[Federal Register: April 28, 2008 (Volume 73, Number 82)]
[Proposed Rules]
[Page 22845-22848]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr28ap08-18]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2008-0414; Directorate Identifier 2007-NM-095-AD]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 747-100, 747-100B, 747-
100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D,
747-400F, and 747SR Series Airplanes
AGENCY: Federal Aviation Administration (FAA), Department of
Transportation (DOT).
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: The FAA proposes to supersede an existing airworthiness
directive (AD) that applies to certain Boeing Model 747 series
airplanes. The existing AD currently requires repetitive inspections
for cracking and corrosion of all exposed surfaces of the carriage
spindles (including the inner bore and aft links) of the trailing edge
flaps, and additional inspection and corrective action if necessary.
The existing AD also requires repetitive overhaul of the carriage
spindle and aft link, which terminates the repetitive inspections. This
proposed AD would add a repetitive inspection to detect broken parts,
and revise the overhaul threshold and repetitive intervals. This
proposed AD results from analysis that showed additional inspections
should be done to prevent the loss of a flap, and that the flight-hour-
based interval should be revised to a flight-cycle-based interval,
because the greatest loads on the spindles happen during takeoff and
landing. We are proposing this AD to detect and correct failed carriage
spindles or aft links for the inboard or outboard trailing edge flaps.
Such failure could cause the flap to depart the airplane, reducing the
flightcrew's ability to maintain the safe flight and landing of the
airplane.
DATES: We must receive comments on this proposed AD by June 12, 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: Gary Oltman, Aerospace Engineer,
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office,
1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425)
917-6443; 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-2008-0414;
Directorate Identifier 2007-NM-095-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
On August 6, 1990, we issued AD 90-17-19, amendment 39-6705 (55 FR
33280, August 15, 1990), for all Boeing Model 747 series airplanes,
except the Model 747SP. That AD requires repetitive inspections for
cracking and corrosion of all exposed surfaces of the carriage spindles
(including the inner bore and aft links) of the trailing edge flaps,
and additional inspection and corrective action if necessary. The
existing AD also requires repetitive overhaul of the carriage spindle
and aft link, which terminates the repetitive inspections. That AD
resulted from a report of failure of two aft links in the spindles on
one flap, causing control problems during approach and landing. We
issued that AD to prevent failure of the trailing edge flaps' carriage
spindles, which could result in reduced controllability of the
airplane.
Actions Since Existing AD Was Issued
Since we issued AD 90-17-19, the manufacturer conducted a dynamic
aerodynamic analysis, which showed that the airplane might not have
[[Page 22846]]
sufficient roll authority to overcome loss of lift caused by a
departure of a single left- or right-hand inboard or outboard trailing
edge flap. The manufacturer then conducted a structural analysis of the
flap attach structure and fail-safe components, which showed that
additional inspections should be done to prevent the loss of a flap,
and that the flight-hour-based interval required by AD 90-17-19 should
be revised to a flight-cycle-based interval because the greatest loads
on the spindles happen during takeoff and landing and not during
flight.
Relevant Service Information
We have reviewed Boeing Service Bulletin 747-27-2280, Revision 6,
dated February 14, 2008. We referred to Boeing Service Bulletin 747-27-
2280, Revision 3, dated November 30, 1989, as the appropriate source of
service information for accomplishing the actions required by AD 90-17-
19. Revision 6 adds a repetitive inspection of all eight carriage
spindles and aft links to detect a broken carriage spindle or aft link,
and corrective action if necessary. The remaining procedures in
Revision 6 of the service bulletin are unchanged from Revision 3 of the
service bulletin. The corrective action is replacing the broken part
before further flight.
Revision 6 of the service bulletin also revises the overhaul
threshold and the repetitive overhaul interval as follows (AD 90-17-19
required the repetitive overhaul):
The initial overhaul threshold is the earlier of 8 years
or a specified number of flight cycles. The number of flight cycles is
either 6,000 or 9,000, depending on the airplane group specified in the
service bulletin and the type and location of carriage originally
installed.
