This section of the FEDERAL REGISTER

contains notices to the public of the proposed

issuance of rules and regulations. The

purpose of these notices is to give interested

persons an opportunity to participate in the

rule making prior to the adoption of the final

rules.

Proposed Rules Federal Register

31891 

Vol. 74, No. 127 

Monday, July 6, 2009 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2009–0609; Directorate 

Identifier 2009–NM–037–AD] 

RIN 2120–AA64 

Airworthiness Directives; Bombardier 

Model DHC–8–102, DHC–8–103, DHC– 

8–106, DHC–8–201, and DHC–8–202 

Series Airplanes 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Notice of proposed rulemaking 

(NPRM). 

SUMMARY: We propose to adopt a new 

airworthiness directive (AD) for the 

products listed above. This proposed 

AD results from mandatory continuing 

airworthiness information (MCAI) 

originated by an aviation authority of 

another country to identify and correct 

an unsafe condition on an aviation 

product. The MCAI describes the unsafe 

condition as: 

During a puncture voltage test of the 

aluminum-loaded paint on an in-service 

DHC–8 aircraft, conducted to validate an 

SFAR 88 [Special Federal Aviation 

Regulation No. 88] related task, Bombardier 

Aerospace (BA) discovered that the top wing 

fuel tank skin between Yw171.20 and 

Yw261.00 was painted with a nonaluminized enamel coating * * *. 

With this type of paint application, it is 

possible that, in the worst case scenario, a 

lightning strike could puncture the wing skin 

and create an ignition source in the fuel tank. 

Ignition sources inside fuel tanks, in 

combination with flammable fuel 

vapors, could result in fuel tank 

explosions and consequent loss of the 

airplane. The proposed AD would 

require actions that are intended to 

address the unsafe condition described 

in the MCAI. 

DATES: We must receive comments on 

this proposed AD by August 5, 2009. 

ADDRESSES: You may send comments by 

any of the following methods: 

• Federal eRulemaking Portal: Go to 

http://www.regulations.gov. Follow the 

instructions for submitting comments. 

• Fax: (202) 493–2251. 

• 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. 

• Hand Delivery: U.S. Department of 

Transportation, Docket Operations, M– 

30, West Building Ground Floor, Room 

W12–40, 1200 New Jersey Avenue, SE., 

Washington, DC, between 9 a.m. and 5 

p.m., Monday through Friday, except 

Federal holidays. 

For service information identified in 

this proposed AD, contact Bombardier, 

Inc., 400 Coˆte-Vertu Road West, Dorval, 

Que ́bec H4S 1Y9, Canada; telephone 

514–855–5000; fax 514–855–7401; email thd.qseries@aero.bombardier.com; 

Internet http://www.bombardier.com. 

You may review copies of the 

referenced service information at the 

FAA, Transport Airplane Directorate, 

1601 Lind Avenue, SW., Renton, 

Washington. For information on the 

availability of this material at the FAA, 

call 425–227–1221 or 425–227–1152. 

Examining the AD Docket 

You may examine the AD docket on 

the Internet at http:// 

www.regulations.gov; or in person at the 

Docket Operations office between 9 a.m. 

and 5 p.m., Monday through Friday, 

except Federal holidays. The AD docket 

contains this proposed AD, the 

regulatory evaluation, any comments 

received, and other information. The 

street address for the Docket Operations 

office (telephone (800) 647–5527) is in 

the ADDRESSES section. Comments will 

be available in the AD docket shortly 

after receipt. 

FOR FURTHER INFORMATION CONTACT: Kyle 

Williams, Aerospace Engineer, Systems 

and Flight Test Branch, ANE–172, FAA, 

New York Aircraft Certification Office, 

1600 Stewart Avenue, Suite 410, 

Westbury, New York 11590; telephone 

(516) 228–7347; fax (516) 794–5531. 

SUPPLEMENTARY INFORMATION: 

Comments Invited 

We invite you to send any written 

relevant data, views, or arguments about 

this proposed AD. Send your comments 

to an address listed under the 

ADDRESSES section. Include ‘‘Docket No. 

FAA–2009–0609; Directorate Identifier 

2009–NM–037–AD’’ at the beginning of 

your comments. We specifically invite 

comments on the overall regulatory, 

economic, environmental, and energy 

aspects of this proposed AD. We will 

consider all comments received by the 

closing date and may amend this 

proposed AD based on those comments. 

