Resetting the-LRU-Replacement-Norm

© 2016 Copernicus Technology Ltd.All Rights Reserved. www.copernicustechnology.com
Resetting the LRU
Replacement Norm

The LRU Replacement Norm
When tasked with repairing an Avionics
fault the default assumption routinely made
by repair technicians is that changing a Line
Replaceable Unit (LRU) will fix the problem

Reported Fault
LRU is the
Cause
LRU is not the
Cause
LRU to be Replaced &
Sent for Repair
LRU ‘Repair’
Fault Not
Found
A Fault Found
& Fixed
No Fault Found

Reported Fault
LRU is the
Cause
LRU is not the
Cause
Sent for Repair
LRU ‘Repair’
Fault Not
Found
A Fault Found
& Fixed
No Fault Found
We need to Reset the
LRU Replacement Norm
to stop incorrect LRU
replacements

LRUs that keep going
round this loop are
‘rogues’ or ‘bad actors’
Reported Fault
LRU is the
Cause
Sent for Repair
LRU ‘Repair’
Fault Not
Found
A Fault Found
& Fixed

Why is this The Norm?
§ ‘The book’ (FIM / TSM / AMM) says change
an LRU
§ ‘There’s one in stock & it’s a quick fix’
§ ‘When you replace the LRU it passes BITE so
that’s it fixed’…and flying somewhere else
§ It’s what we’ve always done’
§ There’s limited maintenance history
available for that LRU so it gets replaced
anyway
§ Despatch rate is so important to reputation
that all the LRUs mentioned in the TSM get
replaced
§ ‘What are you supposed to do when the
symptom has disappeared?
§ The diagnostic process doesn’t reproduce
conditions as per when the symptom
occurred
§ ‘We changed LRU X and the fault came
back so this time we’re going to change
LRU Y’
§ ‘We changed LRU X and the fault came
back so this time we’re going to change
LRU X’
§ ‘Suspect DOA’ or ‘Suspect U/S on fit’
§ ‘Other shift’…
§ ‘This wasn’t covered in training’
§ Lack of data on NFF / FNF / First-Time Fix
rates etc
§ It takes 15 times longer to investigate the
EWIS to see if it’s the cause

Why is this The Norm?
Fault
Diagnosis
Policy
Culture
Technology
Training

A new LRU Replacement
Norm is needed

When tasked with repairing an Avionics
fault the default assumption routinely
made by repair technicians is that
changing a Line Replaceable Unit (LRU)
will fix the problem

Replacing an LRU should be the last resort
for an Avionics repair unless faced with
clear evidence to the contrary

Containment
Measurement
Improvement
Strategy Approach

Containment
Measurement
Improvement
NFF Maturity Model
shortfalls
Manage rogue assets
Intermittent Fault
Detection
(IFD)/Integrity testing
of EWIS and rogue
LRUs
Modify LRU repair
procedures v IFD
results
Symptom Diagnostics:
correlate
symptom/fault/fix
data to upgrade
diagnostic
procedures/training
Correlate Symptom
Diagnostics data with
LRU repair
organisations
Embed new ways of
working in Contracts
NFF Maturity Model
Identify ‘rogue’
ac/LRUs/SRUs
Correlate repeat
arisings v LRU
changes
Analyse Ship or
Shelf data for quick
wins in diagnostic
procedures/training
NFF Reduction
policy
Ship or Shelf
Notify repair
organisations of
repeat arisings v
LRU changes
Strategy Approach

