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Tutorial IEEE PHM

SAFRAN AIRCRAFT ENGINES

Dallas 2017Marion Jedruszek, François Demaison,

Jerome Lacaille, Josselin Coupard, Guillaume Bastard, Yacine Stouky

Prognostics & Health Monitoring @ SafranSafran Aircraft Engines,

77550 Moissy-Cramayel,

France


SAFRAN AIRCRAFT ENGINES PHM / TUTORIAL CONTENTS

June 2017 / R& T2

1 2 3 4

Introduction & Context

Why PHM for Aircraft Engines ?

Global PHM System Architecture

System perimeter

Engine dysfunction analysis

Engine wear modes

System architecture

Embedding a PHM System

Constraints on airborne systems

Harsh environment & monitoring

Operational realizations

PHM Systems on CFM56 & Silvercrest engine

Gaining in confidence in a PHM System

Predictive & Effective maintenance

1 2 3 4 Q

Chapter progress bar


0,121

0,062

0,062

443

June 2017 / R& T3

ABOUT US

1 2 3 4 Q


SAFRAN GROUP IN BRIEF

June 2017 / R& T4

1 single-aisle commercial jet takes off every 2 seconds, powered by our

engines

17,300 nacelle components in

service

More than 40,000 landings a day using our

equipment

1 out of 3 helicopterturbine engines sold

worlwide

500km of electrical wiring on an

Airbus A380

More than 70 successfulAriane5 launches in a raw

Over 35,000 power

transmissions, totaling over 850

million flight-hours

2 3 4 Q

1/4

About us


OVERVIEW OF SAFRAN GROUP

June 2017 / R& T5

SAFRAN TRANSMISSION SYSTEMS

- The power transmission specialist

SAFRAN CERAMICS

- specialist in advanced ceramic materials


- a world leader in aircraft engines

SAFRAN AERO BOOSTERS

- Partner to major engine-makers

SAFRAN ELECTRICAL & POWER

- a world leader in aircraft electrical systems

SAFRAN ELECTRONICS & DEFENSE

- a global leader in aerospace and defense electronics

SAFRAN HELICOPTER ENGINES

- The world leader in helicopter turbine engines

SAFRAN IDENTITY & SECURITY

- Security solutions for people around the world

SAFRAN LANDING SYSTEM

- The world leader in aircraft landing and braking systems

SAFRAN NACELLES

- A world leader in aircraft engine nacelles

2 3 4 Q

2/4

About us


1 2 3 4 Q


June 2017 / R& T6

Over

15,000employees

35facilities

worldwide LEAP*

CFM56*

SAM146

M53

PPS & TMAPlasmic propulsion

Engines for commercial and

military aircrafts

Maintenance,

Repair and

Overhaul (MRO)

services

Electric

propulsion

systems for satellites and

space vehicles

Partners with GE in CFM International since 1974: design and production of the CFM56 and LEAP engines

-15% of FUEL

CONSUMPTION

versus today’s

engines

-50% of NOX

emissions versus

CAEPI6 standards

-15% of CO2

emissions versus

todays engines

99,9% of reliability

rate

1h30 average flight

leg

500,000 flight

hours with SSJ100

Recognized for its unrivaled reliability and low operating and maintenance costs

The benchmark powerplant in the single-aisle commercial jet market

More than 30,000produced since the outset

SA

M1

46

CF

M56

LE

AP

M88

3/4

About us


CFM International

June 2017 / R& T7

A 50/50 joint company between GE(U.S.A) andSafran Aircraft Engines (France), we develop,produce and sell the new advanced-technology LEAPengine and the world’s best-selling CFM56 enginesince 1974

2009-2011 – LEAP selected

by three major aircraft

manufacturers: Airbus

(LEAP-1A), Boeing (LEAP-

1B) and COMAC (LEAP-1C)

74% of the global

market for engines

powering single-aisle

commercial jets

30,000 CFM56

engines delivered (as of December 31, 2016)

LEAP: more than

12,200 engine

orders and

commitments at January

31, 2017

1 2 3 4 Q

4/4

About us


June 2017 / R& T8

2 3 4


System perimeter


Engine wear modes

System architecture





PHM Systems on CFM56 & Silvercrest engine


Predictive & Effective maintenanceIntroduction

& Context

Why PHM

for Aircraft

Engines ?

1 2 3 4 Q

1/201Chapter


CHAPTER 1 ON “WHY PHM IN AIRCRAFT ENGINES ?” CONTENTS

June 2017 / R& T9

Part 1 : Aircraft Engines

Engines : from design to production

Part 2 : Engines operation

Usage & Operational life

Part 3 : Engines Maintenance

Maintenance type and Engine maintenance owner

1

1 2 3 4 Q

2/20

Chapter 1


CHAPTER 1 CONTENTS

June 2017 / R& T10




Maintenance type and Engine

maintenance owner

Aircraft Engines:

Short introduction

from design

to production

1/3 2 3 4 Q

3/20

Chapter 1

Part 1


Engine are

designed with

trade based

on Specific Fuel Consumption, Thrust, Fan Diameter and Direct Maintenance costs with

respect to

specific range

/ Flight legs

About … Aircraft ENGINES

June 2017 / R& T11

Aircraft engines are an essential part of theaircraft as fuel burn is one of the main keydriver for an airline

Over

$1,5 billionDevelopment

costs

Over

20 yearsproduct cycles

span

Can be more expensivethan an

aircraft total

development

cost

around 25%of the aircraft’s

price when sold

Catalog price for

leap-1A is

$13,9

millions

EASA and

FAA have

defined

regulations

with respect to

the conception,

the

manufacturing

and the

maintenance

of an engine.

.

Support for engine for a 15-

year rate per flight hours with

an airline of 20 leaps costs

$3,000 per engine per day

Specific test means may be developed with a new engine

Specific materials (Ceramic

matrix

composites , 3D Woven Carbon Fibers)

Today’s engines such as

LEAP provide 15% fuel

burn difference with older

generation of engines.

Turbofan aircraft engines

consumes oil with a ratio

of 0,1 liter per hour during cruise phase

1/3 2 3 4 Q

4/20

Chapter 1

Part 1


Fan

Size : 78’’ or 198cm18 Composites Fan blades

Max RPM ~ 4,000

Length: 3.328 mMax Width : ~2.5mMax Height 2.37 m

Fan Case:

Composite & Noise t treatment

FADEC is on fan case

Direct Drive engine

3 Stages Low Pressure

Compressor or Booster with

VBV Doors

10 stages High Pressure Compressor

Pressure ratio 22:1

Technical layout of an engine (Leap-1A)

June 2017 / R& T12

Bypass Ratio

between veins

BPR: 11:1

Take-off Thrust :

Leap-1A23 : 106.80 kN,

Leap-1A30 143.05 kN (or

32,160 lbf)

Activeclearancecontrol withHPTACC andLPTACCactuators

2 stages HP Turbine

With 3D aero and advanced

cooling

Max RPM : ~20,000

7 stages LP Turbine

Weight : 2,990-3,153 kg

/ 6,592-6,951 lbs

2 Rotors : 1 high pressure,

1 low pressure

Lean annular combustor

1/3 2 3 4 Q

5/20

Chapter 1

Part 1


Characteristics of a PHM System

June 2017 / R& T131/3 2 3 4 Q

6/20

Chapter 1

Part 1

• Integration from the Start of the Development Cycle.On Board

• The Challenge of the Automatic and Adaptable Data Transmission and connection.

Data Transmission

• A new PHM Standard for an Optimal Workflow.On Ground

PHM – Prognostics & Health Monitoring

Monitor and forecast the health status of an engine.

From the beginning

Automatic & Adaptable

Agile, Based on Standard

And Web accessible


PHM Life Cycle

June 2017 / R& T14

PHMmodels

Needs collection

& Risk analysis

of PHM System

PHM System

Design Phase

PHM System

Operational Phase

At SAFRAN Aircraft Engines PHM is about monitoring and predicting the health of an engine, using operational data to enable our

clients to have a continuity of service while keeping a maintainability of the engine that is cost-oriented and optimal.