We will post all comments we 

receive, without change, to http:// 

www.regulations.gov, including any 

personal information you provide. We 

will also post a report summarizing each 

substantive verbal contact we receive 

about this proposed AD. 

Discussion 

Transport Canada Civil Aviation 

(TCCA), which is the aviation authority 

for Canada, has issued Canadian 

Airworthiness Directive CF–2009–05, 

dated January 29, 2009 (referred to after 

this as ‘‘the MCAI’’), to correct an unsafe 

condition for the specified products. 

The MCAI states: 

During a puncture voltage test of the 

aluminum-loaded paint on an in-service 

DHC–8 aircraft, conducted to validate an 

SFAR 88 [Special Federal Aviation 

Regulation No. 88] related task, Bombardier 

Aerospace (BA) discovered that the top wing 

fuel tank skin between Yw171.20 and 

Yw261.00 was painted with a nonaluminized enamel coating due to a 

misinterpretation of the painting instructions 

in the Structural Repair Manual (SRM). 

With this type of paint application, it is 

possible that, in the worst case scenario, a 

lightning strike could puncture the wing skin 

and create an ignition source in the fuel tank. 

Ignition sources inside fuel tanks, in 

combination with flammable fuel 

vapors, could result in fuel tank 

explosions and consequent loss of the 

airplane. Required actions include 

performing a functional check of the 

dielectric properties of the fuel tank 

skin for aluminum-loaded primer and 

aluminum-loaded enamel coating. For 

airplanes on which the aluminumloaded primer and aluminum-loaded 

enamel coating have been properly 

applied, the required actions include 

restoring the protective finish on the 

areas where the surface finish was 

removed. For airplanes on which the 

aluminum-loaded primer and 

aluminum-loaded enamel coating have 

not been applied or have not been 

properly applied, the required actions 

include stripping the affected wing skin 

surfaces to bare metal and applying 

alodine coating to those areas, 


cprice-sewell on PROD1PC69 with PROPOSALS
31892 Federal Register / Vol. 74, No. 127 / Monday, July 6, 2009 / Proposed Rules 

performing a detailed visual inspection 

of the stripped areas for any sign of 

corrosion or deterioration of the 

protective alodine coating and reapplying the protective alodine coating, 

and painting the affected wing skin 

surfaces with aluminum-loaded primer 

and aluminum-loaded enamel coating. 

You may obtain further information by 

examining the MCAI in the AD docket. 

The FAA has examined the 

underlying safety issues involved in fuel 

tank explosions on several large 

transport airplanes, including the 

adequacy of existing regulations, the 

service history of airplanes subject to 

those regulations, and existing 

maintenance practices for fuel tank 

systems. As a result of those findings, 

we issued a regulation titled ‘‘Transport 

Airplane Fuel Tank System Design 

Review, Flammability Reduction and 

Maintenance and Inspection 

Requirements’’ (66 FR 23086, May 7, 

2001). In addition to new airworthiness 

standards for transport airplanes and 

new maintenance requirements, this 

rule included Special Federal Aviation 

Regulation No. 88 (‘‘SFAR 88,’’ 

Amendment 21–78, and subsequent 

Amendments 21–82 and 21–83). 

Among other actions, SFAR 88 

requires certain type design (i.e., type 

certificate (TC) and supplemental type 

certificate (STC)) holders to substantiate 

that their fuel tank systems can prevent 

ignition sources in the fuel tanks. This 

requirement applies to type design 

holders for large turbine-powered 

transport airplanes and for subsequent 

modifications to those airplanes. It 

requires them to perform design reviews 

and to develop design changes and 

maintenance procedures if their designs 

do not meet the new fuel tank safety 

standards. As explained in the preamble 

to the rule, we intended to adopt 

airworthiness directives to mandate any 

changes found necessary to address 

unsafe conditions identified as a result 

of these reviews. 

In evaluating these design reviews, we 

have established four criteria intended 

to define the unsafe conditions 

associated with fuel tank systems that 

require corrective actions. The 

percentage of operating time during 

which fuel tanks are exposed to 

flammable conditions is one of these 

criteria. The other three criteria address 

the failure types under evaluation: 

Single failures, single failures in 

combination with a latent condition(s), 

and in-service failure experience. For all 

four criteria, the evaluations included 

consideration of previous actions taken 

that may mitigate the need for further 

action. 

