Журнал - The Engine Yearbook 2005

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ENGINE YEARBOOK 2005

companies to reduce their repair

development spending in recent years,” he

says. “Honeywell has increased its level of

spending in both the advanced thermal

coating and advanced-repair-technology

fields. Our investments have helped us to

develop a unique set of technologies and

competencies that we are applying to help

our customers be more successful.”

On the coating edge of technology

Honeywell has been a pioneer in the

science of thermal-barrier coatings

(TBC) that protect critical components

in an engine’s hot section, which can

reach temperatures exceeding 1,000˚C.

In addition to using its propriety TBC

technologies in its own manufacturing

and repair processes, Honeywell is one

of the industry’s foremost licensors of

coating technologies to other

companies. Parts protected by

Honeywell thermal-coating technologies

can be found in most aircraft engines

flying today and in a wide variety of

heavy-duty industrial, commercial and

transportation engines.

The most up-to-date electron

beam/physical vapour deposition (EBPVD)

processes and equipment and other

techniques are used to apply high-

performance aluminide, platinum

aluminide and ceramic coatings to engine

parts. The company is taking advanced

TBC technology to a new level in the

coming year when it intends to lead the

industry in the use of EBPVD-applied

nano-laminates. With Honeywell’s

advanced coating technologies and these

new, exotic advanced materials protecting

them, turbine blades, vanes and other hot-

section parts will last longer and perform

better even under the more extreme

demands of the newest generation of high-

performance jet engines.

Three areas of repair expertise

In the advanced-repair arena,

Honeywell’s capabilities centre on three

core areas of expertise: adaptive

Restoring a worn or damaged

turbine blade to its original

specifications costs about one-

tenth the price of replacing the

part. And Metera estimates that a

typical operator can save up to a

staggering $180,000 per engine

by repairing rather than

replacing the low-pressure

turbine components in a large

commercial engine.

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ENGINE YEARBOOK 2005

machining; laser welding, brazing and

thermal processing; and surface treatment

and advanced-coating technology.

In adaptive machining, Honeywell uses

the latest computer-aided design and

manufacturing systems to repair variable-

geometry three-dimensional components

including turbine airfoils and blades;

nozzle guide vanes; impellers; and blisks.

With recent advancements, technicians

are able to make repairs without changing

the unique contours of the component.

The company is also expert in the field

of laser welding, brazing and thermal

processing. It uses new techniques in

automated and hand-held laser welding,

and brazing-restoration processes —

including crack healing — to perform

repairs customised for a specific

component to restore it to like-new

condition. Finally, it puts its surface-

treatment and advanced-coating expertise

to work with innovative technologies and

processes that prevent corrosion and

improve the ability of critical engine parts

and components to withstand high engine

temperatures.

MRO is a top priority

In an industry that always puts

safety first, aircraft operators devote

considerable resources to implementing

effective engine-inspection,

maintenance and repair programs.

But in recent years MRO

programmes have become even more

important to the commercial airlines

and other operators, which have had

to adjust to the tough economic

conditions that have affected the

entire industry. As a result, operators

are looking for ways to improve

engine performance, boost operating

efficiency, reduce the total cost of

ownership, and extend the working

life of engines and key engine

components.

“There has been a shift in people’s

thinking about engine repairs,” says

Bill Metera, director of sales and

marketing for Honeywell’s newly

formed advanced-repair technology

business. “Operators are still

interested in effectively managing

their repair costs, of course. But many

operations managers are starting to

see MRO as a strategic investment

that can lead to improved

performance, rather than merely as a

cost of doing business.

Customers experience excellent

product performance

“With the latest repair and coating

technologies, we’re taking worn and

damaged engine parts and giving them

new life,” says Metera. “Since

repairing a part costs significantly less

than replacing it, operators can see a

significant positive impact on their

operating costs and their bottom lines

over the life of an engine.”

Metera described a recent informal

experiment conducted by another major

commercial aircraft engine original

equipment manufacturer (OEM). The

OEM sent Honeywell a variety of worn

and damaged components from the hot

section of one of its production jet

engines. Members of Honeywell’s

advanced repair technology team used

various technologies and techniques to

restore the parts and then returned

them to the manufacturer. In a series of

rigorous side-by-side tests that

simulated more than 100 engine cycles,

the restored parts out-performed the

new parts in every facet of the

experiment.

