Presentation on vehicle integrated propulsion research results and planning. This research emphasizes the testing of advanced health management sensors and diagnostics in an aircraft engine that is operated through multiple baseline and fault conditions

Hunter, Gary W.

Lekki, John D.

Simon, Donald L.

Tokars, Roger P.

Woike, Mary

NASA Technical Reports Server

NASA  Aviation Safety Program 
National Aeronautics and Space Administration 
www.nasa.gov 
Vehicle Integrated Propulsion 
Research for the study of 
Health Management 
Capabilities 
 
John Lekki, Don Simon, Gary Hunter, Mark Woike, Roger Tokars 
https://ntrs.nasa.gov/search.jsp?R=20120016773 2019-08-30T23:11:13+00:00Z
NASA  Aviation Safety Program 
Vehicle Integrated Propulsion Research (VIPR) 
Overview 
EHM technology testing is challenging:  
• Expensive 
• Dedicated testing is necessary to demonstrate technology 
against known system “ground truth” state. 
 
Partnerships make it possible: 
• Sharing of costs, results and benefits 
• VIPR partners include NASA, Air Force, Pratt & Whitney and a 
growing list of other government agencies and industry 
partners. 
 
 
 
VIPR test approach: 
• A series of on-wing engine ground tests 
• Includes “nominal” and “faulted” engine operating scenarios 
• Technologies under evaluation include advanced EHM sensors 
and algorithms 
 
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Vehicle testing 
Test Rig 
Component rig testing 
Simulation test and evaluation 
Testing is a necessary and challenging 
component  of Engine Health Management 
(EHM) technology development. 
Conceptual design 
VIPR Test Schedule 
VIPR I (Dec. 2011) VIPR II (2013) VIPR III (2014) 
NASA  Aviation Safety Program 
VIPR I Test Overview 
• VIPR I test was conducted in December 2011 
at NASA Dryden / Edwards Air Force Base 
 
• Test vehicle:  
– Boeing C-17 Globemaster III 
– Equipped with Pratt & Whitney F117 turbofan 
engines 
 
• VIPR 1 EHM ground tests included: 
– A series of nominal and faulted engine test 
cases  
– Data collected over a range of power settings 
including quasi-steady-state and transient 
operating conditions 
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Pratt & Whitney F117 Turbofan Engine 
Boeing C-17 Globemaster III 
NASA  Aviation Safety Program 
VIPR I – EHM Technologies Under Test 
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Emissions Sensor System 
(CO, Hydrocarbons, CO2, 
O2, NOx) 
Self-Diagnostic Accelerometer and 
High Frequency Vibration Sensors 
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Probe #1 -  90 Deg, Average Clearance, mm 
Probe #2 - 180 Deg, Average Clearance, mm
Fan Speed, RPM
Average Blade Tip Clearances (mm) and Fan Speed versus Time, 
Probes #1 & #2, Run #7 9-23-2008
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Microwave Blade Tip Clearance / 
Blade Tip Timing Sensors 
(EMI/EMC checkout only) 
Legacy instrumentation 
• Inlet debris monitoring system 
• Station 2.5 pressure and temp 
• High fidelity fuel flow measurement 
Model-based performance 
estimation and diagnostics 
Multiple EHM sensors/algorithms tested during VIPR I 
Valuable for identifying real-world implementation issues/concerns 
Testing of multiple technologies also allows assessment of information fusion benefits  
NASA  Aviation Safety Program 
Relevance to Aviation Safety Needs 
 
• Engine malfunction coupled with Inappropriate Crew Response is the most statistically 
significant issue  
• Systems Analysis 
– Sensor failure is one of the largest contributors to In Flight Shut Down 
– Blade loss is one of the larger contributors to In flight Shut Down due to high vibration and power 
loss 
 
5 
 
Steve Clark, Grace Balut Ostrom, and Sam Clark, Engine Damage-Related Propulsion System Malfunctions,  DOT/FAA/AR-08/24, December 2008.
  