The Joint Aviation Authorities (JAA) 

has issued a regulation that is similar to 

SFAR 88. (The JAA is an associated 

body of the European Civil Aviation 

Conference (ECAC) representing the 

civil aviation regulatory authorities of a 

number of European States who have 

agreed to co-operate in developing and 

implementing common safety regulatory 

standards and procedures.) Under this 

regulation, the JAA stated that all 

members of the ECAC that hold type 

certificates for transport category 

airplanes are required to conduct a 

design review against explosion risks. 

We have determined that the actions 

identified in this AD are necessary to 

reduce the potential of ignition sources 

inside fuel tanks, which, in combination 

with flammable fuel vapors, could result 

in fuel tank explosions and consequent 

loss of the airplane. 

Relevant Service Information 

Bombardier has issued Service 

Bulletin 8–57–46, Revision ‘A,’ dated 

February 6, 2009. The actions described 

in this service information are intended 

to correct the unsafe condition 

identified in the MCAI. 

FAA’s Determination and Requirements 

of This Proposed AD 

This product has been approved by 

the aviation authority of another 

country, and is approved for operation 

in the United States. Pursuant to our 

bilateral agreement with the State of 

Design Authority, we have been notified 

of the unsafe condition described in the 

MCAI and service information 

referenced above. We are proposing this 

AD because we evaluated all pertinent 

information and determined an unsafe 

condition exists and is likely to exist or 

develop on other products of the same 

type design. 

Differences Between This AD and the 

MCAI or Service Information 

We have reviewed the MCAI and 

related service information and, in 

general, agree with their substance. But 

we might have found it necessary to use 

different words from those in the MCAI 

to ensure the AD is clear for U.S. 

operators and is enforceable. In making 

these changes, we do not intend to differ 

substantively from the information 

provided in the MCAI and related 

service information. 

We might also have proposed 

different actions in this AD from those 

in the MCAI in order to follow FAA 

policies. Any such differences are 

highlighted in a Note within the 

proposed AD. 

Costs of Compliance 

Based on the service information, we 

estimate that this proposed AD would 

affect about 22 products of U.S. registry. 

We also estimate that it would take 

about 24 work-hours per product to 

comply with the basic requirements of 

this proposed AD. The average labor 

rate is $80 per work-hour. Based on 

these figures, we estimate the cost of the 

proposed AD on U.S. operators to be 

$42,240, or $1,920 per product. 

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 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 this 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. 


cprice-sewell on PROD1PC69 with PROPOSALS
Federal Register / Vol. 74, No. 127 / Monday, July 6, 2009 / Proposed Rules 31893 

List of Subjects in 14 CFR Part 39 

Air transportation, Aircraft, Aviation 

safety, Incorporation by reference, 

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. 

§ 39.13 [Amended] 

2. The FAA amends § 39.13 by adding 

the following new AD: 

Bombardier, Inc. (Formerly de Havilland, 

Inc.): Docket No. FAA–2009–0609; 

Directorate Identifier 2009–NM–037–AD. 

Comments Due Date 

(a) We must receive comments by August 

5, 2009. 

Affected ADs 

(b) None. 

Applicability 

(c) This AD applies to Bombardier Model 

DHC–8–102, DHC–8–103, DHC–8–106, DHC– 

8–201, and DHC–8–202 series airplanes; 

certificated in any category; serial numbers 

003 through 663 inclusive. 

Subject 

(d) Air Transport Association (ATA) of 

America Code 57: Wings. 

Reason 

(e) The mandatory continuing 

airworthiness information (MCAI) states: 

During a puncture voltage test of the 

aluminum-loaded paint on an in-service 

DHC–8 aircraft, conducted to validate an 

SFAR 88 [Special Federal Aviation 

Regulation No. 88] related task, Bombardier 

Aerospace (BA) discovered that the top wing 

fuel tank skin between Yw171.20 and 

Yw261.00 was painted with a nonaluminized enamel coating due to a 

misinterpretation of the painting instructions 

in the Structural Repair Manual (SRM). 

With this type of paint application, it is 

possible that, in the worst case scenario, a 

lightning strike could puncture the wing skin 

and create an ignition source in the fuel tank. 

