s

Fundamentals
M15
GAS TURBINE ENGINE
Rev.-ID: 1
Author: GeJ
For Training Purposes Only
ELTT Release: Jul. 10, 2013

M15.16
Turbo-Prop Engines

EASA Part-66
CAT B1

M15.16_B1 E
Training Manual

For training purposes and internal use only.

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Revision Identification:
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Lufthansa Technical Training
GAS TURBINE ENGINE EASA PART-66 M15
TURBO-PROP ENGINES
M15.16

M15 GAS TURBINE ENGINE

M15.16 TURBO-PROP ENGINES
FOR TRAINING PURPOSES ONLY!

HAM US/O-5 DaC Jul 10, 2013 ATA DOC Page 1

Lufthansa Technical Training
GAS TURBINE ENGINE EASA PART-66 M15
TURBO-PROP ENGINES Gas coupled, Free coupled and Gear coupled Turbines
M15.16

GAS COUPLED/FREE TURBINE / GEAR COUPLED TURBINES Helicopters have a maximum speed of 300 km/h.
The performance spectrum of helicopters calls for construction
Introduction characteristics which are not required for TPEs.
Currently the following two combustion turbine engine types are often This especially applies to the design of the intake area, which has to be
described as shaft power engines: adapted to the slow speed. This area often has to be protected by certain
installations against the intake of foreign objects (that have been raised by
S Turboprop Engines, TPE the engine itself).
S Turboshaft Engines, TSE These protective installations may also be necessary on smaller TPE
The Open Rotor Concept represents a possible advancement of the TPE. aircraft, if the construction and the operational conditions do not eliminate
Sometimes Auxilliary Power Units (APUs) are also included under this topic. such danger. Generally these protective installations are part of the engine
Grouping these two engine types together (TPE and TSE) is a sensible idea, nacelle construction rather than part of the engine itsself.
because their development has a common aim: providing drive shaft power for S The diverging requirements result in differences concerning the control of
the creation of thrust without being the thrust provider themselves, which engine, propeller and rotor systems.
distinguishes them essentially from turbojet and turbofan engines. Some manufacturers have developed shaft power engines for performances up
This is basically also true for APUs, but their shaft performance drives other to about 1200 kW. These engines operate successfully in TPE and TSE
power providers like generators for the supply of the electrical system of the configurations.
aircraft pneumatic system.
Nevertheless, as a rule there are significant differences between TPEs, and
TSEs as far as their construction is concerned.:
S In the case of TPEs the reduction gearbox, which has to ensure the rpm
reduction from the high optimal rpm of the gas turbine rotor system to the
(considerably lower) optimal rpm of the propeller, is usually part of the
engine construction.
Turbo shaft engines (like helicopter drive systems) usually do not have such
a gearbox. The necessary gear and shaft systems which drive the rotors
are part of the transmission system.
S In case of a TPE engine the most of the thrust is generated by the propeller
FOR TRAINING PURPOSES ONLY!

(about 90%). The remaining part of the total thrust is generated by the
acceleration of the hot exhaust gases.
This mentioned remaining part of the thrust is neglicable in case of turbo
shaft engines. In some cases, the turbine section which is used for an
increase in shaft performance is laid out for an extreme expansion of the
gas - which means that the exhaust system acts as diffusor.
S Further differences result from the different speeds for which TPEs and
TSEs are used.
Large TPE powered aircraft with two or four engines operate at speeds
between 450 and 600 km/h – in some cases with speeds up to 750 km/h.

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Lufthansa Technical Training
GAS TURBINE ENGINE EASA PART-66 M15
TURBO-PROP ENGINES Gas coupled, Free coupled and Gear coupled Turbines
M15.16

ÎÎÎÎ
ÎÎÎÎ
ÎÎÎÎ
ÎÎÎÎ
ÎÎÎÎ
ÎÎÎÎ
ÎÎÎÎ
ÎÎÎÎ
TURBOPROP ENGINE (TPE)

ÎÎÎÎ
ÎÎÎÎ

ÎÎÎÎ
ÎÎÎÎ
ÎÎÎÎ
OPEN ROTOR CONCEPT (ORC) – PROPFAN
ÎÎÎÎ
FOR TRAINING PURPOSES ONLY!

TURBOSHAFT ENGINE (TSE)

AUXILIARY POWER UNIT (APU)

Figure 1 Shaft Power Gas Turbine Engines – Overview

HAM US/O-5 DaC Jul 10, 2013 01|Intro|L1|A/B1 Page 3
Lufthansa Technical Training
GAS TURBINE ENGINE EASA PART-66 M15
TURBO-PROP ENGINES Operation
M15.16

OPERATION AND BASIC STRUCTURE OF PTL ENGINES

The explanations concerning thrust and propulsive efficiency in M15.02 offer
two basic conclusions:
S In principle you can achieve a certain amount of thrust in two different ways:
− either by a high acceleration of a relatively small mass of air per time unit
− or by a moderate acceleration of a large mass of air per time unit.
S The smaller the speed of the mass of air which has been accelerated by the
engines at a certain air speed, the higher the propuslive efficiency.
At low air speeds the result is, that the required thrust has to be achieved by
a larger mass of air routed through the engines.
The economic thrust creation of TPEs at air speeds of up to 700 kmh is
based on this principle:
S The propeller transports a large mass of air, but accelerates this mass of air
only to a small extent.
S As the TPE has to supply power for the drive of the compressor, the engine
aggregates and the propeller, much more energy is extracted from the hot
gas that leaves the combustion chamber, than is the case with turbojet
engines. This means that in TPE engines the static pressure is almost
completely removed from the gas in the turbine. As a result, only a very
limited acceleration of gas in the exhaust system is possible.
S Due to the transformation of a considerably larger percentage of the energy
of the hot gas into shaft performance, the temperature of the gas leaving
the turbine is also significantly lower as compared to a turbojet engine.
The unused thermal energy that is discharged into the atmosphere together
with the exhaust gas is therefore much lower than in case of turbojet
engines. This makes for the high efficiency of TPE engines.
FOR TRAINING PURPOSES ONLY!

