Federal Register / Vol. 76, No. 102 / Thursday, May 26, 2011 / Rules and Regulations 30529 

mode that is shown to be a stable limit 

cycle oscillation (LCO), with the system 

operative and inoperative. (An LCO is 

considered ‘‘stable’’ if it maintains the 

same frequency and amplitude for a 

given excitation input and flight 

condition.) In addition, the type of 

sustained oscillation covered by these 

special conditions must not be a hazard 

to the airplane nor its occupants with 

the active system failed. These systems 

must be shown to reduce the amplitude 

of the sustained oscillation to acceptable 

levels and effectively control the 

aeroelastic instability. Specifically, the 

following criteria address the existence 

of such a sustained oscillation on the 

Boeing Model 747–8/–8F airplanes and 

the Outboard Aileron Modal 

Suppression (OAMS) system that will 

be used to control it. 

2. In lieu of the requirements 

contained in § 25.629, the existence of a 

sustained, or limit cycle, oscillation that 

is controlled by an active flight control 

system is acceptable, provided that the 

following requirements are met: 

(a) OAMS System Inoperative: The 

sustained, or limit cycle, oscillation 

must be shown by test and analysis to 

be stable throughout the nominal 

aeroelastic stability envelope specified 

in § 25.629(b)(1) with the OAMS system 

inoperative. This should include the 

consideration of disturbances above the 

sustained amplitude of oscillation. 

(b) Nominal Conditions: 

(1) With the OAMS system operative 

it must be shown that the airplane 

remains safe, stable, and controllable 

throughout the nominal aeroelastic 

stability envelope specified in 

§ 25.629(b)(1) by providing adequate 

suppression of the aeroelastic modes 

being controlled. All applicable 

airworthiness and environmental 

requirements should continue to be 

complied with. Additionally, loads 

imposed on the airplane due to any 

amplitude of oscillation must be shown 

to have a negligible impact on structure 

and systems, including wear, fatigue 

and damage tolerance. The OAMS 

system must function properly in all 

environments that may be encountered. 

(2) The applicant must establish by 

test and analysis that the OAMS system 

can be relied upon to control and limit 

the sustained amplitude of the 

oscillation to acceptable levels (per 

§ 25.251) and control the stability of the 

aeroelastic mode. This should include 

the consideration of disturbances above 

the sustained amplitude of oscillation; 

maneuvering flight, icing conditions; 

manufacturing variations; Master 

Minimum Equipment List (MMEL) 

items; spare engine carriage; engine 

removed or inoperative ferry flights; and 

wear, repairs, and modifications 

throughout the service life of the 

airplane by: 

(i) Analysis to the nominal aeroelastic 

stability envelope specified in 

§ 25.629(b)(1), and 

(ii) Flight flutter test to the VDF/MDF

boundary. These tests must demonstrate 

that the airplane has a proper margin of 

damping for disturbances above the 

sustained amplitude of oscillation at all 

speeds up to VDF/MDF, and that there is 

no large and rapid reduction in damping 

as VDF/MDF is approached. 

(iii) The structural modes must have 

adequate stability margins for any 

OAMS flight control system feedback 

loop at speeds up to the fail-safe 

aeroelastic stability envelope specified 

in § 25.629(b)(2). 

(c) Failures, Malfunctions, and 

Adverse Conditions: 

(1) For the OAMS system operative 

and failed, for any failure, or 

combination of failures not shown to be 

extremely improbable, and addressed by 

§§ 25.629(d), 25.571, 25.631, 25.671, 

25.672, 25.901(c) or 25.1309 that results 

in LCO, it must be established by test or 

analysis up to the aeroelastic stability 

envelope specified in § 25.629(b)(2) that 

the LCO: 

(i) Is stable and decays to an 

acceptable limited amplitude once an 

external perturbing force is removed; 

(ii) Does not result in loads that 

would cause static, dynamic, or fatigue 

failure of structure during the expected 

exposure period; 

(iii) Does not result in repeated loads 

that would cause an additional failure 

due to wear during the expected 

exposure period that precludes safe 

flight and landing; 

(iv) Has, if necessary, sufficient 

indication of OAMS failure(s) and crew 

procedures to properly address the 

failure(s); 

(v) Does not result in a vibration 

condition on the flight deck that is 

severe enough to interfere with control 

of the airplane, ability of the crew to 

read the flight instruments, perform 

vital functions like reading and 

accomplishing checklist procedures, or 

to cause excessive fatigue to the crew; 

(vi) Does not result in adverse effects 

on the flight control system or on 

airplane stability, controllability, or 

handling characteristics (including 

airplane-pilot coupling (APC) per 

§ 25.143) that would prevent safe flight 

and landing; and 

(vii) does not interfere with the flight 

crew’s ability to correctly distinguish 

vibration from buffeting associated with 

the recognition of stalls or high speed 

buffet. 