Ignition sources inside fuel tanks, in 

combination with flammable fuel vapors, 

could result in fuel tank explosions and 

consequent loss of the airplane. Required 

actions include performing a functional 

check of the dielectric properties of the fuel 

tank skin for aluminum-loaded primer and 

aluminum-loaded enamel coating. For 

airplanes on which the aluminum-loaded 

primer and aluminum-loaded enamel coating 

have been properly applied, the required 

actions include restoring the protective finish 

on the areas where the surface finish was 

removed. For airplanes on which the 

aluminum-loaded primer and aluminumloaded enamel coating have not been applied 

or have not been properly applied, the 

required actions include stripping the 

affected wing skin surfaces to bare metal and 

applying alodine coating to those areas, 

performing a detailed visual inspection of the 

stripped areas for any sign of corrosion or 

deterioration of the protective alodine 

coating and re-applying the protective 

alodine coating, and painting the affected 

wing skin surfaces with aluminum-loaded 

primer and aluminum-loaded enamel 

coating. 

Actions and Compliance 

(f) Unless already done, do the following 

actions. 

(1) For airplanes on which Bombardier 

Modification 8/0024 has not been done: 

Within 18 months after the effective date of 

this AD, perform a functional check of the 

dielectric properties of the fuel tank skin 

between Yw171.20 and Yw261.00 of the 

upper and lower wing for aluminum-loaded 

primer and aluminum-loaded enamel 

coating, in accordance with the 

Accomplishment Instructions of Bombardier 

Service Bulletin 8–57–46, Revision ‘A’, dated 

February 6, 2009. 

(2) For airplanes on which Bombardier 

Modification 8/0024 has been done: Within 

18 months after the effective date of this AD, 

perform a functional check of the dielectric 

properties of the fuel tank skin between 

Yw171.20 and Yw261.00 of the upper wing 

for aluminum-loaded primer and aluminumloaded enamel coating, in accordance with 

the Accomplishment Instructions of 

Bombardier Service Bulletin 8–57–46, 

Revision ‘A,’ dated February 6, 2009. 

(3) If the functional check required by 

paragraph (f)(1) or (f)(2) of this AD indicates 

that the aluminum-loaded primer and 

aluminum-loaded enamel coating have been 

properly applied, as defined in the 

Accomplishment Instructions of Bombardier 

Service Bulletin 8–57–46, Revision ‘A,’ dated 

February 6, 2009: Before further flight, 

restore the protective finish on the areas 

where the surface finish was removed for the 

functional check, in accordance with the 

Accomplishment Instructions of Bombardier 

Service Bulletin 8–57–46, Revision ‘A,’ dated 

February 6, 2009. 

(4) If the functional check required by 

paragraph (f)(1) or (f)(2) of this AD indicates 

that the aluminum-loaded primer and 

aluminum-loaded enamel coating have not 

been applied or have not been properly 

applied, as defined in the Accomplishment 

Instructions of Bombardier Service Bulletin 

8–57–46, Revision ‘A,’ dated February 6, 

2009: Perform the actions required by 

paragraphs (f)(4)(i), (f)(4)(ii), and (f)(4)(iii) of 

this AD in accordance with the 

Accomplishment Instructions of Bombardier 

Service Bulletin 8–57–46, Revision ‘A,’ dated 

February 6, 2009 (‘‘the service bulletin’’). 

(i) Before further flight, strip the affected 

wing skin surfaces to bare metal and apply 

alodine coating to those areas in accordance 

with the service bulletin. 

(ii) Within 90 flight hours after performing 

the actions required by paragraph (f)(4)(i) of 

this AD, and thereafter at intervals not to 

exceed 90 flight hours: Perform a detailed 

visual inspection of the stripped areas for any 

sign of corrosion or deterioration of the 

protective alodine coating, and re-apply the 

protective alodine coating, in accordance 

with the service bulletin. 

(iii) Within 3 months after performing the 

actions required by paragraph (f)(1) or (f)(2) 

of this AD, as applicable: Paint the affected 

wing skin surfaces with aluminum-loaded 

primer and aluminum-loaded enamel coating 

in accordance with the service bulletin. 

(5) Accomplishment of the actions required 

by paragraph (f)(1) or (f)(2) of this AD, as 

applicable, before the effective date of this 

AD in accordance with Bombardier Service 

Bulletin 8–57–46, dated September 29, 2008, 

is acceptable for compliance with the 

corresponding requirements of this AD. 

