The Gnome Engine A Brief History Recent Developments The ...

The Gnome Engine

A Brief HistoryRecent Developments

&The Future

Sea King Symposium 2007

©2007 Rolls-Royce plcThe information in this document is the property of Rolls-Royce plc and may not be copied or communicated to a third party, or used for any purpose other than that for which it is supplied without the express written consent of Rolls-Royce plc.This information is given in good faith based upon the latest information available to Rolls-Royce plc, no warranty or representation is given concerning such information, which must not be taken as establishing any contractual or other commitment binding upon Rolls-Royce plc or any of its subsidiary or associated companies.

Mark Batchelor Gnome Service Engineering Team Lead

Rolls-Royce data-strictly private

2

Contents

Engine Overview

Reliability

‘Recent’ Developments

Future of the Gnome


3

Engine OverviewApplicationsRoles and Power GrowthFleet Profile


4

Engine Overview - WhirlwindGnome derived from General Electric T58 engine Original GE T58 Engine supplied in 1958Compressor and Turbine designs originally developed by De HavillandControl system developed by Hawker Siddeley Dynamics Engineering (HSDE)Gnome first ran in 1959 in the Westland Whirlwind

Single Engine Application Introduces the world first helicopter computer control systemInnovative in that it removed a significant work load from the pilot specifically in the area of rotor control1000 shp (Gearbox limited to 850 shp)


5

Engine Overview - Wessex

In 1961, the Gnome Powered Agusta Bell 204B entered into service (1000 shp, single engine)The engine was further developed to produce 1350 shpThe H1200 was used to re-engine the Gazelle powered Westland WessexFirst flight took place in 1962

Twin engine application Engines coupled through a gearbox to drive the aircraft transmissionEngines installed at a 35 degree nose down attitude


6

Engine Overview - Vertol

The Gnome H1200 was also installed in the Kawisaki Vertol aircraft (Boeing Sea Knight) and the SRN 6 HovercraftWork continued to upgrade the engine to enable its appication into heavier lift applicationsThe Vertol installations were upgraded to Gnome H1400’s in the 1980’s.


7

Engine Overview – Sea KingIn 1967 the first flight of the H1400 (1500 shp) Sea King took placeAs the all up mass of the Sea King increased, high power ratings were neededThe Gnome H1400-1 engine was developed to deliver 1660 shp

In the 1980s the requirement to operate Sea Kings at higher ambient temperatures led to the development of the H1400-1TThis reduces the power ‘lapse rate’ as ambient temperature increases


8

Engine Overview – Power Growth% INCREASE IN POWER

H1400-1 & H1400-1TIMPROVED 1Stg TURBINE MATERIAL,

INCREASED TET.

1660 41%1660 41%

1500 28%1500 28%

1350 15%1350 15%

H1400INCREASED AIRFLOW, FURTHERMATERIAL IMPROVEMENT,MATERIAL IMPROVEMENT,MATERIAL IMPROVEMENT,SHP MAX

CONTINGENCY INCREASED TET.INCREASED TET.INCREASED TET.

RATINGH1200IMPROVED MATERIALS, INCREASEDTET

11751175 H1000


9

1986 H1400-1

1984 H1400-1T

1982 H1400-1T

1981 H1400-1

1961 H1000

1962 H1000/H1200

1963 H1200

1963 H1200

1964 H1200

1965 H1200

1969 H1400

1973 H1200

1973 H1400

1974 H1400-1

1975 H1400-1

2003 H1400–1T UK MoD

Engine Overview – EIS Time Line

1960 1970 1980 1990 2000


10

Engine Overview - ProductionApproximately 2600 Gnome engines producedThe last Gnome was manufactured in 1998900 engines currently within “supported” fleet, i.e. H1400 series Between 200-400 in “unsupported” fleet

Supported via 2nd hand market Of the “supported” fleet all are original operators and all are still operationalMost operators reviewing Sea King Replacement in terms of EH101, NH90 and Blackhawk


11


12

Fleet Overview - RolesThe Sea King operation world wide involves a number of roles including

ASW (Anti Submarine Warfare)AEW (Airborne Early Warning)SAR (Search And Rescue)Troop Transportation/Supply