1/3 2 3 4 Q

7/20

Development

of PHM System

& data baseSignal

detection

on engine

Capture &

process

Accurate trouble-shooting

and maintenance support

advice

OSA-CBM approach:

• DM – data

manipulation

• SD – state detection

• HA – health estimation

• PA - RUL &

prognostics

Analysis are done to

provide maintenance

support to build CNREngine Failures &

Degradations analysis

Chapter 1

Part 1


Engine design : Example with TP400-D6, the engine of the A400M aircraft

June 2017 / R& T15

1980 20101982 20092002

1990 20001989 2013

1999

2000199019802002

RFI RFPRFI

2006

CDR

Definition of

engine fixed

for

production

1st Ground Test

With propeller

TPI M138 engine

down selected

Europrop TP400

selected1st engine

Test without

propeller

200520042003 2007 2008 2009 2010

2008: A400M

1st Flight

Engine

Flight Clearance

Engine certification

Propeller

certification

2016

Engine 1st

Definition

change

EASA restricted

Certification type

1/3 2 3 4 Q

8/20

Chapter 1

Part 1

A400M timeline

Engine timeline

FLA timeline


Engine production (toward SHM)

June 2017 / R& T16

Production is now facing different high technics materials to

include into the engine. Estimating the quality of the production is

going more on more to rely on big data and SHM functions.

Monitoring of the production and put the data at the same

place than the operational data is one of the challenge of the

data lake.

The answer was ceramics matrix composites. Ceramic matrix composites

(CMCs) are a subgroup of composite materials. They consist of ceramic

fibres embedded in a ceramic matrix, thus forming a ceramic fiber

reinforced ceramic..

“I am third the weight and twice the strength of Ni-base alloy

metals and have 20 per cent greater temperature capability?

What material am I?

1/3 2 3 4 Q

9/20

Chapter 1

Part 1


CHAPTER 1 CONTENTS

June 2017 / R& T17


Engines : from design to

production


Maintenance type and Engine

maintenance owner

1

Aircraft Engines

Usage &

Operational life

2/3 2 3 4 Q

10/20

Chapter 1

Part 2


Aircraft

Engine

Engine operation about thrust and its effect

June 2017 / R& T18

Pilot’s commands

demand

Thrust Leverdemand

A/C power

Eng start /

Fuel cut off

Effective Thrust

Provide fuel

Consumes oil

Degrade its LLP*

A/C events:

• Air Turn Back

• Delay &

Cancellation

• Aborted Tack off

Engine events :

• LOTC & LOPC

(Loss of Thrust

(power) Control)

Thrust

Electrical

Power

Fuel

11/20

2/3 2 3 4 Q

Chapter 1

Part 2

LLP* = life

limited parts


FAA & EASA regulations define certification processes (FAA/EASA e-regulation Part 21,

Airops, Part M, Part 145…) for design, manufacturing of the engines and the aircraft. Also,

the exploitation and the continuity of airworthiness are specific regulation chapter.

Airlines are responsible of the continuity of airworthiness as such they decide what

maintenance action to take. Service are provided by engine OEM that are for guarantee or

guiding decision when an “aircraft on ground” event occurs.

Engine OEM

Design

Part 21Subpart J

Engine operation: Certifications

June 2017 / R& T19

Production

Part 21Subpart G

Airline

Exploitation

AIROPS

Air

Worthiness

PART MPerforming

Maintenance

Part 145

12/20

2/3 2 3 4 Q

Chapter 1

Part 2


Aircraft Engines Monitoring

June 2017 / R& T20

During development Reception

testInspections

maintenance

In service

Operational

life

Engine is monitored throughout development phase as well as during all its life.

Development of an engine goes from 3 to 10 years and

engine’s certification toward EASA or FAA requires evidences.

Proof could be delivered through engine tests.

As such the conduct of the test plan can be hazardous as

some test requires some specific meteo conditions (such as

icing)

Monitoring is done at each test trials often in a manual way by

the engineers as they need to know if the expected behavior is

the one measured. That way first maturation of the fault logics

as well as flight specific health assessment is done.

Monitoring logics are focused on :

- Engine main functions & Engine critical pieces

PHM is about monitoring only during the “in service life”.

Inspections are done

on airlines initiative.

Maintenance are done in shops, may

be outside OEM perimeter.

13/20

2/3 2 3 4 Q

Engine

Chapter 1

Part 2


CHAPTER 1 CONTENTS

June 2017 / R& T21


Engines : from design to production



1 2

Engines MaintenanceMaintenance types

and

Engine maintenance actors

3/3 2 3 4 Q

14/20

Chapter 1

Part 3


Maintenance is shared between the airlines (or aircraft operator), and the OEM.

The responsible toward the authority (for example FAA) is the CAMO (Continuing Airworthiness Management Organisation) that

organize the maintenance. CAMO can have at most only 2 subcontractors (for the whole aircraft) with respect of their activities

according to the Appendix II 1321/2014 AMC M.A.711(a)(3)

OEM can provide maintenance recommendations on demand or on service request but only those made by the CAMO are

accountable for in term of responsibility or engaging orders..

Engine maintenance

June 2017 / R& T22

Typical airline

organisation

Safran Aircraft Engines PSE

15/20

3/3 2 3 4 Q

OEM CNR Service bulletin

Chapter 1

Part 3


Engine maintenance

June 2017 / R& T23

Service

bulletin

16/20

On-Wing Maintenance

Operational

Events

OEM CNR

Maintenance plan

Maintenance Workscope

Inspection

Workscope

3/3 2 3 4 Q

Engine is controlled through visual

inspection (borescope), or NDT

tests.

Engines may need to be overhauled

to proceed to the inspection of zone

not reachable on wings.

Sometimes engine washing is need

to be able to inspect.

Shop

On site

Maintenance

Engine inspection

Inspection

results

Engine overhaul

Engine maintenance may need to

remove the engine from the aircraft.

Operation can be done either on-site

(near aircraft deposit) or in

specialized shop.

An engine can be leased in the

meantime.

Oil refilling, data downloading,

on-wing troubleshooting, LRU

replacing are common events done

by the airline.

Note that technician are certified

with respect to a set of maintenance

operations only and not all possible.

OEM is a supportive

partner for

maintenance on its

product.

Chapter 1

Part 3


• The different type of maintenance are as followed

Hard Time Maintenance: Maintenance is done at fixed intervals (time or cycles)

Maintenance on Condition : Maintenance is performed when condition or statement are required. For example when

occurs a FOD (foreign Object Damage) like hitting a bird a maintenance operation can be done

Maintenance type

June 2017 / R& T24

17/20

3/3 2 3 4 Q

TSN

Time since

New

Fa

ilu

re R

ate

Hard Time Maintenance

margin

Time to failure

Probability of failure & Maintenance

Hard Time Maintenance Condition Based Maintenance

CBM

Predictive

Maintenance

Corrective Maintenance

“Run-To-Failure”

As

se

t c

on

dit

ion

design condition

Advisory

information

Failure

condition

Monitoring

condition

Engine installation

on Aircraft Restoration zone

Precision

Tests

Chapter 1

Part 3

TSN

Time since

New


Engine maintenance: Benefits of PHM today at Safran

June 2017 / R& T25

18/20

3/3 2 3 4 Q

Airline OEM

- Be confident on the engine ability to

provide thrust on demand during a work

day or more

- Have a visibility on the maintenance

operation and early warning to optimize

operation

- Reduce engine-failure trigged events.

- Better know the condition of the engine

and how it’s evolving.

- Better know the client needs based on

engine feedback.

- Provide better feedback to design team

about conception margin.

Engine PHM Benefits

Chapter 1

Part 3


After this point, two threads will be used in order to have consistent examples on PHM at Safran. The two

selected thread are here under :

- Engine take-off capability

Aircraft engine performance is about to lift off the aircraft. Monitoring this performance is required by PART M

certification on a regular basis.

A key parameter to follow is the exhaust gas temperature during the maximum constraint point (generaly the

takeoff). In fact, as the engine ages, it lost its efficiency and for the same takeoff its temperature needs to be

higher.

- Engine Range follow-up

Aircraft engines have their own consumables. The one that has the shortest cycle is the oil that is used to

lubricate its gears and bearings (interface between rotating and fixed parts).

