Derby DE24 BBJ England 

Tel: (+44) 1332 249428 

rebecca. peacock@ rolls-royce.com 

B. Pertinent Section of the Code of Federal Regulations 

Rolls-Royce hereby petitions for an exemption from 14 C.F.R. § 33.27(f)(6). This exemption is 

requested for the HP shaft system only, for the Trent 1000 engine models identified in Section 

C below. The pertinent provisions of 14 C.F.R. § 33.27 are: 

14 C.F.R. § 33.27 Turbine, compressor, fan, and turbosupercharger rotor overspeed. 

(f) Failure of a shaft section may be excluded from consideration in determining the highest 

overspeed that would result from a complete loss of load on a turbine rotor if the applicant: 

{6) Does not exclude the entire shaft. 

C. The Exemption being sought 

Rolls-Royce requests an exemption from 14 C.F.R. § 33.27(f)(6) for the HP shaft system of the 

following new Trent 1000 engine models: 

Model 

Trent 1 000-AE Trent 1 000-CE Trent 1 OOO-AE2 Trent 1000-CE2 

Rating x 1 000 lbs. 

64 

70 

64 

70 

In order to address discrepancies between the engine nomenclature used in engine and aircraft 

certification documentation, the new engine models above, known as "Enhanced Ratings", are 

being introduced. Mechanically the new models are identical to the existing certificated Trent 

1 000 models, differing only in the thrust profiles contained in the engine controller. These thrust 

profiles are very similar to the existing models, and do not affect the Take-Off thrust rating or 

equivalent bare engine take-off thrust. There are no changes to the operating limits of the new 

models compared to existing. 

No exemption is sought for other shaft systems on these, or any other, engine models. The HP 

shaft system will comply with § 33.27, subject to the granting of the exemption from § 33.27(f)(6) 

requested herein. 

Relief from§ 33.27(f)(6) is sought because analysis has failed to show that failure of the HP 

shaft system can never result in overspeed to burst. The design of the HP shaft system is not 

amenable to analysis by shaft section. Rolls-Royce therefore seeks an exemption from § 

33.27(f)(6) to exclude the entire HP shaft system from consideration in determining the highest 

Rolls-Royce pic Registered office:65 Buckingham Gate, London SW1E 6AT 

Company number: 1003142. Registered in England. 

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a. The state-of-the-art engine models (and the HP shaft system) at issue in this petition 

represent the latest generation of engines and engine technology from the Trent engine 

family. The Trent line of engines has established an outstanding track record of 

performance and safety over 41 years and more than 256 million service flight hours. 

Thus, the engine models and shaft system at issue in this petition are based on proven 

expertise and in-service-verified design styles and practices. This experience and track 

record helps to ensure the reliability and safety of the product. As explained further in 

the points immediately below, the introduction of these engine models into service will 

generate valuable public benefits. 

b. The granting of the requested exemption will expedite the entry into service of superior 

engines and engine technology that will enhance the safety and reliability of airline 

operations, and increase the efficiency of aircraft performance, thereby promoting U.S. 

economic interests (including those of Boeing, U.S. airlines, and their employees and 

shareholders) as well as those of the travelling public, while also reducing adverse 

effects on the environment relative to older engine types on other aircraft. All of these 

enhancements constitute substantial public benefits 

c. These state-of-the-art engine models will reduce the operating costs of aircraft, and the 

airlines that operate them, relative to costs associated with aircraft that are currently in 

service. Such a reduction in operating costs will benefit U.S. and international airlines, 

their employees and shareholders. Moreover, such reduced operating costs provide the 

opportunity for airlines to offer more and less expensive air service options to the 

traveling public. 

d. Certification of these state-of-the-art engine models, when operated in the Boeing 787, 

will reduce fuel burn, thereby reducing harmful emissions such as carbon dioxide (C02) 

and NOx from levels experienced with other older engine types currently in service on 

other aircraft. 

e. The Trent 1000 is built with U.S. supplied parts that constitute approximately 16% of 

the engine value. Sales of the engine contribute to the U.S. economy, support U.S. 

jobs, and enhance the U.S. balance of trade and gross domestic product, all of which 

promote the U.S. public interest 

f. The Trent 1000 models are installed on the Boeing 787-8 and 787-9 which has 

customers outside the United States. Sales of the engine contribute to the U.S. 

economy, support U.S. jobs, and enhance the U.S. balance of trade and gross 

domestic product-all of which promote the U.S. public interest. 

g. Certification of these Trent 1000 engine models in the U.S. promotes the regulatory 

standards of the U.S. as a global bench mark for airworthiness. Promotion of the U.S. 

regulatory standards is in the public interest as this increases the number of goods and 

services available to U.S. citizens that are compliant with the U.S. regulatory standards, 

Rolls-Royce pic Registered office:65 Buckingham Gate, London SW1 E 6AT 

Company number: 1 003142. Registered In England. 