The diagram of an ideal brayton cycle of a TPE and a turbojet engine with
comparable gas generators illustrates the above statements.

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GAS TURBINE ENGINE EASA PART-66 M15
TURBO-PROP ENGINES Operation
M15.16

0 2 3 4 8
5ETL
p T4 = Tmax = TIT

p3 + p4 +
+ pmax
ÉÉÉÉÉÉÉÉÉÉ
3

ÉÉÉÉÉÉÉÉÉÉ
4

ÉÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉÉ
ÉÉÉ
ÉÉÉ
ÉÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉÉ ÎÎÎ ÉÉÉ
ÇÇÇÇÇÇÇÇÇÇÇÇÇÇ
p 5ńETLńGG 5ETL/GG
ÎÎÎ ÉÉÉ
ÇÇÇÇÇÇÇÇÇÇÇÇÇÇ
ÇÇÇÇÇÇÇÇÇÇÇÇÇÇ
T5/ETL/GG
ÎÎÎ ÉÉÉ
ÇÇÇÇÇÇÇÇÇÇÇÇÇÇ
ÇÇÇÇÇÇÇÇÇÇÇÇÇÇ 5PTL ÎÎ
ÎÎ ÉÉÉ
ÇÇ
p 5ńPTL
2 T5/PTL
p0 + p8 + 8
ÎÎ ÉÉÉ
ÇÇ
+ pmin 0
ÎÎ ÉÉÉ
ÇÇ
T0=Tmin T8 ÎÎ ÉÉÉ
ÇÇ
ÎÎ ÉÉÉ
ÇÇ
V3 = Vmin V8 = Vmax V
ÎÎ ÉÉÉ
ÇÇ
FOR TRAINING PURPOSES ONLY!

ÉÉÉÉÉ ÎÎ 5GG

ÉÉÉÉÉ
ÉÉÉÉÉ
TECHNICAL WORK TO POWER THE COMPRESSOR AND
ENGINE ACCESSORIES
0
ÎÎ
ÎÎ
2 3 4 5PTL 8

ÇÇÇÇÇ
ÇÇÇÇÇ
TECHNICAL TURBINE WORK TO POWER THE PROPEL-
LER
ÎÎ
ÎÎ
GASGENERATOR

CROSS SECTION OF A TYPICAL AIRFLOW IN AN

p, V − DIAGRAMM
TURBO JET AND TPE

Figure 2 Brayton Cycle of Turbo Jet and Turbo Prop Engines

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Lufthansa Technical Training
GAS TURBINE ENGINE EASA PART-66 M15
TURBO-PROP ENGINES Construction
M15.16

CONSTRUCTION OF TURBO PROP ENGINES − and power or free power turbines for the drive of propellers and other
devices connected to the propeller system.
The general construction of the turbo compressor of a TPE is identical to
that of a turbojet engine, but there are more variations. Exhaust System
One reason for this are the low operation speeds. Another reason is the aim of S Depending on the expansion ratio, the exhaust system can be designed as:
the manufacturers to compensate the disadvantages caused by the weight and − gas exhaust only (with almost total lack of static pressure) or
dimension of the gear mechanism and propeller system. This is partially − with a slightly reduced cross-sectional area as tail pipe, in case the
achieved by the selection and design of the other engine components. energy level present behind the turbine allows acceleration of the
In case of engines that can be used as propeller drive and as turbo engine for exhaust gas jet to produce additional thrust.
powering the rotor systems of helicopters, additional requirements concerning
the construction and design are encountered.
Compressor:
S In case of high performance TPEs axialcompressors are preferred.
At a great pressure ratio they are equipped with air discharge possibilities
and adjustable air inlets and stators. sometimes they are divided into low
and high pressure compressors.
S TPEs with small and medium performance often use centrifugal
compressors (at least as last compressor stage).
A 90 degree deflection of the airstram often is advantageous. This shortens
the length of the engine, reduces the distances between bearings and offers
a larger stability reserve.
Combustion Chamber
S The combustion chamber doesn not differ from other engine types as far as
effectiveness is concerned. The annular combustion chamber design is
used most often.
S In case of TPEs with small and medium performance and axial compressors
or a combination of axial and radial compressors, often combustion
FOR TRAINING PURPOSES ONLY!

chambers that work according to the counter flow principle are used.
Turbine
S Due to the reasons mentioned before, the turbine section of the TPE (which
is almost always an axial reaction type turbine) a higher number of stages
than a comparable turbojet engine.
S In the field of multi-shaft TPEs distingtions are made between:
− gas generator turbines for compressor drive and most of the engine
aggregates [Gas Generator Turbine, Gas Producer Turbine; Compressor
Turbine; HP Turbine, LP Turbine]

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TURBO-PROP ENGINES Construction
M15.16

FRONT HOUSING COMBUSTION CHAMBER AFT BEARING

AND BEARING HOUSING HOUSING
AIR INLET

COUNTER ROTATING COAXIAL DOUBLE REDUCTION GEAR COMPRESSOR

PROPELLER ANULAR COMBUSTION
(REDUCTION RATIO = 11,404 : 1) (14 SAGES) TURBINE
CHAMBER
(5 STAGES)

DOBRYNIN WD-4K (3.210 KW) KUSNEZOW NK-12M (11.185 KW)

FOR TRAINING PURPOSES ONLY!