"We are committed to developing

new repair and coating

technologies that help our

customers reduce costs,keep

their aircraft flying and achieve

their business objectives."

—Bernd Kessler, vice president

and general manager of

Aviation Aftermarket Services

for Honeywell.

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ENGINE YEARBOOK 2005

“The test results were very

gratifying to us, of course, and the

OEM was very pleased with the

performance of these repaired parts,”

says Metera. “The entire engine

industry benefits from technology

advances such as these, because they

improve the quality, reliability and

performance of a whole class of

aerospace products.”

Significant savings potential

With these kinds of results,

customers are obviously impressed

with the quality and performance of

refurbished parts. But it is the

savings potential that really gets

their attention, says Metera. “This

really is the best of both worlds.

Technology advances let us repair a

wider variety of parts than ever

before and the cost of restoring worn

and damaged components to like-new

condition is much less than the price

of replacing them with new parts.”

Restoring a worn or damaged

turbine blade to its original

specifications costs about one-tenth

the price of replacing the part. And

Metera estimates that a typical

operator can save up to a staggering

$180,000 per engine by repairing

rather than replacing the low-pressure

turbine components in a large

commercial engine.

While Honeywell’s advanced

technologies can be used to repair

almost any engine part, the company

focuses most of its efforts on categories

of repairs that offer customers the

greatest potential return on their

investment. Examples include repairs

on gearboxes, impellers, blisks, turbine

blade airfoils, turbine nozzles and other

related parts and components.

Growing business and resources

Operators that fly aircraft equipped

with Honeywell engines remain the

company’s first priority according to

Kessler and Metera. But Honeywell is

also actively working on several current

and potential programmes with other

engine manufacturers. In addition to

the other engine OEMs, potential

customers for Honeywell advanced-

repair and coating technologies include

the commercial airlines; business and

general aviation operators; defence and

space customers; and established third-

party MRO centres.

Honeywell’s sizeable investments in

advanced-repair and coating

technologies have built a highly capable

global Aviation Aftermarket Services

organisation with resources all over the

world. The company has multiple MRO

centres in North America, Europe, Asia

and Australia. Advanced Repair Centres

of Excellence have been established in

Phoenix, Arizona, for cold-section

repairs; Greer, South Carolina, for hot-

section repairs; and Olomouch, Czech

Republic, for sheet metal components.

“We are very proud of our world-

class facilities and equipment,” says

Metera. “We are one of the top

companies when it comes to investing

in repair technology in recent years. But

our primary investment has been in

expertise and human brainpower. We

have succeeded in building one of the

most experienced and capable teams of

engineers, technicians and specialists in

the industry.”

In all, Honeywell’s Aviation

Aftermarket Service organisation

employs more than 3,700 people

worldwide, including more than 100

repair development engineers who

work full-time to research, validate,

document and implement engine repair

techniques and procedures. At least

eight of Honeywell’s development

engineers hold PhD degrees, according

to Metera.

Honeywell’s advanced repair

organisation has achieved repair yields

and successful repair rates that are

better than the industry average,

according to Metera. “Honeywell is one

of the aviation industry’s most

dedicated practitioners of Six Sigma,”

he says. “We’re actively putting the

Honeywell Six Sigma tools and mindset

to work to make sure we’re doing the

best possible job for our customers.”

According to Kessler, “At the end of

the day our entire Aviation Aftermarket

Services team is focused on delivering

value for our customers. We are

committed to developing new repair

and coating technologies that help our

customers reduce costs, keep their

aircraft flying and achieve their

business objectives.” ■

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ENGINE YEARBOOK 2005

Titanium impeller

welding

Modern turbine engines are

subjected to severe

operating conditions.Their

components are exposed to

thermal, corrosive, abrasive

and other damaging

influences which cause them

to crack, pit, erode, and

otherwise degrade. Turbine

and compressor blades are

among the most commonly

repaired of these parts and

can be restored many times

to significantly extend their

useful life. Liburdi

Automation discusses its

new welding system that has

been developed to repair of

complex-geometry engine

parts, such as compressor

impellers.

ike most turbine components,

impellers function in a highly

abrasive environment. This is

particularly true when aircraft are

landing on unpaved runways or are

operating in sandy environments

where erosion is a significant

challenge to engine durability and to

the subsequent repair and overhaul

of turbine engines. Parts most

affected by erosion are typically

located in the compressor section of

the engine. They are predominantly

in the gas path of the compressor and

comprise rotating blades, impellers

and their stationary counterparts,

compressor stators. Most of the wear

occurs at the tip of each blade and at

the leading edge, resulting in

decreased compression efficiency.

