Document ID: FAA-2007-29065-0010
Agency: faa
Document Type: Rule
Title: Airworthiness Directives; Boeing Model 747 Airplanes
Posted Date: 2008-04-22T04:00Z

[Federal Register: April 22, 2008 (Volume 73, Number 78)]
[Rules and Regulations]               
[Page 21521-21523]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr22ap08-2]                         

[[Page 21521]]

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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; 
Amendment 39-15486; AD 2008-09-05]
RIN 2120-AA64

 
Airworthiness Directives; Boeing Model 747 Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: We are adopting a new airworthiness directive (AD) for certain 
Boeing Model 747 airplanes. This AD requires 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 AD also requires, if necessary, 
various inspections to detect discrepancies of the trunnion fork 
assemblies, related investigative/corrective actions, and a terminating 
action. 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.

DATES: This AD is effective May 27, 2008.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of May 27, 
2008.

ADDRESSES: 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 AD, the regulatory evaluation, 
any comments received, and other information. The address for the 
Docket Office (telephone 800-647-5527) is the Document Management 
Facility, U.S. Department of Transportation, Docket Operations, M-30, 
West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., 
Washington, DC 20590.

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:

Discussion

    We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR 
part 39 to include an airworthiness directive (AD) that would apply to 
certain Boeing Model 747 airplanes. That NPRM was published in the 
Federal Register on August 31, 2007 (72 FR 50282). That NPRM proposed 
to 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, 
that NPRM also proposed to require, if necessary, various inspections 
to detect discrepancies of the trunnion fork assemblies, related 
investigative/corrective actions, and a terminating action.

Comments

    We gave the public the opportunity to participate in developing 
this AD. We considered the comments received from the three commenters.

Request To Revise Initial Compliance Time

    Boeing requests that the compliance time specified in paragraph (g) 
of the NPRM be revised from 18 months to either 18 months or within 18 
months after the date of issuance of the original Standard Certificate 
of Airworthiness or the original Export Certificate of Airworthiness, 
whichever occurs later. Boeing states that operators of airplanes 
delivered more than 18 months after the effective date of the AD will 
be unable to comply with the requirements of paragraph (g) of the NPRM.
    We do not agree. We have confirmed with Boeing that affected 
airplanes currently in production are compliant with the requirements 
of this AD. Therefore, for affected airplanes delivered after the 
effective date of the AD, no additional time will be necessary to 
comply with the requirements of paragraph (g) of this AD. We have made 
no change to the compliance time specified in paragraph (g) of this AD 
in this regard.

Requests To Allow Review of Maintenance or Delivery Records

    Boeing and Lufthansa request that, for clarification purposes, 
paragraph (g) of the NPRM be revised to allow review of maintenance or 
delivery records instead of doing the proposed inspection. The 
commenters note that such an alternative is specified in paragraphs 3. 
and 4. of Part 1 of the Accomplishment Instructions of Boeing Alert 
Service Bulletin 747-32A2482. Boeing notes that we have included a 
similar provision in other ADs.
    We agree with the commenters to clarify paragraph (g) of this AD. 
It was our intent that either the inspection or record review be done 
in accordance with the Accomplishment Instructions of Boeing Alert 
Service Bulletin 747-32A2482. Therefore, we have revised paragraph (g) 
of the AD accordingly.

Request To Allow a Magnetic-Particle Inspection

    Boeing requests that we allow a magnetic-particle inspection in 
accordance with Boeing Standard Operating Procedure Manual 20-20-01 as 
an alternative to the high frequency eddy current inspection required 
by paragraph (h)(1) of the NPRM. Boeing states that it intended the 
HFEC inspection to be done ``in-situ'' by the operators. Boeing also 
states that one operator intends to remove the trunnion forks from the 
airplane and inspect them for cracks at an overhaul facility that has 
magnetic-particle inspection capability. In addition, Boeing states 
that it intends to add this option in the next revision of Boeing Alert 
Service Bulletin 747-32A2482, if revised.
    We partially agree. We acknowledge that a magnetic-particle 
inspection may be done instead of an HFEC inspection; however, Boeing 
has not completed developing procedures for a revised service bulletin. 
We may consider approving the revised service bulletin as an 
alternative method of compliance (AMOC) once it has been completed. 
Paragraph (k) of this AD provides for operators' requests for approval 
of an AMOC to address these unique circumstances. Therefore, we have 
made no change to this AD in this regard.

