This section of the FEDERAL REGISTER

contains regulatory documents having general

applicability and legal effect, most of which

are keyed to and codified in the Code of

Federal Regulations, which is published under

50 titles pursuant to 44 U.S.C. 1510.

The Code of Federal Regulations is sold by

the Superintendent of Documents. Prices of

new books are listed in the first FEDERAL

REGISTER issue of each week.

Rules and Regulations Federal Register

24793 

Vol. 76, No. 85 

Tuesday, May 3, 2011 

DEPARTMENT OF AGRICULTURE 

Animal and Plant Health Inspection 

Service 

9 CFR Parts 93, 94, and 95 

[Docket No. APHIS–2006–0074] 

RIN 0579–AC36 

Highly Pathogenic Avian Influenza 

AGENCY: Animal and Plant Health 

Inspection Service, USDA. 

ACTION: Interim rule; reopening of 

comment period. 

SUMMARY: We are reopening the 

comment period for our interim rule 

that amended the regulations 

concerning the importation of animals 

and animal products to prohibit or 

restrict the importation of bird and 

poultry products from regions where 

any subtype of highly pathogenic avian 

influenza is considered to exist. The 

interim rule also imposed restrictions 

concerning importation of live poultry 

and birds that have been vaccinated for 

certain types of avian influenza, or that 

have moved through regions where any 

subtype of highly pathogenic avian 

influenza is considered to exist. This 

action will allow interested persons 

additional time to prepare and submit 

comments. 

DATES: We will consider all comments 

that we receive on or before May 18, 

2011. 

ADDRESSES: You may submit comments 

by either of the following methods: 

• Federal eRulemaking Portal: Go to 

http://www.regulations.gov/fdmspublic/ 

component/ 

main?main=DocketDetail&d=APHIS– 

2006–0074 to submit or view comments 

and to view supporting and related 

materials available electronically. 

• Postal Mail/Commercial Delivery: 

Please send one copy of your comment 

to Docket No. APHIS–2006–0074, 

Regulatory Analysis and Development, 

PPD, APHIS, Station 3A–03.8, 4700 

River Road Unit 118, Riverdale, MD 

20737–1238. Please state that your 

comment refers to Docket No. APHIS– 

2006–0074. 

Reading Room: You may read any 

comments that we receive on this 

docket in our reading room. The reading 

room is located in room 1141 of the 

USDA South Building, 14th Street and 

Independence Avenue, SW., 

Washington, DC. Normal reading room 

hours are 8 a.m. to 4:30 p.m., Monday 

through Friday, except holidays. To be 

sure someone is there to help you, 

please call (202) 690–2817 before 

coming. 

Other Information: Additional 

information about APHIS and its 

programs is available on the Internet at 

http://www.aphis.usda.gov. 

FOR FURTHER INFORMATION CONTACT: Dr. 

Julia Punderson, Senior Staff 

Veterinarian, National Center for Import 

and Export, Animal Health Policy and 

Programs, VS, APHIS, 4700 River Road 

Unit 38, Riverdale, MD 20737; (301) 

734–4356. 

SUPPLEMENTARY INFORMATION: 

Background 

On January 24, 2011, we published in 

the Federal Register (76 FR 4046–4056, 

Docket No. APHIS–2006–0074) an 

interim rule that amended the 

regulations governing the importation 

into the United States of specified 

animals and animal products and 

byproducts in order to prohibit or 

restrict the importation of bird and 

poultry products from regions where 

any subtype of highly pathogenic avian 

influenza is considered to exist. The 

interim rule was effective upon 

publication. 

Comments on the interim rule were 

required to be received on or before 

March 25, 2011. We are reopening the 

comment period on Docket No. APHIS– 

2006–0074 for an additional 15 days. 

This action will allow interested 

persons additional time to prepare and 

submit comments. We will also consider 

all comments received between March 

26, 2011, and the date of this notice. 

Authority: 7 U.S.C. 450, 1622, 7701–7772, 

7781–7786, and 8301–8317; 21 U.S.C. 136 

and 136a; 31 U.S.C. 9701; 7 CFR 2.22, 2.80, 

and 371.4. 