COMMON THREAD for the tutorial

June 2017 / R& T26

19/20

3/3 2 3 4 Q

Chapter 1

Part 3


ETOPS : A regulation need for Monitoring

June 2017 / R& T27

Extended Range Operations with Two-Engined Aeroplanes ETOPS Certification and Operation (AMC 20-6)

For Leap, oil consumption monitoring will be automatized

3/3 2 3 4 Q

20/20N

2 &

EG

T m

arg

inO

ilco

nsu

mp

tio

n

Chapter 1

Part 3


June 2017 / R& T28

13

4







PHM Systems on CFM56 & Silvercrest

engine



1 2 3 4 Q

GLOBAL PHM SYSTEM ARCHITECTURE

System perimeter

Engine dysfunction

analysis

Engine wear mode

System architecture

2Chapter 1/39

Chapter 2


CHAPTER 2 CONTENTS

June 2017 / R& T29 1 2 3 4 Q

Conception process

System engineering approach

Engine Failure Risk Analysis

What to monitor in an aircraft engine ?

Failure Mode & Operational Hazard analysis

Engine degradation & wear mode analysis

Engine Health Monitoring Functions Conception

PHM System Function selection & conception

PHM System Conception

PHM System Architecture

Operational procedures specification

PHM System Industrialization

System Design

KPI of PHM System

Knowledge data base update

1 2 3 4 5

2/39

Chapter 2


CHAPTER 2 CONTENTS

June 2017 / R& T30 1 1/5 3 4 Q









PHM System

Industrialization

System Design

KPI of PHM System

Knowledge data base

update

2 3 4 5

Conceptual

Phase

System

engineering

Engine

operational event

Risk Analysis

3/39

Chapter 2

Part 1


Monitoring is done mainly to reduce opeartional events

such as D&C, ATO, IFSD.

Context on monitoring Aircraft Engines : Trend

June 2017 / R& T31

N2 Core speed deviation

Example of CFM56-5B VBV system detection

• @Cruise flight phase, core parameters increasing is related to air

leakage issue

• ~3 flights detection leadtime

• Customer Notification Report is issued as Aborted Take-Off can

be avoided

EGT deviation

CFM56 figures

8000+ engines monitored in Safran Aircraft Engines zone 2 snapshots per flight, 4 analytics ~10 CNR types per engine

type 3000+ alarms per month

TSNTime since New

Tre

nd

ed

Pa

ram

ete

r

Trend

Gradual deterioration

Gradual deterioration

Discrete event

1 1/5 3 4 Q

4/39

Chapter 2

Part 1


1 1/5 3 4 Q

Brief description on engine and their temperatures

A Turbojet is mainly

composed of a :

Due to dilatation some

clearance are introduce, but

with the wearness of the

engine, its performance

degrade.

June 2017 / R& T

Air Inlet

Engine with Nacelle Bare Engine Turbomachine

Fan Module Booster & High

Pressure Compressor

Combustion

Chambers

Turbine

NozzleExhaust Gas

A degradation on all the veins will be traduce by a higher

EGT (exhaust Gaz temperature) as more power is required

to reach the takeoff velocity.32

400°C1200°C

1800°C

5/39

Chapter 2

Part 1


Context on monitoring Aircraft Engines : Lubrification system

June 2017 / R& T

CBSump A

Oil

tank

En

gin

e o

ille

ve

l

Anti-Leak

Valve

Main

PumpO

ilF

ilter

cart

ridge

Bypass

valve

SACOC

Main Fuel Oil Heat

Exchanger

Sump

AGB

deoiler

deaerator

DeltaP

sensors

Magnetic Chips

Detector bars

Oil Debris monitoring

33 1 1/5 3 4 Q

Particularity of the

lubrification system

on an aircraft

engine is that it’s

an open circuit that

relases oil with a

target consumption

about 0.1 l/h on a

cruise with a

modern engine

6/39

Chapter 2

Part 1



June 2017 / R& T

Machinery Information Management Open System Alliance (MIMOSA)

OSA-CBM (Open System Architecture for Condition-Based

Maintenance) V3.2.1

ISO STANDARDS

ISO 13374-1 Condition Monitoring and diagnostics of machines –Data

processing, communication and presentation –Part 1: General

guidelines (equivalent as OSA-CBM)

ISO 13374-2 Condition monitoring and diagnostics of machines –Data

processing, communication and presentation –Part 2: Data processing

IEEE

IEEE P1856 Standard Framework for Prognostics and Health

Management of Electronic Systems

SAE HM-1 Integrated Vehicle Health Management Committee

ARP4754-A System design process

ARP6275 Determination of Cost Benefits from Implementing an

Integrated Vehicle Health Management System (IVHM)

AS4831A Software Interfaces for Ground-Based Monitoring Systems

ARP6803 IVHM Cornerstone Document (Draft)

ARP 6883 Requirements of an IVHM System (Draft)

ARP6407 Guideline for the Design of an IVHM System (Draft)

34 1 1/5 3 4 Q

7/39

Chapter 2

Part 1


Who is interacting with the PHM System ?

>>the different stake holder implies possibility to have different perception of the needs

clarification of needs and priority between express need is important

System engineering approach: Stakeholders of PHM Systems

June 2017 / R& T

Internal stakeholders

External stakeholders

Operational

life

Design

life

35

Aircraft

manufacturerAirports

Airlines(including

mainenance)

3rd

party

PHM

Shops

Nacelle

manufacturer

Trouble

ShootingEngine Design

Team

Supply

Chain PSE

warranty

1 1/5 3 4 Q

8/39

Chapter 2

Part 1


Aircraft operators (airlines) are in charge of the

continuity of airworthiness of the aircraft and its

engine.

All the data produced by engine, aircraft or

nacelle are the propriety of the airlines.

Note that due to regulation, it is classified that 8 of

the 80 possible aircraft equipments (ATA) of a large

aircraft are located on the IPPS zone.

Engine OEM

Nacelle OEM

Aircraft

Monitoring perimeter : engine or engine zone (IPPS) ?

June 2017 / R& T

Owned by Nacelle OEM

Include mechanical parts

8 ATA are on the IPPS zone

Such as : Bleed Air system (BAS), Fuel systems, hydraulic

power, electrical power …

Owned by Engine OEM (like

Safran Aircraft Engines)

Can be split in more than one

actor

36

Airlines

IPPS: integrated power plant system

Jet engine: A jet engine is

a reaction engine discharging a fast-

moving jet that generates thrust by jet

propulsion.

Engine

Nacelle

Aircraft

1 1/5 3 4 Q

9/39

Chapter 2

Part 1

https://en.wikipedia.org/wiki/Reaction_engine

https://en.wikipedia.org/wiki/Jet_(fluid)

https://en.wikipedia.org/wiki/Thrust

https://en.wikipedia.org/wiki/Jet_propulsion


System engineering

Once the needs are collected an

analysis is done on the perimeter to

address an analysis is done to segment

the system into functions.

Needs are then translated into

requirements and requirement are

allocated on an engine embedded

product and to a ground product.

Requirements are then used for

implementing software solutions

If required verification is done

independently and integration is done

very late in the project. Some PHM

system design’s assumptions are

verified more than 3 years after the entry

in service of the engine.

June 2017 / R& T

Business

Needs

Global PHM

System reqs

Embedded

Req

Ground

Reqs

Global PHM

system

Global PHM

function

Ground PHM

Function

Embedded

PHM function

Algorithm Ground

software

Embedded

HW & SW

Traceability

Verification

Conformity

37 1 1/5 3 4 Q

10/39

Chapter 2

Part 1


Engine failure leading to shop visits

June 2017 / R& T

Legend

Hardware : Equipment faults

LLP : Life limit part with life on engine exhausted

NOEC : No Engine Cause found

Other : other causes

In term of business of airlines, hardware and NOEC

shouldn’t lead to an engine overhaul.

PHM should help to have detected it before leading

to a damage that needs heavy maintenance.