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risk of failure of the whole shaft system is considered and shown to be at least as remote as is 

acceptable for "shaft sections," then the overall level of safety must be at least equal to 

circumstances in which only "shaft sections" are considered, as provided for under§ 33.27(f). 

Subsection 33.27(f)(6) was included in Section 33.27 based on a history of failures associated 

with conventional shaft systems, which raised doubt about the ability of design organizations to 

fully assess the potential failure modes (and failure rate) of an entire shaft system. However, for 

the HP shaft system of the Trent 1000 (and indeed for other Rolls-Royce modern 3 shaft 

engines), this analysis can be carried out with high fidelity because: 

a. The HP shaft system design utilized across the Trent engine family differs significantly 

from conventional shaft systems. For example, it features no bearings or oil system 

components, has high stiffness and significant clearance relative to other shafts; 

consequently, the threats associated with the features of a conventional shaft do not 

apply. A Failure Mode and Effect Analysis has determined that there are no known or 

potential environmental threats to the integrity of the HP shaft system components that 

could lead to a loss of load failure. 

b. In order to ensure a high level of integrity, the special controls applied to the torquetransmitting components (i.e., the HP Compressor Rear Drum and the HP Turbine disc 

of the HP shaft system) are of a higher standard than those of many other shaft 

systems in the past. These mandated controls address, but are not limited to: 

1. Material specifications; 

2. Material properties (e.g., low cycle fatigue, high cycle fatigue, creep); 

3. Manufacturing induced anomalies; 

4. Service induced damage tolerance assessment; 

5. Safe life mandatory inspections; and 

6. Mandatory cycle life limitation. 

c. The theoretical assessment of points 1) and 2) above is supported by the service 

experience of the Rolls-Royce three shaft family of engines, all of which incorporate the 

same design style for the HP shaft system as the Trent 1 000 engine models that are 

the subject of this petition. Over the course of more than 256 million service flight 

hours, there have been no failures of the HP shaft system torque path on the Trent 

family of engines. This performance reflects an extremely remote potential failure rate 

of less than 2.7 x 10-9 failures per flight hour. 

In sum, there is ample evidence that analysis of the complete HP shaft system on the Trent 

1000 models at issue achieves the level of fidelity required for failures of shaft sections under§ 

33.27(f). Therefore, the level of safety under the requested exemption will be at least equal to 

that otherwise provided by§ 33.27, thereby assuring that no adverse effect on safety will result 

from a grant of the requested exemption. 

F. Summary for Federal Register 

In accordance with § 11.81 (f), Rolls-Royce offers the following summary suitable for publication 

in the Federal Register. 

Rolls·Royce pic Registered office:65 Buckingham Gate, London SW1E SAT 

Company number: 1003142. Registered in England. 

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EASA Certification requirements CS-E 840 and CS-E 850 are similar requirements to those of§ 

33.27. The existing Trent 1000 engine models have been previously certified by EASA under 

Type Certificate E.036. To meet the requirements of CS-E 840 and CS-E 850, EASA granted 

an Equivalent Safety Finding. The evidence provided to support this Equivalent Safety Finding 

was similar to that provided in this petition for exemption. The Equivalent Safety Finding was 

accepted by EASA on August 27, 2013. 

H. Privileges of this Exemption Outside the United States 

Per 14 C.F .R. § 11.81 (h), Rolls-Royce requests that the privileges of this exemption be 

extended outside the United States. This extension of privileges is necessary for operations 

based within foreign countries having bilateral agreements with the United States accepting 

FAA 14 C.F.R. Part 33 as their airworthiness standards for transport category aircraft. The 

Trent 1000 is intended for the global marketplace, with customers based in countries utilizing 

the U.S. airworthiness standards. 

I. Good Cause exists to issue the Exemption without Notice or Comment 

Pursuant to 14 C.F.R. § 11 .87, Rolls-Royce requests that this petition be processed without 

publication in the Federal Register for notice and comment, as may otherwise be required. 

Rolls- Royce believes that good cause exists to not delay this action because: 

a. the relief requested is effectively identical to an Equivalent Safety Finding previously 

accepted by EASA 

b. delaying the action would adversely affect Rolls-Royce because the Trent 1000 engine 

models covered by this petition are currently undergoing cross-validation with the FAA, the 

timing of which is aimed at meeting Boeing continued in-service delivery requirements of 

the Boeing 787-8 and 787-9, and significant delays in engine validation would impact the 

Boeing program; and 

c. this petition is timely filed. 

Rebecca Peacock 

Airworthiness Speci list 

Rolls-Royce pte 

Date; Friday, 6111 March 2015 

Rolls-Royce pic Registered office:65 Buckingham Gate, London SW1 E SAT 

Company number: 1003142. Registered In England. 

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