20508 Federal Register / Vol. 77, No. 66 / Thursday, April 5, 2012 / Rules and Regulations 

AD: Within 60 months after the effective date 

of this AD, do the actions specified in 

paragraphs (g)(1) and (g)(2) of this AD. 

(1) Replace the power control relays for the 

main tank fuel boost pumps with new relays 

having a ground fault interrupter (GFI) 

feature; do applicable electrical bonding 

resistance measurements between the GFI 

relays and their installation panel to verify 

that applicable bonding requirements are 

met; and do an operational test to ensure 

correct operation; as specified in Boeing 

Service Bulletin 757–28A0078, Revision 2, 

dated January 11, 2012 (for Model 757–200, 

–200CB, and –200PF series airplanes); or 

Boeing Service Bulletin 757–28A0079, 

Revision 2, dated January 11, 2012 (for Model 

757–300 series airplanes). Do all actions in 

accordance with Part 1 of the 

Accomplishment Instructions of Boeing 

Service Bulletin 757–28A0078, Revision 2, 

dated January 11, 2012 (for Model 757–200, 

–200CB, and –200PF series airplanes); or 

Boeing Service Bulletin 757–28A0079, 

Revision 2, dated January 11, 2012 (for Model 

757–300 series airplanes). 

(2) Replace the power control relays for the 

center tank override fuel boost pumps with 

new relays having a GFI feature, in 

accordance with the actions required in 

paragraph (g)(2)(i) or (g)(2)(ii) of this AD. 

(i) Replace the power control relays with 

new relays having a GFI feature; do 

applicable electrical bonding resistance 

measurements between the GFI relays and 

their installation panel to verify that 

applicable bonding requirements are met; 

and do an operational test to ensure correct 

operation; as specified in Boeing Service 

Bulletin 757–28A0078, Revision 2, dated 

January 11, 2012 (for Model 757–200, 

–200CB, and –200PF series airplanes); or 

Boeing Service Bulletin 757–28A0079, 

Revision 2, dated January 11, 2012 (for Model 

757–300 series airplanes). Do all actions in 

accordance with Part 1 of the 

Accomplishment Instructions of Boeing 

Service Bulletin 757–28A0078, Revision 2, 

dated January 11, 2012 (for Model 757–200, 

–200CB, and –200PF series airplanes), or 

Boeing Service Bulletin 757–28A0079, 

Revision 2, dated January 11, 2012 (for Model 

757–300 series airplanes). 

(ii) Install and maintain TDG Aerospace 

universal fault interrupters (UFIs), in 

accordance with a method approved by the 

Manager, Seattle Aircraft Certification Office 

(ACO), FAA. 

Note 1 to paragraph (g)(2)(ii) of this AD: 

Guidance on installing TDG Aerospace UFIs 

can be found in Supplemental Type 

Certificate ST01950LA (http://rgl.faa.gov/

Regulatory_and_Guidance_Library/rgSTC.

nsf/0/196ec7e864607b5b862573c5007cb3b5/

$FILE/ST01950LA.pdf). 

(h) Inspection 

For airplanes on which the actions 

specified in Boeing Alert Service Bulletin 

757–28A0078, dated July 16, 2008, or 757– 

28A0079, dated July 16, 2008, have been 

accomplished before the effective date of this 

AD: Within 60 months after the effective date 

of this AD, do a general visual inspection to 

verify that each GFI installation screw has 

enough grip length to hold the screws in each 

nut plate, and do applicable electrical 

bonding resistance measurements between 

the GFI relays and their installation panel to 

verify that applicable bonding requirements 

are met. If the screw does not have enough 

grip length, before further flight, install a 

longer screw. Do all actions in accordance 

with Part 2 of the Accomplishment 

Instructions of Boeing Service Bulletin 757– 

28A0078, Revision 2, dated January 11, 2012 

(for Model 757–200, –200CB, and –200PF 

series airplanes); or Boeing Service Bulletin 

757–28A0079, Revision 2, dated January 11, 

2012 (for Model 757–300 series airplanes). 

