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Wind Gearbox Workscope Optimization
PHM Society 2013 Wind Energy Workshop
October 16th, 2013
StandardAero Engineering Services | Alan.Lesmerises©StandardAero.com Page 2 October 16th, 2013
Introduction Today’s presentation is based on the following proposition: • The most sophisticated sensors & predictive / diagnostic
software in the world won’t help equipment stay in service and control Life Cycle Costs if asset owners / maintainers don’t make smart decisions during maintenance events
A Prime Example: • Wind industry doesn’t agree on optimum strategy for bearing
replacement during heavy maintenance events, opting to: - Only replace damaged bearings (to keep shop visit $ low), or - Replace all bearings regardless of their condition or time in service
to avoid unplanned events • Neither approach is optimal
- The “Best” option is somewhere in-between
StandardAero Engineering Services | Alan.Lesmerises©StandardAero.com Page 3 October 16th, 2013
Introduction (con’t) StandardAero has developed new reliability-based methods & tools to enable smarter maintenance decision-making • Goal: Work with asset owners to improve revenue generating
capability and minimize long term costs due to off-tower maintenance
• Created several workscoping and fleet modeling tools for multiple customers / applications
• Jet Engines: 10-20% improvement in Cost / Reliability Undertook engineering study to investigate wind gearbox workscope question (as it applies to bearings)
StandardAero Engineering Services | Alan.Lesmerises©StandardAero.com Page 4 October 16th, 2013
The Maintainer’s Dilemma Workscoping question is common to many industries • Often referred to as the “Maintainer’s Dilemma”
How can you optimize maintenance to maximize revenue & minimize life-cycle costs? • Plot amortized cost per operating hour (shop visit cost / life expectancy) vs. life
expectancy for each possible workscope to identify the best choice
Too Little Maintenance
Poor Availability
Too Much Maintenance
High Cost
Cost
High
Low
Maintenance WorkscopeLight Heavy
Too Much Maintenance
Availability
Life
Cyc
le C
ost
Too Little Maintenance
Too Much Maintenance
Too Much Maintenance
Availability
Life
Cyc
le C
ost
Too Little Maintenance
Too Much Maintenance
Too Much Maintenance
Availability
Life
Cyc
le C
ost
Too Little Maintenance
Too Much Maintenance
Too Much Maintenance
Availability
Life
Cyc
le C
ost
Too Little Maintenance
Too Much Maintenance
Optimum
Repair only what is broken (OCM strategy) & potentially live w/shorter time in service or unexpected times to next failure
Perform extensive overhaul / replacement at this event & potentially incur costs without extending time in service
StandardAero Engineering Services | Alan.Lesmerises©StandardAero.com Page 5 October 16th, 2013
Creating the Reliability Tools
Failure Analyses Data Collection/Mining Data Analysis & Management
Quality Issue
Random
Normal Wear
High Time Wear Out
Reliability Models
Practical Cost Based Models & Tools Reliability Analyses
StandardAero Engineering Services | Alan.Lesmerises©StandardAero.com Page 6 October 16th, 2013
Study Methodology Built reliability/cost models for generic gearbox • Min (L10) lives AGMA spec. 6006-A03
Three (3) workscope approaches analyzed • OCM (replace only failed bearings) • Replace 100% (replace all bearings) • Dynamic Strategy: Bearings replaced based on
individual ages (& time remaining until unit is retired) to optimize LCC @ Shop Visit
