Condition Based Maintenance Summary: The presentation provides an overview of Condition Based Maintenance research performed in the NASA Glenn Tribology and Mechanical Components Branch in support of the Subsonic Rotary Wing Project.
Condition Based Maintenance
Summary: The presentation provides an overview of Condition Based Maintenance research performed in the NASA Glenn Tribology and Mechanical Components Branch in support of the Subsonic Rotary Wing Project.
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National Aeronautics and Space Administration
www.nasa.gov
Fundamental Aeronautics Program
Dr. Paula DempseyTribology & Mechanical Components BranchNASA Glenn
Subsonic Rotary Wing Project
CBM
2011 Technical ConferenceMarch 15-17, 2011Cleveland, OH
What is CBM?
Condition Based Maintenance: Application & integration of processes, technologies &
knowledge via a systems approach to improve aircraft reliability and maintenance effectiveness*
» Reduce maintenance tasks» Increase aircraft availability » Improve flight safety » Reduce costs
*US Army ADS-79 HNDBK2
CBM Functions
Propulsion System Health• Health monitoring of dynamic mechanical components • Monitored by vibration signature analysis methods (condition indicators-
CI) and oil conditionStructural Health• Fatigue life management/component lifing based on actual usage &
regime recognitionExceedance Monitoring• Aircraft operational/parametric data (torque, speed, temperature)Engine Health• Power assurance check/Power ManagementRotor Smoothing• Automated track & balance of rotors to decrease vibrationsFleet Maintenance• Logging maintenance actions/CBM data 3
Propulsion System Health– Improved detection techniques– Improved diagnostic algorithms
• Multi-sensor data fusion• Performance metrics• Damage magnitude assessment
– Validated methods – rotorcraft field verification • Test methods representative of fielded faults
– Future prognostic algorithms• Damage life prediction models – predict remaining useful life
Structural Health & Exceedance Monitoring– Correlate aircraft operational parameters to component life.
Research enabled through Partnerships with the FAA and US Army– FAA funded Space Act Agreements– Access to > 2000 Army HUMS equipped helicopters
SRW CBM Focus - Propulsion
Gear Fault Detection Effectiveness
Objective:•Evaluate gear tooth pitting fatigue fault detection effectiveness
•Evaluate repeatability of gear tooth fault detection methods
•Evaluate CI threshold values
Approach:•Test gears: face gears with tapered involute pinions
•Vibration and oil debris monitoring during gear endurance testing
• Evaluate three common vibration CIs (RMS, FM4, NA4)
Propulsion System Health
Data point0 10000 20000 30000
NA4 (g's) - Healthy
0369
12
Data point0 1000 2000 3000 4000
NA4 (g's) - Faulty
01020304050
NA40 20 40 60 80
Probability density function
0.00.10.20.30.4
False alarm rate0.0 0.2 0.4 0.6 0.8 1.0
Hit rate
0.00.20.40.60.81.0
Healthy
Faulty
NA4=35 4620
40
CI: NA4, Macro-Pitting, Single/Few Teeth
Propulsion System Health
Gear Fault Detection Effectiveness
Planetary Fault DetectionObjective:Demonstrate diagnostics to detect gear and bearing planetary system faults in main-rotor gearboxApproachDevelop algorithms from seeded fault tests on the OH-58 main-rotor transmission (AATD/Bell OSST)
0 45 90 135180225270315360 45 90 135180225270315360 45 90 135180225270315360-5
0
5a) Hunting tooth average of raw data.
Acc
eler
atio
n (V
)
34 35 1 2 3 -2
0
2b) Windowed data,
planet 1 carrier cycle 1.
Acc
eler
atio
n (V
)
Tooth number28 29 30 31 32
-2
0
2
Tooth number22 23 24 25 26
-2
0
2
Tooth number
1 2 3 4 5 6 7 8 9 1011121314151617181920212223242526272829303132333435 1 -2
0
2
Planet gear tooth number
Acc
eler
atio
n (V
) e) Completed planet 1 tooth vector.
Planet 1 first pass Planet 1 second pass Planet 1 third pass
c) Windowed data, planet 1 carrier cycle 2.
d) Windowed data, planet 1 carrier cycle 3.
Carrier rotation, deg
Propulsion System Health
Acc
eler
atio
n, g
's
-15-10
-505
1015
Acc
eler
atio
n, g
's
-15-10
-505
1015
Acc
eler
atio
n, g
's
-10
-5
0
5
10
Planet gear tooth number1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35
Acc
eler
atio
n, g
's
-10
-5
0
5
10
Accelerometer numberA1 A2 A3 A4 A5 A6 A7 A8
M8A
0
500
1000
1500
20001500020000 Healthy
Faulty
Fault
Propulsion System HealthPlanetary Fault Detection
99
Time Domain
Frequency Domain
time steps
undamaged
damagedSu
n G
ear D
ispl
acem
ent
Objective:Develop analysis method to simulate dynamic response of gear or bearing surfaces with damage
Approach:•Defect geometries defined by actual measurements
•Forces between components calculated via contact mechanics
•Deformations and vibration responses calculated via finite element
Propulsion System Health
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Objective:• Demonstrate (CI) responds to
failure progression & correlates to remaining useful life
Approach:• UH60 tail gearbox output shaft
thrust bearings • Removed from helicopters
installed in test stand• Periodic inspections to
measure spall growth• CI data mapped to the damage
state did not perform well for magnitude assessment
• Oil debris sensor monitored debris generation & indicated progression & remaining life.
Propulsion System Health
FAA Space Act Agreement Validation & Demonstration of HUMS for Maintenance Credits,
modified inspection & removal criteria,via FAA AC-29-2C, Section MG-15
Objectives:• Develop CI validation methods in the lab that represent fielded faults• Identify limitations of seeded fault data sets. • Case Study: Component with naturally occurring faults in the field and
test stand.Spiral bevel gears in the Apache nose gearbox (NGB)Spiral bevel gears tested in the Spiral Bevel Gear Fatigue Test Rig
Approach• Rig gears designed/tested with loads/speed scaled to NGB• Field units studied for failure modes & operational environment • Field/Rig data studied for CI performance• Usage data studied to determine if failure can be correlated to usage
Collaborative Team Effort: FAA, US Army, NASA, Boeing
s
Pinion Magnetic Tach
Oil Debris Sensor
MSPU IAC Model 1087
MDSS
Torque Meter
Chip Detector
Gear Optical Tach
s
Spiral Bevel Gear Fatigue Rig
FAA Space Act Agreement
13
FAA Space Act Agreement
Assess CI performance from field & lab
0
25
50
75
100
125
150
1 10 100 1000 10000 100000
Torq
ue (%
)
Hours
Correlate usage to failures
SRW Phase II SBIR
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OH-58 main rotor transmission
NASA GRC 500-hp transmission test facility
Ridgetopwireless sensors
Embedded Data Acquisition Tools for Rotorcraft HUMS (Ridgetop)
Objective:Develop MEMS wireless sensor for fault detection in rotorcraft transmission applications
Approach:• Develop MEMS vibration-monitoring
accelerometer, microcontroller conditioner, wireless transmitter, and receiving unit for data collection.
• Mount directly on helicopter transmission component of interest to measure abnormalities and faults.
SRW Phase I SBIR
15
Optical oil-debris sensor for rotorcraft health monitoring (Translume)
Objective:Develop an oil debris sensor to monitor rotorcraft power train oil.
Approach:• Develop sensor to simultaneously
detect both metallic and non-metallic debris
• Optimize sensor to detect, count and size particles
• Conduct a feasibility demonstration on a laboratory scale
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