(i) Credit for Previous Actions 

This paragraph provides credit for the 

actions required by this AD, if those actions 

were performed before the effective date of 

this AD using Boeing Service Bulletin 757– 

28A0078 or 757–28A0079, both Revision 1, 

both dated August 24, 2010. 

(j) Alternative Methods of Compliance 

(AMOCs) 

(1) The Manager, Seattle ACO, FAA, has 

the authority to approve AMOCs for this AD, 

if requested using the procedures found in 14 

CFR 39.19. In accordance with 14 CFR 39.19, 

send your request to your principal inspector 

or local Flight Standards District Office, as 

appropriate. If sending information directly 

to the manager of the ACO, send it to the 

attention of the person identified in the 

Related Information section of this AD. 

Information may be emailed to: 9-ANMSeattle-ACO-AMOC-Requests@faa.gov. 

(2) Before using any approved AMOC, 

notify your appropriate principal inspector, 

or lacking a principal inspector, the manager 

of the local flight standards district office/ 

certificate holding district office. 

(k) Related Information 

For more information about this AD, 

contact Georgios Roussos, Aerospace 

Engineer, Systems and Equipment Branch, 

ANM–130S, Seattle ACO, FAA, 1601 Lind 

Avenue SW., Renton, Washington 98057– 

3356; phone: (425) 917–6482; fax: (425) 917– 

6590; email: Georgios.Roussos@faa.gov. Or, 

email information to 9-ANM-Seattle-ACOAMOC-Requests@faa.gov. 

(l) Material Incorporated by Reference 

(1) You must use the following service 

information to do the actions required by this 

AD, unless the AD specifies otherwise. The 

Director of the Federal Register approved the 

incorporation by reference (IBR) under 5 

U.S.C. 552(a) and 1 CFR part 51 of the 

following service information: 

(i) Boeing Service Bulletin 757–28A0078, 

Revision 2, dated January 11, 2012. 

(ii) Boeing Service Bulletin 757–28A0079, 

Revision 2, dated January 11, 2012. 

(2) For service information identified in 

this 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; email me.boecom@boeing.com; 

Internet https://www.myboeingfleet.com. 

(3) You may review copies of the 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. 

(4) You may also review copies of the 

service information that is incorporated by 

reference at the National Archives and 

Records Administration (NARA). For 

information on the availability of this 

material at an NARA facility, 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 March 9, 

2012. 

Ali Bahrami, 

Manager, Transport Airplane Directorate, 

Aircraft Certification Service. 

[FR Doc. 2012–6642 Filed 4–4–12; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2010–0821; Directorate 

Identifier 2010–NE–30–AD; Amendment 39– 

17004; AD 2012–06–23] 

RIN 2120–AA64 

Airworthiness Directives; Rolls-Royce 

plc Turbofan Engines 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Final rule; request for 

comments. 

SUMMARY: We are superseding an 

existing airworthiness directive (AD) for 

all Rolls-Royce plc (RR) RB211–Trent 

875–17, RB211–Trent 877–17, RB211– 

Trent 884–17, RB211–Trent 884B–17, 

RB211–Trent 892–17, RB211–Trent 

892B–17, and RB211–Trent 895–17 

turbofan engines. That AD currently 

requires initial and repetitive ultrasonic 

inspections (UIs) of certain low-pressure 

(LP) compressor blades identified by 

serial number (S/N). This AD requires 

the same actions but expands the 

population of blades. This AD was 

prompted by RR concluding that 

additional blades affected must be 

inspected. We are issuing this AD to 

prevent LP compressor blades from 

failing due to blade root cracks, which 

could lead to uncontained engine failure 

and damage to the airplane. 

DATES: This AD is effective April 20, 

2012. 

The Director of the Federal Register 

approved the incorporation by reference 

of a certain publication listed in the AD 

as of April 20, 2012. 

We must receive any comments on 

this AD by May 21, 2012. 