Done in Washington, DC, this 28th day of 

April 2011. 

Gregory L. Parham, 

Administrator, Animal and Plant Health 

Inspection Service. 

[FR Doc. 2011–10715 Filed 5–2–11; 8:45 am] 

BILLING CODE 3410–34–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2010–0562; Directorate 

Identifier 2009–NE–29–AD; Amendment 39– 

16669; AD 2011–09–07] 

RIN 2120–AA64 

Airworthiness Directives; Rolls-Royce 

plc (RR) RB211–524 Series and RB211 

Trent 500, 700, and 800 Series 

Turbofan Engines 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Final rule. 

SUMMARY: We are adopting a new 

airworthiness directive (AD) for the 

products listed above. This AD results 

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. The MCAI describes the unsafe 

condition as: 

During manufacture of a number of HP 

Compressor Stage 1 and 2 discs with axial 

dovetail slots, anomalies at the disc post 

corners have been found. Fatigue crack 

initiation and subsequent crack propagation 

at the disc post may result in release of two 

blades and the disc post. This may 

potentially be beyond the containment 

capabilities of the engine casings. Thus, these 

anomalies present at the disc posts constitute 

a potentially unsafe condition. 

We are issuing this AD to detect 

cracks in the high-pressure compressor 

(HPC) Stage 1 and 2 disc posts, which 

could result in failure of the disc post 

and release of HPC blades, release of 

uncontained engine debris, and damage 

to the airplane. 

DATES: This AD becomes effective June 

7, 2011. The Director of the Federal 

Register approved the incorporation by 

reference of certain publications listed 

in this AD as of June 7, 2011. 

ADDRESSES: The Docket Operations 

office is located at Docket Management 
24794 Federal Register / Vol. 76, No. 85 / Tuesday, May 3, 2011 / Rules and Regulations 

Facility, U.S. Department of 

Transportation, 1200 New Jersey 

Avenue, SE., West Building Ground 

Floor, Room W12–140, Washington, DC 

20590–0001. 

FOR FURTHER INFORMATION CONTACT: 

Alan Strom, Aerospace Engineer, Engine 

Certification Office, FAA, Engine and 

Propeller Directorate, 12 New England 

Executive Park, Burlington, MA 01803; 

e-mail: alan.strom@faa.gov; telephone 

(781) 238–7143; fax (781) 238–7199. 

SUPPLEMENTARY INFORMATION: 

Discussion 

We issued a notice of proposed 

rulemaking (NPRM) to amend 14 CFR 

part 39 to include an AD that would 

apply to the specified products. That 

NPRM was published in the Federal 

Register on June 15, 2010 (75 FR 33738). 

That NPRM proposed to correct an 

unsafe condition for the specified 

products. The MCAI states that: 

During manufacture of a number of HP 

Compressor Stage 1 and 2 discs with axial 

dovetail slots, anomalies at the disc post 

corners have been found. Fatigue crack 

initiation and subsequent crack propagation 

at the disc post may result in release of two 

blades and the disc post. This may 

potentially be beyond the containment 

capabilities of the engine casings. Thus, these 

anomalies present at the disc posts constitute 

a potentially unsafe condition. 

For the reasons described above, this AD 

requires repetitive inspections of the axial 

dovetail slots and follow-on corrective 

action, depending on findings. 

Comments 

We gave the public the opportunity to 

participate in developing this AD. We 

considered the comments received. 

Request To Change the Definition of a 

Shop Visit 

Five commenters request that we 

change the criteria for carrying out the 

inspections to be consistent with the 

European Aviation Safety Agency 

(EASA) AD. The commenters ask that 

we require performing the inspections at 

the first shop visit after accumulating 

1,000 hours-since-new (HSN) and 

whenever a Level 3 (Refurbishment) or 

Level 4 (Overhaul) shop visit occurs. 

The commenters feel that requiring the 

inspections any time a major flange is 

separated would result in more 

inspections than required by the EASA 

AD. Some of the inspections would cost 

significantly more than what is 

estimated in the Costs of Compliance 

section of the proposed AD. 