38 1 1/5 3 4 Q

En

gin

e V

ibra

tio

n

En

gin

e d

isp

atc

h

exp

ira

tio

n

En

gin

e flu

idle

ak

11/39

Chapter 2

Part 1


CHAPTER 2 CONTENTS

June 2017 / R& T 1 2/5 3 4 Q






PHM System

Industrialization

System Design

KPI of PHM System

Knowledge data base

update

3 4 5

Conceptual Phase



1

What to monitor in

an aircraft engine ?Failure Mode &

Operational

Hazard analysis

Engine

degradation &

wear mode

analysis

39

12/39

Chapter 2

Part 2



OEM classify the piece of the engines with

respect of their criticality and the damage

tolerance.

It standard to speak about damage

classifications for critical parts.

N1 are pieces that are represented with red

here, and the engine must function with only a

tolerance (2mm crack) on these pieces and

acceptable damages are below that tolerance.

LLP parts design all the pieces that are to be

changed at fixed cycles or engines usage time.

For engine design, typical missions scenarios

are used based on airframer assumptions.

During operational life, the number of cycle are

to be more followed-up.

June 2017 / R& T40 1 2/5 3 4 Q

13/39

Chapter 2

Part 2


Full Engine

Fan CompressorCombustion chambers

Turbine

Blades

Clearance

Engine Failure Modes & Operational Hazards analysis

June 2017 / R& T

Fan degradation is

mainly caused by

events such as

(FOD).

Note: Event such

as large bird strike

lead to inspection.

Erosion, and dust

can stick to the

compressor

elements.

leads to

compressor

performance drop

No trend on fuel

chamber only

cracks or fuel

system

degradation

Erosion, corrosion

monitoring

leads to turbine

performance drop

Damage

estimation based

on usage

leads to turbine

performance drop

Exhaust Gas Temperature

N2

Fuel flow is monitored

41 1 2/5 3 4 Q

14/39

Chapter 2

Part 2


Monitoring aircraft engine degradation

June 2017 / R& T42

Usage

Environment

Corrosion

Fluid

Contamination

Erosion

FOD

1 2/5 3 4 Q

15/39

Chapter 2

Part 2


Engine wear modes analysis: using EGT indicators

June 2017 / R& T

Engine storage

No

rma

lize

dE

GT

cycles

43 1 2/5 3 4 Q

Dust ingestion

Leads to

compressor

performance

drop

EG

T

Water wash

Compressor

restoration

Engine Storage

Bad storage

degrades the

engine.

Borescope

inspection

Opportunity of PHM: A pre-diagnostics on maintenance to make the proper maintenance operation at the

less impacting time for the company

Normalization of trend parametersBased on Online Normalization Algorithm for Engine

Turbofan Monitoring, January 2014, J. Lacaille.

Objective : to extract a

reduced number of

dimensions on which the

data may be explained.

The reduction of

dimension enables the

computation of meaningful

distances (i.e. and allows

the computation of

scores.)

EGT

High dispertion

Normalized EGT

16/39

Chapter 2

Part 2


Engine Failure Modes & Operational Hazards analysis

Lubrification circuit

June 2017 / R& T

SACOC:

Fatigue & FOD

Leading to

performance drop

FOHE:

Fluid contamination

Leading to leaks

Bearing & Sump : particles release in oil circuit

Leaks in sump: oil consumption increased

Oil :

Oil with debris

or bubblePumps (main &

scavenge):

Particle release

Deoiler:

More Oil ejected with air as

performance decrease

44 1 2/5 3 4 Q

17/39

Chapter 2

Part 2


Engine wear modes in real

June 2017 / R& T

Oil leak impact on thrust reverser doorsOil tube is damaged (fan frame)

45 1 2/5 3 4 Q

18/39

Chapter 2

Part 2


Monitoring aircraft engine lubrification system degradation

June 2017 / R& T46

Usage

Environment

Particules

releasedThermal

env.

1 2/5 3 4 Q

VibrationsCorrosion

19/39

Chapter 2

Part 2


CHAPTER 2 CONTENTS

June 2017 / R& T




PHM System

Industrialization

System Design

KPI of PHM System

Knowledge data base

update

4 5Conceptual Phase



1




2

Engine Health Monitoring

Functions Conception

PHM system

functions

conception &

selection

1 3/5 3 4 Q47

20/39

Chapter 2

Part 3


How to assess the most prioritary items to monitoring ?

June 2017 / R& T

Solutions selections

Functional Architecture

Detailed design

Technical needs are collected to define

the system. However clarification is

needed as well as some priorization.

However as some needs may be

different to address the same

perimeter, a priorization must be done

like a negociation between different

stake holders.

QFD method for example

Cost on value approach

Design efforts are taken into

account as well as costs

(Non reccurent & reccurent).

Value

Effort

(with risks)

Regrouping the needs into logicial functions is a step

that rationalize the project content. Functional blocs

are identified to split the different needs and major

function into component that can be requirements for

sub-systems. Blocs mapping may also be known as it

can be linked to a referential of tech blocs.

A description of the project can be done in SysML to

help clarify the scenarios and the function needs.

Components design

Interface design

Architecture conception

Preliminary design

is used for system

assessment. To check its

feasibility

48 1 3/5 3 4 Q

21/39

Chapter 2

Part 3

Needs priorization


OSA-CBM

June 2017 / R& T49 1 3/5 3 4 Q

22/39

Chapter 2

Part 3

Early Warning system:

An early warning system can be implemented as a chain of

information that comprises sensors and event detection decision

support and message broker to forecast any signal

Health status:

Indicator that reflect the asset / component condition

Trend Deviation:

In a noisy signal a trend estimation is made with a statistical technique to

aid interpretation of data. Deviation spots an inflexion in the signal.

Anomaly detection:

anomaly detection (also outlier detection) is the identification of items,

events or observations which do not conform to an expected pattern or

other items in a dataset.

Definitions

Prognostics:

Can be different

corresponding to

different health

status:

- Confirmed fault

- Early warning

- Early detection


How to assess the most prioritary items to monitoring ?

TRL/MRL/DRL and gain/effort matrix

Development effort is one of the driver to have the deployment of a new technology different scales are used to assess the development

effort that are to be done.

June 2017 / R& T50 1 3/5 3 4 Q

23/39

Chapter 2

Part 3

Technology readiness level

(model based)

EIS

Target (new engine)

FETT

RFP Data readiness level

(data driven)

FETT

RFP

EIS

Maturity readiness level

(CMMI rule)


Harvest Data

Analyze Data

Activate Analytics

Optimize Analytics

Strategies on building PHM functions

Model based vs Data Driven functions

June 2017 / R& T51

24/39

Chapter 2

Part 3

Test on

devices

integration

modeling

physics

simulation

KPI of

model share

discoverengage

Listen

Pro: Optimize Data usage – adapted on ground.

Development costs

Con: Dependent on data sources

Pro: Centered on product integration (Embedded or ground).

Validation Costs

Con: Physics must be known

1 3/5 3 4 Q


Life of an indicator

June 2017 / R& T

anomaly

Trend

speed

Output

indicator

1..k

0..y1..z

Endogene inputs Exogenes inputs

Signal/Noise ratio Trend speed

Confirmation time

precision robustness

influence

52

25/39

Chapter 2

Part 3

1 3/5 3 4 Q


Simplification issues

Because detection may likely to trig an huge amount of variables an important point is about

function segmentation and variable reduction.

Robustness and algorithm maturity will depend on the data size, and if we take assumption on

the KPI will need much more data to be assessed. It seems to take and exponential law to

provide the right amount of points.

Usage of for example a LASSO criterion such as described in the article « Sudden Change

detection in turbofan engine behaviour » J. Lacaille 2011 can provide interesting information. A

LARS (Least Angle Regression) algorithm Effron 2004, can be used to estimate all the solution

of the LASSO criterion for all possble values of C with respect with the KPI error that is to be

mimimized.