All of these roles require a different operational profile and different demands from the aircraft/engine systemA vast proportion of the operators use their aircraft predominately in a SAR operationEngine reliability specifically starting is therefore paramount for these operatorsHowever the environment in which they work and the operation they undertake is varied and in some cases extremely harshIn the SAR role, R-R believe that the number of persons rescued by Gnome powered aircraft worldwide exceeds 80,000


13

Engine ReliabilityApplicationsProductionRoles and Power GrowthFleet Profile


14

Reliability - SummaryMain use of Sea King Aircraft is either

ASW (Anti Submarine Warfare)AEW (Airborne Early Warning)SAR (Search And Rescue)Troop Transportation/Supply

Different roles do have an effect on engine reliabilityGnome is a mature product hence reliability is stableThe main cause for engine removal is basic unplannedThe Basic planned rates are constantRecent work within the MoD under revised contracting arrangements has improved their basic unplanned rate


15

Reliability - StabilityGnome is a mature product hence reliability is stable Occasional issues occur with “One off” type failures which are

Difficult to identify route causeDifficult to diagnose (intermittent)Difficult to resolve either short or long term due to cost involved for 1 off type failures.

Occasional failures focus around the Control systemAircraft induced issues which result in engine rejection

- Vibration- Torque Problems- Handling issues

General rectified by component replacementRejected components are often ‘Fault not Found’


16

Reliability – Unplanned RemovalsThe main cause for engine removal is basic unplannedBUR Rate fluctuates mainly due to

Operations outside of normal operating environments I.e conflict preventionThe re-establishment of a significantly large percentage of the fleet to a “overhauled” standard following significant front line operationsAs an example the UK MoD have operated in

- Eastern Europe- Middle East- Africa- Central Asia

Generally all engines age and reliability degrades at the same rateThus engine reliability around a specific level improves and degrades in constant cycles


17

Reliability – Unplanned Removals

Middle East

No.1 Seal


18

Reliability - Unplanned Removals

Perform

ance

Bearin

g sea

lsOil l

eak/H

OC

Exhau

st ca

se cr

acke

dFCU/Fue

l Pum

pVibr

ation

Torque

Prob

lems

Start P

roblem

sOthe

rs

Others

(non-b

asic)

Distribution of Basic Unplanned Removals

SARUtility/ASW/AEWDeployed


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Reliability – Top Causes of RemovalPerformance

General life related - Dirty compressors- Erosion (Wear Out)- Corrosion.

IGV system wear – loss of datum settingOil Leaks/High Oil Consumption

General Flange leaksNo. 5 bearing leaksStarter Jaw Seal Leaks

Cracked Exhaust CasingsOperator maintenance practice

In some operators FoD has reduced, this is sustainable due to introduction of EAPS/Centrisep Filter


20

Recent DevelopmentsTropical ApplicationsImproved Erosion Protection


21

The H1400-1T is a derivative of the H1400-1 designed to operate in higher ambient temperatureIt has a reduced power lapse rate

This is the rate at which power drops off as ambient temperature increasesTherefore at high ambients it retains power at a better rate than the H1400-1 engine

The H1400-1T is rated at ISA + 30 Deg C.This is achieved by optimising the Turbine Entry Temperature (TET) and is facilitated by trimming of the Power Turbine Inlet Temperature (PTIT) signalIt provides positive benefits over the H1400-1 engine at all rating conditions at higher ambient temperatures

Tropical Applications


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Tropical Applications - RatingsMaximum Continuous Rating


23

Tropical Applications - Ratings1 Hour Power Rating


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Tropical Applications - RatingsMaximum Contingency Rating


25

Basic mechanical components within the engine types are the sameConversion is achieved with the introduction of a PTIT trimmer assemblyThere are a number of modifications which must be embodied in the H1400-1T engine:

Compressor Vane 1/4 PacksCast Stage 3 Nozzle AssemblyPower Turbine Wheel and shaft made from A285Improved number 3 bearingMk 1A Fuel Control system

H1400-1T has a Stage 1 Turbine Blade life of 1600 hoursMinor aircraft modification to the cockpit gauge

Tropical Applications - Core


26

Tropical Applications - TrimmingThe Gnome engine Temperature measurement is taken from the Power Turbine Inlet Temperature (PTIT) Thermocouple ReadingPower on a temperature basis is derived from the Turbine Entry Temperature (TET) position – this can not be measured.It can however be calculated from engine measurement parameters