ADDRESSES: You may send comments by 

any of the following methods: 


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Federal Register / Vol. 77, No. 66 / Thursday, April 5, 2012 / Rules and Regulations 20509 

• 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 AD, contact Rolls-Royce plc, 

Corporate Communications, P.O. Box 

31, Derby, England, DE248BJ, telephone: 

011–44–1332–242424; fax: 011–44– 

1332–245418, or email:http://www.rollsroyce.com/contact/civil_team.jsp. You 

may review copies of the referenced 

service information at the FAA, Engine 

& Propeller Directorate, 12 New England 

Executive Park, Burlington, MA. For 

information on the availability of this 

material at the FAA, call 781–238–7125. 

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 street address for 

the Docket Office (phone: 800–647– 

5527) is in the ADDRESSES section. 

Comments will be available in the AD 

docket shortly after receipt. 

FOR FURTHER INFORMATION CONTACT: 

Alan Strom, Aerospace Engineer, Engine 

Certification Office, FAA, Engine & 

Propeller Directorate, 12 New England 

Executive Park, Burlington, MA 01803; 

phone: 781–238–7143; fax: 781–238– 

7199; email: alan.strom@faa.gov. 

SUPPLEMENTARY INFORMATION: 

Discussion 

On April 1, 2011, we issued AD 2011– 

08–07, Amendment 39–16657 (76 FR 

24798, May 3, 2011), for all RR RB211– 

Trent 875–17, RB211–Trent 877–17, 

RB211–Trent 884–17, RB211–Trent 

884B–17, RB211–Trent 892–17, RB211– 

Trent 892B–17, and RB211–Trent 895– 

17 turbofan engines. On September 9, 

2011, we also issued a correction (76 FR 

59013, September 23, 2011) to that AD. 

That AD requires initial and repetitive 

UIs of certain LP compressor blades 

identified by S/N. That AD resulted 

from mandatory continuing 

airworthiness information (MCAI) 

issued by an aviation authority of 

another country to identify and correct 

an unsafe condition on an aviation 

product. We issued that AD to prevent 

LP compressor blades from failing due 

to blade root cracks, which could lead 

to uncontained engine failure and 

damage to the airplane. 

Actions Since AD Was Issued 

Since we issued AD 2011–08–07 (76 

FR 24798, May 3, 2011), RR determined 

that additional S/Ns of LP compressor 

blades are affected and require 

inspection. EASA has also issued AD 

2012–0025, dated February 8, 2012, to 

expand the population of affected LP 

compressor blades operating in Europe. 

About 2,300 of the added blades require 

inspection within 70 cycles of the 

effective date of the AD since those 

blades have more fatigue damage from 

prior use. 

This superseding AD differs from 

EASA AD 2012–0025. This AD only 

requires inspection of LP compressor 

blades that are listed in Appendices 3A 

through 3G of RR Alert Service Bulletin 

(ASB) No. RB.211–72–AG244, Revision 

4, dated December 22, 2011. We are 

developing another AD to require 

inspection of LP compressor blades 

listed in Appendices 3H through 3L of 

RR ASB No. RB.211–72–AG244, 

Revision 4, dated December 22, 2011. 

Relevant Service Information 

We reviewed Rolls-Royce plc ASB No. 

RB.211–72–AG244, Revision 4, dated 

December 22, 2011. The service 

information describes procedures for 

performing UIs of the LP compressor 

blades. 

FAA’s Determination 

We are issuing this AD because we 

evaluated all the relevant information 

and determined the unsafe condition 

described previously is likely to exist or 

develop in other products of the same 

type design. 

AD Requirements 

This AD requires accomplishing the 

actions specified in the service 

information described previously except 

that this AD only requires inspection of 

LP compressor blades that are listed in 

Appendices 3A through 3G of RR ASB 

No. RB.211–72–AG244, Revision 4, 

dated December 22, 2011. 

FAA’s Justification and Determination 

of the Effective Date 

An unsafe condition exists that 

requires the immediate adoption of this 

AD. The FAA has found that the risk to 

the flying public justifies waiving notice 

and comment prior to adoption of this 

rule because about 2,300 LP compressor 

blades require inspection within 70 

cycles after the effective date of the AD. 

This equates to about one month’s time 

for Trent 800 engines flying two flights 

per day. Therefore, we find that notice 

and opportunity for prior public 

comment are impracticable and that 

good cause exists for making this 

amendment effective in less than 30 

days. 