TRUE SCALE COMPARISON OF A HIGH PERFORMANCE

PISTON ENGINE WITH A TURBO PROP ENGINE

Figure 3 Comparison of TPE and Piston Engines

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GAS TURBINE ENGINE EASA PART-66 M15
TURBO-PROP ENGINES Construction
M15.16

Single Spool Turbo Prop Engines

Sometimes Single Spool Turbo Prop Engines are also called Single Shaft
Turboprop or Single Shaft Direct Drive engines.
“Direct Drive“ refers to the engine, which generally has a multi stage design
and supplies the power for the compressor, the engine aggregates and the
propeller via a shaft system.
The compressor and the aggregates actually take their power from the engine
and the propeller receives the remaining power via the reduction gear.
The advantages of this design are:
S relatively uncomplicated construction design
S good acceleration
S simple operation (usually one throttle lever operation)
The disadvantages are:
S To ensure a high efficiency of the turbo compressor and the propeller
system, the reduction ratio has to be rather high. This will call for a
complicated and heavy reduction gear.
S The change in propeller rpm has a direct influence on the pressure increase
of the compressor. This is why single shaft TPEs operate with an
unchanging rpm or with with a very limited rpm selection scope.
S The single shaft TPE requires a high drive performance of the starter
mechanisms, because they must rotate the complete rotor system including
the propeller during the starting process.
S Complex safety installations are necessary to prevent dangerous conditions
(for example negative thrust or excess rotation speed) in case of engine
failure or failure of the propeller automatic system.
FOR TRAINING PURPOSES ONLY!

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TURBO-PROP ENGINES Construction
M15.16

TWO-STAGE
PLANETARY
REDUCTION
GEARS
REVERSE FLOW
ANNULAR
COMBUSTION
CHAMBER FUEL
NOZZLE
FOR TRAINING PURPOSES ONLY!

RPM TPE331−10 *)
NGG: 41,730
NProp: 2,000 (CW ALF)
1,591 (CCW ALF) TWO-STAGE THREE-STAGE
AIR INLET RADIAL AXIAL
COMPRESSOR TURBINE
*) www.honeywell.com

Figure 4 Single-Spool TPE Honeywell TPE331

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GAS TURBINE ENGINE EASA PART-66 M15
TURBO-PROP ENGINES Construction
M15.16
Dual-Spool Turboprop Engines
Modern TPEs are usually dual-spool constructions with kinematically
independent turboprop engines with free power turbines.
The rpm which is generated by the free power turbine and transmitted via the
gear to the propeller (mechanically independent of the gas generator) has
many advantages:
S These advantages are
− possible different rpm of the two rotors
− facilitation of start and acceleration
− improvement of part load behaviour (better efficiency) and
− thus a reduction of the specific fuel consumption
S Since the free power turbine is kinematically independent of the rotor of the
gas generator, the rpm of the turbine can be considerably smaller than that
of the turbo compressor.
As a result the reduction ratio and thereby also the complexity and mass of
the reduction gear can be reduced.
S Since the free power turbine has only a gas-dynamical interface with the
gas generator turbine, a change of the rpm of the propeller turbine has no
influence on the pressure increase of the gas generator compressor (as is
the case with single shaft TPEs with variable rpm in the performance
spectrum).
The construction design of two shaft TPEs is more complicated, but the
operational advantages outbalance this disadvantage and often allow for
designs with reduced mass.
The two shaft TPE Pratt & Whitney Canada PT6A is designed with shaft
systems that are arranged in a row and a complete inversion of the direction of
FOR TRAINING PURPOSES ONLY!

airflow. According to the performance data (T.O., SLS, STD Day), three basic
types can be distinguished: 1)
− PT6A (Small) (A−11 to A-36, A−140) 600 to 1,075 ESHP
− PT6A (Medium) (A−41 to A−62) 1,000 to 1,400 ESHP
− PT6A (Large) (A−64 to A−68) 1,400 to 1,900 ESHP

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TURBO-PROP ENGINES Construction
M15.16

EXHAUST ANNULAR COMPRESSOR

OUTLET REVERSE FLOW BLEED
COMBUSTION VALVE
CHAMBER

1st
STAGE
2nd
STAGE
4 AXIAL
FOR TRAINING PURPOSES ONLY!

STAGES
PROPELLER REDUCTION FREE POWER CENTRIFUGAL
SHAFT GEARBOX TURBINE STAGE
(CW; Np) (CW; Nf)

COMPRESSOR COMPRESSOR AIR INLET ACCESSORY

TURBINE GEARBOX
(WITH INTEGRAL
OIL TANK)
GAS GENERATOR SPOOL
(CCW, Ng)

Figure 5 Dual-Spool TPE wit Free Power Turbine – Pratt & Whitney Canada PT6A (Large) Engine
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TURBO-PROP ENGINES Construction
M15.16
Dual-Spool Turboprop Engines cont.
If higher compressor pressure conditions are required for more drive power, the
two shaft TPE can be equipped with two compressors.
In this case, the low pressure turbine drives the propeller and the low pressure
compressor.
This increases (as in case of the turbojet engine) the stability reserve of the
compressor system and the efficiency in turndown operation is improved.
However, this design has rarely been used. The best known example for its
use is the Rolls-Royce “Tyne“. Before the development of the three shaft
TPE TP400−D6 for the Airbus A400M, it was known as the serial TPE with the
highest performance values in the western world.
From 1960 onward, it was used in the four engine Vickers „Van- guard“ (Mk.
505/512; 4985/5545 eshp) and Canadair CL-44 (Mk.515; 5730 eshp). From
1965 onward it was installed in the two engine submarine hunter Breguet
„Atlantique“ (Mk. 21; 6100 eshp). From 166 onward, it powered the four engine
transporter Shorts „Belfast“ (Mk. 515). The biggest part of the total of 1481
produced engines was installed in the military transporter C-160 “Transall“.
From 1968 onward, 600 engines of the series Mk.22 and 522 (6100 eshp) were
manufactured for this airplane.
FOR TRAINING PURPOSES ONLY!

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TURBO-PROP ENGINES Construction
M15.16

AIR INLET TUBO-ANNULAR SINGLE−STAGE 3−STAGE

HP TURBINE LP TURBINE EXHAUST
6−STAGE 9−STAGE COMBUSTION
LP COMPRESSOR HP COMPRESSOR CHAMBER

PROPELLER
SHAFT

REDUCTION
GEARBOX LP LP
GEARBOX
INTERMEDIATE CONNECTING TGT
INPUT SHAFT
SHAFT SHAFT
c T pt 1 2 24 25 3 4 44 5 6
(ft/sec) (_C) (psi)

2000 1000 200

Maximum Permissible Rotor Speeds and

Turbine
1500 750 150
Gas Temperature at Take Off (R. Ty. 20
Mk. 22) *)
FOR TRAINING PURPOSES ONLY!