Power Turbine Inlet TemperatureTurbine Entry

Temperature


27

Tropical Applications - TrimmingThe relationship between TET and PTIT is not constant. Therefore for a sample of engines with a PTIT of 795 Deg C the TET will vary. Engine power on a temperature basis is actually determined by the TET, therefore some engines will not be able to operate to their maximum temperature based power

H1400-1

740

750

760

770

780

790

800

810

820

1270 1280 1290 1300 1310 1320 1330 1340 1350 1360

TET

PTI

T

TET Limit

Max Contingency operating limit

Scatter of engine PTIT v’s TET . Note: No engines have optimum PTIT v’s TET Relationship. I.e 795 PTIT @ 1357 TET

Indicative engine running lines


28

This inability to operate to the max TET figure is especially noticeable as the ambient temperature increasesIn order to maximise the TET whilst still being able to use the PTIT as a measurement position trimming is introducedTrimming requires, during test bed running, calculation of the TET using a number of engine measurement parametersOnce the TET is calculated, a relationship between the TET and PTIT can be derivedThis allows via the selection of a resistor the PTIT signal to be trimmed so that on all engines the maximum PTIT is reached as the maximum TET is reachedTherefore trimming allows the optimum TET to be achieved and hence engine power on a temperature basis

Tropical Applications - Trimming


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Tropical Applications - TrimmingH1400-1

740

750

760

770

780

790

800

810

820

1270 1280 1290 1300 1310 1320 1330 1340 1350 1360

TET

PTI

T

H1400-1T COMPUTER SIGNAL

740

750

760

770

780

790

800

810

820

1270 1280 1290 1300 1310 1320 1330 1340 1350 1360

TET

PT

IT U

NT

RIM

ME

D

H1400-1T COCKPIT GUAGE

700

710

720

730

740

750

1270 1280 1290 1300 1310 1320 1330 1340 1350 1360

TET

PT

IT T

RIM

ME

D


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Erosion Protection – Coated BladesTitanium Nitride Coating process developed by ‘MDS Prad’In service trial already complete by GE on various engine typesR-R is currently undertaking a trial on Gem and Gnome engines with the assistance of UK MoDIt is anticipated that the coating will deliver improved erosion protection giving

greater on wing lifeReduced cost of operationGreat performance retention


31

Future of The GnomeDesign Improvements OSD’s and Fleet Run DownSupport Initiatives


32

Design Improvements – PTIT HarnessExisting harness suffers from

Fitting and removal damageFrettingStorage and transportation damage

Designed as consumable (non repairable)High cost itemNew design features

Protected (caged) sensing tipImproved insulation resistanceHead angle of 80 degrees to facilitate fittingDeeper hexagon flats on the mounting nutsProvision for thermocouple replacement if damaged e.g. by fretting


33

Design Improvements – IGV Linkage Current VGV system is prone to:

Cracking of the bracketDeformation of links and bell cranksWear of pivot pins

This is known to cause:Increased scheduled and additional unplanned maintenanceEngine rejection and poor compressor / engine installed performance

Results on cost of ownership are:High cost of scheduled maintenanceHigh cost of engine rejection and part repair / replacement


34

Design Improvements – IGV Linkage Redesign IGV bracket utilises RTM322 technologySelf lubricating bearing surfacesSealed pivots to eliminate dirt ingress leading to wearIncreased stiffnessResign will not improve engine performance, but improve

performance retention

Current Design

Improved Design


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Operators are extending OSD’s without reducing fleet sizesSpare/surplus engines will not therefore become available for many more yearsRR operates a lead time business and does not hold long lead time items on the shelfThis presents significant challenges for both RR and operatorsIn partnership with operators RR is seeking to change the way inwhich it provides support at all levels (1st, 2nd and 4th line)RR and accessory OEM’s committed to Gnome support to OSD’s

Out of Service Dates


36

0

10

20

30

40

50

60

70

80

90

100

Now 2006-2009 2010-2012 2012-2015 2015-2018 2018 plus

Year

% F

rom

200

6 Fi

gure

Fleet Run Down Profile


37

UK MoD

Federal German Navy

Belgian Air Force

Royal Norwegian Air Force

Egyptian Air Force

Qatari Emeri Air Force

Pakistan Navy

Indian Navy

Royal Australian Navy

Swedish Armed Forces

Out of Service Dates

Now


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New support initiatives within the Mission Ready Management Solutions (MRMS) support frame work offer operators and RR a more cost effective way of managing fleetsDrive toward spares forecasting managed by RR, providing benefits of higher volume provisioning giving LT benefitsUK MoD and R-R driving towards expanding the current Ssupportframework an Asset Availability Service (AAS)This will transfer a number of traditionally ‘operator’ supported activities into Rolls-Royce control, including

