[Federal Register Volume 72, Number 59 (Wednesday, March 28, 2007)]
[Rules and Regulations]
[Pages 14395-14397]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-5557]



[[Page 14395]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2004-19755; Directorate Identifier 2004-NM-23-AD; 
Amendment 39-15003; AD 2007-07-03]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747 Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for 
certain Boeing Model 747 airplanes. This AD requires repetitive tests 
to detect hot air leaking from the trim air diffuser ducts or sidewall 
riser duct assemblies (collectively referred to in this AD as 
``TADDs''), related investigative actions, and corrective actions if 
necessary. This AD also provides an optional terminating action for the 
repetitive tests. This AD results from reports of sealant deteriorating 
on the outside of the center wing fuel tank and analysis that sealant 
may deteriorate inside the tank due to excess heat from leaking TADDs. 
We are issuing this AD to prevent leakage of fuel or fuel vapors into 
areas where ignition sources may be present, which could result in a 
fire or explosion.

DATES: This AD becomes effective May 2, 2007.
    The Director of the Federal Register approved the incorporation by 
reference of certain publications listed in the AD as of May 2, 2007.

ADDRESSES: You may examine the AD docket on the Internet at http://dms.dot.gov or in person at the Docket Management Facility, U.S. 
Department of Transportation, 400 Seventh Street, SW., Nassif Building, 
Room PL-401, Washington, DC.
    Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, 
Washington 98124-2207, for service information identified in this AD.

FOR FURTHER INFORMATION CONTACT: Dan Kinney, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone 
(425) 917-6499; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION: 

Examining the Docket

    You may examine the AD docket on the Internet at http://dms.dot.gov 
or in person at the Docket Management Facility office between 9 a.m. 
and 5 p.m., Monday through Friday, except Federal holidays. The Docket 
Management Facility office (telephone (800) 647-5227) is located on the 
plaza level of the Nassif Building at the street address stated in the 
ADDRESSES section.

Discussion

    The FAA issued a supplemental notice of proposed rulemaking (NPRM) 
to amend 14 CFR part 39 to include an AD that would apply to certain 
Boeing Model 747 airplanes. That supplemental NPRM was published in the 
Federal Register on September 26, 2006 (71 FR 56064). That supplemental 
NPRM proposed to require repetitive tests to detect hot air leaking 
from the trim air diffuser ducts or sidewall riser duct assemblies 
(collectively referred to in the AD as ``TADDs''), related 
investigative actions, and corrective actions if necessary. That 
supplemental NPRM also provided an optional terminating action for the 
repetitive tests.

Comments

    We provided the public the opportunity to participate in the 
development of this AD. We have considered the comments received.

Supportive Comment

    Boeing has reviewed the supplemental NPRM and concurs with the 
content.

Request To Delay Corrective Actions

    Lufthansa German Airlines asks that, if any hot air leak is found 
during any test required by paragraph (f) of the supplemental NPRM, we 
give relief for the corrective actions specified in paragraphs (g) and 
(h) of the supplemental NPRM. It suggests we do this by allowing 
deactivation of the zone trim air modulation valve of the affected 
TADDs for at least ten days. Lufthansa states that this would allow a 
delay in performing the inspection and corrective actions until after 
that extension ends; this delay would permit the operator to better 
plan the actions required if any hot air leak is found during the 
repetitive tests required by paragraph (f).
    We do not agree with the commenter. The zone trim air modulation 
valves are located downstream of the potential leakage area; therefore, 
deactivating them would not prevent hot air leakage from the TADDs. We 
have made no change to the AD in this regard.

Clarification of Test Requirements Specified in Paragraph (f)

    Lufthansa asks for clarification of the test requirements specified 
in paragraph (f) of the supplemental NPRM. Lufthansa states that the 
repetitive tests specified in paragraph (f) are to be done in 
accordance with Boeing Service Bulletin 747-21A2418, Revision 4, dated 
November 17, 2005. Lufthansa adds that Note 2 of the supplemental NPRM 
refers to Chapters 21-61-20 and 21-61-21 of the Boeing 747 Airplane 
Maintenance Manual as an additional source of service information for 
the test and inspections of the TADDs. Lufthansa notes that those 
chapters describe the temperature measurement procedure for the 
repetitive hot air leak inspection and specify temperature measurements 
of all TADDs after thirty seconds, one minute, two minutes, and then 
every two minutes, for a duration of twenty minutes. Lufthansa states 
that it is not clear whether the temperature measurements must be 
performed simultaneously on all ducts, or sequentially with one or more 
ducts at a time; however, the description suggests performing the 
measurements simultaneously on all ducts. Lufthansa adds that 
performing the temperature measurements sequentially with one or more 
ducts would ease the measurement procedure. Lufthansa notes that it 
does not understand why the temperature has to be measured on all TADDs 
every two minutes for a duration of twenty minutes, mainly because the 
airplane maintenance manual for Model 747-200 Combi airplanes has only 
baseline and 10-minute measurements and there is no requirement for 
additional measurements. Lufthansa asks that the intervals be reduced 
to 1- and 10-minute intervals, with the possibility of performing each 
measurement sequentially.
    We acknowledge and agree with the commenter's concern and provide 
clarification. The temperature measurement procedure identified by the 
commenter does specify performing the measurements simultaneously on 
all ducts. If the procedure were done sequentially, before making each 
measurement, the initial conditions of the airplane would have to be 
re-established, and the time required for that would be prohibitive. 
Measuring the temperatures frequently allows detection of the highest 
achieved temperature, given that the temperature may not increase 
steadily. In addition, Model 747-200 Combi airplane configurations are 
different; therefore, different procedures are used for those