Data Reduction

June 2017 / R& T53

26/39

Chapter 2

Part 3


PHM Function design – EGT Trending

June 2017 / R& T54

27/39

Chapter 2

Part 3

DA DM SD HA PAobjectives Data saved

(max EGT)

EGT

@ISA25

Trend EGT

Events

EGT

Temperature

for each module

Pressure

for each module

Estimation may

be realized

All available

data

Model

on EGTAnomaly

detection

based on model

output

Trend on

EGT

Engine condition

need calibration

With experts vote


Tech Bricks – a component approach to define PHM functions

June 2017 / R& T55

28/39

Chapter 2

Part 3

objectives Data saved

(Begin/End)

EOL

@iso

conditions

Trend EOC

EventsEOC

DA DM SD HA PALubrification

system

condition

Oil dilatation law

EOL/EOT

All available

data

Resolution

issues

Anomaly detection


CHAPTER 2 CONTENTS

June 2017 / R& T

PHM System

Industrialization

System Design

KPI of PHM System

Knowledge data base

update

5Conceptual Phase



1




2Engine Health Monitoring


PHM System Function selection &

conception

3PHM System

Architecture

Operational procedures

specification


1 4/5 3 4 Q56

29/39

Chapter 2

Part 4


PHM System architecture

PHM System : Black Box

Depending on the maturity of a product there may be in a PHM System :

Raw Indicators only, Visualizations, Business Indicators, Engine level condition indicators, Customer Preformatted Recommendation on

the Ouptput size, and FADEC or other systems for the INPUT side.

Humans have to intervene before the end of the system.

June 2017 / R& T

PHM System

(Global)

Configuration

Indicators

FADEC Data and

aircraft Data

Fleet Manager

Data Base

57

30/39

Chapter 2

Part 4

CNR

Architecture conception works on defining subsystem from main system


June 2017 / R& T


58

31/39

Chapter 2

Part 4

• Snapshot acquisition @ takeoff

• Environment severity estimation (sand, ice)

Data Acquisition

• Snapshot enriched with previous and following data

• Sensor error to be estimated

Sense• Specific Raw data

• Max EGT computed

Acquire

• Information sent on flight basis on ground

• Transfer engine configuration information

Transfer

• Normalized EGT with defined environment condition

DM

• Anomaly tracking with model (that contain aging information)

SD • Signature classification on EGT trend (dust ingestion, water wash…)

HA

• Prognostic on EGT

PA • CNR made in case of event that will be confirmed by operator

AG



June 2017 / R& T59

32/39

Chapter 2

Part 4

• Snapshot acquisition @ beginning and end of flight

• Environment severity estimation (temperature)

Data Acquisition

• Sensor error to be estimated (oil level, oil tank temperature)

Sense• Specific Raw data

• Oil level difference in a flight and flight duration

Acquire

• Information sent on flight basis on ground

• Transfer engine configuration information

Transfer

• Normalized oil level difference with defined environment condition

DM

• Anomaly tracking with model

SD • Analyse done manually on signature

HA

• Manual prognostics on oil consumption trending

PA • CNR made in case of event that will be confirmed by operator

AG


PHM System operational process

June 2017 / R& T60

33/39

Chapter 2

Part 4



Architecture is mainly made on choices. Trade are conception choices that defines the system and its performance. This

slide and the next ones are about possible trades that can be made during a conception.

Design option1 : aircraft integrated architecture or not

June 2017 / R& T61

34/39

Chapter 2

Part 4

Today : Independant engines Tomorrow : Aircraft integrated ?

Engine PHM system is autonomous

mainly use aircraft to transmit information on the ground station.

Engine Embedded system are

constraints in term of CPU and

memory.

One counter measure would be

to host computation ECU into

the aircraft

The cost is more dependancy

toward aircraft manufacturer



Design option 2 : full embedded or full ground ?

June 2017 / R& T62

35/39

Chapter 2

Part 4

Full Embedded PHM System Full Ground PHM System

Objective: be fully autonomous without satellite

link to make PHM indicators

Gain : no specific infrastructure on ground for

data hosting, easy scalability toward fleet

Deployment.

Cons: Accessibility and software update.

Objective: be able to update analytics very quickly

and have data driven models running on fleets.

Gain : optimization of model, new algorithm

(machine learning)

Cons: Data to be put on ground

More difficult to know the sensor to add in a new

project..


CHAPTER 2 CONTENTS

June 2017 / R& T

Conceptual Phase



1




2Engine Health Monitoring


PHM System Function selection &

conception

3

Operational life preparation




4System Design

KPI of PHM System

Knowledge data base

update

1 5/5 3 4 Q63

36/39

Chapter 2

Part 5


PHM System design – DBS example

June 2017 / R& T64

37/39

Chapter 2

Part 5

System will be split into different components.

PBS – Product Breakdown structure and

DBS – Document Breakdown structure will help to understand better.

On board

3

6

22

On ground

Deta

iled

conception


PHM System KPIs

KPI are issued on PFA and POD that can be modeled as alpha and beta here >>

Detection quality are juged through those KPI, however they need to beassociated on events as all are not equaly seen by the customer.

First of all here is a brief description of airlines. In fact, IATA have definethe Completion Rate indicator as such

CR = (scheduled flights – cancelliing + affretings)/scheduled flights

Performance is based on individual performances + machine availibility.

It exists : CR WATOG and CR Total

CR WATOG is World Airline Technical Operation Glossary : 1st technical problem is taken intoaccount and not its consequences.CR Total : all events are taken into accounts.

Airlines are as such interested in the different performance with respect to different events that canoccurs

@ aircraft level : Delay & Cancellation, Aborted Take-Off, Air Turn-Back

OEM are more interested to know on the engine side:

@engine level : LOTC/LOPC, Dispatch …

June 2017 / R& T65

38/39

Chapter 2

Part 5


PHM data base update

June 2017 / R& T 1 2 3 4 Q66

39/39

Chapter 2

Part 5

Data Storage

Analytics running &

optimization

Operator base of

knowledge

Certified Data : QAR, DAR, SAR

Engineering data: CEOD, FFD, RWD

KPIs

Quality factors

Engine configuration & CDM

Damage models, engine

configuration information

Technical Guides & models

AMM, FIM, FIP, HAZOP, …

Customer Support Center

& PSE Client Notifications

Contracts

Contract management

CloudApplication & Services

Today : Data are provided by airlines to PSE

Tomorrow : Data are sent automatically


June 2017 / R& T67

14




PHM Systems on CFM56 & Silvercrest

engine




System perimeter


Engine wear mode

System architecture

3Chapter

Constraints on airborne

systems

Harsh environment &

monitoring

EMBEDDING A PHM SYSTEM

1 3 4 Q32


Appropriate number of sensors « PHM

dedicated »

High accuracy

Introduction - Ideal PHM Embedded System

June 2017 / R& T68

Real time transmission

All data, whole flight

Measure

Compute

Transmit

Flight

Engine

Ground

station

Basic processing No loss of usefull information

Main challenge : deal with a huge amount of data

No

Constraint

1 3 4 Q32

1/2

Chapter 3

Intro


Introduction - Real Embedded PHM System

June 2017 / R& T69

Measure

Compute

Transmit

Flight

Engine

Ground

station

Re-use of regulation/monitoring sensors

Insufficient accuracy

Sporadic transmission (at the end of a mission or less frequently)

Part of data, specific mission phases

Complex processing Loss of usefull information

Main challenge : data recovery and improvement + deal

with a high amount of data

Environment, installation,

weight

Environment, H/W techno,

S/W development costs

Transmission techno,

operational costs1

2

3

Embedded processing is driven by transmission capability on the one hand, and by the best re-use of

existing sensors on the other

1 3 4 Q32

2/2

Chapter 3

Intro


CHAPTER 3 CONTENTS

Mars 2016 / DIRECTION SUPPORT CLIENTS

Transmission

Aircraft to Ground

Engine to Aircraft

1part

1 3 4 Q32

Computation

Hardware in Engine environment

Computation optimization

3

Measurement

Choice of Sensors

Accuracy retrieval methods

2


• Some engine characteristics

• 16 000 parts, 2 400 references, …30 sensors and

thousands of parameters

• Phenomena to be monitored with dynamics up to several kHz

For a 2h flight, it represents several GB of data per engine

• More than 30 000 CFM56 engines produced

TRANSMISSION - A few Orders of Magnitude

June 2017 / R& T71

Case of an A320 or B737 aircraft (single aisle)