The repetitive overhaul interval is also the earlier of 8
years or the same specified number of flight cycles based on the same
variables.
We have also reviewed Boeing Service Bulletin 747-27-2371, dated
December 20, 2000, which applies only to Group 1 and Group 3 airplanes
identified in Boeing Service Bulletin 747-27-2280, Revision 6. Boeing
Service Bulletin 747-27-2371 describes procedures for replacing the
link assemblies with new link assemblies made from improved corrosion-
resistant steel (CRES) that has a bearing race that is machined into
the link. Doing this replacement eliminates the need for the repetitive
overhauls specified in Boeing Service Bulletin 747-27-2280, Revision 6,
for that aft link only.
Accomplishing the actions specified in the service information is
intended to adequately address the unsafe condition.
FAA's Determination and Requirements of the Proposed AD
We have evaluated all pertinent information and identified an
unsafe condition that is likely to develop on other airplanes of the
same type design. For this reason, we are proposing this AD, which
would supersede AD 90-17-19 and would retain certain requirements of
the existing AD at revised intervals. This proposed AD would also
require a repetitive inspection to detect a broken carriage spindle or
broken aft link, and corrective action if necessary. The proposed AD
would also include, for certain airplanes, procedures for replacing the
link assemblies with new link assemblies made from improved CRES that
has a bearing race that is machined into the link, which would end the
need for the repetitive overhauls specified in Boeing Service Bulletin
747-27-2280, Revision 6, for that aft link only.
Changes to Existing AD
This proposed AD would retain certain requirements of AD 90-17-19.
Since AD 90-17-19 was issued, the AD format has been revised, and
certain paragraphs have been rearranged. As a result, the corresponding
paragraph identifiers have changed in this proposed AD, as listed in
the following table:
Revised Paragraph Identifiers
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Corresponding requirement
Requirement in AD 90-17-19 in this proposed AD
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paragraph A............................... paragraph (f).
paragraph A.1............................. paragraph (f).
paragraph A.2............................. paragraph (f)(1).
paragraph A.3............................. paragraph (f)(2).
paragraph A.4............................. paragraph (f)(3).
paragraph A.5............................. paragraph (f)(4).
paragraph B............................... paragraph (g).
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We have revised paragraph A.5. of AD 90-17-19 (paragraph (f)(4) of
this proposed AD) to allow any part of both carriage spindle/aft link
assemblies to be repaired according to data that conform to the
airplane's type certificate and that are approved by an Authorized
Representative for the Boeing Commercial Airplanes Delegation Option
Authorization Organization whom we have authorized to make such
findings.
In this proposed AD, the ``detailed visual inspection'' specified
in AD 90-17-19 is referred to as a ``detailed inspection.'' We have
included the definition for a detailed inspection in Note 1 of the
proposed AD. We have also included the definition of a general visual
inspection in Note 2 of this AD. That definition was not included in AD
90-17-19.
Costs of Compliance
There are about 925 airplanes of the affected design in the
worldwide fleet, which includes 160 airplanes of U.S. registry. The
following table provides the estimated costs for U.S. operators to
comply with this proposed AD. The average labor rate is $80 per work
hour.
Estimated Costs
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Action Work hours Parts Cost per airplane Fleet cost
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Inspection and overhaul (required Between 120 and 140, $0 Between $9,600 and Between $1,536,000
by AD 90-17-19). per flap per cycle. $11,200, per flap and $1,792,000, per
per overhaul cycle. flap per cycle.
Repetitive inspection for broken 2, per inspection 0 $160, per inspection $25,600, per
parts (new proposed action). cycle. cycle. inspection cycle.
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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
[[Page 22847]]
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 have 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 that the 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.
We prepared a regulatory evaluation of the estimated costs to
comply with this proposed AD and placed it in the AD docket. See the
ADDRESSES section for a location to examine the regulatory evaluation.