We partially agree. We agree that the 

current wording would result in more 

inspections than required by the EASA 

AD, and some of the inspections would 

cost significantly more than what we 

estimated in the Costs of Compliance 

section of the proposed AD. We do not 

agree with using the Level 3 or Level 4 

criteria as a definition of ‘‘engine shop 

visit’’ for the purpose of this AD. The 

definitions of Level 3 and Level 4 are 

not specific enough to ensure the 

inspections are conducted frequently 

enough to prevent the unsafe condition. 

We changed the definition of shop visit 

in paragraph (f) of the proposed AD 

from ‘‘For * * * an ‘‘engine shop visit’’ 

is the induction of an engine into the 

shop for maintenance involving the 

separation of pairs of major mating 

engine flanges, * * *’’ to ‘‘For * * * an 

‘‘engine shop visit’’ is whenever the 

engine high-pressure compressor 

module is separated from the 

intermediate case.’’ 

Request To Change the Summary of the 

Proposed AD 

One commenter, RR, asks us to 

consider changing the Summary from 

‘‘Thus, these anomalies present at the 

disc posts constitute a potentially 

unsafe condition’’ to ‘‘Thus, if these 

anomalies are present at the disc posts, 

they constitute a potentially unsafe 

condition.’’ The commenter believes that 

the MCAI description implies that all 

discs have the anomalies in question. 

The AD does not assume that to be true. 

We don’t agree. The second paragraph 

of the Summary quotes the EASA AD. 

We did not change the AD. 

Request To Correct a Disc Part Number 

The same commenter asks us to 

change paragraph (c)(1) part number (P/ 

N) ‘‘FK20195’’ to ‘‘FW20195.’’ The 

commenter states that the NPRM 

contains a typographical error. 

We agree. We changed the part 

number in paragraph (c)(1) of the 

proposed AD from ‘‘FK20195’’ to 

‘‘FW20195.’’ 

Request To Change the Unsafe 

Condition Statement 

The same commenter asks us to 

change the unsafe condition statement 

in the Summary and in paragraph (d) of 

the proposed AD from ‘‘* * * failure of 

the disc post, which could result in 

failure of the disc post and HPC blades, 

release * * * airplane’’ to ‘‘* * * failure 

of the disc post, resulting in release of 

HPC blades, release * * * airplane.’’ 

The commenter states the NPRM 

implies that high-pressure compressor 

blades may themselves fail, when in fact 

they are released as a result of disk post 

failure. 

We agree. We changed the unsafe 

condition statement in the Summary 

and in paragraph (d) of the proposed AD 

to ‘‘which could result in failure of the 

disc post, release of HPC blades, release 

of uncontained debris, * * * airplane.’’ 

Request To Ensure the Disc is Cleaned 

before Inspection 

The same commenter asks us to 

change paragraph (e)(1) of the proposed 

AD from ‘‘Perform a * * * later. Use 

paragraph 3.E.(1) through 3.E.(10)(i) 

* * * inspections’’ to ‘‘Clean and 

perform * * * later. Use paragraph 3.A 

through 3.E.(10)(i) * * * inspections.’’ 

The commenter believes the change will 

ensure adequate cleaning before 

inspection, which is essential to make 

sure the small cracks are visible. 

We agree. Because the corrective 

action is looking for small cracks 

underneath a dry film lubricant coating, 

the cleaning procedure prior to 

fluorescent penetrant inspection (FPI) is 

critical to the corrective action. We 

changed paragraph (e)(1) of the 

proposed AD to ‘‘Clean and perform 

* * * later. Use paragraph 3.A through 

3.E.(11) * * * inspections.’’ We also 

added paragraph 3.E.(11) to ensure that 

the blades will be re-coated prior to reinstallation. 

Request To Change Nomenclature of 

HPC Rotor Shaft 

One commenter, Hawaiian Airlines, 

asks us to change ‘‘HPC rotor shaft’’ to 

‘‘HP compressor drum.’’ The commenter 

states that the HPC drum in the Trent 

700 engine is a six stage rotor and is 

referred to as the ‘‘HPC rotor shaft.’’ 