This type of wear can typically be

repaired by removing the damaged

region, and by depositing new

material which can be subsequently

re-contoured to the required profile.

The majority of turbine impellers

are repaired using old-fashioned

manual gas tungsten arc welding

(GTAW) techniques. While manual

repair is inefficient (some impellers

will require as many as 12 hours in

the hands of a skilled welder), no

automated solutions have been

available. The reason for this is the

complex geometry of the part itself

and the fact that it takes full

integration of several technologies

including motion, scanning and

welding, just to repair a single blade.

Although many companies specialise

in each of these technologies, few can

integrate them and thereby supply an

automated system. The ability to

perform the 3D restoration of parts is

a unique and complex achievement

and whilst rapid prototyping has

been achieved using laser and

powder systems, the requirement for

critical rotating hardware to have no

defects — such as porosity or

inclusions — is difficult when using

powder feed systems.

Over the past three years Liburdi

Automation Incorporated has been

developing an automated welding

system capable of performing such

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ENGINE YEARBOOK 2005

repairs. As a result of this work, a

system has been developed which is

capable of performing a full impeller

repair (blade contour as well as

leading and trailing edges) with next

to no operator intervention.

Laser and wire process

Since 1979, the Liburdi Group,

based in Hamilton, Ontario and

Charlotte, North Carolina, has

provided highly-specialised

technologies, systems and services for

turbine, aerospace, and industrial

applications. Having pioneered the

development of metallurgical

processes required for analysis and

refurbishment of aero and industrial

gas turbine components, it has

become a global leader in turbine-

repair, analysis, and life-extending

technologies within those industries.

Against this backdrop, Liburdi has

designed a unique (patent-pending)

blade-repair process using laser and

filler wire for metal deposition.

According to Automation Group senior

engineer, Janusz Bialach, who has

worked on the design and test phases of

the process for the past year, “Our new

wire process is a faster, cleaner repair

method, which brings a whole new

level of control and metallurgical

quality to impeller blade

refurbishment.”

The system is based on laser and wire

technology developed by Liburdi (US

patent 6,727,459). The technique

utilises a continuous wave Nd:YAG laser

combined with a precision wire feeder.

The combination of these two elements

produces repeatable, X-ray quality

welds. The laser power and wire feed

functions are fully synchronised with

each other and with the motion system.

This capability enables the production

of welds with “near-net-shape”

geometry (i.e. the width of the deposit

varies with width of each blade). The

primary benefit of doing so is reduction

in the blending requirements and

increased deposition efficiency.

Motion system

In view of the complexity of the

impeller geometry, six axes of motion

are required to achieve the necessary

weld path. This is driven by the need to

implement three-dimensional motion

and the requirement to achieve a build-

up that matches the ever-changing

blade contour. All six axes are fully

coordinated, resulting in smooth,

repeatable motion.

New software was developed for this

application and this allows the operator

to program the surface weld speed. The

controller automatically compensates

feed-rate for each axis so that the

surface weld speed remains constant,

independent of the R,T positioner

motion with respect to the X,Y, Z weld

head motion.

Laser scanning and process

capability

After several thousand hours running

in a jet engine and exposure to a couple

of repair cycles, no two blades are the

same. Even within a single part there

can be substantial difference in

geometry and thickness of each blade.

This variation requires the welding

process to be self-adaptive.

"Our new wire process is a faster,

cleaner repair method,which

brings a whole new level of

control and metallurgical quality

to impeller blade refurbishment."

—Liburdi Automation Group

senior engineer, Janusz Bialach.

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Liburdi scanning technology is an

integral part of the impeller welding

system. The scanner provides feedback for

the process control software. Before

welding, each blade is scanned to capture

its actual geometry and any variation in

thickness. This information is used for

several purposes. Firstly, the condition of

the impeller is inspected and if, for

example, blade thinning is excessive the

part will be rejected. Secondly, the

scanning data is used in the generation of

weld path data. The software captures

deviations from nominal geometry and

performs full 3-D motion compensation.