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 Federal Aviation Administration (FAA) amends Sec. 39.13 by
removing amendment 39-6705 (55 FR 33280, August 15, 1990) and adding
the following new airworthiness directive (AD):
Boeing: Docket No. FAA-2008-0414; Directorate Identifier 2007-NM-
095-AD.
Comments Due Date
(a) The FAA must receive comments on this AD action by June 12,
2008.
Affected ADs
(b) This AD supersedes AD 90-17-19.
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, and 747SR series airplanes, certificated in any category.
Unsafe Condition
(d) This AD results from analysis that showed that additional
inspections should be done to prevent the loss of a flap, and that
the flight-hour-based interval should be revised to a flight-cycle-
based interval, because the greatest loads on the spindles happen
during takeoff and landing. We are issuing this AD to detect and
correct failed carriage spindles or aft links for the inboard or
outboard trailing edge flaps. Such failure could cause the flap to
depart the airplane, reducing the flightcrew's ability to maintain
the safe flight and landing of the airplane.
Compliance
(e) You are responsible for having the actions required by this
AD performed within the compliance times specified, unless the
actions have already been done.
Requirements of AD 90-17-19
Repetitive Inspections
(f) For all airplanes except those airplanes on which the
repetitive overhauls required by paragraph B. of AD 90-17-19 are
being accomplished as of the effective date of this AD: Prior to the
accumulation of 30,000 flight hours or 8 years on each new or
previously overhauled flap carriage spindle, whichever occurs first,
remove the aft link and thrust collars from the trailing edge flaps'
carriage spindles and perform a detailed inspection of all exposed
surfaces of the carriage spindles, including inner bore, and aft
links to detect cracking and corrosion, in accordance with the
Accomplishment Instructions of Boeing Service Bulletin 747-27-2280,
Revision 3, dated November 30, 1989.
Note 1: 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
mirror, magnifying lenses, etc., may be necessary. Surface cleaning
and elaborate procedures may be required.''
(1) If no cracking or corrosion is found, repeat the inspections
required by paragraph (f) of this AD at intervals not to exceed 12
months until the carriage spindles are overhauled in accordance with
paragraph (g) of this AD.
(2) If a cracked carriage spindle or aft link is found, prior to
further flight, replace the part(s) in accordance with the service
bulletin.
(3) If corrosion is found on any part of the carriage spindle/
aft link assembly, but not on the other assembly on the same flap,
perform a repetitive general visual inspection in accordance with
the service bulletin at intervals not to exceed 2 months. Overhaul
or replace corroded parts in accordance with the service bulletin
within 36 months after detection of the corrosion.
(4) If corrosion is found on any part of both carriage spindle/
aft link assemblies on the same flap, prior to further flight,
overhaul or replace the part(s) in accordance with the service
bulletin or repair in accordance with the procedures specified in
paragraph (m) of this AD.
Note 2: For the purposes of this AD, a general visual inspection
is: ``A visual examination of an interior or exterior area,
installation, or assembly to detect obvious damage, failure, or
irregularity. This level of inspection is made from within touching
distance unless otherwise specified. A mirror may be necessary to
ensure visual access to all surfaces in the inspection area. This
level of inspection is made under normally available lighting
conditions such as daylight, hangar lighting, flashlight, or
droplight and may require removal or opening of access panels or
doors. Stands, ladders, or platforms may be required to gain
proximity to the area being checked.''
Initial and Repetitive Overhauls
(g) For all airplanes: Prior to the accumulation of 8 years or
30,000 flight hours on any new or previously overhauled flap
carriage spindle, whichever occurs later, remove the carriage
spindle and aft link, and overhaul in accordance with the
Accomplishment Instructions of Boeing Service Bulletin 747-27-2280,
Revision 3, dated November 30, 1989. Repeat the overhaul thereafter
at intervals not to exceed 8 years or 30,000 flight hours, whichever
occurs earlier. Accomplishment of initial overhaul required by this
paragraph terminates the requirements of paragraph (f) of this AD.
