Federal Register / Vol. 72, No. 59 / Wednesday, March 28, 2007 / Rules and Regulations 14395 

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. 

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 reestablished, 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 


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14396 Federal Register / Vol. 72, No. 59 / Wednesday, March 28, 2007 / Rules and Regulations 

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

Action Work hours Average labor 

rate per hour Cost per airplane 

Number of 

U.S.-registered 

airplanes 

Fleet cost 

Hot air leak test ..................... 3 $80 $240, per test cycle .............. 216 $51,840, per test cycle. 

General visual inspection ...... 5 $80 $400, per inspection cycle .... 216 $86,400, per inspection 

cycle. 

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 

■ Accordingly, under the authority 

delegated to me by the Administrator, 

the FAA amends 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. 

§ 39.13 [Amended] 

■ 2. The Federal Aviation 

Administration (FAA) amends § 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. 


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Federal Register / Vol. 72, No. 59 / Wednesday, March 28, 2007 / Rules and Regulations 14397 

TABLE 1.—COMPLIANCE TIMES

Do this action— Initially at the later of— 

Then repeat within this interval until paragraph (j) is 

done— 

(1) Repetitive test to detect hot air leaking from TADDs. Prior to the accumulation of 21,200 total flight hours, or 

within 1,200 flight hours after the effective date of this 

AD.

1,200 flight hours. 

(2) General visual inspection for damage or discrepancies of the TADDs.Prior to the accumulation 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.

12,000 flight hours. 

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 § 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/federalregister/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 


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