• The aircraft stops at the airport gate for approximately 30min

Need for a bandwidth of several hundreds of KB/s

L = 3,3m

D = 2m

1 3 4 Q32

1/6

Chapter 3

Part 1


In flight

High recurring costs

Upgradability : less flexible system

Complex embedded treatments

Data sent in flight

Well known technologies

Radio + Satellite communications

Low volume of data

Immediate On ground

No recurring costs

Strong upgradability : algorithms can

easily be modified or new ones can be

introduced

Basic embedded treatments

Real Time : data can be immediately

treated by the ground system

Ideal World : no implemented

technology yet

“Big Data” problematics on the

Ground PHM System (Data Mining,

data storage)

Low recurring costs

Upgradability : more flexible system

Simple embedded treatments

Data sent on ground : airport must be

properly equipped – aircraft must be powered

up – limited time to download data

New technologies : not always accepted by

the stakeholders

“Big Data” problematics on the Ground

PHM System (Data Mining, data storage)

Ideal World

TRANSMISSION – From Aircraft to ground

June 2017 / R& T72

3G / 4G / WiFi

All data High volume of data

1 3 4 Q32

2/6

Chapter 3

Part 1


TRANSMISSION – From Aircraft to ground

June 2017 / R& T73

Pitfall : - too complex embedded treatments

- not enough data transmitted

Embedded / Ground Split

Oil Consumption example:

■ Send all data

■ Selection of oil level + other influencial

data and all computation on ground

■ Select oil level data + influencial data; pre-

treatment on board and send compressed

data

■ Further computation on ground

■ Select and send only oil level + other

influencial data

■ All computation on ground

Embedded Ground Embedded Ground Embedded Ground

In flight

Radio + Satellite communications

Low volume of data

Immediate On ground

Ideal World

All data High volume of data

Pitfall : - too complex ground treatments (complexity and maintainability vs. efficiency)

3G / 4G / WiFi

1 3 4 Q32

3/6

Chapter 3

Part 1


New engine programs (ex : Ideal World)

• Development includes PHM service

• PHM taken into account in development

choices

• Architecture and interfaces optimization

Legacy Aircraft (ex : A320 / B737 with CFM56 engine)

• Development with no PHM

• Frozen architecture and technologies

• Avionic and embedded systems optimized to the needs

Re-use of current engine configuration with the least modifications

TRANSMISSION – From Engine to Aircraft

June 2017 / R& T74

Engine

System

Avionics

Example : addition of a link

High costs and weight increase exploitation costs increase

• Cable harness modification

• A few decades of meters added a few kg

• Computational units (both aircraft and engine) modification

• Interfaces (pins) and hardware, software

1 3 4 Q32

4/6

Chapter 3

Part 1


New engine programs (ex : New middle of market

aircraft)

• Development includes PHM service

• Engine to aircraft link

• Ethernet allowing high frequency data sending

(~MHz)

• Data treatment unit location : usually on the engine

• Eases re-use and more flexible

Legacy Aircraft (ex : A320 / B737 with CFM56 engine)

• Development with no PHM

• PHM is subject to the engine to aircraft existing link

• ARINC (aircraft communication standard) allowing only low

frequency data sending (~Hz)

More complex compression treatments

• Data treatment unit location : usually in the aircraft bay

• No room left on the engine to add a PHM specific computational unit

Less flexible because of more aircraft dependencies

Limited evolutions (new functions, functions upgrading)

possiblities

TRANSMISSION - Engine to Aircraft

June 2017 / R& T75

Engine

System

Avionics

1 3 4 Q32

5/6

Chapter 3

Part 1


6/6TRANSMISSION - To sum up

June 2017 / R& T76

Measure

Compute

Transmit

Flight

Engine

Ground

station

1

2

3

Maximum transmission bandwidth known

? Which data to select and send ?

Aircraft to ground

• Bandwidth limited due to transmission technology

Engine to Aircraft

• Different approach if legacy or new engine program

• Legacy : bandwidth is subject to the avionic already in place

• New : bandwidth benefits from a more recent avionic

1 3 4 Q32

Chapter 3

Part 1


CHAPTER 3 CONTENTS


2part

1 3 4 Q32

Measurement

Choice of Sensors

Accuracy retrieval

methods

Computation

Hardware in Engine environment

Computation optimization

3Transmission

Aircraft to Ground

Engine to Aircraft

1


The Aircraft Engine is a major system :

Safety is the priority !

It embeds different functions

It operates in a wide envelope

And has to fulfill many requirements

MEASURE - Aircraft Engine in a nutshell

June 2017 / R& T78

Wide operating

envelope

PHMTrouble

shooting

Engine

environment

Safety

Engine

control

Weight

Performances

Operating costs

Equipment installation

« Green »

engine

1 3 4 Q32

1/14

Chapter 3

Part 2


MEASURE – PHM inputs selection

June 2017 / R& T79

Safety

Some Sensor’s characteristics

• Trueness (Accuracy, Precision,

Resolution)

• Reliability, Robustness

• Sensitivity to influential non-measured

parameters

• Operational domain

• Weight , Size, Shape

• Costs

Re-Use of engine control sensors

Wide operating

envelope

PHMTrouble

shooting

Engine

environment

Safety

Engine

control

Weight

Performances Equipment installation

« Green »

engineOperating costs

1 3 4 Q32

2/14

Chapter 3

Part 2


MEASURE - Costs of an additional sensor – butterfly effect

June 2017 / R& T80

Additional Weight Additional Fuel Burn Additional recurring costs

Additional maintenance/ in service

support costs

• Troubleshooting, maintenance operator formation,

engine complexity

• Spare parts storage costs

Additional development costs

• Signal processing

• Impacts on CPU usage,

computational load, calculation

Time

• Software modification + V&V

• Transmission & bandwidth availability

SensorSignal processing unit

(HW modification)Harness

Conditioner

+ + (+ +…+ )

1 3 4 Q32

3/14

Chapter 3

Part 2


4/14MEASURE - Engine controls and PHM

June 2017 / R& T81

Engine controls in a nutshell

• Controls the engine : computes the commands and sends it to actuators

• Engine protection functions : overspeed protection, fire protection…

• Communicates with the aircraft :

• Receives the aircraft data necessary to fulfill its role

• Send information to the aircraft (maintenance information, alerts…)

Opportunity for PHM

• PHM can use data computed by engine controls

• Additional internal engine data and parameters

• Detection logics

• Models : temperatures, pressures

• Data validity status

Sensors Actuators

Avionics &

Aircraft Systems

PHM Engine

Controls

But also associated limitations

• Due to different needs between Engine Controls and PHM

• Limited number of sensors

• Accuracy, precision and/or acquisition frequency not

always sufficient for PHM needs

1 3 4 Q32

Chapter 3

Part 2


5/14MEASURE - Engine controls: data status computation

June 2017 / R& T82

Sensor redundancy

• 2 sensors measuring the same data independently

• Data from each sensors are sent and processed independently

A status is computed and a selection is performed

PHM can use the data status

• As a current data status for PHM functions

• For a specific monitoring function

Engine Controls

1 3 4 Q32

Channel A Channel B

Cross check

Status computation

& Data Selection

Range check

Range check

Selected value Data Status

Chapter 3

Part 2


6/14MEASURE – Sensor technology selection

June 2017 / R& T83

Example : oil level sensor

• Both Engine Controls and PHM need the oil level measure

• Some other factors to take into account to choose a sensor

• Installation constraints : oil tank design, oil sensor installation in the tank

• Compact solutions

• Sensor robustness to engine environment : strong thermic and mechanical stress

• Avoid sensors with mechanical contacts

• Sensor’s low sensitivity to influential parameters (temperature, vibrations…)

• Possibility to implement a compensation (model…)

• Costs

Objective Needs on the sensor

Engine Control - Detect low oil level (safety aspects)

- Detect if the tank is full or needs refill (binary)

- Accuracy around extreme positions (full and

empty tank)

- Very reliable

PHM - Monitor the oil consumption and detect

anomalies in the oil consumption

- Accuracy on the whole oil level range

Tank section

1 3 4 Q32

Chapter 3

Part 2


• Continuous measurement

MEASURE - Oil level sensors technologies – some examples

June 2017 / R& T84

Resistive sensors Capacitive sensors

VM

AX

Vmi

n

Vref Vou

t

1 2 3

Rfault detection

resistor

Sensitive to oil pollution

• Discrete measurement

Also other technologies, but too costly or too much impacted by the environmental constraints

• Differential pressure sensor • Wave sensors• Magnetostrictive sensors

𝐶 = 𝜖𝑆

𝑑

𝑅 = 𝜌𝑙

𝑆

Accuracy depending on the step width between the floats and

the tank design

ℎ

𝜖 variations

In case of fuel leakage

1 3 4 Q32

7/14

𝑆 = 2𝜋𝑟ℎ

Chapter 3

Part 2


8/14MEASURE – Accuracy and precision recovery

June 2017 / R& T85

Measurements come with numerous sources of errors

First step : Sources of error identification in the measurement of the monitored parameter

This step implies the sensor expert, the system specialist but also a lot of data visualization

Then : Sources of error classification

• Systematic errors impact on accuracy

• Random errors impact on precision

Action for each source of error is taken in order to

improve the trueness

Process may be iterative with the trend design of the monitored

parameter. Trend variation analysis may indicate if further improvement

is necessary or not.

