[Federal Register: August 31, 2007 (Volume 72, Number 169)]
[Proposed Rules]
[Page 50278-50282]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr31au07-18]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2007-29062; Directorate Identifier 2007-NM-020-AD]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 737-100, -200, -200C, -
300, -400, and -500 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 adopt a new airworthiness directive (AD)
for all Boeing Model 737-100, -200, -200C, -300, -400, and -500 series
airplanes. For certain airplanes, this proposed AD would require
replacing the outboard stabilizing fitting and certain adjacent
components of the main landing gear (MLG) support beam. This proposed
AD would also require repetitive inspections for discrepancies of the
outboard stabilizing fitting, walking beam hanger, and rear spar
attachment, and corrective actions if necessary. For certain airplanes,
this proposed AD would provide an alternative one-time inspection of
the outboard stabilizing fitting for discrepancies and corrective
actions if necessary, which would extend the compliance time for the
replacement of the outboard stabilizing fitting. For certain other
airplanes, this proposed AD would also require performing a torque
check of the aft pin of the outboard stabilizing fitting, and
corrective actions if necessary. This proposed AD results from reports
of findings of fatigue cracking of the outboard stabilizing fitting and
stress corrosion cracking of the bolts attaching the fitting to the
wing rear spar. We are proposing this AD to detect and correct that
cracking, which could result in disconnection of the MLG actuator from
the rear spar and support beam, and consequent damage to the hydraulic
system causing hydraulic fluid leakage and loss of control of the
airplane.
DATES: We must receive comments on this proposed AD by October 15,
2007.
[[Page 50279]]
ADDRESSES: Use one of the following addresses to submit comments on
this proposed AD.
DOT Docket Web site: Go to http://dms.dot.gov and follow
the instructions for sending your comments electronically.
Government-wide rulemaking Web site: Go to http://
www.regulations.gov and follow the instructions for sending your
comments electronically.
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.
Fax: (202) 493-2251.
Hand Delivery: Room W12-140 on the ground floor of the
West Building, 1200 New Jersey Avenue, SE., Washington, DC, between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
Contact Boeing Commercial Airplane Group, P.O. Box 3707, Seattle,
Washington 98124-2207, for the service information identified in this
proposed AD.
FOR FURTHER INFORMATION CONTACT: Nancy Marsh, Aerospace Engineer,
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office,
1601 Lind Avenue SW., Renton, Washington 98055-4056; telephone (425)
917-6440; fax (425) 917-6590.
SUPPLEMENTARY INFORMATION:
Comments Invited
We invite you to submit any relevant written data, views, or
arguments regarding this proposed AD. Send your comments to an address
listed in the ADDRESSES section. Include the docket number ``FAA-2007-
29062; Directorate Identifier 2007-NM-020-AD'' at the beginning of your
comments. We specifically invite comments on the overall regulatory,
economic, environmental, and energy aspects of the proposed AD. We will
consider all comments received by the closing date and may amend the
proposed AD in light of those comments.
We will post all comments we receive, without change, to http://
dms.dot.gov, including any personal information you provide. We will
also post a report summarizing each substantive verbal contact with FAA
personnel concerning this proposed AD. Using the search function of
that Web site, anyone can find and read the comments in any of our
dockets, including the name of the individual who sent the comment (or
signed the comment on behalf of an association, business, labor union,
etc.). You may review DOT's complete Privacy Act Statement in the
Federal Register published on April 11, 2000 (65 FR 19477-78), or you
may visit http://dms.dot.gov.
Examining the Docket
You may examine the AD docket on the Internet at http://
dms.dot.gov, or in person at the Docket Operations office between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays. The
Docket Operations office (telephone (800) 647-5527) is located on the
ground floor of the West Building at the DOT street address stated in
the ADDRESSES section. Comments will be available in the AD docket
shortly after the Docket Management System receives them.