Request To Include a Parts Installation Paragraph

    Boeing requests that we add a parts installation paragraph to the 
NPRM for Category A, B, C, or D trunnion fork assemblies that are 
installed after the terminating action specified in Boeing Alert 
Service Bulletin 747-32A2482 has been done (i.e., Part 5 of the 
Accomplishment Instructions of the service bulletin). Boeing states 
that such a paragraph will ensure that the actions specified in the 
service bulletin are done on spare parts within the compliance times 
mandated by the NPRM. Boeing is concerned about

[[Page 21522]]

landing gear parts being interchanged between airplanes.
    We partially agree. We acknowledge that spare parts must be 
addressed due to the interchangeability of landing gears. However, it 
is not necessary to change the AD. The AD refers to Boeing Alert 
Service Bulletin 747-32A2482 as the appropriate source of service 
information for doing the required actions. Note (b) of Tables 4 (for 
Categories A and C trunnion fork assemblies) and 5 (for Categories B 
and D trunnion fork assemblies) of paragraph 1.E, ``Compliance,'' of 
the service bulletin specifies that the following three types of 
trunnion fork assemblies can be installed:
    1. New trunnion fork assembly;
    2. Category Not Affected trunnion fork assembly; or
    3. Category B (Group 1 airplanes) or D (Group 2 airplanes) trunnion 
fork assembly on which Part 3 or Part 4 of Boeing Alert Service 
Bulletin 747-32A2482 has been done.
    Once the compliance threshold has been reached for doing the 
terminating action required by this AD, operators are prohibited under 
14 CFR 39.3 from replacing a trunnion fork assembly with an assembly 
other than one identified in note (b) of Tables 4 and 5. Therefore, we 
have made no change to the final rule in this regard.

Request To Correct Typographical Errors

    Boeing requests that the categories specified in the first column 
in Table 1 of the NPRM be corrected to match those specified in Tables 
4 and 5 of paragraph 1.E., ``Compliance,'' of Boeing Alert Service 
Bulletin 747-32A2482. Boeing states that ``Categories A and D'' should 
be ``Categories A and C'' in paragraph (h)(1) of Table 1, and 
``Categories B and C'' should be ``Categories B and D'' in paragraph 
(h)(2) of Table 1.
    We agree that two typographical errors appear in Table 1 of the 
NPRM. It was our intent to align the categories of Table 1 with those 
in Tables 4 and 5 of paragraph 1.E., ``Compliance,'' of Boeing Alert 
Service Bulletin 747-32A2482. Therefore, we have revised this AD 
accordingly.

Conclusion

    We reviewed the relevant data, considered the comments received, 
and determined that air safety and the public interest require adopting 
the AD with the changes described previously. We also determined that 
these changes will not increase the economic burden on any operator or 
increase the scope of the AD.

Costs of Compliance

    There are about 1,055 airplanes of the affected design in the 
worldwide fleet. This AD affects about 215 airplanes of U.S. registry. 
The required inspection for part number, serial number, and category 
takes about 1 work hour per airplane, at an average labor rate of $80 
per work hour. Based on these figures, the estimated cost of the 
inspection required 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

    This AD will not have federalism implications under Executive Order 
13132. This AD will 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 this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Is not a ``significant rule'' under 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, Incorporation by 
reference, Safety.

Adoption of the Amendment

0
Accordingly, under the authority delegated to me by the Administrator, 
the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
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]

0
2. The FAA amends Sec.  39.13 by adding the following new AD:

2008-09-05 Boeing: Amendment 39-15486. Docket No. FAA-2007-29065; 
Directorate Identifier 2007-NM-142-AD.

Effective Date

    (a) This airworthiness directive (AD) is effective May 27, 2008.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to 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; 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. A review of airplane 
maintenance or delivery records is acceptable instead of the 
inspection if the part number and serial number of the installed 
fork assembly can be conclusively determined from that review. Do 
the actions in accordance with the Accomplishment Instructions of 
the service bulletin.

[[Page 21523]]

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
----------------------------------------------------------------------------------------------------------------
              For--                           Do--                      And--                     Or--
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(1) Categories A and C trunnion    A detailed inspection for  An ultrasonic inspection  Do the terminating
 fork assemblies.                   damage to the protective   to determine the wall     action (Part 5).
                                    finish and for corrosion   thickness in the area
                                    of the trunnion fork       forward of the outer
                                    assembly and a high        cylinder attach lugs in
                                    frequency eddy current     8 zones, and a hardness
                                    (HFEC) inspection to       measurement if
                                    detect cracks (Part 2).    applicable (Part 3).
(2) Categories B and D trunnion    An ultrasonic inspection   None....................  None.
 fork assemblies.                   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 
Accomplishment Instructions 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.

Material Incorporated by Reference

    (l) You must use Boeing Alert Service Bulletin 747-32A2482, 
dated June 14, 2007, to do the actions required by this AD, unless 
the AD specifies otherwise.
    (1) The Director of the Federal Register approved the 
incorporation by reference of this service information under 5 
U.S.C. 552(a) and 1 CFR part 51.
    (2) For service information identified in this AD, contact 
Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 
98124-2207.
    (3) You may review copies of the service information 
incorporated by reference at the FAA, Transport Airplane 
Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the 
National Archives and Records Administration (NARA). For information 
on the availability of this material at NARA, call 202-741-6030, or 
go to: http://www.archives.gov/federal_register/code_of_federal_
regulations/ibr_locations.html.

    Issued in Renton, Washington, on April 14, 2008.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E8-8530 Filed 4-21-08; 8:45 am]

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