Offset correction Filter

Poor Accuracy Poor Precision

1 3 4 Q32

Chapter 3

Part 2


MEASURE – Example of Oil level measurement error analysis

June 2017 / R& T86

oil level measurement

accuracy

oil temperature influence

oil flow influence

aircraft attitude influence

type of oil

Objective : monitor oil consumption and detect

anomalies in oil consumption

First step : Sources of error identification

1 3 4 Q32

Chapter 3

Part 29/14


Due to installation constraints, oil level sensor is not

centered in oil tank.

This makes the measurement sensitive to aircraft

movements (acceleration/deceleration, pitch/roll, …)

because of oil surface inclination

First action is to select flight phase that minimize aircraft

attitude: take off, climb, approach are excluded

In flight attitude can be corrected but requires more parameters from the aircraft

and add extra complexity.

Remaining attitudes are filtered.

MEASURE - Aircraft attitude influence

June 2017 / R& T87

ay

az

g

lr

Lr

lf

Lf

Oil tank: top view

qSteady oil surface

Oil surface

with attitude

Oil tank: lateral view

Oil level

sensor

h

1 3 4 Q32

Chapter 3

Part 210/14


11/14MEASURE - Oil level measurement accuracy

Sources of errors are analyzed and

classified in categories

Lot of errors impact only accuracy and do not vary from one

flight to another for same engine. They are cancelled when

looking at trend variation.

Some errors are random and affect precision. Denoising will be

necessary.

Some errors are dependent from external parameters: a model

can be used to reduce it.

Measurement is discrete here

Measurement resolution has a strong impact on precision

Rising and falling edges are preferred instants to save

measurement.

June 2017 / R& T88

Reed switch

float

Tank section

Error sources impact

Floatability of the float in function of EOT f(Oil Temp)

Switch position tolerance accuracy

Sensor position / tank accuracy

Float weight tolerance accuracy

Hysteresis switch/magnet precision

Measurement electric noise precision

1 3 4 Q32

Chapter 3

Part 2


Oil temperature has primary effect on oil level

(dilatation + gulping)

Oils temperature follow a repeatable behavior

during taxi out when engine is heating.

A model is built and used on ground

Model is fitted with least square error reduction.

This offers several advantages:

> It is possible to estimate the oil level at a temperature reference

level in order to be comparable from flight to flight

> This reduces random errors has well as oil level quantization

error.

MEASURE - Oil temperature influence

June 2017 / R& T89

Decision to record only rising edges on board

1 3 4 Q32

12/14

Oil

Le

ve

l

Oil Temperature

Chapter 3

Part 2


Not all errors can be completely cancelled

for several reasons:

> Accuracy of models is not perfect

> Some parameters remain unknown

Remaining errors are smoothed in final

trend.

Accuracy improvement lowers detection time

Some robustness may be also included in

threshold detection (k among n)

MEASURE - Remaining errors

June 2017 / R& T90

oil level measurement

accuracy

oil temperature influence

oil flow influence

aircraft attitude influence

type of oil

1 3 4 Q32

Chapter 3

Part 213/14


14/14


Data and trueness recovery methods identified

? How to implement data acquisition and recovery methods ?

MEASURE - To sum up

June 2017 / R& T91

Measure

Compute

Transmit

Flight

Engine

Ground

station

1

2

3

Sensor technology selection is influenced by the

engine specificities

Measurements come with sources of error

Recovery methods are defined

1 3 4 Q32

Chapter 3

Part 2


CHAPTER 3 CONTENTS


3part

1 3 4 Q32

Computation

Hardware in Engine

Envrionment

Computation

Optimization

Measurement

Choice of Sensors

Accuracy retrieval methods

Transmission

Aircraft to Ground

Engine to Aircraft

1 2


COMPUTE - Embedded computational unit vs. Smartphone

June 2017 / R& T93 1 3 4 Q32

1/9

CPU, RAM, NVM

10 x~ Vibration

Lightning

Cosmic radiation

Development Duration

~-50°C ~ 100°C

~ -20°C ~ 45°C

Altitude

~ 5-10 years development

~ 20-30 years in serviceEach year, a new

smartphone

Chapter 3

Part 3


COMPUTE - A set of challenging constraints limits the CPU throughput

and memory

June 2017 / R& T94

miniaturizationLithography

resolution

Data/code

corruption

Cosmic rays

Increase sensitivity

CONSTRAINTS

weightsurface volume

Component

obsolescencevibrations

Active

cooling

reliability

Thermal

dissipation

Component extended

temperature range

Different dilatation

coefficient

shear

shear

BGA grid

resolution

1 3 4 Q32

2/9

Chapter 3

Part 3


COMPUTE - Consequences

June 2017 / R& T95

Hardware limitations

• Storage memory less than 1 GB (several GB for ACMS)

• CPU throughput generally less than 1 Gflop

Extra development efforts

• Storage optimization (number of bits reduced to 8 when possible, undersampling, …)

• Computation time is not only linked to the number of operations but also to the amount of data to load to the CPU

Effort is spent in reduction of the number of operations

Effort is also spent on the reduction on the bandwidth between memories and CPU: data flow optimization and cache usage

1 3 4 Q32

3/9

Chapter 3

Part 3


Defining on board simplified extraction rules

June 2017 / R& T96

Number of inputs is reduced:

• Flight phase restricted to

domains aircraft attitude are

limited

• Aircraft attitude have been

characterized in retained flight

phases and aircraft data have

been removed from inputs

1 3 4 Q32

N2 Core Speed

Oil temperature

Oil level

4/9

Chapter 3

Part 3


Defining on board simplified extraction rules

June 2017 / R& T97 1 3 4 Q32

5/9

Extracted samplesNumber of outputs is reduced:

• Only samples bringing

information are extracted

Chapter 3

Part 3


Treatment scheduling

June 2017 / R& T98

Several PHM functions

embedded in the same unit

Quantity of operation exceeds real time

capability Scheduling

Treatment is differed and prioritized

Altitude

time

Startup processing

Taxi out oil data

Take off gas path data

sensors data

Gas path cruise data

taxi in oil data

Post flight report (PFS)

1 3 4 Q32

6/9

Chapter 3

Part 3


Data flow optimization

June 2017 / R& T99 1 3 4 Q32

7/9

Generally, more than 50% of computation time is spent in

exchanging data between CPU and memories

• It is generally better to work on small chunks of data

• Keep data in cache memory as long as possible to avoid multiple

load/store cycles

• Compromise between differed time that requires extra data exchange

and real time for lighter algorithms that reduces data exchange

Processor

L1 cache

program

L1 cache

data

L2 cache

External RAM

Spatial and temporal proximity

Chapter 3

Part 3


Data flow optimization

June 2017 / R& T100 1 3 4 Q32

8/9

Processor

L1 cache

program

L1 cache

data

L2 cache

External RAM

Prototyping with scripting interpreted languages introduce a different data flow philosophy

• Example : extracting a maximum and a minimum

Interpreted

(prototyping)Embedded

M = Max(X_vect));

m = min(X_vect));

For all x in X_vect

if x > M

M = x

end if

if x < m

m =x

end if

End for

Max :

For all x in X_vect

if x > M

M = x

end if

End for

min :