Since each engine model has different 

nomenclature, they request that we use 

a common name when we refer to the 

subject part such as ‘‘HP compressor 

Drum.’’ The commenter believes that 

this will ensure a common 

understanding of the parts involved. 

We don’t agree. While the service 

bulletin uses the term ‘‘HPC drum,’’ the 

AD consistently refers to the HPC disks 

by stage number. 

Conclusion 

We reviewed the available data, 

including the comments received, and 

determined that air safety and the 

public interest require adopting the AD 

with the changes described previously. 

We determined that these changes will 

not increase the economic burden on 

any operator or increase the scope of the 

AD. 

Costs of Compliance 

Based on the service information, we 

estimate that this AD would affect about 

371 products of U.S. registry. We also 

estimate that it would take about 20 

work-hours per product to comply with 

this AD. The average labor rate is $85 

per work-hour. No parts would be 
Federal Register / Vol. 76, No. 85 / Tuesday, May 3, 2011 / Rules and Regulations 24795 

required per product. Based on these 

figures, we estimate the cost of the AD 

on U.S. operators to be $630,700. 

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 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 this AD: 

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 AD and placed it in the AD docket. 

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 AD, the regulatory 

evaluation, any comments received, and 

other information. The street address for 

the Docket Operations office (phone 

(800) 647–5527) is provided in the 

ADDRESSES section. Comments will be 

available in the AD docket shortly after 

receipt. 

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 FAA amends § 39.13 by adding 

the following new AD: 

2011–09–07 Rolls-Royce plc (RR): 

Amendment 39–16669. Docket No. 

FAA–2010–0562; Directorate Identifier 

2009–NE–29–AD. 

Effective Date 

(a) This airworthiness directive (AD) 

becomes effective June 7, 2011. 

Affected ADs 

(b) None. 

Applicability 

(c) This AD applies to RR model RB211– 

524G2–T–19, –524G3–T–19, –524H–T–36, 

and –524H2–T–19; and RB211 Trent 553–61, 

553A2–61, 556–61, 556A2–61, 556B–61, 

556B2–61, 560–61, 560A2–61; RB211 Trent 

768–60, 772–60, 772B–60; and RB211 Trent 

875–17, 877–17, 884–17, 884B–17, 892–17, 

892B–17, and 895–17 turbofan engines that 

have a high-pressure (HP) compressor stage 

1 to 4 rotor disc with a part number (P/N) 

listed in Table 1 of this AD. These engines 

are installed on, but not limited to, Boeing 

747, 767, and 777 series airplanes and Airbus 

A330 and A340 series airplanes. 

TABLE 1—AFFECTED HP COMPRESSOR STAGE 1 TO 4 ROTOR DISC P/NS BY ENGINE MODEL

Engine model HP compressor stage 1 to 4 rotor disc P/N 

(1) RB211–524G2–T–19, –524G3–T–19, –524H–T–36, and –524H2– 

T–19.

FW20195, FK25502, or FW23711. 

(2) RB211 Trent 553–61, 553A2–61, 556–61, 556A2–61, 556B–61, 

556B2–61, 560–61, and 560A2–61.

FK30524. 

(3) RB211 Trent 768–60, 772–60, and 772B–60 .................................... FK22745, FK24031, FK26185, FK23313, FK25502, FK32129, 

FW20195, FW20196, FW20197, FW20638, or FW23711. 

(4) RB211 Trent 875–17, 877–17, 884–17, 884B–17, 892–17, 892B– 

17, and 895–17.

FK24009, FK26167, FK32580, FW11590, or FW61622. 

Reason 

(d) This AD results from reports that: 

During manufacture of a number of HP 

Compressor Stage 1 and 2 discs with axial 

dovetail slots, anomalies at the disc post 

corners have been found. Fatigue crack 

initiation and subsequent crack propagation 

at the disc post may result in release of two 

blades and the disc post. This may 

potentially be beyond the containment 

capabilities of the engine casings. Thus, these 

anomalies present at the disc posts constitute 

a potentially unsafe condition. 