Calculate MTBF & cost of each workscope • MTBF based on the combination of items / ages • Cost: Unit repair cost + next event cost
- Crane, lost revenue, shipping, labor RR Gbx
Determined $/Hr of each possible workscope
HSS ISS LSS PLC & PG
Cont
rol D
ata
Control Data
Characteristic Life
Bearing Position:
L10 Life
Data Date: 19-Apr-11
SN-00003 55,000
Bearing Failed? TSO WorkscopePLC-A 15,000PLC-B 15,000
PL-G1-A 15,000PL-G1-B 15,000PL-G2-A 15,000PL-G2-B 15,000PL-G3-A 15,000PL-G3-B 15,000LSS-A 15,000LSS-B 15,000ISS-A 15,000ISS-B 15,000HSS-A 15,000HSS-B 15,000
Cost CPH$0 $0.00
Reliability Reliability Final Incr Counter Accuracy1 0.499831684 0 10,000
23,756
Wind Gearbox Bearing WCO (Rev 2.1)
MTTF
ReplaceReplaceReplaceReplace
Data Date: 19-Apr-11
SN-00003 55,000
Bearing Failed? TSO WorkscopePLC-A 15,000PLC-B 15,000
PL-G1-A 15,000PL-G1-B 15,000PL-G2-A 15,000PL-G2-B 15,000PL-G3-A 15,000PL-G3-B 15,000LSS-A 15,000LSS-B 15,000ISS-A 15,000ISS-B 15,000HSS-A 15,000HSS-B 15,000
Cost CPH$0 $0.00
Reliability Reliability Final Incr Counter Accuracy1 0.499831684 0 10,000
23,756
Wind Gearbox Bearing WCO (Rev 2.1)
MTTF
ReplaceReplaceReplaceReplace
Cos
t Per
Hou
r
Time on Wing
Optimum Work Scope
Mean Time to Next Failure
AGMA Specification
StandardAero Engineering Services | Alan.Lesmerises©StandardAero.com Page 7 October 16th, 2013
Results: OCM vs Replace 100% Reliability Impact: • OCM:
- MTBF after repair continually decreases as unit ages
• Replace 100%: - Buys reliability that can’t be used
Cost / Hr Impact: • OCM:
- Typically more expensive - Trends upward until MTBF
exceeds planned life • Replace 100%:
- Generally better than OCM - Buys reliability that can’t be used
Avg Total O-M Costs: $10/MWH (Wind Energy Update)
Costs Per Hour of Use vs Work Scope StrategyOCM, 100% Replacement, Replace ISS / HSS Brgs
75,000 hr Planned Life
$-
$5.00
$10.00
$15.00
$20.00
$25.00
$30.00
$35.00
$40.00
$45.00
$50.00
5,000 15,000 25,000 35,000 45,000 55,000 65,000 75,000
Total Age At Work Scope (Hrs )
Cos
ts P
er H
our o
f Use
(C
ost o
f Rem
oval
+Shi
ppin
g+R
epai
r)
/MT
TFOCM
Repaplace 100%
Mean Time To Next Failure After a Repair Dynamic vs Static Approach
75,000 hr Planned Life
05
10152025303540
0 10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000
Thou
sand
s
Total Age At Work Scope (Hrs)
MTT
F (H
ours
)
OCM
Replace 100%Un-useable Reliabilty
StandardAero Engineering Services | Alan.Lesmerises©StandardAero.com Page 8 October 16th, 2013
Results: OCM vs Replace 100%
Avg Total O-M Costs: $10/MWH (Wind Energy Update)
Mean Time To Next Failure After a Repair Dynamic vs Static Approach
75,000 hr Planned Life
05
10152025303540
0 10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000
Thou
sand
s
Total Age At Work Scope (Hrs)
MTT
F (H
ours
)
OCM
Replace 100%Un-useable Reliabilty
StandardAero Engineering Services | Alan.Lesmerises©StandardAero.com Page 9 October 16th, 2013
Results: OCM vs Replace 100%
Avg Total O-M Costs: $10/MWH (Wind Energy Update)
Costs Per Hour of Use vs Work Scope StrategyOCM, 100% Replacement, Replace ISS / HSS Brgs
75,000 hr Planned Life
$-
$5.00
$10.00
$15.00
$20.00
$25.00
$30.00
$35.00
$40.00
$45.00
$50.00
5,000 15,000 25,000 35,000 45,000 55,000 65,000 75,000
Total Age At Work Scope (Hrs )
Cos
ts P
er H
our o
f Use
(C
ost o
f Rem
oval
+Shi
ppin
g+R
epai
r)
/MT
TF
OCM
Repaplace 100%
StandardAero Engineering Services | Alan.Lesmerises©StandardAero.com Page 10 October 16th, 2013