[[Page 14396]]

airplanes and those procedures cannot be used for the other airplane 
models specified in this AD. However, according to the provisions of 
paragraph (l) of this AD, we may approve requests for another method 
which accomplishes the intent of the maintenance manual tasks if the 
request includes data which prove that method would provide an 
acceptable level of safety. We have made no change to the AD in this 
regard.

Conclusion

    We have carefully reviewed the available data, including the 
comments received, and determined that air safety and the public 
interest require adopting the AD as proposed in the supplemental NPRM.

Costs of Compliance

    There are about 1,081 airplanes of the affected design in the 
worldwide fleet. The following table provides the estimated costs for 
U.S. operators to comply with this AD.

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                 Number of U.S.-
            Action               Work hours     Average labor      Cost per        registered       Fleet cost
                                                rate per hour      airplane         airplanes
----------------------------------------------------------------------------------------------------------------
Hot air leak test............               3             $80  $240, per test               216  $51,840, per
                                                                cycle.                            test cycle.
General visual inspection....               5             $80  $400, per                    216  $86,400, per
                                                                inspection                        inspection
                                                                cycle.                            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 
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 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.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this 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, 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 Federal Aviation Administration (FAA) amends Sec.  39.13 by 
adding the following new airworthiness directive (AD):

2007-07-03 Boeing: Amendment 39-15003. Docket No. FAA-2004-19755; 
Directorate Identifier 2004-NM-23-AD.

Effective Date

    (a) This AD becomes effective May 2, 2007.

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; line numbers 1 through 1316 inclusive.

Unsafe Condition

    (d) This AD results from reports of sealant deteriorating on the 
outside of the center wing fuel tank and analysis that sealant may 
deteriorate inside the tank due to excess heat from leaking trim air 
diffuser ducts or sidewall riser duct assemblies (collectively 
referred to in this AD as ``TADDs''). We are issuing this AD to 
prevent leakage of fuel or fuel vapors into areas where ignition 
sources may be present, which could result in a fire or explosion.

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.

Repetitive Tests and Inspections

    (f) Do the actions in Table 1 of this AD at the times specified 
in Table 1 of this AD, in accordance with the Accomplishment 
Instructions of Boeing Service Bulletin 747-21A2418, Revision 4, 
dated November 17, 2005. When the compliance times for a hot air 
leak test and a general visual inspection coincide, the hot air leak 
test is not required at that time, but is required within 1,200 
flight hours (i.e., one repeat interval) after the general visual 
inspection.

[[Page 14397]]



                                           Table 1.--Compliance Times
----------------------------------------------------------------------------------------------------------------
                                         Initially at the later of--    Then repeat within this interval until
            Do this action--                                                   paragraph (j) is done--
----------------------------------------------------------------------------------------------------------------
(1) Repetitive test to detect hot air    Prior to the accumulation   1,200 flight hours.
 leaking from TADDs..                     of 21,200 total flight
                                          hours, or within 1,200
                                          flight hours after the
                                          effective date of this AD.
(2) General visual inspection for        Prior to the accumulation   12,000 flight hours.
 damage or discrepancies of the TADDs.    of 32,000 total flight
                                          hours, or within 12,000
                                          flight hours after the
                                          effective date of this
                                          AD, except as provided by
                                          paragraph (g) of this AD.
----------------------------------------------------------------------------------------------------------------


    Note 1: 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.''


    Note 2: Boeing Service Bulletin 747-21A2418, Revision 4, refers 
to Chapters 21-61-20 and 21-61-21 of the Boeing 747 Airplane 
Maintenance Manual as an additional source for service information 
for the test and inspections of the TADDs.

    (g) If any hot air leak is found during any test required by 
paragraph (f) of this AD: Before further flight, do the general 
visual inspection for damage or discrepancies of the TADDs, in 
accordance with the Accomplishment Instructions of Boeing Service 
Bulletin 747-21A2418, Revision 4, dated November 17, 2005.