Finally, the data is used to generate

welding parameters.

Variations in blade width will mean

that no single set of parameters can be

consistently used to weld these parts. As

the blade width increases, for example,

the wire feed rate and the laser power

need to increase as well, in order to

maintain uniform build-up height.

The system is capable of repairing the

blade contour as well as the leading and

trailing edges. The rotary/tilt positioner

provides enough articulation to perform

all three welds in one setup.

Effect of blade width on process

parameters

The tooling requirements are

minimal. In most cases, a simple fixture

is used to locate the part on the

positioner faceplate. In some cases,

where impeller geometry and the

extent of the repair combine to produce

excessive platform distortion, a

restraining fixture might be required.

The process does not require

vacuum or argon chambers. All of the

welding is done with local shielding

only (even on titanium parts). This

speeds up the loading and unloading

of the parts. The cycle time is a

function of impeller geometry. The

build-up height per pass is limited

by the blade thickness. It is not

feasible, for example, to produce a

0.060in build-up on a 0.020in blade

section in one pass. The build-up

height typically ranges from 0.040in

to 0.060in per pass. Typical welding

speed is approximately 5 inches per

minute.

Considering an average impeller

with 15 blades, 0.080in of ‘cut-back’,

average blade width of 0.040in and

blade length of 3.5in, the cycle time

would break down as follows

(contour weld only):

Scanning time:

45 seconds = 45 seconds

Welding time/pass

45 seconds x 2 passes = 90 seconds

Pre-purge:

7 seconds x 2 passes = 14 seconds

Post purge:

8 seconds x 2 passes = 16 seconds

Move to start:

5 seconds x 3 times = 15 seconds

Total per blade = 180 seconds

Total per impeller = 180 sec x 15

blades = 45 min

The impeller welding system is

based on a LAWS platform and by

no means is it limited to welding

impellers. It has enough flexibility

to weld compressor blades, air seals,

vanes, blisks and many other engine

components. A 6-axis CNC precision

motion platform with rotation/tilt

positioner is the best match for this

application. The accuracy of the

system is critical to the repeatability

of the repairs and ultimate yield of

the system in production.

Each of the above platforms can be

fitted with a Class I laser enclosure.

ENGINE YEARBOOK 2005

After several thousand hours

running in a jet engine and

exposure to a couple of repair

cycles,no two blades are the

same.Even within a single part

there can be substantial

difference in geometry and

thickness of each blade.This

variation requires the welding

process to be self-adaptive.

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ENGINE YEARBOOK 2005

LAWS 4000 and 5000 enclosures have

access doors designed for heavy

component loading using overhead

cranes. The laser source used with

the laser and wire process is a 1kW

continuous wave Nd:YAG laser. This

power source is capable of welding

almost all impeller types. Other

power ranges are also available. GSI

Lumonics JK series lasers are the

preferred power sources but other

lasers can be integrated upon

customer request.

The wire feeder is one of the most

important components. The system is

equipped with a low backlash,

precision wire feeder with encoder

feedback for precise metering of the

wire into the molten pool. The wire

feed system provides the accuracy

and repeatability necessary to yield

high quality welds with minimal

distortion of the parts. Good quality

welds with no interpretable porosity

is the key for highly critical parts.

With the high-efficiency

performance turbine engines of

today, OEMs are concerned with the

effects of porosity in weld repairs of

0.002in.

The system uses an external power

meter for calibration purposes. The

device enables the capture of all system

losses and allows for calibration of

‘actual’ laser power. The meter is fully

integrated with the software so that the

system ‘self-calibrates’ without any

operator intervention.

The break-away device provides a

link between the welding head and the

rest of the system. In the case of a

collision, a pneumatically-loaded

chamber disengages the head,

minimising the damage to the system.

Upon activation the device also shuts

down the laser and stops all system

motion.

Weld monitoring

Weld monitoring enables the

operator to display a live image of the

weld on the control screen. The image

is magnified and it allows the operator

to see exactly what is happening at the

weld. If required, the video can be

stored in a digital format and

transferred to a CD for future

reference.