Comments Invited 

This AD is a final rule that involves 

requirements affecting flight safety, and 

we did not provide you with notice and 

an opportunity to provide your 

comments before it becomes effective. 

However, we invite you to send any 

written data, views, or arguments about 

this AD. Send your comments to an 

address listed under the ADDRESSES

section. Include the docket number 

FAA–2010–0821 and directorate 

identifier 2010–NE–30–AD at the 

beginning of your comments. We 

specifically invite comments on the 

overall regulatory, economic, 

environmental, and energy aspects of 

this AD. We will consider all comments 

received by the closing date and may 

amend this 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 AD. 

Costs of Compliance 

Based on the service information, we 

estimate that this AD will affect about 

158 engines installed on airplanes of 

U.S. registry. We also estimate that it 

will take about 3 hours per engine 

inspection, and six inspections per year. 

The average labor rate is $85 per workhour. We estimate that one LP 

compressor blade per year will need 

replacement, at a cost of about $82,000. 

Based on these figures, we estimate the 

annual cost of the AD on U.S. operators 

to be $323,740. Our cost estimate is 

exclusive of possible warranty coverage. 

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, 


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20510 Federal Register / Vol. 77, No. 66 / Thursday, April 5, 2012 / Rules and Regulations 

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), 

(3) Will not affect intrastate aviation 

in Alaska, and 

(4) 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. 

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 part 39 of the Federal 

Aviation Regulations (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 

removing airworthiness directive (AD) 

2011–08–07, Amendment 39–16657 (76 

FR 24798, May 3, 2011) and adding the 

following new AD: 

2012–06–23 Rolls-Royce plc: Amendment 

39–17004; Docket No. FAA–2010–0821; 

Directorate Identifier 2010–NE–30–AD. 

(a) Effective Date 

This airworthiness directive (AD) becomes 

effective April 20, 2012. 

(b) Affected ADs 

This AD supersedes AD 2011–08–07, 

Amendment 39–16657 (76 FR 24798, May 3, 

2011). 

(c) Applicability 

This AD applies to Rolls-Royce plc (RR) 

RB211–Trent 875–17, RB211–Trent 877–17, 

RB211–Trent 884–17, RB211–Trent 884B–17, 

RB211–Trent 892–17, RB211–Trent 892B–17, 

and RB211–Trent 895–17 turbofan engines. 

(d) Unsafe Condition 

This AD was prompted by the 

determination by RR that additional serial 

numbers (S/Ns) of low-pressure (LP) 

compressor blades are affected and need to 

be inspected. We are issuing this AD to 

prevent LP compressor blades from failing 

due to blade root cracks, which could lead 

to uncontained engine failure and damage to 

the airplane. 

(e) Actions and Compliance 

Unless already done, do the following 

actions. 

(1) Perform an initial ultrasonic inspection 

(UI) of the affected LP compressor blades 

identified by S/N in Appendices 3A through 

3G of RR Alert Service Bulletin (ASB) No. 

RB.211–72–AG244, Revision 4, dated 

December 22, 2011. Use Table 1 of this AD 

to determine your initial inspection 

threshold. 

TABLE 1—INITIAL INSPECTION THRESHOLDS

Appendix number of RR ASB No. RB.211–72–AG244, revision 4, that 

identifies affected LP compressor blades by S/N Initial inspection threshold 

3A and 3B ................................................................................................. Within 70 flight cycles after the effective date of this AD. 

3C ............................................................................................................. Within 10 months after the effective date of this AD. 

3D ............................................................................................................. Within 22 months after the effective date of this AD. 

3E ............................................................................................................. Within 34 months after the effective date of this AD. 

3F .............................................................................................................. Within 46 months after the effective date of this AD. 

3G ............................................................................................................. Within 58 months after the effective date of this AD. 

(2) Thereafter, perform repetitive UIs of the 

affected LP compressor blades within every 

100 flight cycles. 