We are issuing this AD to detect cracks in the 

high-pressure compressor (HPC) Stage 1 and 

2 disc posts, which could result in failure of 

the disc post and release of HPC blades, 

release of uncontained engine debris, and 

damage to the airplane. 

Actions and Compliance 

(e) Unless already done, do the following 

actions. 

(1) Clean and perform a fluorescent 

penetrant inspection of the HP compressor 

stage 1 to 4 rotor discs at the first shop visit 

after accumulating 1000 cycles since new on 

the stage 1 to 4 rotor disks or at the next shop 

visit after the effective date of this AD, 

whichever occurs later. Use paragraph 3.A 

through 3.E.(11) of the Accomplishment 

Instructions of Rolls-Royce Alert Service 

Bulletin (ASB) RB.211–72–AF964, Revision 

1, dated June 6, 2008 to do the inspections. 

(2) Thereafter at every engine shop visit, 

perform the inspection specified by 

paragraph (e)(1) of this AD. 

Definitions 

(f) For the purpose of this AD, an ‘‘engine 

shop visit’’ is whenever the engine highpressure compressor module is separated 

from the intermediate case. 

Other FAA AD Provisions 

(g) Alternative Methods of Compliance 

(AMOCs): The Manager, Engine Certification 

Office, FAA, has the authority to approve 
24796 Federal Register / Vol. 76, No. 85 / Tuesday, May 3, 2011 / Rules and Regulations 

AMOCs for this AD, if requested using the 

procedures found in 14 CFR 39.19. 

Related Information 

(h) See European Aviation Safety Agency 

Airworthiness Directive 2009–0073R1, dated 

April 8, 2009, for related information. 

(i) Contact Alan Strom, Aerospace 

Engineer, Engine Certification Office, FAA, 

Engine and Propeller Directorate, 12 New 

England Executive Park, Burlington, MA 

01803; e-mail: alan.strom@faa.gov; telephone 

(781) 238–7143; fax (781) 238–7199, for more 

information about this AD. 

Material Incorporated by Reference 

(j) You must use Rolls-Royce Alert Service 

Bulletin RB.211–72–AF964, Revision 1, 

dated June 6, 2008, to do the actions required 

by this AD, unless the AD specifies 

otherwise. 

(1) The Director of the Federal Register 

approved the incorporation by reference of 

this service information under 5 U.S.C. 

552(a) and 1 CFR part 51. 

(2) For service information identified in 

this AD, contact Rolls-Royce plc, P.O. Box 

31, Derby, DE24 8BJ, United Kingdom; 

phone: 011 44 1332 242424, fax: 011 44 1332 

249936; e-mail: tech.help@rolls-royce.com. 

(3) You may review copies at the FAA, 

New England Region, 12 New England 

Executive Park, Burlington, MA; 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/ibrlocations.html. 

Issued in Burlington, Massachusetts, on 

April 12, 2011. 

Peter A. White, 

Acting Manager, Engine and Propeller 

Directorate, Aircraft Certification Service. 

[FR Doc. 2011–10517 Filed 5–2–11; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2008–1165; Directorate 

Identifier 2008–NE–38–AD; Amendment 39– 

16685; AD 2011–10–04] 

RIN 2120–AA64 

Airworthiness Directives; Rolls-Royce 

plc RB211–Trent 800 Series Turbofan 

Engines 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Final rule. 

SUMMARY: We are adopting a new 

airworthiness directive (AD) for the 

products listed above. This AD results 

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. The MCAI describes the unsafe 

condition as: 

During manufacture of high-pressure (HP) 

compressor stage 1 discs, a small number of 

parts have been rejected due to a machining 

defect that was found during inspection. 

Analysis of the possibility of less severe 

examples having been undetected and passed 

into service has concluded that action is 

required to reduce the risk of failure. It was 

therefore necessary to reduce the life limit. 

The HP compressor stage 1 disc is part 

of the HP compressor stage 1–4 shaft, 

part number (P/N) FK32580. We are 

issuing this AD to prevent failure of the 

HP compressor stage 1 disc, 

uncontained engine failure, and damage 

to the airplane. 

