locations in the fuselage skins at section 41. We are issuing this
AD to detect and correct fuselage skin cracks at fastener locations
along the skin-to-stringer attachments, which could join together
and become large and consequently result in rapid decompression of
the cabin.
Compliance
(e) Comply with this AD within the compliance times specified,
unless already done.
Repetitive Inspections and Related Investigative/Corrective Actions
(f) At the applicable compliance times specified in Tables 1 and
2 of paragraph 1.E. of Boeing Alert Service Bulletin 747-53A2704,
dated October 4, 2007: Do a general visual inspection of the
fuselage skins at section 41 to find any external doublers that
cover the inspection area and to identify the external doublers that
end on a stringer in the inspection area and those that do not, and
do all the related investigative and corrective actions as
applicable, by accomplishing all of the applicable actions specified
in the Accomplishment Instructions of the service bulletin, except
as provided by paragraph (g) of this AD. Repeat the related
investigative actions thereafter at the interval specified in Tables
1 and 2 of the service bulletin, as applicable.
Exceptions to the Service Bulletin
(g) Where Tables 1 and 2 of paragraph 1.E. of Boeing Alert
Service Bulletin 747-53A2704, dated October 4, 2007, specify
counting the compliance time from ``* * * after the date on this
service bulletin,'' this AD requires counting the compliance time
from the effective date of this AD. Where Figure 19 of the service
bulletin specifies doing a ``detailed visual inspection'' for any
crack at fastener holes common to the stringer, this AD would
require doing a detailed inspection. In Figure 3 of the service
bulletin, also inspect the areas at stringer 5 (S-5) and S-5A
between station (STA) 340 and STA 360 (similar to Figure 8 for the
right side). In Figure 15 of the service bulletin, also inspect the
area at S-14A between STA 200 and STA 220 (similar to Figure 17 for
the right side).
Alternative Methods of Compliance (AMOCs)
(h)(1) The Manager, Seattle Aircraft Certification Office, FAA,
ATTN: Ivan Li, Aerospace Engineer, Airframe Branch, ANM-120S, 1601
Lind Avenue, SW., Renton,
[[Page 7488]]
Washington 98057-3356; telephone (425) 917-6437; fax (425) 917-6590;
has the authority to approve AMOCs for this AD, if requested using
the procedures found in 14 CFR 39.19.
(2) To request a different method of compliance or a different
compliance time for this AD, follow the procedures in 14 CFR 39.19.
Before using any approved AMOC on any airplane to which the AMOC
applies, notify your appropriate principal inspector (PI) in the FAA
Flight Standards District Office (FSDO), or lacking a PI, your local
FSDO.
(3) An AMOC that provides an acceptable level of safety may be
used for any repair required by this AD, if it is approved by an
Authorized Representative for the Boeing Commercial Airplanes
Delegation Option Authorization Organization who has been authorized
by the Manager, Seattle ACO, to make those findings. For a repair
method to be approved, the repair must meet the certification basis
of the airplane, and the approval must specifically refer to this
AD.
Issued in Renton, Washington, on January 31, 2008.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. E8-2352 Filed 2-7-08; 8:45 am]
BILLING CODE 4910-13-P