Discussion
We have received several reports indicating findings of fatigue
cracking of the outboard stabilizing fitting and stress corrosion
cracking of the bolts attaching the fitting to the wing rear spar and
certain adjacent components of the main landing gear (MLG) support beam
on Boeing Model 737-100, -200, -200C, -300, -400, and -500 series
airplanes. Those reports include the following: Cracking of the
outboard stabilizing fitting attributed to fatigue, loose or missing
forward pins that attach the stabilizing fitting to the stud assembly;
a fractured aft pin that attaches the tube assembly to the aft
stabilizing fitting, and fractured H-11 bolts that attach the inboard
and outboard stabilizing fittings to the wing rear spar. These failures
could result in disconnection of the MLG actuator from the rear spar
and support beam, and consequent damage to the hydraulic system fluid
supply tube causing hydraulic fluid leakage and loss of control of the
airplane.
Other Relevant Rulemaking
On December 30, 1998, we issued AD 98-11-04 R1, amendment 39-10984
(64 FR 987, January 7, 1999), for all Boeing Model 737-100 and -200
series airplanes. That AD supersedes AD 91-14-20 to continue to require
that the FAA-approved maintenance program be revised to include
inspections that will give no less than the required damage tolerance
rating for each Structural Significant Item (SSI). AD 98-11-04 R1 also
requires additional and expanded inspections, and repair of cracked
structure. That AD was prompted by a structural re-evaluation by the
manufacturer which identified additional structural elements where, if
damage were to occur, supplemental inspections may be required for
timely detection. We issued that AD to ensure the continued structural
integrity of the Boeing Model 737-100 and -200 fleet.
Relevant Service Information
We have reviewed Boeing Alert Service Bulletin 737-57A1266,
Revision 1, dated January 3, 2007. For certain airplanes, the service
bulletin describes procedures for replacing the outboard stabilizing
fitting and certain adjacent components of the MLG support beam. The
replacement procedures and configuration group to which the airplane
belongs, are as follows.
For airplanes identified in the service bulletin as Groups
1, 2, 3, 4, and 5, the procedures describe replacing the outboard
stabilizing fitting with a new titanium fitting and replacing the H-11
bolts that attach the fitting to the wing rear spar with new Inconel
718 bolts. In addition, the procedures describe replacing the aft pin
that attaches the tube assembly to the aft outboard stabilizing fitting
with a titanium bolt, replacing the forward pin, and replacing the H-11
bolts for the inboard stabilizing fitting with new Inconel 718 bolts.
As part of the replacement of the H-11 bolts, the service bulletin
recommends contacting Boeing if corrosion damage is found which cannot
be removed. The service bulletin also recommends prior or concurrent
accomplishment of Part IV of Boeing Service Bulletin 737-57-1052,
Revision 4, dated October 24, 1980, for Group 1 and 3 airplanes. Part
IV describes procedures for replacing the existing tube assembly of the
MLG support beam with a new assembly. For airplanes that had the aft
pin of the aft outboard stabilizing fitting replaced per Boeing Alert
Service Bulletin 737-57A1266, dated May 8, 2003, the procedures specify
performing a torque check of the aft pin of the aft outboard
stabilizing fitting and corrective actions if necessary. If the torque
is greater than 570 in. lbs., the corrective action is replacing the
aft pin and aft outboard stabilizing fitting. If the torque is less
than 570 in. lbs., the corrective action is replacing the aft pin.
For airplanes identified in the service bulletin as Groups
6 and 7, the procedures describe replacing the outboard stabilizing
fitting with a titanium fitting and replacing the H-11 bolts that
attach the fitting to the wing rear spar with new Inconel 718 bolts. In
addition, the procedures describe replacing the forward pin that
attaches the stud assembly to the outboard stabilizing fitting with a
titanium pin. The procedures also describe replacing the H-11 bolts for
the inboard stabilizing fitting with new Inconel 718 bolts for Group 6
only.
[[Page 50280]]
For airplanes identified in the service bulletin as Group
8, the procedures describe replacing the outboard stabilizing fitting
with a titanium fitting, and replacing the forward pin that attaches
the stud assembly to the outboard stabilizing fitting with new
components.
For airplanes identified in the service bulletin as Group
9, the procedures describe doing a general visual inspection of the
outboard stabilizing fitting and fasteners for discrepancies, and
corrective actions if necessary. The corrective action is contacting
Boeing if any discrepancies are found.