- Spares provisioning (1st 2nd and 4th line)- Post Design Services- Transportation of assets- Accessory management and repair and overhaul- Engine storage

Currently working with other operators to expand the MRMS umbrella increasing benefits to all the fleet

Future Support Initiatives


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SummaryAlthough reliability is stable, RR is committed to the introduction of new technologies to improve

Cost of ownershipAvailability

RR and operators continue to invest in the future of the Gnome engineDue to changing mission demands a number of operators are upgrading to H1400-1TThe Gnome will remain in service beyond 2020


40

Future Developments!


41

Questions


42

Total Gnome engine hours 7,706,523 (all mks)

Flying rate (world fleet) = 9900 hours (monthly average)

Number of engines in operation = 883 (Sea King only)

Number of aircraft = 299 (Sea King only)

Number of operators = 17 (some unsupported)

Overhaul (second line) workshops = 7 (12)

Removal rate all causes = 2.45/1000 efh (MTBR* 410 hours)

Removal rate basic unplanned = 1.23/1000 efh (MTBR* 813 hours)

In flight shut down rate UK Mod = 0.03/1000 efh (4 yr average)

*Mean Time Between Removals

Engine Overview – Fleet Stats


43

Engine Overview – Control System

CompressorCombustion

systemGas

generatorturbine

Powerturbine

Ngtachometer

Nftachometer

Ptit

NgPtit

Nf

SpeedSelectLever

ManualThrottle

Centrifugalfuelfilter

Integratedfuel system

Throttleactuator

Computer

Basic Engine Control

NgPtitNfMechanical

Key

ElectricalFuel flowGn/3.1.1/d/a1

CollectivePitchanticipator

CompressorCombustion

systemGas

generatorturbine

Powerturbine

Ngtachometer

Nftachometer

Ptit

NgPtit

Nf

SpeedSelectLever

ManualThrottle

Centrifugalfuelfilter

Integratedfuel system

Throttleactuator

Computer

Basic Engine Control

NgPtitNfMechanical

Key

ElectricalFuel flowGn/3.1.1/d/a1

CollectivePitchanticipator


44

Tropical Applications - RatingsPerformance differences for minimum brochure engines.

1465

1380

1050

-1T

-4.5

0.3

10.8

%

Difference

1375

1085

810

-1

ISA SLS (Uninstalled)

[shp]

27.215401535Max 1 Hour Power

6.515851660Max Contingency

29.613851250Max Continuous

%-1T-1Rating

DifferenceISA SLS

(Uninstalled)[shp]


45

Tropical Applications - Trimming

1 765432 Wf1 = Compressor entry - Measured - Temperature, Pressure and Mass Flow2 = Compressor exit – Measured - Temperature and Pressure3 = Gas Generator Turbine Entry = TET - Calculated4 = Gas Generator Turbine Exit = Calculated5 = Power Turbine Inlet Temperature = PTIT Measured - Temperature6 = Power Turbine Exit Temperature = Measured - Temperature7 = Jet Pipe Temperature = Measured – TemperatureWf = Fuel Flow = Measured


46

Publications Update

R-R is currently in the process of updating all of the Gnome publicationsConversion to AECMA formatDistributed on CD and via the web (www.aeromanager.com)Provides

Lower cost productionRapid amendmentsRapid distributionEasy incorporation

http://www.aeromanager.com/

http://www.aeromanager.com/


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Design Improvements – Liner Locating pin and boss wear

Fuel manifold not shown

Existing combustion liner suffers from excessive wear of the location pins and bosses

Loss of liner locationLiner and nozzle damageHigh overhaul/repair cost

Improved location pin geometry and build method under development Reduced repair and overhaul costs


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Year

75

80

85

90

95

100

105

2006 2007 2008 2009 2010 2011 2012 2013 2014 2015

Perc

enta

ge o

f 200

6 Fl

ying

Rat

eForecast Flying Rates

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