Results: Dynamic vs Static Strategy Reliability Impact: • Dynamic strategy is less than
100% replacement, but more than OCM
• Much less unused reliability Cost / Hr Impact: • Dynamic always Lowest • Equivalent to “OCM” very
young and very old lives
Avg Total O-M Costs: $.01/MWH (Wind Energy Update)
Costs Per Hour of Use vs Work Scope StrategyOCM, 100% Replacement, Minimum
75,000 hr Planned Life
$-
$5.00
$10.00
$15.00
$20.00
$25.00
$30.00
5,000 15,000 25,000 35,000 45,000 55,000 65,000 75,000
Total Age At Work Scope (Hrs )
Cos
ts P
er H
our o
f Use
(C
ost o
f Rem
oval
+Shi
ppin
g+R
epai
r) /M
TTF OCM
Repaplce 100%
Dynamic Strategy
Mean Time To Next Failure After a Repair Dynamic vs Static Approach
75,000 hr Planned Life
05
10152025303540
0 10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000
Thou
sand
s
Total Age At Work Scope (Hrs)
MTT
F (H
ours
)
OCM
Replace 100%Un-useable ReliabiltyOptimized
Workscope Occures Between Avg Cost
Delta ($/Hr) $/KWH21-30,000 Hours 2.22$ 0.0015$ 30-45,000 Hours 5.19$ 0.0035$ 45-63,000 Hours 11.24$ 0.0075$ 63-72,000 Hours 14.41$ 0.0097$ 72-75,000 Hours 36.67$ 0.0246$
StandardAero Engineering Services | Alan.Lesmerises©StandardAero.com Page 11 October 16th, 2013
Results: Dynamic vs Static Strategy
Avg Total O-M Costs: $.01/MWH (Wind Energy Update)
Mean Time To Next Failure After a Repair Dynamic vs Static Approach
75,000 hr Planned Life
05
10152025303540
0 10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000
Thou
sand
s
Total Age At Work Scope (Hrs)
MTT
F (H
ours
)
OCM
Replace 100%Un-useable ReliabiltyOptimized
StandardAero Engineering Services | Alan.Lesmerises©StandardAero.com Page 12 October 16th, 2013
Results: Dynamic vs Static Strategy
Avg Total O-M Costs: $.01/MWH (Wind Energy Update)
Costs Per Hour of Use vs Work Scope StrategyOCM, 100% Replacement, Minimum
75,000 hr Planned Life
$-
$5.00
$10.00
$15.00
$20.00
$25.00
$30.00
5,000 15,000 25,000 35,000 45,000 55,000 65,000 75,000
Total Age At Work Scope (Hrs )
Cos
ts P
er H
our o
f Use
(C
ost o
f Rem
oval
+Shi
ppin
g+R
epai
r) /M
TTF OCM
Repaplce 100%
Dynamic Strategy
StandardAero Engineering Services | Alan.Lesmerises©StandardAero.com Page 13 October 16th, 2013
Conclusions The main points to take away from this study: • MTBF of OCM workscopes degrade significantly w/age • MTBFs for different workscopes are dictated by which components
are replaced or not, their ages, & inherent reliability of components • Optimum workscope is affected by several factors including:
- Age of other bearings, and planned retirement age of the unit • “Static” workscope strategy tends to result in highest LCC
- Doing the same thing for the entire service life of the unit • A “Dynamic” strategy is best
- Determining an “Optimum” build at each point in the unit’s life • Cost impacts from “Worst” to “Best” workscopes vary widely
- $2.00/Hr ($.00149/kWH) early in unit’s life - Over $14.00/Hr ($.0096/kWH) late in unit’s life
• Wind turbine asset owners need a repair source that can: - Quantify reliability & costs of different workscopes (thru gbx life) - AND can act on the data such that it minimizes Life Cycle Costs
StandardAero Engineering Services | Alan.Lesmerises©StandardAero.com Page 14 October 16th, 2013
For More Information: Alan L. Lesmerises, MS, CRE Reliability & Life Cycle Management Engineer StandardAero Engineering Services 3523 General Hudnell Dr. San Antonio, TX, 78226 United States of America Office: (210) 334-6187 Fax: (210) 334-6181 [email protected]