(2) The applicant must show that 

particular risks such as engine failure, 

uncontained engine, or APU rotor burst, 

or other failures not shown to be 

extremely improbable, will not 

adversely or significantly change the 

aeroelastic stability characteristics of the 

airplane. 

(3) No MMEL dispatch is allowed 

with the OAMS system inoperative. 

Issued in Renton, Washington, on May 20, 

2011. 

Ali Bahrami, 

Manager, Transport Airplane Directorate, 

Aircraft Certification Service. 

[FR Doc. 2011–13022 Filed 5–25–11; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2010–0994; Directorate 

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

16707; AD 2011–11–08] 

RIN 2120–AA64 

Airworthiness Directives; Rolls-Royce 

plc (RR) RB211–535 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: 

There have been several findings of 

cracking at the firtrees of LP Turbine discs. 

Fatigue crack initiation and subsequent crack 

propagation at the firtree may result in 

multiple LP Turbine blade release. The latter 

may potentially be beyond the containment 

capabilities of the engine casings. Thus, 

cracking at the firtrees of LP Turbine discs 

constitutes a potentially unsafe condition. 

We are issuing this AD to detect cracks 

in the low-pressure (LP) turbine stage 1, 

2, and 3 discs, which could result in an 

uncontained release of LP turbine 

blades and damage to the airplane. 

DATES: This AD becomes effective June 

30, 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 


srobinson on DSK4SPTVN1PROD with RULES
30530 Federal Register / Vol. 76, No. 102 / Thursday, May 26, 2011 / Rules and Regulations 

Floor, Room W12–140, Washington, DC 

20590–0001. 

FOR FURTHER INFORMATION CONTACT: 

Frederick Zink, Aerospace Engineer, 

Engine Certification Office, FAA, Engine 

and Propeller Directorate, 12 New 

England Executive Park, Burlington, MA 

01803; e-mail: frederick.zink@faa.gov; 

telephone (781) 238–7779; 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 October 5, 2010 (75 FR 

61361). That NPRM proposed to correct 

an unsafe condition for the specified 

products. The MCAI states: 

There have been several findings of 

cracking at the firtrees of LP Turbine discs. 

Fatigue crack initiation and subsequent crack 

propagation at the firtree may result in 

multiple LP Turbine blade release. The latter 

may potentially be beyond the containment 

capabilities of the engine casings. Thus, 

cracking at the firtrees of LP Turbine discs 

constitutes a potentially unsafe condition. 

Therefore this Airworthiness Directive 

requires a change to the inspection intervals 

of LP Turbine Discs. 

Comments 

We gave the public the opportunity to 

participate in developing this AD. We 

considered the comments received. 

Request To Change Related Information 

Paragraph 

One commenter, Rolls-Royce plc 

asked us to use a different statement for 

Rolls-Royce contact information in 

paragraph (i) of the proposed AD. RollsRoyce is concerned that responses to 

requests for information will be delayed 

if the statement is not clear on how to 

request information on service bulletins. 

We partially agree. Paragraph (i) is 

now paragraph (j) of this AD, and we 

have changed paragraph (j) of the AD to 

supply the relevant contact information. 

Support for the Proposed AD as Written 

Two commenters, Continental 

Airlines and The Boeing Company 

support the proposed AD as written. 

Request To Change the Definition of a 

Shop Visit 

Three commenters, FedEx, American 

Airlines, and Rolls-Royce plc asked us 

to change the definition of a shop visit 

to the definition in the Rolls-Royce 

Alert Service Bulletin (ASB) RB.211– 

72–AG272,’’at every engine 

refurbishment and at every 04 and 05 

Module Level 3 (Refurbishment) or 

Level 4 (Overhaul) shop visit.’’ The 

commenters believed that the proposed 

AD definition of a shop visit is too 

conservative and will result in 

unnecessarily increased costs without a 

significant improvement in safety. 