For airplanes identified in the service bulletin as Group 8, and
Groups 1 through 7 on which the existing H-11 bolts were previously
replaced with Inconel 718 bolts, the procedures describe an alternative
magnetic test of the attach bolts to determine if inspections could be
done that may extend the compliance time for the replacement of the
outboard stabilizing fitting. If any bolt is magnetic, do not do the
alternative inspection. If none of the bolts are magnetic, do a one-
time general visual inspection of the stabilizing fitting for
discrepancies (damage, failure, or irregularity), and a high frequency
eddy current (HFEC) inspection for cracking of the fitting inboard and
outboard lug faces, the fillet radii, and the fitting lug hole, and
verify the fitting hole is within limits, and corrective actions if
necessary. Performing the alternative inspection extends the compliance
time from 36 to 60 months for replacing the fitting if no cracking is
found.
The corrective actions for the alternative inspections are as
follows:
If cracking is found during the alternative inspection,
the service bulletin specifies doing the replacement of the fitting as
specified in Part II of the service bulletin. If no cracking is found,
the service bulletin specifies doing an installation of replacement
bushings and reaming the bushing holes to final size, replacing the
forward pin, and for Groups 1 through 5, replacing the aft pin. If any
other damage is found or if the fitting hole is beyond the hole size
limits, the service bulletin recommends contacting Boeing for repair
instructions.
For all airplanes, the service bulletin describes procedures for
repetitive inspections for discrepancies of the outboard stabilizing
fitting, walking beam hanger, and rear spar attachment fitting, and
corrective actions if necessary. The corrective action is contacting
Boeing if any discrepancies are found.
Service Bulletin 737-57A1266 refers to the following service
bulletins as acceptable sources of service information:
Boeing Service Bulletin 737-57-1231, dated December 1, 1994, is an
acceptable source of service information for accomplishment of the
replacement of the H-11 attachment bolts of the inboard stabilizing
fitting with new components for some airplane groups.
Boeing Service Bulletin 737-57-1073, Revision 4, dated April 12,
1985, is an acceptable source of service information for previous
accomplishment of the replacement of the MLG support beam.
We have determined that accomplishment of the actions specified in
Service Bulletin 737-57A1266 will 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 exist or develop on other airplanes
of this same type design. For this reason, we are proposing this AD,
which would require accomplishing the actions specified in the Boeing
Alert Service Bulletin 737-57A1266, Revision 1, except as discussed
under ``Differences Between the Proposed AD and Alert Service Bulletin
737-57A1266.''
Differences Between the Proposed AD and Alert Service Bulletin 737-
57A1266
For airplanes identified in the service bulletin as Groups 1
through 5 on which the aft pin of the outboard stabilizing fitting has
been replaced in accordance with the original issue of the service
bulletin: The service bulletin recommends accomplishing the torque
check of the aft pin within 36 months after the original issue date of
the service bulletin, and, if the aft pin does not pass the torque
check, replacing the aft pin and aft outboard stabilizing fitting
within an additional 36 months after the torque check. However, we have
determined that interval would not address the identified unsafe
condition soon enough to ensure an adequate level of safety for the
affected fleet. We find that a compliance time of within 36 months
after accomplishing the replacement, or 36 months after the effective
date of this AD, whichever is later, for doing the torque check and
doing all applicable corrective actions before further flight,
represents an appropriate interval of time for affected airplanes to
continue to operate without compromising safety. This difference has
been coordinated with the manufacturer.
Certain sections in Parts I, II, and V of the Accomplishment
Instructions of the service bulletin specify ``For 737-100 and -200
airplanes'' and ``For 737-300 and -500 airplanes.'' Those sections are
applicable to Model 737-100, -200, and -200C airplanes, and Model 737-
300, -400, and -500 airplanes, respectively. Model 737-200C and -400
airplanes were inadvertently excluded from those sections.
The service bulletin also specifies to contact the manufacturer for
instructions on how to repair certain conditions, but this proposed AD
would require repairing those conditions in one of the following ways:
Using a method that we approve; or
Using data that meet the certification basis of the
airplane, and that have been approved by an Authorized Representative
for the Boeing Commercial Airplanes Delegation Option Authorization
Organization whom we have authorized to make those findings.
