The Gnome Engine
A Brief History
Recent Developments
&
The Future
Sea King Symposium 2007
Mark Batchelor Gnome Service Engineering Team Lead
©2007 Rolls-Royce plc
The 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.
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Contents
z Engine Overview
z Reliability
z ‘Recent’ Developments
z Future of the Gnome
Rolls-Royce data-strictly private
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Engine Overview
z Applications
z Roles and Power Growth
z Fleet Profile
Rolls-Royce data-strictly private
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Engine Overview - Whirlwind
z Gnome derived from General
Electric T58 engine
z Original GE T58 Engine
supplied in 1958
z Compressor and Turbine
designs originally developed
by De Havilland
z Control system developed by
Hawker Siddeley Dynamics
Engineering (HSDE)
z Gnome first ran in 1959 in the Westland Whirlwind
z Single Engine Application
z Introduces the world first helicopter computer control system
z Innovative in that it removed a significant work load from the pilot
specifically in the area of rotor control
z 1000 shp (Gearbox limited to 850 shp)
Rolls-Royce data-strictly private
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Engine Overview - Wessex
z In 1961, the Gnome Powered
Agusta Bell 204B entered into
service (1000 shp, single engine)
z The engine was further
developed to produce 1350 shp
z The H1200 was used to re-engine
the Gazelle powered Westland
Wessex
z First flight took place in 1962
z Twin engine application
z Engines coupled through a gearbox to drive the aircraft transmission
z Engines installed at a 35 degree nose down attitude
Rolls-Royce data-strictly private
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Engine Overview - Vertol
z The Gnome H1200 was
also installed in the
Kawisaki Vertol aircraft
(Boeing Sea Knight) and
the SRN 6 Hovercraft
z Work continued to upgrade
the engine to enable its
appication into heavier lift
applications
z The Vertol installations
were upgraded to Gnome
H1400’s in the 1980’s.
Rolls-Royce data-strictly private
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Engine Overview – Sea King
z In 1967 the first flight of the H1400
(1500 shp) Sea King took place
z As the all up mass of the Sea King
increased, high power ratings were
needed
z The Gnome H1400-1 engine was
developed to deliver 1660 shp
z In the 1980s the requirement to
operate Sea Kings at higher
ambient temperatures led to the
development of the H1400-1T
z This reduces the power ‘lapse rate’
as ambient temperature increases
Rolls-Royce data-strictly private
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Engine Overview – Power Growth
% INCREASE IN POWER
H1400-1 & H1400-1T
1660 41% IMPROVED 1Stg TURBINE MATERIAL,
INCREASED TET.
H1400
1500 28% INCREASED AIRFLOW, FURTHER
SHP MAX MATERIAL IMPROVEMENT,
INCREASED TET.
CONTINGENCY
RATING
H1200
1350 15%
IMPROVED MATERIALS, INCREASED
TET
1175 H1000
Rolls-Royce data-strictly private
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Engine Overview – EIS Time Line
2003 H1400–1T UK MoD
1969 H1400
1982 H1400-1T
1965 H1200
1964 H1200 1984 H1400-1T
1974 H1400-1
1963 H1200 1986 H1400-1
1963 H1200 1981 H1400-1
1973 H1200
1962 H1000/H1200
1973 H1400
1961 H1000 1975 H1400-1
1960 1970 1980 1990 2000
Rolls-Royce data-strictly private
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Engine Overview - Production
z Approximately 2600 Gnome
engines produced
z The last Gnome was
manufactured in 1998
z 900 engines currently within
“supported” fleet, i.e. H1400
series
z Between 200-400 in
“unsupported” fleet
z Supported via 2nd hand market
z Of the “supported” fleet all are
original operators and all are still
operational
z Most operators reviewing Sea
King Replacement in terms of
EH101, NH90 and Blackhawk
Rolls-Royce data-strictly private
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Rolls-Royce data-strictly private
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Fleet Overview - Roles
z The Sea King operation world wide involves a number of roles
including
z ASW (Anti Submarine Warfare)
z AEW (Airborne Early Warning)
z SAR (Search And Rescue)
z Troop Transportation/Supply
z All of these roles require a different operational profile and different
demands from the aircraft/engine system
z A vast proportion of the operators use their aircraft predominately in
a SAR operation
z Engine reliability specifically starting is therefore paramount for
these operators
z However the environment in which they work and the operation they
undertake is varied and in some cases extremely harsh
z In the SAR role, R-R believe that the number of persons rescued by
Gnome powered aircraft worldwide exceeds 80,000
Rolls-Royce data-strictly private
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Engine Reliability
z Applications
z Production
z Roles and Power Growth
z Fleet Profile
Rolls-Royce data-strictly private
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Reliability - Summary
z Main use of Sea King Aircraft is either
z ASW (Anti Submarine Warfare)
z AEW (Airborne Early Warning)
z SAR (Search And Rescue)
z Troop Transportation/Supply
z Different roles do have an effect on engine reliability
z Gnome is a mature product hence reliability is stable
z The main cause for engine removal is basic unplanned
z The Basic planned rates are constant
z Recent work within the MoD under revised contracting
arrangements has improved their basic unplanned rate
Rolls-Royce data-strictly private
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Reliability - Stability
z Gnome is a mature product hence reliability is stable
z Occasional issues occur with “One off” type failures
which are
z Difficult to identify route cause
z Difficult to diagnose (intermittent)
z Difficult to resolve either short or long term due to cost
involved for 1 off type failures.
z Occasional failures focus around the Control system
z Aircraft induced issues which result in engine rejection
- Vibration
- Torque Problems
- Handling issues
z General rectified by component replacement
z Rejected components are often ‘Fault not Found’
Rolls-Royce data-strictly private
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Reliability – Unplanned Removals
z The main cause for engine removal is basic unplanned
z BUR Rate fluctuates mainly due to
z Operations outside of normal operating environments I.e
conflict prevention
z The re-establishment of a significantly large percentage of the
fleet to a “overhauled” standard following significant front line
operations
z As an example the UK MoD have operated in
- Eastern Europe
- Middle East
- Africa
- Central Asia
z Generally all engines age and reliability degrades at the same
rate
z Thus engine reliability around a specific level improves and
degrades in constant cycles
Rolls-Royce data-strictly private
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Reliability – Unplanned Removals
No.1 Seal
Middle East
Rolls-Royce data-strictly private
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Reliability - Unplanned Removals
Distribution of Basic Unplanned Removals
Deployed
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SAR
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Rolls-Royce data-strictly private
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Reliability – Top Causes of Removal
z Performance
z General life related
- Dirty compressors
- Erosion (Wear Out)
- Corrosion.
z IGV system wear – loss of datum setting
z Oil Leaks/High Oil Consumption
z General Flange leaks
z No. 5 bearing leaks
z Starter Jaw Seal Leaks
z Cracked Exhaust Casings
z Operator maintenance practice
z In some operators FoD has reduced, this
is sustainable due to introduction of
EAPS/Centrisep Filter
Rolls-Royce data-strictly private
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Recent Developments
z Tropical Applications
z Improved Erosion Protection
Rolls-Royce data-strictly private
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Tropical Applications
z The H1400-1T is a derivative of the H1400-1 designed to
operate in higher ambient temperature
z It has a reduced power lapse rate
z This is the rate at which power drops off as ambient
temperature increases
z Therefore at high ambients it retains power at a better rate
than the H1400-1 engine
z The H1400-1T is rated at ISA + 30 Deg C.
z This is achieved by optimising the Turbine Entry
Temperature (TET) and is facilitated by trimming of the Power
Turbine Inlet Temperature (PTIT) signal
z It provides positive benefits over the H1400-1 engine at all
rating conditions at higher ambient temperatures
Rolls-Royce data-strictly private
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Tropical Applications - Ratings
z Maximum Continuous Rating
Rolls-Royce data-strictly private
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Tropical Applications - Ratings
z 1 Hour Power Rating
Rolls-Royce data-strictly private
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Tropical Applications - Ratings
z Maximum Contingency Rating
Rolls-Royce data-strictly private
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Tropical Applications - Core
z Basic mechanical components within the engine types are
the same
z Conversion is achieved with the introduction of a PTIT
trimmer assembly
z There are a number of modifications which must be
embodied in the H1400-1T engine:
z Compressor Vane 1/4 Packs
z Cast Stage 3 Nozzle Assembly
z Power Turbine Wheel and shaft made from A285
z Improved number 3 bearing
z Mk 1A Fuel Control system
z H1400-1T has a Stage 1 Turbine Blade life of 1600 hours
z Minor aircraft modification to the cockpit gauge
Rolls-Royce data-strictly private
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Tropical Applications - Trimming
z The Gnome engine Temperature measurement is taken from
the Power Turbine Inlet Temperature (PTIT) Thermocouple
Reading
z Power on a temperature basis is derived from the Turbine
Entry Temperature (TET) position – this can not be measured.
z It can however be calculated from engine measurement
parameters
Power Turbine
Turbine Entry Inlet Temperature
Temperature
Rolls-Royce data-strictly private
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Tropical Applications - Trimming
z The relationship between TET and PTIT is not constant.
z Therefore for a sample of engines with a PTIT of 795 Deg C
the TET will vary.
z 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
Scatter of engine PTIT v’s
820 Max Contingency TET . Note: No engines
810 operating limit have optimum PTIT v’s TET
800
790
Relationship. I.e 795 PTIT
@ 1357 TET
PTIT
780
770
760 Indicative engine
750 running lines TET Limit
740
1270 1280 1290 1300 1310 1320 1330 1340 1350 1360
TET
Rolls-Royce data-strictly private
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Tropical Applications - Trimming
z This inability to operate to the max TET figure is especially
noticeable as the ambient temperature increases
z In order to maximise the TET whilst still being able to use the
PTIT as a measurement position trimming is introduced
z Trimming requires, during test bed running, calculation of the
TET using a number of engine measurement parameters
z Once the TET is calculated, a relationship between the TET and
PTIT can be derived
z This 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 reached
z Therefore trimming allows the optimum TET to be achieved and
hence engine power on a temperature basis
Rolls-Royce data-strictly private
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Tropical Applications - Trimming
H1400-1
820
810
800
790
PTIT
780
770
760
750
740
1270 1280 1290 1300 1310 1320 1330 1340 1350 1360
TET
H1400-1T COMPUTER SIGNAL H1400-1T COCKPIT GUAGE
820 750
810
740
800
PTIT UNTRIMMED
PTIT TRIMMED
790 730
780
770 720
760
710
750
740 700
1270 1280 1290 1300 1310 1320 1330 1340 1350 1360 1270 1280 1290 1300 1310 1320 1330 1340 1350 1360
TET TET
Rolls-Royce data-strictly private
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Erosion Protection – Coated Blades
z Titanium Nitride Coating process
developed by ‘MDS Prad’
z In service trial already complete
by GE on various engine types
z R-R is currently undertaking a
trial on Gem and Gnome engines
with the assistance of UK MoD
z It is anticipated that the coating
will deliver improved erosion
protection giving
z greater on wing life
z Reduced cost of operation
z Great performance retention
Rolls-Royce data-strictly private
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Future of The Gnome
z Design Improvements
z OSD’s and Fleet Run Down
z Support Initiatives
Rolls-Royce data-strictly private
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Design Improvements – PTIT Harness
z Existing harness suffers from
z Fitting and removal damage
z Fretting
z Storage and transportation damage
z Designed as consumable (non repairable)
z High cost item
z New design features
z Protected (caged) sensing tip
z Improved insulation resistance
z Head angle of 80 degrees to facilitate fitting
z Deeper hexagon flats on the mounting nuts
z Provision for thermocouple replacement if damaged e.g. by
fretting
Rolls-Royce data-strictly private
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Design Improvements – IGV Linkage
z Current VGV system is prone to:
z Cracking of the bracket
z Deformation of links and bell
cranks
z Wear of pivot pins
z This is known to cause:
z Increased scheduled and additional
unplanned maintenance
z Engine rejection and poor
compressor / engine installed
performance
z Results on cost of ownership are:
z High cost of scheduled
maintenance
z High cost of engine rejection and
part repair / replacement
Rolls-Royce data-strictly private
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Design Improvements – IGV Linkage
z Redesign IGV bracket utilises RTM322 technology
z Self lubricating bearing surfaces
z Sealed pivots to eliminate dirt ingress leading to wear
z Increased stiffness
z Resign will not improve engine performance, but improve
performance retention
Current Design
Improved Design
Rolls-Royce data-strictly private
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Out of Service Dates
z Operators are extending OSD’s without reducing fleet sizes
z Spare/surplus engines will not therefore become available for
many more years
z RR operates a lead time business and does not hold long lead
time items on the shelf
z This presents significant challenges for both RR and operators
z In partnership with operators RR is seeking to change the way in
which it provides support at all levels (1st, 2nd and 4th line)
z RR and accessory OEM’s committed to Gnome support to OSD’s
Rolls-Royce data-strictly private
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Fleet Run Down Profile
100
90
80
70
% From 2006 Figure
60
50
40
30
20
10
0
Now 2006-2009 2010-2012 2012-2015 2015-2018 2018 plus
Year
Rolls-Royce data-strictly private
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Out of Service Dates
Swedish Armed Forces
Royal Australian Navy
Indian Navy
Pakistan Navy
Qatari Emeri Air Force
Egyptian Air Force
Royal Norwegian Air Force
Belgian Air Force
Federal German Navy
UK MoD
Now
Rolls-Royce data-strictly private
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Future Support Initiatives
z New support initiatives within the Mission Ready Management
Solutions (MRMS) support frame work offer operators and RR a
more cost effective way of managing fleets
z Drive toward spares forecasting managed by RR, providing
benefits of higher volume provisioning giving LT benefits
z UK MoD and R-R driving towards expanding the current Ssupport
framework an Asset Availability Service (AAS)
z 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
z Currently working with other operators to expand the MRMS
umbrella increasing benefits to all the fleet
Rolls-Royce data-strictly private
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Summary
z Although reliability is stable, RR
is committed to the introduction
of new technologies to improve
z Cost of ownership
z Availability
z RR and operators continue to
invest in the future of the Gnome
engine
z Due to changing mission
demands a number of operators
are upgrading to H1400-1T
z The Gnome will remain in service
beyond 2020
Rolls-Royce data-strictly private
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Future Developments!
Rolls-Royce data-strictly private
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Questions
Rolls-Royce data-strictly private
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Engine Overview – Fleet Stats
z Total Gnome engine hours 7,706,523 (all mks)
z Flying rate (world fleet) = 9900 hours (monthly average)
z Number of engines in operation = 883 (Sea King only)
z Number of aircraft = 299 (Sea King only)
z Number of operators = 17 (some unsupported)
z Overhaul (second line) workshops = 7 (12)
z Removal rate all causes = 2.45/1000 efh (MTBR* 410 hours)
z Removal rate basic unplanned = 1.23/1000 efh (MTBR* 813 hours)
z In flight shut down rate UK Mod = 0.03/1000 efh (4 yr average)
*Mean Time Between Removals
Rolls-Royce data-strictly private
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Engine Overview – Control System
Speed
Select
Basic Engine Control Lever
Ng Nf
Ptit
Collective
Throttle Pitch
Manual actuator anticipator
Throttle
Centrifugal
fuel
Integrated
filter fuel system
Computer
Key
Nf Ng
Ng tachometer Ptit
tachometer Ptit
Nf
Mechanical
Combustion Gas Power
generator Electrical
Compressor system turbine Fuel flow
Gn/3.1.1/d/a1 turbine
Rolls-Royce data-strictly private
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Tropical Applications - Ratings
z Performance differences for minimum brochure engines.
ISA SLS ISA SLS
(Uninstalled) Difference (Uninstalled) Difference
[shp] [shp]
Rating -1 -1T % -1 -1T %
Max Continuous 1250 1385 10.8 810 1050 29.6
Max 1 Hour Power 1535 1540 0.3 1085 1380 27.2
Max Contingency 1660 1585 -4.5 1375 1465 6.5
Rolls-Royce data-strictly private
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Tropical Applications - Trimming
1 2 Wf 3 4 5 6 7
z 1 = Compressor entry - Measured - Temperature, Pressure and Mass Flow
z 2 = Compressor exit – Measured - Temperature and Pressure
z 3 = Gas Generator Turbine Entry = TET - Calculated
z 4 = Gas Generator Turbine Exit = Calculated
z 5 = Power Turbine Inlet Temperature = PTIT Measured - Temperature
z 6 = Power Turbine Exit Temperature = Measured - Temperature
z 7 = Jet Pipe Temperature = Measured – Temperature
z Wf = Fuel Flow = Measured
Rolls-Royce data-strictly private
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Publications Update
z R-R is currently in the process
of updating all of the Gnome
publications
z Conversion to AECMA format
z Distributed on CD and via the
web (www.aeromanager.com)
z Provides
z Lower cost production
z Rapid amendments
z Rapid distribution
z Easy incorporation
Rolls-Royce data-strictly private
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Design Improvements – Liner
Locating pin and
z Existing combustion liner boss wear
Fuel suffers from excessive wear
of the
manifold not location pins and
shownbosses
z Loss of liner location
z Liner and nozzle damage
z High overhaul/repair cost
z Improved location pin
geometry and build method
under development
z Reduced repair and
overhaul costs
Rolls-Royce data-strictly private
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Forecast Flying Rates
105
100
Percentage of 2006
95
Flying Rate
90
85
80
75
2006 2007 2008 2009 2010 2011 2012 2013 2014 2015
Year
Rolls-Royce data-strictly private