S HP rpm 18,150
(100%)
1000 500 100 *)S LP Technische
rpm 15,250
Schule der Luftwaffe 3
(100%)
Fassberg
S Prop Shaft rpm
Schulungshandbuch 975 (at LP
C-160
rpm =
„Transall“ 100%)
500 250 50
S TGT (_C) 685

0 0 0

Figure 6 Dual-Spool TPE Rolls-Royce „Tyne“ (Layout and Airflow Schematic – Simplified)
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TURBO-PROP ENGINES Construction
M15.16
Triple Spool Turbo Prop Engines
In case of triple spool turbo prop engines, the turbo compressor (gas
generator) is designed as two shaft system with low pressure rotor and high
pressure rotor. The propeller is powered by the free power turbine, which is
installed behind the low pressure turbine.
This design allows for the combination of the advantages we know from two
shaft turbojet engines (high compressor pressure conditions and relatively low
number of stages combined with a high stability reserve of the turbo
compressor) with the advantages of the mentioned two shaft TPE.
The three shaft Pratt & Whitney Canada PW100 TPE series, that comprises
more than 30 types, was developed for the regional aircraft market.
By an increase in compressor pressure conditions and turbine entry
temperature as well as application of new technologies, the performance could
almost be triplicated. as can be seen in the list below:

Engine Model PW120 PW127 PW150

Program Launch 1979 1990 1995
Weight (kg) 417 481 690
Thermal Power (kW) 1782 2457 4982
PWR/WT Ratio (kW/kg) 4.27 5.11 7.22
Max. GBX PWR (kW) 1491 2050 3781
ESFC (kg/kW·hr) 0.286 0.273 0.255
TIT (_C) X X + 58 X + 187
Airflow (kg/sec) 6.70 8.49 14.44
OPR 12.14 15.77 17,97
FOR TRAINING PURPOSES ONLY!

Engine Control Supervisory FADEC with FADEC

digital electronic hydromechanical dual channel
control with me- back-up control
chanical back-up
Initial Installation Dash 8−100 ATR-72 Dash 8−400

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TURBO-PROP ENGINES Construction
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REDUCTION GEARBOX LP SPOOL

(RGB) (CCW; NL)
HOUSING COMPONENTS

HP SPOOL
FRONT REAR INPUT LP (CW; Nh) LP
HOUSING HOUSING DRIVE COMPRESSOR TURBINE
HOUSING CPR = 4.1 : 1 c)
POWER REFE- OUTPUT PT HP HP POWER
SHAFT RENCE (TORQUE) SHAFT COMPRESSOR TURBINE TURBINE
(CW, Np) SHAFT SHAFT (CW, Npt) CPR = 2.8 : 1 d) (CW, Npt)
(CW, Npt)
FOR TRAINING PURPOSES ONLY!

SECOND FIRST
STAGE STAGE
REDUCTION REDUCTION
RATIO RATIO BEARING NO. 1 2 3 4 5 6 7
4.16 : 1 4.01 : 1 a)
AND TYPE B R B B R R R

REMARKS:
REDUCTION GEARING a) PW120/121 only; c) PW118/120/121 only;
LP INTERNAL ANNULAR
REDUCTION RATIO PW118/119: 3.85 PW119: 5.6 : 1 DIFFUSER HP REVERSE FLOW
16.67 : 1 b) b) c)
PIPE DIFFUSER COMBUSTION
PW120/121 only; PW118/120/121 only;
(21 OFF) PIPES CHAMBER
PW118/119: 15.38 PW119: 2.6 : 1

Figure 7 Pratt & Whitney Canada (PWC) PW100 Series Engine (PW121, Simplified)
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F3 F4 F5 A1 I2 A2 F6 O1 – OIL TANK P1 – PROPELLER CONTROL UNIT

(PCU) PUMP
O2 – OIL TANK CHIP DETECTOR
P2 – PROPELLER OVERSPEED GOVERNOR
O3 – OIL PUMP PACK
P3 – ELECTRIC FEATHERING PUMP
O4 – PRESSURE OIL FILTER
(LOCATION)
O5 – OIL PRESSURE REGULATING VALVE
P4 – TORQUE SIGNAL CONDITIONER (TSC)
O6 – CENTRIFUGAL BREATHER OUTLET
O7 – RGB OIL FEED LINE S1 – STARTER GENERATOR (LOCATION)
O8 – RGB OIL SCAVENGE LINE S2 – IGNITOR BOX
O9 – RGB SCAVENGE OIL FILTER S3 – IGNITOR PLUG
O10 – RGB CHIP DETECTOR

ON RGB REAR SIDE (NOT SHOWN):

S PROPELLER CONTROL
UNIT (PCU)
M1
S HYDRAULIC PUMP M2 I3

S3 S AC GENERATOR

O8 A3 I1 S1 O6 F1 F2 P2 P1
A1 – P2.5 AIR CHECK VALVE
A2 – P3 BLEED ADAPTOR P4 F7 O4 O1 O5
A3 – AIR SWITCHING VALVE O2

F1 – FUEL PUMP
F2 – HYDROMECHANICAL UNIT (HMU)
F3 – POWER & CONDITION LEVERS (HMU)
F4 – LP FUEL FILTER
F5 – FUEL HEATER
F6 – FUEL MANIFOLD
FOR TRAINING PURPOSES ONLY!

(WITH FUEL FLOW DIVIDER IN 06:00)

F7 – ENGINE ELECTRONIC CONTROL (EEC)

I1 – Nh SPEED SENSOR
I2 – NL SPEED SENSOR
I3 – NP SPEED SENSOR
I4 – BUS BARS T6 (ITT) SYSTEM

M1 – FRONT MOUNTING PAD (2 OFF, LH & RH)

M2 – FRONT MOUNTING PAD (TOP)
M3 – TORQUE MOUNTING PAD (2 OFF, LH & RH) I4 M4 O3 O9 S2 O7 O10 M3 P3
M4 – REAR MOUNTING PAD (2 OFF, LH & RH)

Figure 8 PW120 (RH View) and PW120 Turbomachinery Module (LH View)
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TURBO-PROP ENGINES Construction
M15.16

ACCESSORY GEARBOX ANGLE DRIVE GEARBOX

FORWARD GAS GENERATOR CASE

REAR INLET CASE
LOOKING AFT

FRONT INLET CASE

OIL
SUPPLY

TO PW120
BRG
NO. 1 & 2
IN TURBOMACHINERY
MODULE

OIL TANK

INTERCOMPRESSOR CASE TURBINE SUPPORT

CASE
LP DIFFUSER CASE DIFFUSER PIPES

PW150
SERIES
ENGINE
FOR TRAINING PURPOSES ONLY!