The system can also be equipped

with a wire-diameter inspection unit

which monitors the size of the wire. If

the wire size deviates from a

predefined, acceptable range, the device

notifies the operator, allowing him to

take corrective action.

Results

The combination of the appropriate

software, hardware and process know-

how offer the potential customer the

ability to restore hardware that would

traditionally be scrapped or stock-piled

in a quarantine room for future

consideration.

Compressor geometries that require 3-

D restoration due to wear are ideal for

the laser and wire process. The laser

offers a very stable power source and

the wire offers the same stability in a

fusion process where metallurgical

defects cannot be tolerated because of

mechanical limitations in the design of

the parts.

Impellers that traditionally take six to

12 hours to weld manually now only

require two to four hours to repair. The

cost savings are advantageous for

overhaulers and OEMs alike. ■

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ENGINE YEARBOOK 2005

The latest in aerospace

testing equipment

Advances in computer

technology bring with them

opportunities to further

advance other technologies.

Bartley Blume, test cell

marketing manager of Aero

Systems Engineering, St. Paul,

Minnesota, explains how

such advances are creating

better, more accurate and

more reliable aerospace

testing equipment.

s a market leader in aerospace

testing equipment, Aero

Systems Engineering (ASE)

makes it its business to be knowledge-

able of emerging technologies and

incorporates these into its products

when the opportunities arise. Its high-

technology products include thrust-

measuring stands; power lever throttle

controllers; temperature scanners; data

acquisition and control systems; high-

speed wind tunnels; and captive trajec-

tory systems.

ASE has been designing and

developing state-of-the-art engine test

cells since 1967. In those 37 years it has

built test cells and equipment for all

engines, from the smallest of APUs and

cruise missile engines, to military

engine with afterburners and the

largest of commercial engines, including

the GE90-115B, the world’s largest

commercial aero-engine. ASE’s test cell

designs include a 13-metre test cell,

capable of running engines up to

150,000lb thrust, and a seven-metre test

cell, capable of up to 40,000lb thrust.

The latter has become very popular

over recent years because of the

increased number of regional jet airlines

in operation. It is an efficient, off-the-

shelf design that can be built in 10

months from start to finish. ASE also

builds test cells for turboprop, turbo-

shaft and industrial gas turbines.

The company has been designing and

developing state-of-the-art wind

tunnels since 1952, initially as the

FluiDyne Engineering Company until

the merger of ASE and FluiDyne in

1993. Many of ASE’s earliest wind

tunnels were used to advance rocket

and space programme designs. The

company’s wind tunnels have always

been on the cutting edge of technology

driving the challenge of positioning

accuracy, data accuracy and high

Reynold’s number testing.

ASE owns and operates several wind

tunnels in Plymouth, Minnesota. Its

FluiDyne Aerotest Laboratory possesses

a broad range of aerodynamic test

facilities and is highly regarded

throughout the propulsion industry for

data quality and accuracy. Performance

testing of exhaust nozzle systems, from

static to hypersonic conditions, is its

primary area of expertise. As well as

the wind tunnel laboratory there is a

highly reputable model shop. The group

is currently working with major engine

manufacturers to come up with new,

innovative nozzle designs that will

reduce engine noise.

ASE2000

At the forefront of high-technology

engine testing equipment is the

ASE2000 control and instrumentation

system. It was originally developed in

1997, but has evolved and been

enhanced as technology has advanced.

Its architecture is based on distributed

‘input/output’ (I/O) and this allows

continual evolution and enhancement to

take place. The distributed I/O

architecture comprises one or more

independently-operating input and/or

output devices that are supervised by a

central host computer. These

synchronised front-end devices utilise

their own internal processors to scan

inputs, make calculations, apply

calibration curves, as required, and

return engineering units back to the

host. This host computer sends setup

instructions to the I/O devices, collects

the acquired data into a central

database and carries out any required

additional calculations. Expansion,

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ENGINE YEARBOOK 2005

major engine overhauler and long-term

customer to provide a similar device for

temperature measurement, it teamed

with Pressure Systems Inc who assisted

in the design and development of a

temperature scanner.

