DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-1025; Project Identifier MCAI-2020-00757-E;
Amendment 39-21630; AD 2021-14-03]
RIN 2120-AA64

Airworthiness Directives; Rolls-Royce Deutschland Ltd & Co KG
(Type Certificate Previously Held by BMW Rolls-Royce GmbH and BMW
Rolls-Royce Aero Engines) Turbofan Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for
certain Rolls-Royce Deutschland Ltd. & Co KG (RRD) BR700-715A1-30,
BR700-715B1-30, and BR700-715C1-30 model turbofan engines. This AD was
prompted by reports of HPT stage 1 blades failing in service due to
sulphidation and subsequent crack initiation. This AD requires removal
and replacement of the HPT stage 1 blade and HPT stage 1 blade damper.
The FAA is issuing this AD to address the unsafe condition on these
products.

DATES: This AD is effective August 19, 2021.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of August 19,
2021.

ADDRESSES: For service information identified in this final rule,
contact Rolls-Royce Deutschland Ltd. & Co KG, Eschenweg 11, 15827
Blankenfelde-Mahlow, Germany; phone: +49 (0) 33 708 6 0; email:
rrd.techhelp@rolls-royce; website: https://www.rolls-royce.com/contact-
us.aspx. You may view this service information at the FAA,
Airworthiness Products Section, Operational Safety Branch, 1200
District Avenue, Burlington, MA 01803. For information on the
availability of this material at the FAA, call (781) 238-7759. It is
also available at https://www.regulations.gov by searching for and
locating Docket No. FAA-2020-1025.

Examining the AD Docket

You may examine the AD docket at https://www.regulations.gov by
searching for and locating Docket No. FAA-2020-1025; or in person at
Docket Operations between 9 a.m. and 5 p.m., Monday through Friday,
except Federal holidays. The AD docket contains this final rule, any
comments received, and other information. The address for Docket
Operations is 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: Barbara Caufield, Aviation Safety
Engineer, ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803;
phone: (781) 238-7146; fax: (781) 238-7199; email:
barbara.caufield@faa.gov.

SUPPLEMENTARY INFORMATION:

Background

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding an AD that would apply to certain RRD BR700-
715A1-30, BR700-715B1-30, and BR700-715C1-30 model turbofan engines.
The NPRM published in the Federal Register on November 13, 2020 (85 FR
72608). The NPRM was prompted by reports of HPT stage 1 blades failing
in service due to sulphidation and subsequent crack initiation, due to
contamination of the blade shank passing by the blade damper. In the
NPRM, the FAA proposed to require removal and replacement of the HPT
stage 1 blade and HPT stage 1 blade damper. The
FAA is issuing this AD to address the unsafe condition on these
products.
The European Aviation Safety Agency (EASA), which is the Technical
Agent for the Member States of the European Community, has issued EASA
AD 2018-0194, dated September 4, 2018 (referred to after this as ``the
MCAI''), to address the unsafe condition on these products. The MCAI
states:

Occurrences have been reported on RRD BR700-715 engines where
certain HP turbine stage 1 blades failed in service. Investigation
of these events showed that these were caused by sulphidation and
subsequent crack initiation, due to contamination of the blade shank
passing by the blade damper.
This condition, if not corrected, could lead to further HP
turbine stage 1 blade failures, possibly resulting in engine in-
flight shut-down and consequent reduced control of the aeroplane. To
address this potential unsafe condition, RRD published the NMSB to
provide instructions to replace the affected assembly.
For the reasons described above, this [EASA] AD requires
determination of the engine configuration and, depending on
findings, removal of the engine from service to replace the affected
assembly.

You may obtain further information by examining the MCAI in the AD
docket at https://www.regulations.gov by searching for and locating
Docket No. FAA-2020-1025.

Discussion of Final Airworthiness Directive

Comments

The FAA received comments from one commenter. The commenter was
Delta Airlines (Delta). The following presents the comments received on
the NPRM and the FAA's response to each comment.

Request To Revise Definition of "Parts Eligible for Installation"

Delta requested that the FAA revise the definition of ``parts
eligible for installation'' to avoid the necessity of an alternate
method of compliance (AMOC) request each time Rolls-Royce introduces a
new part number for the HPT stage 1 blade or HPT stage 1 damper.
The FAA agrees and revised the definition of ``parts eligible for
installation'' to allow installation of HPT stage 1 blades and HPT
stage 1 dampers approved as eligible for installation in accordance
with certain RRD service information.

Request To Clarify Compliance Time Language

Delta requested that the FAA revise paragraph (g)(1)(i) in the
Required Actions section of this AD to refer to ``flight cycles since
new'' instead of ``flight cycles since first installation,'' as
proposed in the NPRM. Delta noted that the proposed language could be
misinterpreted as referring to any affected HPT stage 1 blade,
regardless of whether the affected HPT stage 1 blade is currently
installed on an engine.
The FAA partially agrees. The FAA agrees to update this reference
to avoid possible misinterpretation, but disagrees with the specific
language proposed by the commenter. The FAA has updated paragraph
(g)(1)(i) of this AD to read: ``Before an affected HPT stage 1 blade
exceeds 10,000 flight cycles (FCs) since first installation . . .''

Conclusion

The FAA reviewed the relevant data, considered any comments
received, and determined that air safety requires adopting this AD as
proposed. Accordingly, the FAA is issuing this AD to address the unsafe
condition on these products. Except for minor editorial changes and any
other changes described previously, this AD is adopted as proposed in
the NPRM. None of the changes will increase the economic burden on any
operator.

Related Service Information Under 1 CFR Part 51

The FAA reviewed RRD BR700 Series Alert Non-Modification Service
Bulletin (NMSB) SB-BR700-72-A900640, Revision 1, dated August 31, 2018.
The Alert NMSB describes procedures for removing and replacing the HPT
stage 1 blade and HPT stage 1 blade damper. This service information is
reasonably available because the interested parties have access to it
through their normal course of business or by the means identified in
ADDRESSES.

Other Related Service Information

The FAA reviewed RRD Service Bulletin (SB) SB-BR700-72-102005,
dated March 20, 2018; RRD NMSB SB-BR700-72-900118, dated June 6, 2017;
and RRD SB SB-BR700-72-101671, dated January 29, 2010. RRD SB SB-BR700-
72-102005, dated March 20, 2018, introduces a new HPT stage 1 blade
damper with a front restrictor that reduces the average airflow into
the blade shank cavity, thereby reducing deposition of particles in the
cavity. RRD NMSB SB-BR700-72-900118, dated June 6, 2017, describes
procedures for recording the serial numbers of the cleaned, crack
tested, and examined HPT stage 1 blades. RRD SB SB-BR700-72-101671,
dated January 29, 2010, introduces a redesigned HPT stage 1 blade that
improves robustness and stress characteristics.

Costs of Compliance

The FAA estimates that this AD affects 222 engines installed on
airplanes of U.S. registry. The agency estimates that the service life
of both the HPT stage 1 blade and HPT stage 1 blade damper are 5.5
years. Based on this life estimate, the agency is providing an
estimated annual cost to replace these parts.
The FAA estimates the following costs to comply with this AD:

Estimated Costs

The FAA has included all known costs in its cost estimate.
According to the manufacturer, however, all of the costs of this AD may
be covered under warranty, thereby reducing the cost impact on affected
individuals.

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.
The FAA is 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

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) Will not affect intrastate aviation in Alaska, 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.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.

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.

Sec. 39.13 [Amended]

2. The FAA amends Sec. 39.13 by adding the following new airworthiness
directive: