PO Box31 

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 1 OOO-CE2 

Rating x 1000 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 

1000 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. 

Rolls-Royce pic Registered oHice.65 Buckingham Gate, london SW1E SAT 

Company number: 1003142. Registered in England. 

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D. Statement of Public Interest 

Granting this exemption will promote and serve the public interest because: 

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. 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. 

c. 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. 

E. Statement of no Adverse Effect on Safety 

The FAA's grant of this requested exemption will have no adverse effect on safety. Compliance 

with § 33.27 is significant for safety purposes because it demonstrates that an engine's rotors 

will not fail under a varying range of potential operating conditions. The requirements contained 

in § 33.27(f) are significant for safety because this subsection allows failures of shaft sections to 

be excluded from the range of conditions considered under § 33.27, but only if a design 

organization can demonstrate that the risk of such shaft section failures is sufficiently remote. 

Subsection 33.27(f)(6) does not in itself impose any additional safety requirement. Clearly, if 

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: 

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

Company number: 1003142. Registered In England. 

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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 1000 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. 

Petitioner: Rolls-Royce plc 

Section of 14 C.F.R. Affected: 14 C.F.R. § 33.27(f)(6) 

Description of Relief Sought: 

Rolls-Royce requests an exemption from 14 C.F.R. § 33.27(f)(6) to be applied to Rolls-Royce 

Trent1000 engine models Trent 1000-AE, Trent 1000-CE, Trent 1000-AE2 and Trent 1000-

CE2. Rolls-Royce seeks to exclude the entire HP shaft system from consideration in 

determining the highest overspeed that would result from a complete loss of load on a turbine 

rotor. 

G. Additional Supporting Information 

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. 

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

Company number: 1003142. Registered In England. 

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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 Specialist 

Rolls-Royce pic 

Date; Wednesday 21 51 January 2015 

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

Company number: 1003142. Registered in England. 

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