(3) Use paragraphs 3.A.(1) through 3.A.(2) 

of Accomplishment Instructions of RR ASB 

No. RB.211–72–AG244, Revision 4, dated 

December 22, 2011, and paragraphs 1 

through 3.B. of Appendix 1 of that ASB, or 

paragraphs 3.B.(1) through 3.B.(3) of 

Accomplishment Instructions of RR ASB No. 

RB.211–72–AG244, Revision 4, dated 

December 22, 2011, and paragraphs 1 

through 3.C. of Appendix 2 of that ASB, to 

perform the UIs. 

(4) Do not return to service any engine with 

blades that failed the inspection required by 

this AD. 

(5) For blades that are removed from the 

engine and pass inspection, re-apply dry film 

lubricant, and install all blades in their 

original position. 

(6) After the effective date of this AD, do 

not install any affected LP compressor blade 

unless it has passed the initial and repetitive 

UIs required by this AD. 

(f) Credit for Previous Actions 

You may take credit for the initial 

inspection that is required by paragraph 

(e)(1) of this AD if you performed the initial 

inspection before the effective date of this AD 

using RR ASB No. RB.211–72–AG244, dated 

August 7, 2009; ASB No. RB.211–72–AG244, 

Revision 1, dated January 26, 2010; ASB No. 

RB.211–72–AG244, Revision 2, dated August 

18, 2011; or ASB No. RB.211–72–AG244, 

Revision 3, dated December 13, 2011. 

(g) FAA AD Differences 

This AD differs from EASA AD 2012–0025, 

dated February 8, 2012. That AD requires 

inspecting LP compressor blades that are 

listed in Appendices 3A through 3L of RR 

ASB No. RB.211–72–AG244, Revision 4, 

dated December 22, 2011, whereas this AD 

only requires inspection of LP compressor 

blades that are listed in Appendices 3A 

through 3G of the ASB. 

(h) Alternative Methods of Compliance 

The Manager, Engine Certification Office, 

FAA, may approve AMOCs for this AD. Use 

the procedures found in 14 CFR 39.19 to 

make your request. 

(i) Related Information 

(1) For more information about this AD, 

contact Alan Strom, Aerospace Engineer, 

Engine Certification Office, FAA, Engine & 

Propeller Directorate, 12 New England 

Executive Park, Burlington, MA 01803; 

phone: 781–238–7143; fax: 781–238–7199; 

email: alan.strom@faa.gov. 

(2) Refer to EASA AD 2012–0025, dated 

February 8, 2012, for related information. 

(j) Material Incorporated by Reference 

(1) You must use Rolls-Royce plc Alert 

Service Bulletin No. RB.211–72–AG244, 

Revision 4, dated December 22, 2011, 


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Federal Register / Vol. 77, No. 66 / Thursday, April 5, 2012 / Rules and Regulations 20511 

Appendix 1, Appendix 2, and Appendices 

3A through 3G of that ASB, to do the actions 

required by this AD, unless the AD specifies 

otherwise. The Director of the Federal 

Register approved the incorporation by 

reference under 5 U.S.C. 552(a) and 1 CFR 

part 51. 

(2) For service information identified in 

this AD, contact Rolls-Royce plc, Corporate 

Communications, P.O. Box 31, Derby, 

England, DE248BJ, telephone: 011–44–1332– 

242424; fax: 011–44–1332–245418, or email: 

http://www.rolls-royce.com/contact/ 

civil_team.jsp. 

(3) You may review copies of the service 

information at the FAA, Engine & Propeller 

Directorate, 12 New England Executive Park, 

Burlington, MA. For information on the 

availability of this material at the FAA, call 

781–238–7125. 

(4) You may also review copies of the 

service information that is incorporated by 

reference 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 Burlington, Massachusetts, on 

March 20, 2012. 

Peter A. White, 

Manager, Engine & Propeller Directorate, 

Aircraft Certification Service. 

[FR Doc. 2012–8163 Filed 4–4–12; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2010–0858; Directorate 

Identifier 2010–NM–183–AD; Amendment 

39–16974; AD 2012–05–02] 

RIN 2120–AA64 

Airworthiness Directives; The Boeing 

Company Airplanes 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Final rule. 