New Requirements of This AD
Terminating Requirements
(h) The actions specified in paragraphs (i) and (j) of this AD
must be accomplished in their entirety, at the specified compliance
times, to terminate the requirements of paragraphs (f) and (g) of
this AD. There is no terminating action for the requirements of
paragraphs (i) and (j) of this AD.
Repetitive Inspection for Broken Parts
(i) For all airplanes: Within 12 months or 400 flight cycles
after the effective date of this AD, whichever occurs earlier, do a
general visual inspection of all eight carriage spindles and aft
links to detect a broken carriage spindle or broken aft link, and do
all applicable corrective actions before further flight. Repeat the
inspection thereafter at intervals not to exceed 400 flight cycles.
Do all actions in accordance with the Accomplishment Instructions of
Boeing Service Bulletin 747-27-2280, Revision 6, dated February 14,
2008. For airplanes identified in Note (d) of Table 1 in paragraph
1.E., ``Compliance,'' of Boeing Service Bulletin 747-27-2280,
Revision 6, dated February 14, 2008, the initial compliance
[[Page 22848]]
time and repetitive interval for a flap may be extended to 1,000
flight cycles when new carriages are installed at both the inboard
and outboard carriage locations on the flap.
Repetitive Overhauls
(j) For all airplanes: At the later of the times specified in
paragraph (j)(1) or (j)(2) of this AD, remove the carriage spindle
and aft link, and overhaul in accordance with the Accomplishment
Instructions of Boeing Service Bulletin 747-27-2280, Revision 6,
dated February 14, 2008. Repeat the overhaul thereafter at the
applicable repeat interval specified in paragraph 1.E.,
``Compliance,'' of Boeing Service Bulletin 747-27-2280, Revision 6,
dated February 14, 2008.
(1) The applicable threshold specified in paragraph 1.E.
``Compliance,'' of Boeing Service Bulletin 747-27-2280, Revision 6,
dated February 14, 2008.
(2) Within 48 months after the effective date of this AD.
Optional Terminating Action
(k) For Groups 1 and 3 airplanes identified in Boeing Service
Bulletin 747-27-2280, Revision 6, dated February 14, 2008: Replacing
the existing 4340M aft link with a new corrosion resistant steel
(CRES) aft link in accordance with the Accomplishment Instructions
of Boeing Service Bulletin 747-27-2371, dated December 20, 2000,
terminates the repetitive inspection requirements of paragraph (f)
of this AD, and the repetitive overhaul requirements of paragraphs
(g) and (j) of this AD for that aft link only. The repetitive
inspections for broken parts required by paragraph (i) of this AD
cannot be terminated.
Credit for Previous Revision of Service Bulletin
(l) Actions done before the effective date of this AD in
accordance with Boeing Service Bulletin 747-27-2280, Revision 4,
dated April 26, 2001, are acceptable for compliance with the
corresponding requirements of paragraphs (f) and (g) of this AD.
Actions done before the effective date of this AD in accordance with
Boeing Service Bulletin 747-27-2280, Revision 5, dated April 5,
2007, are acceptable for compliance with the corresponding
requirements of paragraphs (i) and (j) of this AD.
Alternative Methods of Compliance (AMOCs)
(m)(1) The Manager, Seattle Aircraft Certification Office (ACO),
FAA, has the authority to approve AMOCs for this AD, if requested in
accordance with 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) AMOCs approved previously in accordance with AD 90-17-19 are
approved as AMOCs for the corresponding provisions of this AD.
(4) Adjustments to the compliance times approved previously in
accordance with AD 90-17-19 are not approved for the corresponding
provisions of this AD.
(5) 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 April 18, 2008.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. E8-9122 Filed 4-25-08; 8:45 am]
BILLING CODE 4910-13-P