Corrective Actions

    (h) If any damage or discrepancy is found during any general 
visual inspection for damage required by paragraph (f) or (g) of 
this AD: Do the actions in paragraphs (h)(1), (h)(2), (h)(3), and 
(h)(4) of this AD, as applicable. Do all of these actions in 
accordance with the Accomplishment Instructions of Boeing Service 
Bulletin 747-21A2418, Revision 4, dated November 17, 2005.
    (1) Before further flight: Perform a general visual inspection 
for damage of the primary and secondary fuel barriers of the center 
wing tank; structure adjacent to the discrepant TADD; and cables, 
cable pulleys, and raised cable seals in the over-wing area. If no 
damage is found on the side of the airplane where the damaged or 
discrepant TADD is found, inspecting the other side of the airplane 
is not required.
    (2) Before further flight: Repair all damage or discrepancies 
found.
    (3) Before further flight: Replace any damaged TADD with a new 
TADD having the same part number or a new or serviceable, improved 
TADD having a part number listed in the ``New TADD Part Number'' or 
``New Sidewall Riser Duct Assy Part Number'' column, as applicable, 
of the tables in Section 2.C.2. of the service bulletin.
    (4) Repeat the test and inspection required by paragraph (f) of 
this AD at the times specified in Table 1 of this AD, except as 
provided by paragraphs (i) and (j) of this AD.
    (i) For any original-material TADD that is replaced with a new 
TADD having the same part number as the TADD being replaced: Within 
21,200 flight hours after the TADD is replaced, do the test to 
detect hot air leaking from the replaced TADD, and within 32,000 
flight hours after the TADD is replaced, do the general visual 
inspection for damage, as specified in paragraph (f) of this AD. 
Thereafter, repeat the test and inspection at the repetitive 
intervals specified in Table 1 of this AD, except when the times for 
a hot air leak test and a general visual inspection coincide, the 
leak test is not required.

Optional Terminating Action

    (j) Replacing existing TADDs with new or serviceable, improved 
TADDs terminates repetitive test and inspection requirements as 
specified in paragraphs (j)(1), (j)(2), and (j)(3) of this AD. New 
or serviceable, improved TADDs are those having a part number listed 
in the ``New TADD Part Number'' or ``New Sidewall Riser Duct Assy 
Part Number'' column, as applicable, of the tables in Section 2.C.2. 
of Boeing Service Bulletin 747-21A2418, Revision 3, dated December 
21, 2004; or Revision 4, dated November 17, 2005.
    (1) The repetitive general visual inspections required by 
paragraph (f)(2) of this AD are terminated for each TADD that is 
replaced with a new or serviceable, improved TADD.
    (2) Replacing all TADDs on one side of the airplane with new or 
serviceable, improved TADDs terminates all repetitive tests required 
by paragraph (f)(1) of this AD and all repetitive inspections 
required by paragraph (f)(2) of this AD only for the side of the 
airplane on which the improved TADDs are installed.
    (3) Replacing all TADDs on both sides of the airplane with new 
or serviceable, improved TADDs terminates all repetitive tests 
required by paragraph (f)(1) of this AD and all repetitive 
inspections required by paragraph (f)(2) of this AD.

Previously Accomplished Actions

    (k) Actions done before the effective date of this AD in 
accordance with Boeing Alert Service Bulletin 747-21A2418, dated 
November 14, 2002; Revision 1, dated October 16, 2003; Revision 2, 
dated March 4, 2004; or Boeing Service Bulletin 747-21A2418, 
Revision 3, dated December 21, 2004; are acceptable for compliance 
with the corresponding actions required by this AD.

Alternative Methods of Compliance (AMOCs)

    (l)(1) The Manager, Seattle Aircraft Certification Office, FAA, 
has the authority to approve AMOCs for this AD, if requested in 
accordance with the procedures found in 14 CFR 39.19.
    (2) Before using any AMOC approved in accordance with Sec.  
39.19 on any airplane to which the AMOC applies, notify the 
appropriate principal inspector in the FAA Flight Standards 
Certificate Holding District Office.

Material Incorporated by Reference

    (m) You must use Boeing Service Bulletin 747-21A2418, Revision 
4, dated November 17, 2005, to perform the actions that are required 
by this AD, unless the AD specifies otherwise. The Director of the 
Federal Register approved the incorporation by reference of this 
document in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. 
Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, 
Washington 98124-2207, for a copy of this service information. You 
may review copies 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/cfr/ibr-locations.html.

    Issued in Renton, Washington, on March 20, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E7-5557 Filed 3-27-07; 8:45 am]
BILLING CODE 4910-13-P