REDUCTION GEARBOX
MODULE
NOTE:
THE CROSS SECTIONS ARE APPROXIMATELY TO SCALE. TURBOMACHINERY MODULE

Figure 9 PW120 Turbomachinery Module vs. PW150 Series Engine

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M15.16
Due to the high thrust effectiveness at small and medium flight mach numbers The companies that have joined to form this syndicate: ITP (Spain), Rolls-
and because of the wing slip flow caused by the propeller (which increases lift Royce (GB), MTU Aero Engines (Germany) und SNECMA (France) have
and therefore allows for short take off distances and higher take off weights), developed an engine which ensures a high efficiency factor in a broad scope of
the TPE engine was chosen for the transporter Airbus A400M as the most application that spans from extended missions in low altitudes to high speed
attractive option. cruise flight. These properties are based on:
The following specific properties of the TPE are additional advantages over the S an advanced aerodynamic and component design
Turbo Fan Engines chosen by other manufacturers: S low fuel consumption and weight
S low SFC and resulting longer range The engine is equipped with an integrated engine and propeller control system
S excellent maneuvering properties of the aircraft and and it was certified by EASA on May 16th 2011 (TCDS E.033, Issue 02).
S short acceleration times, that are symptomatic for TPEs The propeller which was developed by Ratier-Figeac was granted certification
The three shaft TPE TP400−D6 was developed by Europrop International for its left and right turning version (seen in flight direction) FH385 (CCW) and
(EPI GmbH) for the A400M. H 386 (CW) respectively on May 22nd 2012 (TCDS P.012, Issue 01).

ENGINE

FREE
REDUCTION POWER
GEARBOX (LP)
TURBINE

DUAL-SPOOL
GAS GENERATOR
FOR TRAINING PURPOSES ONLY!

VARIABLE PITCH
TRACTOR PROPELLER
WITH FEATHERING AND
REVERSING CAPABILITY
FH385 (CCW), FH386 (CW)

Figure 10 Powerplant of the Airbus A400M Military Transport Aircraft

HAM US/O-5 DaC Jul 10, 2013 04|Construction|L1|A/B1 Page 18
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TURBO-PROP ENGINES Construction
M15.16

INTERMEDIATE PRESSURE
SPOOL
(CCW; NI)

REDUCTION GEARBOX
(RGB) IP COMPRESSOR HIGH PRESSURE IP LOW PRESSURE TURBINE
(5 STAGES) SPOOL TURBINE (POWER TURBINE)
CCW (P/N EL 1006) 3 STAGES
CPR = 3.5 : 1 (CW; NH)
CW (P/N ER 1006) (CCW; NL)
TRANSMISSION RATIO:
9.929 : 1 HP COMPRESSOR HP
(6 STAGES) TURBINE
CPR = 7 : 1
FOR TRAINING PURPOSES ONLY!

PROPELLER
SHAFT STATIONARY SUPPORT FRONT INTERMEDIATE CASE HP/IP TURBINE TURBINE
(CW or CCW; STRUCTURES FRAME (WITH ACCESSORY GEARBOX) BEARING SUPPORT EXHAUST CASE
NP)

Figure 11 Triple-Spool TPE Europrop International TP400−D6

HAM US/O-5 DaC Jul 10, 2013 04|Construction|L1|A/B1 Page 19
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TURBO-PROP ENGINES Operation
M15.16

As compared to other aircraft engines, the TPE has the following advantages Disadvantages of the TPE as compared to turbo jet and bypass engines
and disadvantages: S The flying speed is usually limited to medium speed due to the efficiency
factor characteristics of the propeller.
Advantages of the TPE as compared to piston type engines:
S The TPE is heavier without producing more cruise flight performance.
S Less complex design and construction
S Higher interference liability because of the high stresses on the reduction
The TPE has less movable parts. As a result, the number of components
gear and the propeller.
that can fail due to abrasion is lower as well.
S Very complex control procedures
Due to the above reasons, the operational life of the TPE is normally longer.
S Rpm control and limitation is necessary
S Higher performance, less mass and a smaller frontal area.
S Higher vibration stresses of the cell as a result of the creation of radial
Performance - mass - ratio: Piston engine: 1,0 ... 2,2 kW/kg
pressure surge caused by the propeller.
TPE: 1,3 ... 5,0 kW/kg
Due to the smaller frontal area, a low resistance installation into nacelles
and fuselages is possible.
S Higher absolute performance.
− Highly developed piston engines can produce a performance of up to
3.200 kW at a mass of more than two tons.
− The TPE with the highest performance can produce a performance of
11.030 kW at a dry mass of 2.35 tons.
S Smooth operation due to the lack of oscillating movements.
S Less complicated operation and maintenance, faster operational availability.
S Superior performance and effectiveness in altitudes up to 11 km.
S Lower specific fuel consumption at medium flying speeds.

Disadvantages of TPEs as compared to piston engines

S Higher fuel consumption at low flying speeds
S A more complex reduction gear is necessary.
FOR TRAINING PURPOSES ONLY!

S More complicated propeller control

Advantages of the TPE as compared to turbo jet engines and turbo fan
engines.
S Superior heat efficiency (lower exhaust gas heat loss)
S Better overall efficiency and therefore superior specific fuel consumption at
low and medium flying speeds.
S Superior acceleration as a result of propeller adjustment. Possibility to
achieve a brake impact in order to shorten the rolling distance after touch
down. Special thrust reverser systems are not required.