The new temperature scanner was

based upon the hugely successful 9016

NetScanner pressure scanner. While

pressure-sensing elements were removed,

other aspects of the scanner were

retained including the processor,

multiplexer and A/D converter. A new

signal-conditioning module (SCM) was

developed to interconnect the measured

signal to the motherboard and this was

also used for cold-junction

compensation. To accomplish very

accurate cold-junction compensation, the

thermocouple SCMs incorporate a

precision temperature device located

between the thermocouple input sockets.

This gives a very precise measurement of

each cold junction temperature, which

contributes to the overall accuracy of the

module. The Model 9046 Ethernet

intelligent temperature scanner is a

component of the PSI NetScanner™ data

acquisition concept. Multiple

NetScanner units may be networked

together to form a distributed intelligent

data acquisition system.

The Model 9046 Ethernet intelligent

temperature scanner is a completely

self-contained high-performance

temperature acquisition module for

multiple measurements from multiple

devices. It can be configured to read

thermocouples (all types), RTDs (385

and 7990), thermistors, voltage signals

up to 5V and/or resistance. The scanner

integrates 16 individual, high-accuracy

(+/-0.01˚C) uniform temperature

references (UTRs) with a microprocessor

in a compact, low-cost package. Each

UTR contains its own thermocouple

reference which is in physical contact

with both thermocouple/copper

junctions, therefore improving accuracy

compared with a single uniform

temperature reference. This

arrangement makes the module unique

in that it guarantees accuracy under

any circumstances, even in thermally

dynamic environments. RTD channels

use four wire connections to the

scanner, which eliminates error due to

lead wire resistances.

enhancement and evolution of the

ASE2000 are easily managed through

changes to the distributed I/O. The

premise of the distributed I/O

architecture is not new but the wide

range of emerging Ethernet devices has

made it very easy to develop and

expand.

One of the great advantages to this

Ethernet-based distributed I/O

architecture is reduced complexity. The

ASE2000’s architecture eliminates the

need for large numbers of long copper

wires from the test device to the control

room, being replaced by a few Ethernet

and power cables. The elimination of

these long cable runs simplifies

installation, maintenance and

troubleshooting, and reduces the overall

cost of ownership.

Another distinct advantage of these

devices is the ability to put data

acquisition very close to the

measurement point. This reduces the

length of slow-acting pressure tubes or

thermocouple wires that are very

susceptible to noise.

9046 Ethernet intelligent

temperature scanner

Aero Systems Engineering has used

the PSI NetScanner™ pressure

measurement system in conjunction

with its ASE2000 control &

instrumentation system for a long time

now. When ASE was requested by a

This pre-engineered approach to

temperature acquisition offers

guaranteed system accuracy, unlike

individual thermocouple or RTD wire

runs where stated accuracy is met only

if many user considerations are

addressed, especially with respect to

wire length, noise and multiple

connector effects. The Model 9046

Ethernet intelligent temperature

scanner guarantees accuracy better than

+/- 0.25˚C when used with

thermocouples and +/- 0.04 per cent

when used with RTDs.

The top connection panel can be

configured for any mix of thermocouple

types and RTDs. An internal 32-bit

microprocessor corrects for sensor zero,

span and non-linearity errors. The

module is also available with side-

mounted feed through or MS connector.

Temperature data in engineering units

is output through a 10Mbit Ethernet

802.3 interface using TCP/IP protocol.

The 9046 provides the capability to

sample using three scan lists

concurrently at rates up to 10

measurements per channel per second

and is supplied with start-up software

for PC-compatible computers. Field

firmware upgrades are facilitated using

the Host Ethernet interface. The 9046

features hardware- and software-

triggered data acquisition, onboard

engineering unit conversion (mV, Ohms,

˚C, ˚F), parallel outputs for alternate

data display, fuse-protected inputs, open

circuit detection, a user-adjustable filter

and user-accessible memory. The 9046

was originally developed for use in jet-

engine test cells and is therefore rugged,

shock resistant and virtually airtight.

The smart throttle system

Another Ethernet-based device used

in the ASE2000 is the ‘smart throttle

system’ (STS). This is an advanced,

digital power lever/throttle control

system. STS can control virtually any

hydro-mechanically or electronically

controlled engine. It controls hydro-

mechanical engines directly by linking

the power lever actuator to the engine

power lever/throttle input shaft. It

controls electronic engines by sending

the appropriate electrical signal directly

to the engine’s ‘full authority digital

electronic control’ (FADEC).

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