For all x in X_vect

if x < m

m = x

end if

End for

This can increase the data flow

bandwidth by more than 1000%

Code optimization : advices completely opposite between

interpreted script and embedded software

Chapter 3

Part 3


COMPUTE - To sum up

June 2017 / R& T101

Measure

Compute

Transmit

Flight

Engine

Ground

station

1

2

3

Hardware limitations due to engine environment

Need to simplify and optimize embedded

computation

• Reduce the number of operations

• Reduce data flow exchange


Data and trueness recovery methods identified

Data acquisition and trueness recovery methods implemented

1 3 4 Q32

9/9

Chapter 3

Part 3


1/1A delicate compromise between aircraft and engine constraints

June 2017 / R& T102

Engine-aircraft and aircraft-ground bandwidth introduces the need of a data compression

• Lossless compression may be impossible

Embedded constraints may limit the compression capability

Data loss rate is to be tuned in function of the available bandwidth, the computing capability and

the monitoring accuracy need

1 3 4 Q32

Chapter 3

Conclusion


PHM Systems on

CFM56 & Silvercrest

engine

Gaining in confidence

in a PHM System

Predictive & Effective

maintenance

SAFRAN AIRCRAFT ENGINES PHM / TUTORIAL CONTENTS

June 2017 / R& T103

1 2 3




System perimeter


Engine wear modes

System architecture




1 2 3 4 Q

OPERATIONAL REALIZATIONS

1/22

Chapter 4


CHAPTER 4 CONTENTS

June 2017 / R& T

Safran Monitoring Systems

CFM56

Silvercrest

Data collection

Gaining confidence in PHM System

Industrialization of PHM System

Iterative process


Certification of PHM Systems

Lifing on Engine

Configuration Tracking

1 2 3

1 2 3 4 Q104

Chapter 4

2/22


Chapitre 4

Présentation systèmes de monitoring Safran

CFM56 : ACARS & GMS v2 solution

Forevision : A new step in monitoring by Safran.

Gaining confidence

Industrialization & Maturity (EIS / EIS +3)

Predictive & effective maintenance

challenge of PHM systems is to help maintenance to gain in prediction & effectiveness.

June 2017 / R& T1 2 3 4 Q

105

Chapter 4

3/22


CHAPTER 4 CONTENTS

June 2017 / R& T



Iterative process



Lifing on Engine


2 3

Safran Monitoring

Systems

CFM56

Silvercrest

Data collection

1 2 3 1/3 Q106

Chapter 4

Part 14/22


Mature Engines CFM56 & SaM146

• Limited monitoring due to available data

on aircraft avionics.

• New development are hindered by complexity to

add a new system that is to be certified after EIS.

New Engines like Leap or Silvercrest

• Embedded Monitoring system designed by the

OEM to control the data generation.

• Global system approach to be sure to have an

optimized ground & embedded systems.

Engine program

June 2017 / R& T1 2 3 4 Q

107

Chapter 4

Part 15/22


CFM56

June 2017 / R& T1 2 3 4 Q

Oil system•Oil & Pressure monitoring•Filter by-pass•Oil consumption•Debris monitoring & Smart filters

General•Anomaly detection•Fusion decision making•Fleet mapping

Performances•Global analysis•Modular analysis

Control system•Sensor checking•Actuator checking•Aided troubleshooting•Fault isolation

Mechanical health•Balancing analysis•Bearings & gears•Fleeting events

Start capability•Hot /Hung start•Start system health•Sparks health

Fuel system•Filter by-pass•Smart filters•Fuel pump monitoring

Chapter 4

Part 16/22

Functions Needs Diagram

109


CFM56

June 2017 / R& T1 2 3 4 Q

109

Chapter 4

Part 17/22

The CFM International CFM56 (U.S.

military designation F108) series is a family

of high-bypass turbofan aircraft engines

made by CFM International (CFMI), with a

thrust range of 18,500 to 34,000 pounds-

force (82 to 150 kilonewtons).

Number built 30,000 (as of July 2016)

Unit cost US$10 million (list price)

Engine Engine

ACMS

Transfer to the ground

3 possibilities (depending on the

application)

During the flight (ACARS)

End of the flight (GSM or

WiFi)

At Scheduled time

Engine Engine

ACMS

GMS ACARS

GMS Diag

Data

loading

orchestration

algorithms

export

engineering

Query

tools

ReGen

SPC, Trends, Alert

diagnostics

GMS ACARS

GMS Diag

Data

loading

orchestration

algorithms


CFM56

Performance (EGT trend, score)

June 2017 / R& T1 2 3 4 Q

110

Chapter 4

Part 18/22


CFM56 – oil report example

June 2017 / R& T1 2 3 4 Q

111

Chapter 4

Part 19/22

Snapshot taken when the level is changing and only during ground idle phase.


CFM56

June 2017 / R& T1 2 3 4 Q

Regression slope is the

average consumption

between 2 servicing

Lost report

More than 10000

EFH of raw data

stored.

Since 2012,

some Safran

ACMS does that

computation on

fleet.

112

Chapter 4

Part 110/22

Distance between regression

lines estimates the oil

servicing quantity


Silvercrest monitoring within support organization

June 2017 / R& T1 2 3 4 Q

113

Chapter 4

Part 111/22

Silvercrest fleet will be monitored by Safran Aircraft Engines’ front office follow the sun organization among 3 hubs

Data is generated all along the flight before engine start

after engine shutdown

Data is transferred during the flight for dispatch information

after the flight for non dispatch information

Data is automatically processed on ground

Results are analyzed by front office for short term assessments When a shift occurs, an alarm is raised, then investigated

Customer support delivers a maintenance recommendation to the customer

by back office for mid-long term assessments

Data and analysis results are available on a secured web portal for customers


SCR Functional perimeter

June 2017 / R& T1 2 3 4 Q

Silvercrest Engine Health Management is

based on Safran Aircraft Engines

Algorithms able to:

Nacelle Monitoring

Nacelle Anti Ice Valve

Thrust Reverser Actuation System

Performance Condition

Monitoring

Performance Health

Monitoring

Performance Analysis

Unbalance Modular Analysis

Mechanical Diagnostics

Bearing Monitoring

Controls

Engine Oil Condition

Actuator Loop

Smart Filter

Engine Start Capability

Sensors Aging Drift

Sensors Intermittences

Actuator Use

Mission Cycle Count

9114

Chapter 4

Part 112/22


SCR PHM System

June 2017 / R& T115

Engine Engine

MMS GMS ACARS

Forevision

Data

loading

orchestration

algorithms

Qurey

tools

Portal

SPC, Trends, AlertTransfer to the ground

2 possibilities (depending on the

application)

During the flight

(SATCOM)

Scheduled time

Thrust range 10,000-12,000 lbf

(44-53 kN)

Chapter 4

Part 113/22


SCR Performance Diagnostics

June 2017 / R& T1 2 3 4 Q

116

Chapter 4

Part 114/22


SCR Performance Prognostics

June 2017 / R& T117

Chapter 4

Part 115/22

1 2 3 4 Q


Example of results

June 2017 / R& T118

Chapter 4

Part 116/22


Oil Consumption on new engine

June 2017 / R& T119

Chapter 4

Part 117/22


CHAPTER 4 CONTENTS

June 2017 / R& T



Lifing on Engine


3


CFM56

Silvercrest

Data collection

1

Gaining confidence

in PHM SystemIndustrialization

of PHM System

Iterative process

1 2 3 2/3 Q120

Chapter 4

Part 218/22


June 2017 / R& T1 2 3 4 Q

121

Chapter 4

Part 219/22


CHAPTER 4 CONTENTS

June 2017 / R& T


CFM56

Silvercrest

Data collection

1

Predictive & Effective

maintenance

Certification of

PHM Systems



Iterative process

2

1 2 3 3/3 Q122

Chapter 4

Part 320/22


Certification and lifing

June 2017 / R& T123

Chapter 4

Part 3

1 2 3 3/3 Q

21/22

Certified PHM zone

Certified PHM is whenthe function of the system dedicated to data recording is at least certified level D.Then the produced data have credit with respect to EASA or FAA.

PHM in Safran is dedicated mainly on events tracking. Such as D&C, ATO and IFSDAnd it complete the PSE offer of services to trend.


124

QUESTIONS ?

June 2017 / R& T

22/22

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