FAA AD Differences 

Note 1: This AD differs from the MCAI 

and/or service information as follows: No 

differences. 

Other FAA AD Provisions 

(g) The following provisions also apply to 

this AD: 

(1) Alternative Methods of Compliance 

(AMOCs): The Manager, New York Aircraft 

Certification Office, FAA, has the authority to 

approve AMOCs for this AD, if requested 

using the procedures found in 14 CFR 39.19. 

Send information to ATTN: Kyle Williams, 

Aerospace Engineer, Systems and Flight Test 

Branch, ANE–172, FAA, New York Aircraft 

Certification Office, 1600 Stewart Avenue, 

Suite 410, Westbury, New York 11590; 

telephone (516) 228–7347; fax (516) 794– 

5531. Before using any approved AMOC on 

any airplane to which the AMOC applies, 

notify your principal maintenance inspector 

(PMI) or principal avionics inspector (PAI), 

as appropriate, or lacking a principal 

inspector, your local Flight Standards District 

Office. The AMOC approval letter must 

specifically reference this AD. 

(2) Airworthy Product: For any requirement 

in this AD to obtain corrective actions from 

a manufacturer or other source, use these 

actions if they are FAA-approved. Corrective 

actions are considered FAA-approved if they 

are approved by the State of Design Authority 

(or their delegated agent). You are required 

to assure the product is airworthy before it 

is returned to service. 

(3) Reporting Requirements: For any 

reporting requirement in this AD, under the 

provisions of the Paperwork Reduction Act, 

the Office of Management and Budget (OMB) 

has approved the information collection 

requirements and has assigned OMB Control 

Number 2120–0056. 

Related Information 

(h) Refer to Canadian Airworthiness 

Directive CF–2009–05, dated January 29, 

2009, and Bombardier Service Bulletin 8–57– 

46, Revision ‘A,’ dated February 6, 2009, for 

related information. 


cprice-sewell on PROD1PC69 with PROPOSALS
31894 Federal Register / Vol. 74, No. 127 / Monday, July 6, 2009 / Proposed Rules 

Issued in Renton, Washington, on June 25, 

2009. 

Stephen P. Boyd, 

Acting Manager, Transport Airplane 

Directorate, Aircraft Certification Service. 

[FR Doc. E9–15810 Filed 7–2–09; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2009–0608; Directorate 

Identifier 2008–NM–215–AD] 

RIN 2120–AA64 

Airworthiness Directives; Boeing 747– 

200C and –200F Series Airplanes 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Notice of proposed rulemaking 

(NPRM). 

SUMMARY: We propose to adopt a new 

airworthiness directive (AD) for all 

Boeing 747–200C and –200F series 

airplanes. This proposed AD would 

require a high frequency eddy current 

inspection for cracks of certain fastener 

holes, and corrective action if necessary. 

This proposed AD would also require 

repetitive replacements of the upper 

chords, straps (or angles), and radius 

fillers of certain upper deck floor beams, 

and, for any replacement that is done, 

detailed and open-hole HFEC 

inspections for cracks of the modified 

upper deck floor beams, and corrective 

actions if necessary. This proposed AD 

results from a report from the 

manufacturer that the accomplishment 

of certain existing inspections, repairs, 

and modifications is not adequate to 

ensure the structural integrity of the 

affected 7075 series aluminum alloy 

upper deck floor beam upper chords on 

airplanes that have exceeded certain 

thresholds. We are proposing this AD to 

prevent cracking of the upper chords 

and straps (or angles) of the floor beams, 

which could lead to failure of the floor 

beams and consequent loss of 

controllability, rapid decompression, 

and loss of structural integrity of the 

airplane. 

DATES: We must receive comments on 

this proposed AD by August 20, 2009. 

ADDRESSES: You may send comments by 

any of the following methods: 

• Federal eRulemaking Portal: Go to 

http://www.regulations.gov. Follow the 

instructions for submitting comments. 

• Fax: 202–493–2251. 

• 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. 

• Hand Delivery: U.S. Department of 

Transportation, Docket Operations, M– 

30, West Building Ground Floor, Room 

W12–140, 1200 New Jersey Avenue, SE., 

Washington, DC 20590, between 9 a.m. 

and 5 p.m., Monday through Friday, 

except Federal holidays. 

