# I Rolls-Royce

PO Box 31, Derby DE24 BBJ, England Telephone

: 

### +44
(0) 1332 242424 

### Fax

: +44 

### (O) 1332 249936 

### www

. rolls-royce

. com 

# Petition

for Exemption

from 14 C.F.R.



# § 33.27(1)(6), Amendment

31 A. Name, Address

and Contact Information

of the Petitioner Rebecca Peacock

- Airworthiness Specialist ML-52 Rolls-Royce

pic 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.

Reg

is tered

in England

.

Page

1[IRolls-RoyceRelieffrom§33.27(f)(6)issoughtbecauseanalysishasfailedtoshowthatfailureoftheHPshaftsystemcanneverresultinoverspeedtoburst.ThedesignoftheHPshaftsystemisnotamenabletoanalysisbyshaftsection.Rolls-Roycethereforeseeksanexemptionfrom§33.27(1)(6)toexcludetheentireHPshaftsystemfromconsiderationindeterminingthehighestoverspeedthatwouldresultfromacompletelossofloadonaturbinerotor.However,asdemonstratedinSectionEbelow,thelevelofsafetyaffordedbycompliancewith§33.27fortheHPshaftsystemwillbeunaffectedbythegrantingofanexemptionfrom§33.27(f)(6).Insum,Rolls-Royceisrequestingthisexemptionbecausecompliancewith§33.27cannotbeshownabsentanexemptionfrom§33.27(f)(6).However,compliancecanbeshown,withatleastanequallevelofsafetytothatrequiredtomeet§33.27,iftheexemptionisgranted.D.StatementofPublicInterestGrantingthisexemptionwillpromoteandservethepublicinterestbecause:a.Thestate-of-the-artenginemodels(andtheHPshaftsystem)atissueinthispetitionrepresentthelatestgenerationofenginesandenginetechnologyfromtheTrentenginefamily.TheTrentlineofengineshasestablishedanoutstandingtrackrecordofperformanceandsafetyover41yearsandmorethan256millionserviceflighthours.Thus,theenginemodelsandshaftsystematissueinthispetitionarebasedonprovenexpertiseandin-service-verifieddesignstylesandpractices.Thisexperienceandtrackrecordhelpstoensurethereliabilityandsafetyoftheproduct.Asexplainedfurtherinthepointsimmediatelybelow,theintroductionoftheseenginemodelsintoservicewillgeneratevaluablepublicbenefits.b.Thesestate-of-the-artenginemodelswillreducetheoperatingcostsofaircraft,andtheairlinesthatoperatethem,relativetocostsassociatedwithaircraftthatarecurrentlyinservice.SuchareductioninoperatingcostswillbenefitU.S.andinternationalairlines,theiremployeesandshareholders.Moreover,suchreducedoperatingcostsprovidetheopportunityforairlinestooffermoreandlessexpensiveairserviceoptionstothetravelingpublic.c.TheTrent1000modelsareinstalledontheBoeing787-8and787-9whichhascustomersoutsidetheUnitedStates.SalesoftheenginecontributetotheU.S.economy,supportU.S.jobs,andenhancetheU.S.balanceoftradeandgrossdomesticproduct-allofwhichpromotetheU.S.publicinterest.E.StatementofnoAdverseEffectonSafetyTheFAA'sgrantofthisrequestedexemptionwillhavenoadverseeffectonsafety.Compliancewith§33.27issignificantforsafetypurposesbecauseitdemonstratesthatanengine'srotorswillnotfailunderavaryingrangeofpotentialoperatingconditions.Therequirementscontainedin§33.27(f)aresignificantforsafetybecausethissubsectionallowsfailuresofshaftsectionstobeexcludedfromtherangeofconditionsconsideredunder§33.27,butonlyifadesignorganizationcandemonstratethattheriskofsuchshaftsectionfailuresissufficientlyremote.Subsection33.27(f)(6)doesnotinitselfimposeanyadditionalsafetyrequirement.Clearly,ifriskoffailureofthewholeshaftsystemisconsideredandshowntobeatleastasremoteasisacceptablefor"shaftsections,"thentheoveralllevelofsafetymustbeatleastequaltocircumstancesinwhichonly"shaftsections"areconsidered,asprovidedforunder§33.27(f).Subsection33.27(f)(6)wasincludedinSection33.27basedonahistoryoffailuresassociatedwithconventionalshaftsystems,whichraiseddoubtabouttheabilityofdesignorganizationstofullyassessthepotentialfailuremodes(andfailurerate)ofanentireshaftsystem.However,fortheHPshaftsystemoftheTrent1000(andindeedforotherRolls-Roycemodern3shaftengines),thisanalysiscanbecarriedoutwithhighfidelitybecause:Rolls-RoycepicRegisteredoffice:65BuckinghamGate,LondonSW1ESATCompanynumber:1003142.RegisteredInEngland.Page2

# II Rolls-Royce 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 thetorquetransmitting 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 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 Eng

l and

.

Page

3IRolls-RoyceH.PrivilegesofthisExemptionOutsidetheUnitedStatesPer14C.F.R.§11.81(h),Rolls-Roycerequeststhattheprivilegesofthisexemptionbeextended outsidetheUnitedStates.ThisextensionofprivilegesisnecessaryforoperationsbasedwithinforeigncountrieshavingbilateralagreementswiththeUnitedStatesacceptingFAA14C.F.R.Part33astheirairworthinessstandardsfortransportcategoryaircraft.TheTrent1000isintendedfortheglobalmarketplace,withcustomersbasedincountriesutilizingtheU.S.airworthinessstandards.I.GoodCauseexiststoissuetheExemptionwithoutNoticeorCommentPursuantto14C.F.R.§11.87,Rolls-RoycerequeststhatthispetitionbeprocessedwithoutpublicationintheFederalRegisterfornoticeandcomment,asmayotherwiseberequired.Rolls-Roycebelievesthatgoodcauseexiststonotdelaythisactionbecause:a.thereliefrequestediseffectivelyidenticaltoanEquivalentSafetyFindingpreviouslyacceptedbyEASAb.delayingtheactionwouldadverselyaffectRolls-RoycebecausetheTrent1000enginemodelscoveredbythispetitionarecurrentlyundergoingcross-validationwiththeFAA,thetimingofwhichisaimedatmeetingBoeingcontinuedin-servicedeliveryrequirementsoftheBoeing787-8and787-9,andsignificantdelaysinenginevalidationwouldimpacttheBoeingprogram;andc.thispetitionistimelyfiled.RebeccaPeacockAirworthinessSpecialistRolls-RoycepicDate;Wednesday2151January2015Rolls-RoycepicRegisteredoffice:65BuckinghamGate,LondonSW1E6ATCompanynumber:1003142.RegisteredinEngland.Page4