DATES: This AD becomes effective June 

7, 2011. 

ADDRESSES: The Docket Operations 

office is located at Docket Management 

Facility, U.S. Department of 

Transportation, 1200 New Jersey 

Avenue, SE., West Building Ground 

Floor, Room W12–140, Washington, DC 

20590–0001. 

FOR FURTHER INFORMATION CONTACT: 

Alan Strom, Aerospace Engineer, Engine 

Certification Office, FAA, Engine & 

Propeller Directorate, 12 New England 

Executive Park, Burlington, MA 01803; 

e-mail: alan.strom@faa.gov; telephone 

(781) 238–7143; fax (781) 238–7199. 

SUPPLEMENTARY INFORMATION: 

Discussion 

We issued a notice of proposed 

rulemaking (NPRM) and a supplemental 

notice of proposed rulemaking (SNPRM) 

to amend 14 CFR part 39 to include an 

AD that would apply to the specified 

products. That NPRM was published in 

the Federal Register on February 18, 

2009 (74 FR 7563) and that SNPRM was 

published in the Federal Register on 

October 4, 2010 (75 FR 61114). That 

SNPRM proposed to correct an unsafe 

condition for the specified products. 

The MCAI states that: 

During manufacture of high-pressure (HP) 

compressor stage 1 discs, a small number of 

parts have been rejected due to a machining 

defect that was found during inspection. 

Analysis of the possibility of less severe 

examples having been undetected and passed 

into service has concluded that action is 

required to reduce the risk of failure. It was 

therefore necessary to reduce the life limit. 

The HP compressor stage 1 disc is 

part of the HP compressor stage 1–4 

shaft, P/N FK32580. Since we issued the 

original NPRM on February 10, 2009 

(74 FR 7563, February 18, 2009), EASA 

issued AD 2010–0087, dated May 5, 

2010 (corrected May 6, 2010), which 

retains certain requirements of 

superseded EASA AD 2008–0099, and 

imposes more restrictive life limits in 

the Heavy Flight Profile Parts. You may 

obtain further information by examining 

the MCAI in the AD docket. 

Comments 

We gave the public the opportunity to 

participate in developing this AD. We 

considered the comments received. 

Request To Revise the Compliance 

Times 

Four commenters, American Airlines, 

Delta Airlines, Rolls-Royce plc, and The 

Boeing Company, request that we revise 

the compliance times to be consistent 

with the service bulletin and the 

airworthiness limitations section (ALS) 

of the engine manual. Doing this would 

account for the later AD release date and 

for the entire Trent 800 series fleet 

instead of just certain US operators’ 

expected cyclic usage. The commenters 

state that the proposed requirements 

would have a severe adverse economic 

impact to operators relative to the 

service bulletin requirements. The 

simplified compliance requirements in 

the SNPRM relative to the service 

bulletin requirements, may not 

accurately reflect the risk of an 

uncontained event, and are confusing. 

We do not agree. The requirements in 

the SNPRM were developed to 

minimize the risk of uncontained disc 

failure, based on the age of the parts in 

the field at the time the SNPRM was 

issued. The service bulletin 

requirements were developed at a time 

when the age of the parts in service was 

lower than when the SNPRM was 

issued. Because the risk of failure 

increases as the age of the parts in the 

field increase, any revision to the 

requirements of the SNPRM would 

again have to take the increased age of 

the parts in service into account. As 

such, an analysis would result in 

removal requirements more stringent 

than the requirements in the SNPRM, 

and a follow-on NPRM would be 

required. Therefore, we determined that 

it is in the public interest to keep the 

removal requirements the same as 

published in the SNPRM. We did not 

change the AD. 

Request for Clarity and Interpretation 

Delta Airlines states that it would be 

helpful if we could provide some clarity 

in the AD as to how an operator should 

interpret the differing information 

between the AD, the ALS of the RollsRoyce Time Limits Manual, and the 

service bulletin. The commenter is 

concerned that there will be three 

locations where the life limit of the