For service information identified in 

this proposed AD, contact Boeing 

Commercial Airplanes, Attention: Data 

& Services Management, P.O. Box 3707, 

MC 2H–65, Seattle, Washington 98124– 

2207; telephone 206–544–5000, 

extension 1, fax 206–766–5680; e-mail 

me.boecom@boeing.com; Internet 

https://www.myboeingfleet.com. You 

may review copies of the referenced 

service information at the FAA, 

Transport Airplane Directorate, 1601 

Lind Avenue, SW., Renton, Washington. 

For information on the availability of 

this material at the FAA, call 425–227– 

1221 or 425–227–1152. 

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 proposed AD, the 

regulatory evaluation, any comments 

received, and other information. The 

street address for the Docket Office 

(telephone 800–647–5527) is in the 

ADDRESSES section. Comments will be 

available in the AD docket shortly after 

receipt. 

FOR FURTHER INFORMATION CONTACT: Ivan 

Li, Aerospace Engineer, Airframe 

Branch, ANM–120S, FAA, Seattle 

Aircraft Certification Office, 1601 Lind 

Avenue, SW., Renton, Washington 

98057–3356; telephone (425) 917–6437; 

fax (425) 917–6590. 

SUPPLEMENTARY INFORMATION: 

Comments Invited 

We invite you to send any written 

relevant data, views, or arguments about 

this proposed AD. Send your comments 

to an address listed under the 

ADDRESSES section. Include ‘‘Docket No. 

FAA–2009–0608; Directorate Identifier 

2008–NM–215–AD’’ at the beginning of 

your comments. We specifically invite 

comments on the overall regulatory, 

economic, environmental, and energy 

aspects of this proposed AD. We will 

consider all comments received by the 

closing date and may amend this 

proposed AD because of those 

comments. 

We will post all comments we 

receive, without change, to http:// 

www.regulations.gov, including any 

personal information you provide. We 

will also post a report summarizing each 

substantive verbal contact we receive 

about this proposed AD. 

Discussion 

We have received reports that 

operators have found cracks in the 

upper chords and straps (or angles) of 

the upper deck floor beams. The 

airplanes had accumulated between 

16,264 and 23,561 total flight cycles. In 

addition, we received a report from the 

manufacturer that the accomplishment 

of certain existing inspections, repairs, 

and modifications is not adequate to 

ensure the structural integrity of the 

affected 7075 series aluminum alloy 

upper deck floor beam upper chords on 

airplanes that have exceeded certain 

thresholds. Cracks in the upper chords 

or straps (or angles) of an upper deck 

floor beam that are not found and 

repaired could become large and fully 

sever the floor beam. A severed floor 

beam can lead to large deflection or 

deformation of the floor and of the 

adjacent body skin, frames, and 

stringers, and could result in damage 

and unintended inputs to the wire 

bundles and control cables routed 

through the floor beams which could 

affect airplane controllability. If not 

corrected, adjacent severed floor beams 

could result in consequent loss of 

controllability, rapid decompression, 

and loss of structural integrity of the 

airplane. 

Related ADs 

As a result of these reports of cracks, 

Boeing issued Alert Service Bulletin 

747–53A2439, dated July 5, 2001. 

Boeing Alert Service Bulletin 747– 

53A2439 provides procedures for an 

open-hole high frequency eddy current 

(HFEC) or surface HFEC inspection to 

find fatigue cracking in the upper chord 

of the upper deck floor beams, and 

applicable related investigative and 

corrective actions. The actions in Boeing 

Alert Service Bulletin 747–53A2439, 

dated July 5, 2001, are required by AD 

2006–08–02, amendment 39–14556 (71 

FR 18618, April 12, 2006). 

In addition, Boeing has received many 

reports of cracks in the upper chords 

and straps (or angles) of the affected 

floor beams at the fastener locations 

where the upper chords attach to the 

body frames. As a result of these reports 

of cracks, Boeing issued Alert Service 

Bulletin 747–53A2420, dated March 26, 

1998; and Boeing Alert Service Bulletin 

747–53A2429, dated March 22, 2001. 

Boeing Alert Service Bulletin 747– 

53A2420 provides procedures for 

detailed and open-hole HFEC 


cprice-sewell on PROD1PC69 with PROPOSALS