Costs of Compliance
There are about 3,130 airplanes of the affected design in the
worldwide fleet. This proposed AD would affect about 1,380 airplanes of
U.S. registry.
For all airplanes: The proposed replacement would take between 20
and 24 work hours per airplane to do, depending on the airplane's
configuration, at an average labor rate of $80 per work hour. Required
parts would cost between $3,658 and $4,272 per airplane, depending on
the airplane's configuration. Based on these figures, the estimated
cost of the proposed replacement is estimated to be up to between
$7,256,040 and $8,544,960, or between $5,258 and $6,192 per airplane,
depending on the airplane's configuration.
For Groups 1 through 8 airplanes: The alternative inspection, if
done, would take about 12 work hours per airplane to do, at an average
labor rate of $80 per work hour. Based on these figures, the estimated
cost of the alternative inspection is estimated to be up to $1,324,800,
or $960 per airplane.
For Group 9 airplanes: The general visual inspection would take
about 2 work hours per airplane to do, at an average labor rate of $80
per work hour. Based on these figures, the estimated cost of the
general visual inspection is estimated to be up to $220,800, or $160
per airplane.
For Groups 1 through 5 airplanes that had steel pins replaced per
the original issue of the service bulletin: The torque check would take
about 7 work hours
[[Page 50281]]
per airplane to do, at an average labor rate of $80 per work hour.
Based on these figures, the estimated cost of the torque check is
estimated to be up to $772,800, or $560 per airplane.
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 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
adding the following new airworthiness directive (AD):
Boeing: Docket No. FAA-2007-29062; Directorate Identifier 2007-NM-
020-AD.
Comments Due Date
(a) The FAA must receive comments on this AD action by October
15, 2007.
Affected ADs
(b) None.
Applicability
(c) This AD applies to all Model 737-100, -200, -200C, -300, -
400, and -500 series airplanes, certificated in any category.
Unsafe Condition
(d) This AD results from reports of findings of fatigue cracking
of the outboard stabilizing fitting and stress corrosion cracking of
the bolts attaching the fitting to the wing rear spar. We are
issuing this AD to detect and correct that cracking, which could
result in disconnection of the main landing gear (MLG) actuator from
the rear spar and support beam, and consequent damage to the
hydraulic system causing hydraulic fluid leakage and loss of control
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.
Service Bulletin Reference
(f) The term ``alert service bulletin'' as used in this AD,
means the Accomplishment Instructions of Boeing Alert Service
Bulletin 737-57A1266, Revision 1, dated January 3, 2007.
Replacement/Repetitive Inspections
(g) For airplanes identified as Groups 1 through 8, as specified
in the alert service bulletin, except as provided by paragraphs (h)
and (k) of this AD: Within 36 months after the effective date of
this AD, replace the outboard stabilizing fitting, H-11 bolts,
forward pin, and aft pin, as applicable, with new components by
doing all the applicable actions in accordance with Part II of the
alert service bulletin, except as provided by paragraph (j) of this
AD. Within 120 months after accomplishing the replacement, do a
general visual inspection for discrepancies of the outboard
stabilizing fitting, walking beam hanger, and rear spar attachment
fitting, and do all applicable corrective actions, by doing all the
actions, except as provided by paragraph (j) of this AD, in
accordance with Part V of the alert service bulletin. Do all
corrective actions before further flight. Repeat the inspection at
intervals not to exceed 120 months.
Alternative Inspection
(h) For airplanes identified as Groups 1 through 8, as specified
in the alert service bulletin, on which the existing H-11 bolts were
replaced before the effective date of this AD with Inconel 718
bolts, in lieu of doing the actions required by paragraph (g) of
this AD: Within 4,500 flight cycles or 36 months after the effective
date of this AD, whichever is later, do a magnetic test of the
attach bolts in accordance with the alert service bulletin. If any
bolt is magnetic, discontinue the alternative inspection specified
in the alert service bulletin and accomplish the actions required by
paragraph (g) before further flight. If none of the bolts are
magnetic, do all the applicable actions in accordance with Part I of
the alert service bulletin before further flight.