SUMMARY: We are adopting a new 

airworthiness directive (AD) for certain 

The Boeing Company Model 737–600, 

–700, –700C, –800, and –900 series 

airplanes. This AD was prompted by 

reports of heat damage to the inner wall 

of the thrust reversers, which could 

result in separation of adjacent 

components and consequent structural 

damage to the airplane, damage to other 

airplanes, and injury to people on the 

ground. This AD requires modifying the 

thrust reverser inner walls, inspecting 

for damage of the upper and lower inner 

wall insulation blankets, measuring the 

electrical conductivity on the aluminum 

upper compression pads 2 and 3 as 

applicable, inspecting for discrepancies 

of the inner wall of the thrust reverser, 

and corrective actions if necessary. This 

AD also requires, for certain airplanes, 

doing various concurrent actions 

(including replacing the inner wall 

blanket insulation, installing updated 

full-authority digital electronic control 

software, and modifying the thrust 

reverser inner wall and insulation 

blankets). We are issuing this AD to 

correct the unsafe condition on these 

products. 

DATES: This AD is effective May 10, 

2012. 

The Director of the Federal Register 

approved the incorporation by reference 

of certain publications listed in the AD 

as of May 10, 2012. 

ADDRESSES: For Boeing service 

information identified in this 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; email 

me.boecom@boeing.com; Internet 

https://www.myboeingfleet.com. For 

CFM service information identified in 

this AD, contact CFM International, 

Technical Publications Department, 1 

Neumann Way, Cincinnati, Ohio 45215; 

phone: 513–552–2800; fax: 513–552– 

2816; Internet: http://www.cfm56.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. 

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 (phone: 800–647–5527) is 

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: 

Chris Parker, Aerospace Engineer, 

Propulsion Branch, ANM–140S, FAA, 

Seattle Aircraft Certification Office 

(ACO), 1601 Lind Avenue SW., Renton, 

Washington 98057–3356; phone: 425– 

917–6496; fax: 425–917–6590; email: 

chris.r.parker@faa.gov. 

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 The 

Boeing Company Model 737–600, –700, 

–700C, –800, –900, and –900ER series 

airplanes. That NPRM was published in 

the Federal Register on September 27, 

2010 (75 FR 59167). That NPRM 

proposed to require modifying the inner 

walls of the thrust reverser (TR), 

inspecting for damage of the upper and 

lower inner wall insulation blankets, 

measuring the electrical conductivity on 

the aluminum upper compression pads 

2 and 3 as applicable, inspecting for 

discrepancies of the TR inner wall, and 

corrective actions if necessary. That 

NPRM also proposed to require, for 

certain airplanes, doing various 

concurrent actions (including replacing 

the inner wall blanket insulation, 

installing updated full-authority digital 

electronic control software, and 

modifying the TR inner wall and 

insulation blankets). 

Comments 

We gave the public the opportunity to 

participate in developing this AD. The 

following presents the comments 

received on the proposal (75 FR 59167, 

September 27, 2010) and the FAA’s 

response to each comment. 

Request To Withdraw NPRM (75 FR 

59167, September 27, 2010) 

Despite fully supporting the 

implementation of the actions of the 

NPRM (75 FR 59167, September 27, 

2010), Boeing stated that it does not 

consider thermal overheat on the TR 

inner walls on the affected airplanes to 

be a safety issue. The structural integrity 

of the inner wall may deteriorate due to 

pre-cooler air ingress behind the 

blankets, but the Boeing Safety Review 

Board determined that this does not 

constitute a safety hazard to the airplane 

or to persons on the ground. Boeing 

identified support data for this 

determination, which included a safety 

assessment, full-scale test 

demonstration, and structural analysis. 

We infer that Boeing wants us to 

withdraw the NPRM (75 FR 59167, 

September 27, 2010), because there is no 

unsafe condition. We disagree. The 

thermal overheat could affect the 

structural capability of the inner wall of 

the thrust reverser such that, if a 

pneumatic duct bursts, the inner wall 

could fail, causing uncontrollable 

asymmetric thrust during a rejected 

takeoff, or causing large parts to hit the 

fuselage or empennage in flight. 


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