Copernicus Technology “No Fault Found” Maturity Model © 2015. Copernicus Technology Ltd. All Rights Reserved.
No Fault Found Maturity Model
Unmanaged Developing Advanced Dynamic
Strategy
Policy No published policy
Policy is published but not used or
reviewed
Published policy is successfully used
and frequently reviewed/updated
Champion
There is no NFF reduction
‘champion’ in the organisation
It is an implied role against a specific
post
It is a secondary duty against a
specified post but is not deemed a
priority
NFF champion is empowered and
proactive in implementation, KPIs &
best practice
Contracts
Contracts with repair bodies don’t
include NFF reduction
NFF reduction is included but with
no targets
NFF reduction is included with
targets/KPIs
Contracts include gainshare
opportunity from NFF reduction
Data
Exploitation
Impact on
Cost
Not recorded across the repair
chain
Recorded in some parts of the repair
chain but not used
chain and used occasionally/in isolation
Recorded and used proactively
throughout the repair chain for
evidence-based decision-making
Impact on
Downtime
chain
chain but not used
Symptom
& Repair
Not used to support fault diagnosis
Used occasionally to inform fault
diagnosis
Policy mandates use of Symptom &
Repair data to inform fault diagnosis
Symptom & Repair data is codified,
correlated & quantified automatically
for fault diagnosis use
Fault
Diagnosis
Training
Does not cover NFF or ‘unable to
reproduce symptom’ (UTRS) or
intermittent fault scenarios
Anecdotally covers NFF/UTRS/
intermittent faults
Specifically includes NFF/UTRS/
intermittent fault strategies
Dedicated NFF/UTRS/intermittent fault
training provided and regularly refined
by Symptom & Repair data findings
Manuals
Do not cover NFF/UTRS/
NFF/UTRS/intermittent faults
addressed by LRU replacement only
Provide greater latitude for root-cause
analysis when diagnosing
NFF/UTRS/intermittent fault problems
NFF/UTRS/intermittent fault content is
regularly refined by Symptom & Repair
data findings
LRUs
All LRUs replaced during trouble-
shooting are shipped for repair
LRUs replaced during trouble-
shooting are occasionally held back
pending repair-success confirmation
Policy enables quarantine of LRUs
replaced during trouble-shooting
LRU-quarantine results vs repair-
success data is used to optimise fault
diagnosis training and manuals
Test
Equipment
Rarely used due to lack of
familiarity
Used occasionally in trouble-
shooting but only as a last resort
Effectively deployed in trouble-
shooting to detect ‘hard’ faults
Effectively deployed to successfully
detect ‘hard’ and intermittent faults
Score per box: 1 2 3 4

Copernicus Technology “No Fault Found” Maturity Model © 2015. Copernicus Technology Ltd. All Rights Reserved.
Unmanaged Developing Advanced Dynamic
Strategy
Policy No published policy
Policy is published but not used or
reviewed
and frequently reviewed/updated
Champion
There is no NFF reduction
‘champion’ in the organisation
It is an implied role against a specific
post
It is a secondary duty against a
specified post but is not deemed a
priority
NFF champion is empowered and
proactive in implementation, KPIs &
best practice
Contracts
Contracts with repair bodies don’t
include NFF reduction
NFF reduction is included but with
no targets
NFF reduction is included with
targets/KPIs
Contracts include gainshare
opportunity from NFF reduction
Data
Exploitation
Impact on
Cost
chain
chain but not used
Impact on
Downtime
chain
chain but not used
Symptom
& Repair
Not used to support fault diagnosis
Used occasionally to inform fault
diagnosis
Policy mandates use of Symptom &
Repair data to inform fault diagnosis
Symptom & Repair data is codified,
correlated & quantified automatically
for fault diagnosis use
Fault
Diagnosis
Training
Does not cover NFF or ‘unable to
reproduce symptom’ (UTRS) or
Anecdotally covers NFF/UTRS/
intermittent fault
Specifically includes NFF/UTRS/
intermittent fault strategies
Dedicated NFF/UTRS/intermittent fault
training provided and regularly refined
by Symptom & Repair data findings
Manuals
Do not cover NFF/UTRS/
NFF/UTRS/intermittent faults
addressed by LRU replacement only
Provide greater latitude for root-cause
analysis when diagnosing
NFF/UTRS/intermittent fault problems
NFF/UTRS/intermittent fault content is
regularly refined by Symptom & Repair
data findings
LRUs
All LRUs replaced during trouble-
shooting are shipped for repair
LRUs replaced during trouble-
shooting are unofficially held back
Policy enables quarantine of LRUs
replaced during trouble-shooting
LRU-quarantine results vs repair-
success data is used to optimise fault
diagnosis training and manuals
Test
Equipment
Rarely used due to lack of
familiarity
Used occasionally in trouble-
shooting but only as a last resort
Effectively deployed in trouble-
shooting to detect ‘hard’ faults
Effectively deployed to successfully
detect ‘hard’ and intermittent faults
Score per box: 1 2 3 4
ü
ü
ü
ü
ü
ü
ü
ü
ü
ü
ü
ü
ü
ü
ü
ü
ü ü
ü
In the above example
the score is 28 / 100
Apply these scores, by
column, to each
completed box
10 12 6 0
No Fault Found Maturity Model
Scoring Method

Conclusions (1)
The LRU Replacement Norm
Is a major driver of repeats arisings, NFFs
& degraded readiness/availability/
dispatch performance
Is caused by policy, culture, training &
technology factors
The NFF Maturity Model is the basis of
resetting the Norm through:
• Containment
• Measurement
• Improvement

Conclusions (2)
Essential areas to target:
• Data correlation at and between
airframe and LRU maintenance
levels
• Use of Symptom Diagnostics & Ship
or Shelf data to optimise Fault
Diagnosis procedures & training
• Managing ‘rogues’
• IFD testing of rogue systems’ EWIS
and rogue LRUs

info@copernicustechnology.com
+44 (0)1343 842406
@CopernicusTech
www.copernicustechnology.com

Resetting the-LRU-Replacement-Norm

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