HAM US/O-5 DaC Jul 10, 2013 05|Advantages|L2|B1 Page 20

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TURBO-PROP ENGINES Operation
M15.16

OPEN ROTOR CONCEPT

HIGH BPR
TURBOPROP ENGINE
TFE
90

hp 80

(%)
PROPULSIVE EFFICIENCY

70

LOW BPR
60 TFE
FOR TRAINING PURPOSES ONLY!

50
TURBOJET ENGINE
40

30
0 200 400 600 800 1000 1200

AIRSPEED vF (km/h)

Figure 12 Propulsive Efficiency vs. Airspeed

HAM US/O-5 DaC Jul 10, 2013 05|Advantages|L2|B1 Page 21
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TURBO-PROP ENGINES Reduction Gears
M15.16

REDUCTION GEARS
General
When selecting the optimal rpm of the propeller it must be ensured, that the
flow rate (resulting from circumferential speed and airspeed) of the propeller
blades does not exceed the speed of sound. Otherwise compression shocks
with a high density increase will develop at the airfoil of the propeller. This will
strongly decrease the efficiency of the propeller and will subject the blades to
high stresses.
When the rpm is increased, the centrifugal force acting on the propeller blades
will be increased too. This will put stresses on the hub assembly of the
propeller.
Depending on the diameter of the propeller, the propeller platform, the airfoil of
the blade and the general design of the propeller system (single or coaxial
arrangement of propeller blades), the optimal rpm of the propeller is
between 850 and 2500.
The rpm of the turbo compressor that is driving the propeller is much higher
to achieve an advantageous mass/performance ratio. Depending on the design
(single or multi shaft, performance range) between 8000 up to more than
50 000 rpm are possible.
Due to this serious difference in rpm, the installation of a reduction gearbox is
necessary between the turbo compressor and the propeller.
Depending on the rpm ratio, the reduction ratio of this gear wheel planetary
drive can be in the range between 5:1 and 26:1.
In the following list you find the rpm of the turbo compressor, the free power
turbine (drive rpm min–1), the optimal propeller rpm (min–1) and the resulting
reduction ratio of different TPEs.:
FOR TRAINING PURPOSES ONLY!

Engine type TPE331−10 AI-20 PT6A-67R Tyne 20 Mk.22 TP400−D6

number of shafts 1 1 2 2 3
output speed 41.730 12.300 29.894 15.250 8.579
propeller speed 1.591 1.100 1.700 975 864
reduction ratio 26,22 11,18 17,58 15,64 9,929

HAM US/O-5 DaC Jul 10, 2013 06|Red. Gear|L1|A/B1 Page 22

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TURBO-PROP ENGINES Reduction Gears
M15.16

? PROPELLER SHAFT
NPROP = 1591 RPM
TORQUE [ 3103 FT. LBF
?
?
?

OUTPUT/
NOSE
CASE

GAS GENERATOR
OUTPUT DRIVE SHAFT
ACCESSORY
? CASE NGG = 41.730 RPM
FOR TRAINING PURPOSES ONLY!

TORQUE [ 126 FT. LBF

?
DIAPHRAGM
ASSEMBLY

Figure 13 Honeywell TPE331−10 Reduction Gearbox

HAM US/O-5 DaC Jul 10, 2013 06|Red. Gear|L1|A/B1 Page 23
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TURBO-PROP ENGINES Variable Pitch
M15.16

VARIABLE PITCH PROPELLER

In case of the variable pitch propeller, the blade angle can be adjusted during
propeller operation. Thus it can be adjusted to different conditions. This
causes, that the propeller has an improved efficiency in a larger speed range.
Today almost exclusively propellers with hydraulic adjustment are used. The
variable pitch propeller has blades which are pivoted in the hub by means of
ball bearings, roller bearings or needle bearings.
The blades are manufactured from forged light metal alloys, wood or
fiber-reinforced synthetic materials.
The components necessary for propeller adjustment are installed in the hub or
in front of the hub. The most important of these components are the
adjustment piston and the adjustment cylinder. Axial movement is possible with
either the cylinder or the piston. The axial movement of the piston or the
cylinder is changed into a rotary movement for of the propeller blades via pins,
bevel gear wheels or linkage assemblies. The oil necessary for the hydraulic is
taken from the oil pressure system of the engine lubrication circuit. It is routed
by a regulator valve through the hollow propeller shaft to the adjustment piston
and cylinder. The topic “propeller and propeller control“ is illustrated in ATA
chapter 61.
Adjustment areas:
The propeller blade can be adjusted to any angle between the positons “low
pitch“ (low airspeed) and “high pitch“ (high airspeed).
In case of multiengine planes and power gliders, an engine that has been
switched off in flight should create as little drag as possible. Due to this
requirement, there is the additional possibility to rotate the blades into the
“feathering position“ (smallest resistance). In case of larger airplanes, the
generation of a backward thrust shall shorten the deceleration distance. The
FOR TRAINING PURPOSES ONLY!

propellers are adjusted to the reverse position for this purpose.

Hydraulically adjustable propellers are available in the following designs:
S Constant Speed Propeller (adjustable between low and high pitch)
S Constant Speed Propeller with feathering position
S Constand Speed Propeller with feathering and reverse positions (for
turboprop engines)

HAM US/O-5 DaC Jul 10, 2013 07|Var. Pitch|L1|A/B1 Page 24

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TURBO-PROP ENGINES Variable Pitch
M15.16

Low Pitch

High Pitch

Pitch Change Range

Reverse
FOR TRAINING PURPOSES ONLY!

Feather Position

Figure 14 Pitch Ranges

HAM US/O-5 DaC Jul 10, 2013 07|Var. Pitch|L1|A/B1 Page 25
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TURBO-PROP ENGINES System Overview
M15.16

TURBOPROP ENGINE SYSTEM OVERVIEW

General
In principle PTL engines − apart from the propeller control system − have the
same systems as other engine types, but the design and control has in this
engine type some specifics.