We partially agree. We agree that the 

current definition in the proposed AD is 

too broad because inspecting the LP 

turbine disks every time an unrelated 

major flange is separated is not required. 

We disagree with using the definition in 

the service bulletin because the service 

bulletin definition is not sufficient for 

our needs. We changed paragraph (f) of 

the proposed AD to ‘‘For the purpose of 

this AD, an ‘‘engine shop visit’’ is the 

induction of an engine into the shop for 

maintenance involving the separation of 

the intermediate-pressure/low-pressure 

(IP/LP) turbine module from the engine, 

separation of the IP turbine case from 

the combustion outer case, or separation 

of the LP turbine case from the IP 

turbine case, except that the separation 

of engine flanges solely for the purposes 

of transportation without subsequent 

engine maintenance does not constitute 

an engine shop visit.’’ 

Request To Clarify the Compliance 

Time 

One commenter, American Airlines, 

asked us to clarify the compliance time 

in paragraph (e)(1) of the proposed AD 

to state that for engines currently in the 

shop on the effective date of the AD, the 

initial inspection is to be carried out if 

the affected parts are exposed and 

rebuild has not yet started. The 

commenter believed that the proposed 

AD is unclear as to whether engines 

which have begun their shop visits prior 

to the effective date of the AD are 

required to undergo the initial 

inspection before re-introduction into 

service. 

We agree. Engines currently in the 

shop at piece part exposure or in a 

condition prior to, must comply with 

the AD before any approval for return to 

service. Engines built up beyond this 

point will not require compliance with 

the AD until the next piece part 

exposure. Engines that are in the shop 

and have been approved for return to 

service are considered not to be in the 

shop. We changed paragraph (f) of the 

proposed AD to clarify a shop visit. 

Request To Change the Initial 

Inspection Requirements 

One commenter, American Airlines, 

asked us to change the initial inspection 

requirements in paragraph (e)(1) of the 

proposed AD to specify ‘‘paragraphs 3.C 

through 3.E.’’ in ASB RR.211–72– 

AG272, instead of ‘‘Section 3.’’ The 

commenter believed that only Section 

3.C. through 3.E. address the unsafe 

condition. 

We partially agree. The ASB we 

reference in paragraph (e)(1) of the 

proposed AD is not incorporated by 

reference, so requiring operators to 

follow specific paragraphs in the ASB is 

unnecessary. We agree, however, that 

including the reference may induce 

confusion. We deleted the reference 

from the proposed AD. 

Request To Change the Costs of 

Compliance 

One commenter, American Airlines, 

asked us to change the Costs of 

Compliance Section of the proposed 

AD. American Airlines stated the 

number of 90 products installed on U.S. 

registered airplanes and the number of 

work-hours for performing the 

inspections are incorrect. American 

Airlines stated that they operate more 

RB211–535 engines than the number 

listed in the proposed AD. American 

Airlines also stated that ASB RB.211– 

72–AG272 lists the total hour for 

accomplishing the required actions as 

70 work-hours. American Airlines 

requests that the AD reflect the workhours required as 70 work-hours if 

limited to refurbishment shop visits. If 

non-refurbishment shop visits are 

included, American Airlines estimates 

the average work-hours at 1,300 hours 

per shop visit. 

We partially agree. As of July 9, 2010, 

588 installed engines were on U.S. 

registered airplanes. We changed the 

Costs of Compliance Section from ‘‘90 

products of U.S. registry’’ to ‘‘588 

products of U.S. registry.’’ We also 

changed the ‘‘cost of the AD on U.S. 

operators’’ from $229,500 to $1,499,400. 

We don’t agree with the request to 

change the time to comply if performed 

during non-refurbishment shop visits. 

We base the number of hours in the cost 

estimate on performing the inspection 

during the next shop visit as defined in 

this AD. We made no change to the AD. 

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 scope of the AD. 

Costs of Compliance 

Based on the service information, we 

estimate that this AD would affect about 

588 products installed on airplanes of 

U.S. registry. We also estimate that it 

would take about 30 work-hours per 

product to comply with this AD. The 

average labor rate is $85 per work-hour. 


srobinson on DSK4SPTVN1PROD with RULES
Federal Register / Vol. 76, No. 102 / Thursday, May 26, 2011 / Rules and Regulations 30531 

Required parts would cost about $0 per 

product. Based on these figures, we 

estimate the cost of the AD on U.S. 

operators to be $1,499,400. 