(1) If any crack is found: Stop the inspection and before
further flight do the actions required by paragraph (g) of this AD.
Repetitive inspections must be done after replacing the fitting at
the interval specified in paragraph (g) of this AD.
(2) If no crack is found: Before further flight, replace the
forward pin and aft pin, as applicable, in accordance with the alert
service bulletin, and within 60 months after the effective date of
this AD, do the remaining replacement required by paragraph (g) of
this AD. Repetitive inspections must be done after replacing the
fitting at the interval specified in paragraph (g) of this AD.
(3) If damage other than cracking is found, or if the fitting
lug hole is beyond hole size limits, before further flight, repair
using a method approved in accordance with the procedures specified
in paragraph (p) of this AD.
General Visual Inspection
(i) For airplanes identified as Group 9, as specified in the
alert service bulletin: Within 36 months or 4,500 flight cycles
after the effective date of this AD, whichever occurs later, do a
general visual inspection of the outboard stabilizing fitting and
fasteners for discrepancies, and do all applicable corrective
actions in accordance with Part IV of the alert service bulletin,
except as provided by paragraphs (j) and (k) of this AD. Within 120
months after the inspection specified in Part IV has been done, do a
general visual inspection for discrepancies of the outboard
stabilizing fitting, walking beam hanger and rear spar attachment
fitting in accordance with Part V of the alert service bulletin, and
do all applicable corrective actions in accordance with Part V of
the alert service bulletin, except as provided by paragraphs (j) and
(k). Do all applicable corrective actions before further flight.
Repeat the Part V inspection at intervals not to exceed 120 months.
Exceptions to Alert Service Bulletin Specifications
(j) During any inspection required by this AD, if any corrosion
damage is found that cannot be removed, or if any damage is found
[[Page 50282]]
that is outside the limits specified in the alert service bulletin,
or if any discrepancy is found and the alert service bulletin
specifies contacting the manufacturer for disposition of certain
repair conditions: Before further flight, repair using a method
approved in accordance with the procedures specified in paragraph
(p) of this AD.
(k) Certain sections in Parts I, II, and V of the Accomplishment
Instructions of the alert service bulletin specify ``For 737-100 and
-200 airplanes'' and ``For 737-300 and -500 airplanes.'' However,
those sections are applicable to Model 737-100, -200, and -200C
airplanes, and Model 737-300, -400, and -500 airplanes,
respectively.
Torque Check
(l) For airplanes identified as Groups 1 through 5, as specified
in the alert service bulletin, on which the aft pin of the aft
outboard stabilizing fitting was replaced before the effective date
of this AD, in accordance with Boeing Alert Service Bulletin 737-
57A1266, dated May 8, 2003: Within 36 months after the effective
date of this AD, do a torque check to determine whether the aft pin
is correctly installed. Do all applicable corrective actions before
further flight. Do the actions in accordance with Part III of the
alert service bulletin.
Concurrent Requirements
(m) For airplanes identified as Groups 1 and 3, as specified in
the alert service bulletin: Prior to or concurrently with
accomplishment of paragraph (g) of this AD, do the replacement of
the existing tube assembly of the outboard stabilizing fitting as
specified in Part IV of Boeing Service Bulletin 737-57-1052,
Revision 4, dated October 24, 1980.
Credit for Previously Accomplished Actions
(n) Replacement of the tube assembly before the effective date
of this AD in accordance with Boeing Service Bulletin 737-57-1073,
Revision 4, dated April 12, 1985, is acceptable for compliance with
the replacement specified in paragraph (l) of this AD.
(o) For Groups 1 through 4, as specified in the alert service
bulletin: Replacement of the H-11 bolts for the inboard stabilizing
fitting before the effective date of this AD, in accordance with
Boeing Service Bulletin 737-57-1231 dated December 1, 1994, is
acceptable for compliance with the replacement specified in
paragraph (g) of this AD.
Alternative Methods of Compliance (AMOCs)
(p)(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) 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 August 17, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. E7-17290 Filed 8-30-07; 8:45 am]
BILLING CODE 4910-13-P