Oil System
In older TPE engines seperate lubrication systems are provided due to the
different loads acting on the gear and turbo compressor.
Other engine designs use to avoid this difficult lubrication system, special
lubricants that are significantly different in their density and viscosity
characteristics than the usually for turbo jet and fan engines used lubricants.
Often air−oil coolers are used for cooling the oil. The air or lubricant flow can be
influenced by appropriated valve systems, depending on the oil temperature.
The storage and retrieval of the lubricant reservoir (with hydraulic adjustment at
engine failure) is designed so that under all conditions the required feathering
reserve is guaranteed. At smaller TPE engines, the lubricant tank is often an
integral part of the gearbox housing.
Fuel System and Control
While the fuel systems with those of other engine types is largely comparable
(one or two shaft system) the fuel control, depending on the design of the
propeller engine, has some special features (power limiter, ß−control, etc.)
Performance Monitoring
The sufficient for turbo jet and turbo fan engines indication of the speed(s)
and / or the engine pressure ratio [EPR] as a performance indicator is
FOR TRAINING PURPOSES ONLY!

synonymous insufficient for the TPE engines.

As a result of the propeller−blade adjustment, the power or torque transmitted
to the propeller system is different at a certain speed.
For this reason, TPE engines are equipped with a torque measuring system
(braking torque).

HAM US/O-5 DaC Jul 10, 2013 08|Systems|L1|A/B1 Page 26

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TURBO-PROP ENGINES System Overview
M15.16

PW123, Dash 8 Series 300

A
A
FOR TRAINING PURPOSES ONLY!

PW123, Dash 8 Series 300

Figure 15 Torque Indicating System

HAM US/O-5 DaC Jul 10, 2013 08|Systems|L1|A/B1 Page 27
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TURBO-PROP ENGINES Propeller Control
M15.16

PROPELLER CONTROL
Prop. Governing Mode
This typical engine control stand shows the control levers of the engines and the
propellers. The yellow coloured power lever controls the engine power and the
drive moment in alpha mode. The power lever takes direct influence on the blade
angle in beta mode. The green coloured condition lever or propeller lever (speed
lever) controls the propeller rotation speed in alpha mode. The forward stop is the
T/O position. When the condition lever is retarded the feather position is selected.
In beta mode you take direct influence on the engine power.
FOR TRAINING PURPOSES ONLY!

HAM US/O-5 DaC Jul 10, 2013 09|Prop. Ctrl.|L1|A/B1 Page 28

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TURBO-PROP ENGINES Propeller Control
M15.16

POWER LEVERS

FWD RPM FLT IDLE LATCH ARM

THRUST HI FLIGHT HI
P
CONDITION
O
LO GROUND LO LEVERS
W FLT IDLE
(SPEED LEVERS)
E
GND IDLE
R ENGINE STOP
REV AND
THRUST EMERGENCY
FEATHER

FRICTION LOCKS
FRICTION

alpha mode beta mode

FOR TRAINING PURPOSES ONLY!

engine POWER LEVER CONDITION LEVER

governor CONDITION LEVER POWER LEVER

Figure 16 Control Stand

HAM US/O-5 DaC Jul 10, 2013 09|Prop. Ctrl.|L1|A/B1 Page 29
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TURBO-PROP ENGINES Propeller Control
M15.16
The Constant Speed Propeller System
Apart from the variable pitch propeller the components which belong to the system
are the propeller control lever in the cockpit, the propeller governor and an oil
supply from the engine hydraulic oil and scavenge oil system.
The governor receives its RPM signal either from its installed position on the
engine. The governor is set to the selected RPM via rods or a push−pull cable from
the cockpit.
lowest pitch
Inside the governor there is a pilot valve. This valve either supplies hydraulic oil
to the change mechanism, allows the oil to flow back into the scavenge oil system, PROPELLER LEVER
or locks the system hydraulically to keep the selected blade pitch constant.
The pilot valve is controlled by a centrifugal regulator (flyweights), which is also
located in the governor and is sensitive to engine rpm. This regulator works against highest pitch
a spring, the tension of which can be adjusted by the propeller control lever in the
cockpit. (RPM selection). HIGH RPM STOP
LOW RPM STOP
The governor continuously compares the selected RPM with the actual RPM and
adjusts the pilot valve accordingly.
The propeller control lever is also called speed lever or condition lever.

TO GOVERNOR
CONTROL LEVER

Figure 17 Propeller Control Lever

FOR TRAINING PURPOSES ONLY!

HAM US/O-5 DaC Jul 10, 2013 09|Prop. Ctrl.|L1|A/B1 Page 30

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TURBO-PROP ENGINES Propeller Control
M15.16

single acting, -single engine

propeller governing system

SCAVENGE OIL
FOR TRAINING PURPOSES ONLY!

SCAVENGE OIL SCAVENGE OIL

Figure 18 Constant Speed System

HAM US/O-5 DaC Jul 10, 2013 09|Prop. Ctrl.|L1|A/B1 Page 31
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TURBO-PROP ENGINES Propeller Control
M15.16

Prop. Governing Mode

In the flight range (alpha mode, prop governing mode) the propeller operates
as a constant speed propeller. Here the propeller is controlled with the aid of
the prop governor in the same way as the constant speed propeller of the
piston engine. In the system shown here of the TPE 331 engine the
underspeed governor is located in the fuel control unit. It regulates the RPM
below the range controlled by the prop governor. The propeller is of the single
acting type. The RPM range in alpha mode is relatively small, from 95% to
100%. RPM is selected with the condition lever and power is set between flight
idle and maximum with the power lever.
FOR TRAINING PURPOSES ONLY!

HAM US/O-5 DaC Jul 10, 2013 10|Prop. Ctrl.|L2|B1 Page 32

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TURBO-PROP ENGINES Propeller Control
M15.16

Engine and Propeller Control in Propeller Governing Mode

(Take Off and Flight Operation)
Prop Governor
controls RPM Power Lever movement
PROP PROP PITCH CONTROL has no effect on PPC
FLIGHT IDLE
GOVERNOR (BETA VALVE) and Prop Governor
FUEL FLOW

FLIGHT IDLE
Pressure

PROP RPM MAX FF

GROUND IDLE
MAXIMUM

POWER LEVER REVERSE

Power Lever Cond. Lever

Condition Lever controls influence on USPD
sets RPM Fuel Flow Gov. inhibited

PROP GOVERNING MODE FUEL CONTROL UNIT

Blade Angle: +14° to +40°

FOR TRAINING PURPOSES ONLY!