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: 

2011–11–08 Rolls-Royce plc: Amendment 

39–16707. Docket No. FAA–2010–0994; 

Directorate Identifier 2009–NE–39–AD. 

Effective Date 

(a) This airworthiness directive (AD) 

becomes effective June 30, 2011. 

Affected ADs 

(b) None. 

Applicability 

(c) This AD applies to Rolls-Royce plc 

RB211–535E4–37, –535E4–B–37, –535E4–B– 

75, and –535E4–C–37 turbofan engines. 

These engines are installed on, but not 

limited to, Boeing 757–200 series, –200PF 

series, –200CB series, and –300 series 

airplanes and Tupolev Tu204 series 

airplanes. 

Reason 

(d) This AD results from several findings 

of cracking at the firtrees of low-pressure (LP) 

turbine discs. Fatigue crack initiation and 

subsequent crack propagation at the firtree 

may result in multiple LP turbine blade 

release. We are issuing this AD to detect 

cracks in the LP turbine stage 1, 2, and 3 

discs, which could result in an uncontained 

release of LP turbine blades and damage to 

the airplane. 

Actions and Compliance 

(e) Unless already done, do the following 

actions. 

Initial Inspection Requirements 

(1) At the next engine shop visit after the 

effective date of this AD, perform a visual 

and a fluorescent penetrant inspection (FPI) 

of the LP turbine stage 1, 2, and 3 disc. 

Repeat Inspection Requirements 

(2) At each engine shop visit after 

accumulating 1,500 cycles since the last 

inspection of the LP turbine stage 1, 2 and 

3 discs, repeat the inspections specified in 

paragraph (e)(1) of this AD. 

Remove Cracked Discs 

(3) If you find cracks, remove the disc from 

service. 

Definitions 

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

shop visit’’ is: 

(1) Induction of an engine into the shop for 

maintenance involving the separation of the 

intermediate-pressure/low-pressure (IP/LP) 

turbine module from the engine, or 

(2) Separation of the IP turbine case from 

the combustion outer case, or 

(3) Separation of the LP turbine case from 

the IP turbine case, except that the separation 

of engine flanges solely for the purposes of 

transportation without subsequent engine 

maintenance does not constitute an engine 

shop visit. 

(g) Engines that have been approved for 

return to service but are still physically in the 

shop are not considered to be in the shop. 

FAA AD Differences 

(h) This AD differs from the Mandatory 

Continuing Airworthiness Information 

(MCAI) and or service information as follows 

in that while the MCAI compliance requires 

action at a current shop visit, this AD 

requires compliance at the next shop visit 

after the effective date of this AD. 

Other FAA AD Provisions 

(i) Alternative Methods of Compliance 

(AMOCs): The Manager, Engine Certification 

Office, FAA, has the authority to approve 

AMOCs for this AD, if requested using the 

procedures found in 14 CFR 39.19. 

Related Information 

(j) Refer to MCAI European Aviation Safety 

Agency Airworthiness Directive 2009–0244, 

dated November 9, 2009, and Rolls-Royce plc 

Alert Service Bulletin No. RB.211–72–AG272 

for related information. Contact Rolls-Royce 

plc., P.O. Box 31, Derby, DE24 8BJ, United 

Kingdom; phone: 011 44 1332 242424, fax: 

011 44 1332 249936; or e-mail from:http:// 

www.rollsroyce.com/contact/civil_team.jsp, 

for a copy of this service information or 

download the publication from https:// 

www.aeromanager.com. 

(k) Contact Frederick Zink, Aerospace 

Engineer, Engine Certification Office, FAA, 

Engine and Propeller Directorate, 12 New 

England Executive Park, Burlington, MA 

01803; e-mail: frederick.zink@faa.gov; 

telephone (781) 238–7779; fax (781) 238– 

7199, for more information about this AD. 

Material Incorporated by Reference 

(l) None. 

Issued in Burlington, Massachusetts, on 

May 20, 2011. 

Peter A. White, 

Acting Manager, Engine and Propeller 

Directorate, Aircraft Certification Service. 

[FR Doc. 2011–13014 Filed 5–25–11; 8:45 am] 

BILLING CODE 4910–13–P 


srobinson on DSK4SPTVN1PROD with RULES