FR Doc E7-17284

[Federal Register: August 31, 2007 (Volume 72, Number 169)]
[Proposed Rules]
[Page 50282-50284]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr31au07-19]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-29065; Directorate Identifier 2007-NM-142-AD]
RIN 2120-AA64

Airworthiness Directives; Boeing Model 747 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 certain Boeing Model 747 airplanes. This proposed AD would require
inspecting the trunnion fork assembly of the wing landing gears to
determine the part number and serial number and to determine the
category of the trunnion fork assemblies. For certain airplanes, this
proposed AD also would require, if necessary, various inspections to
detect discrepancies of the trunnion fork assemblies, related
investigative/corrective actions, and a terminating action. This
proposed AD results from a report of a fractured trunnion fork
assembly. We are proposing this AD to prevent a fractured trunnion fork
assembly, which could result in the collapse of a wing landing gear on
the ground and possible damage to hydraulic equipment and the aileron
and spoiler cables. Such damage could result in reduced controllability
of the airplane.

DATES: We must receive comments on this proposed AD by October 15,
2007.

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 Airplanes, P.O. Box 3707, Seattle,
Washington 98124-2207, for the service information identified in this
proposed AD.

FOR FURTHER INFORMATION CONTACT: Berhane Alazar, Aerospace Engineer,
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office,
1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425)
917-6577; 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-
29065; Directorate Identifier 2007-NM-142-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.

[[Page 50283]]

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 level 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 a report indicating that a fractured trunnion fork
assembly was found during push back and tow of an airplane. Analysis
showed that a crack was initiated by fatigue on the inner surface and
eventually fractured by ductile rupture. The analysis also showed that
the crack most likely initiated as a result of two manufacturing
anomalies. A fractured trunnion fork assembly could result in the
collapse of a wing landing gear on the ground and possible damage to
hydraulic equipment and the aileron and spoiler cables. Such damage
could result in reduced controllability of the airplane.

Relevant Service Information

We have reviewed Boeing Alert Service Bulletin 747-32A2482, dated
June 14, 2007. The service information describes procedures for
inspecting the pad-up area on the forward upper inboard surface of the
trunnion fork assembly of both the left and right wing landing gears to
determine the part number and serial number and to determine the
category of the trunnion fork assemblies. For certain airplanes, the
service information describes the following procedures, as applicable:
Doing an initial detailed inspection for damage to the
protective finish and for corrosion of the trunnion fork assembly, and
an initial high frequency eddy current (HFEC) inspection to detect
cracks of the trunnion fork assembly (Part 2).
Doing an ultrasonic inspection to determine the wall
thickness in the area forward of the outer cylinder attach lugs in 8
zones, and a hardness measurement if the wall thickness is less than
the specified value (Part 3).
Doing related investigative/corrective actions if
necessary. The related investigative actions include repetitive
detailed and HFEC inspections (Part 2). The corrective actions include
overhauling the trunnion fork assembly (Part 4), and replacing the
trunnion fork assembly (Part 5); as applicable.
Replacing the trunnion fork assembly of the wing landing
gear with a certain trunnion fork assembly (Part 5). Accomplishing the
replacement ends the need for the actions specified in the service
information.
Accomplishing the actions specified in the service information is
intended to adequately address the unsafe condition. The compliance
time for the initial detailed, HFEC, and ultrasonic inspections and
replacement specified in the service information is either 18 months or
6 years, depending on the category of the trunnion fork assembly. The
compliance time for the related investigative/corrective actions
specified in the service information ranges between before further
flight and 10 years, depending on the condition of the trunnion fork
assembly.

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 service
information described previously.

Costs of Compliance

There are about 1,055 airplanes of the affected design in the
worldwide fleet. This proposed AD would affect about 215 airplanes of
U.S. registry. The proposed inspection for part number, serial number,
and category would take about 1 work hour per airplane, at an average
labor rate of $80 per work hour. Based on these figures, the estimated
cost of this inspection proposed by this AD for U.S. operators is
$17,200, or $80 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-2007-29065; Directorate Identifier 2007-NM-
142-AD.

Comments Due Date

(a) The FAA must receive comments on this AD action by October
15, 2007.

Affected ADs

(b) None.

Applicability

[[Page 50284]]

747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and
747SP series airplanes, certificated in any category; as identified
in Boeing Alert Service Bulletin 747-32A2482, dated June 14, 2007.

Unsafe Condition

(d) This AD results from a report of a fractured trunnion fork
assembly. We are issuing this AD to prevent a fractured trunnion
fork assembly, which could result in the collapse of a wing landing
gear on the ground and possible damage to hydraulic equipment and
the aileron and spoiler cables. Such damage could result in reduced
controllability 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

(f) The term ``service bulletin,'' as used in this AD, means
Boeing Alert Service Bulletin 747-32A2482, dated June 14, 2007.

Initial Inspection for Part Number, Serial Number, and Category

(g) Within 18 months after the effective date of this AD,
inspect the pad-up area on the forward upper inboard surface of the
trunnion fork assembly of both the left and right wing landing gears
to determine the part number and serial number and to determine the
category of the trunnion fork assemblies, in accordance with the
Accomplishment Instructions of the service bulletin.

Follow-On Actions for Category A, B, C, or D Trunnion Fork Assemblies

(h) If any part number and serial number identified as Category
A, B, C, or D in Tables 2 and 3 of paragraph 1.E., ``Compliance,''
of the service bulletin is found installed during the inspection
required by paragraph (g) of this AD: At the applicable compliance
time(s) listed in Table 4 or 5 of paragraph 1.E., ``Compliance,'' of
the service bulletin, except as provided by paragraph (i) of this
AD, do the applicable action(s) in Table 1 of this AD and applicable
related investigative/corrective actions, in accordance with the
Accomplishment Instructions of the service bulletin.

Table 1.--Requirements for Category A, B, C, or D Trunnion Fork Assemblies
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For-- Do-- And-- Or--
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(1) Categories A and D trunnion fork A detailed inspection An ultrasonic Do the terminating
assemblies. for damage to the inspection to action (Part 5).
protective finish and determine the wall
for corrosion of the thickness in the area
trunnion fork assembly forward of the outer
and a high frequency cylinder attach lugs
eddy current (HFEC) in 8 zones, and a
inspection to detect hardness measurement
cracks (Part 2). if applicable (Part 3).
(2) Categories B and C trunnion fork An ultrasonic None................... None.
assemblies. inspection to
determine the wall
thickness in the area
forward of the outer
cylinder attach lugs
in 8 zones, and a
hardness measurement
(Part 3).
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(i) Where paragraph 1.E., ``Compliance,'' of the service
bulletin specifies a compliance time after the date on the service
bulletin, this AD requires compliance within the specified
compliance time after the effective date of this AD.

Terminating Action

(j) Replacing the trunnion fork assembly of the wing landing
gear with a trunnion fork assembly identified in Part 5 of the
service bulletin, in accordance with and at the applicable time
specified in Table 4 or 5 of paragraph 1.E., ``Compliance,'' of the
service bulletin, constitutes terminating action for the
requirements of this AD for that side only.

Alternative Methods of Compliance (AMOCs)

(k)(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.

Issued in Renton, Washington, on August 17, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. E7-17284 Filed 8-30-07; 8:45 am]

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