100%

Engine RPM: 95% to 100%

95%
HIGH
METERING UNDERSPEED
LOW
SECTION GOVERNOR
FUEL
ENGINE STOP
FLOW

FEATHER
CONDITION LEVER
(SPEED LEVER)

Figure 19 Alpha Mode

HAM US/O-5 DaC Jul 10, 2013 10|Prop. Ctrl.|L2|B1 Page 33
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TURBO-PROP ENGINES Propeller Control
M15.16
Electronic Propeller Control
In the case of turboprop engines with electronic propeller control the task of the
propeller governor is taken over by the propeller electronic control unit (PEC). A
mechanical overspeed governor is also installed on the engine and the pitch
control unit (PCU) takes over the hydromechanical functions in the control system.
Electrical control of the PEC is carried out via the servo valve located in the PCU.
With constant speed control (prop governing mode) the flow of oil to the propeller
is controlled solely by the PEC via the servo valve.
FOR TRAINING PURPOSES ONLY!

HAM US/O-5 DaC Jul 10, 2013 10|Prop. Ctrl.|L2|B1 Page 34

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TURBO-PROP ENGINES Propeller Control
M15.16

PROPELLER ELECTRONIC CONTROL SYSTEM

(FOKKER 50)
ON

IAU MTP
ERSP

FAULT
PROP. SPEED
NP DEMAND
NP SENSOR MPU

PEC
SERVO VALVE
FOR TRAINING PURPOSES ONLY!

PCU

Figure 20
HAM US/O-5 DaC Jul 10, 2013 10|Prop. Ctrl.|L2|B1 Page 35
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TURBO-PROP ENGINES Overspeed protection
M15.16

OVERSPEED PROTECTION
Propellers must be protected from over-speed conditions because this can
cause serious damage to the blades and the blade supports. Several different
methods are used to prevent over-speed conditions.
If the propeller speed increases the first action is always to move the blades
into a more coarse position. This results in higher drag of the propeller and
therefore in higher braking force. Often a separate over-speed governor is used
as a back-up of the normal speed control system.
If the over-speed governor can not eliminate the over-speed condition, the
engine power is reduced on some engines by a separate governor at a pre-set
speed by decreasing the fuel flow to the engine combustor.
On engines with a FADEC system and an electronic propeller control system
there is still a mechanical over-speed governor used as a back-up.
FOR TRAINING PURPOSES ONLY!

HAM US/O-5 DaC Jul 10, 2013 11|overs prot|L1/A/B1 Page 36

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TURBO-PROP ENGINES Overspeed protection
M15.16

PEC

OIL TO/FROM
FOR TRAINING PURPOSES ONLY!

PROPELLER

Figure 21 Pitch Control Unit with Servovalve

HAM US/O-5 DaC Jul 10, 2013 11|overs prot|L1/A/B1 Page 37
M15.16 B1 E

TABLE OF CONTENTS
M15 GAS TURBINE ENGINE . . . . . . . . . . . . . 1
M15.16 TURBO-PROP ENGINES . . . . . . . . . . . . . . . . . . 1
GAS COUPLED/FREE TURBINE / GEAR COUPLED TURBINES
2
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
OPERATION AND BASIC STRUCTURE OF PTL ENGINES . . . .
4
CONSTRUCTION OF TURBO PROP ENGINES . . . . . . 6
REDUCTION GEARS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
VARIABLE PITCH PROPELLER . . . . . . . . . . . . . . . . . . . 24
TURBOPROP ENGINE SYSTEM OVERVIEW . . . . . . . . 26
PROPELLER CONTROL . . . . . . . . . . . . . . . . . . . . . . . . . . 28
OVERSPEED PROTECTION . . . . . . . . . . . . . . . . . . . . . . . 36

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TABLE OF CONTENTS

Page ii
M15.16 B1 E

TABLE OF FIGURES
Figure 1 Shaft Power Gas Turbine Engines – Overview . . . . . . . . . . . . . 3
Figure 2 Brayton Cycle of Turbo Jet and Turbo Prop Engines . . . . . . . . 5
Figure 3 Comparison of TPE and Piston Engines . . . . . . . . . . . . . . . . . . 7
Figure 4 Single-Spool TPE Honeywell TPE331 . . . . . . . . . . . . . . . . . . . . 9
Figure 5 Dual-Spool TPE wit Free Power Turbine – Pratt & Whitney Canada
PT6A (Large) Engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Figure 6 Dual-Spool TPE Rolls-Royce „Tyne“ (Layout and Airflow Schematic
– Simplified) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Figure 7 Pratt & Whitney Canada (PWC) PW100 Series Engine (PW121,
Simplified) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Figure 8 PW120 (RH View) and PW120 Turbomachinery Module (LH View)
16
Figure 9 PW120 Turbomachinery Module vs. PW150 Series Engine . . 17
Figure 10 Powerplant of the Airbus A400M Military Transport Aircraft . 18
Figure 11 Triple-Spool TPE Europrop International TP400−D6 . . . . . . . 19
Figure 12 Propulsive Efficiency vs. Airspeed . . . . . . . . . . . . . . . . . . . . . . 21
Figure 13 Honeywell TPE331−10 Reduction Gearbox . . . . . . . . . . . . . . 23
Figure 14 Pitch Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Figure 15 Torque Indicating System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Figure 16 Control Stand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Figure 17 Propeller Control Lever . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Figure 18 Constant Speed System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Figure 19 Alpha Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Figure 20 .................................................... 35
Figure 21 Pitch Control Unit with Servovalve . . . . . . . . . . . . . . . . . . . . . . 37

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TABLE OF FIGURES

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M15.16 B1 E

TABLE OF FIGURES

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M15.16 B1 E

TABLE OF FIGURES

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