 
NASA  Aviation Safety Program 
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Microwave Tip Clearance Sensor Technology 
•  Microwave blade tip clearance sensor technology for use in turbine engines 
–  Structural health monitoring – tip clearance and tip timing 
–  Active closed loop clearance control - tip clearance 
•  Targeted for use in hot sections of turbine engines (High 
Pressure Turbine section)	

–  Rated for use in high temperature environment, ~1200 ºC 	

–  Highly accurate, current goal of ~25um for this technology	

–  Able to see through contaminants that exist in the engine 
flow	

•  Sensors have been used on several experiments at GRC 
to evaluate & demonstrate their performance.  Goal is to 
use sensors on an actual aero engine.	

Microwave sensors installed on the NASA 
Turbofan Test Rig at the GRC’s 9x15 LSWT 	

Clearance data acquired on the NASA Turbofan 
Test Rig 	

NASA  Aviation Safety Program 
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Self Diagnostic Accelerometer (SDA) 
• Vehicle Health Management Systems may make 
mission critical health assessments based upon sensor 
information 
• It is critical that sensor measurements be validated 
before a health management system may take such 
action 
• Sensor validation is often accomplished through multiple 
sensors voting  - MAS 777-200 flight in 2005 is a case 
where 2 failed sensors outvoted a third healthy sensor 
This Self Diagnostic Accelerometer System was successfully demonstrated in providing electro-mechanical 
data including the health of the sensor-part attachment under varying temperature, torque-attachment, and 
electro-mechanical noise. 
Manual Data from 
Signal Analyzer 
Self Diagnostic Accelerometer (SDA) System 
Autonomous Data 
from SDA System  
SDA Controller 
System  
Base 
Accel. 
T-Box Connector 
SDA System 
NASA  Aviation Safety Program 
• Multispecies microsensor detection in single package to allow miniaturization of the detection 
apparatus 
•  Quantify composition of critical constituents in turbine engine exhaust products, E.G., CO, CO2, 
NOX, O2, HC (unburned Hydrocarbons) and H2 
• Improve accuracy in measuring exhaust products 
•  Engine Test Objectives:  
– Obtain correlated emissions data in conjunction with gas path diagnostics data so that the 
benefit for inclusion of emissions information in gas path diagnostics can be studied 
 
 
CO2 Sensor 
CO 
Sensor 
 SiC  
Hydrocarbon  
Sensor 
Standard Multi-gas 
Analyzer 
MEMS Emissions Sensors 
Engine Tests and Testing 
High Temperature Electronic Nose 
 MEMS Based Emission Sensors 
NASA  Aviation Safety Program 
Propulsion Gas Path Health Management 
Technical Approach:  
• Develop optimal sensor placement 
methodology for gas path diagnostics 
• Enhanced adaptive modeling techniques for 
on-line engine performance deterioration 
trending and fault diagnostics 
• Gas Path Diagnostics also enable the model-
based estimation of unmeasured parameters 
critical for IVHM 
 
Engine Test Objectives: 
• Obtain data containing simulated faults for 
testing of current and future diagnostic 
algorithms 
• Obtain diagnostic data concurrently with tip 
clearance and emission sensor data so that 
initial studies for the inclusion of these 
sensors in a diagnostic model can be made  
On-Board 
Adaptive Model 
Gas-Path 
Diagnostics 
Performance Trending and Fault 
Diagnostics 
Sensed Measurements 
• Pressures, temperatures, 
rotor  speeds, etc. 
Model-Based Diagnostics Architecture 
Engine 
FADEC 
C-17 Aircraft 
NASA  Aviation Safety Program 
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Test Implementation 
NASA  Aviation Safety Program 
VIPR I testing of the Self Diagnostic Accelerometer  
Roger Tokars (GRC) John Lekki (GRC)                           December 2011 
Test Locations C-17 Aircraft 
The Self Diagnostic Accelerometer (SDA) was 
mounted and tested on the C-17 engine in order to 
demonstrate the SDA’s flight worthiness and 
robustness. 
Results 
 
The Self Diagnostic Accelerometer System 
was successfully demonstrated in providing 
electro-mechanical data including the health 
of the sensor attachment under the extremes 
of an aircraft engine environment. 
 
Conclusion 
Ideal 
Min. 
Noise 
Mod. 
Noise 
Max. 
Noise 
 
Pattern recognition software successfully discriminates all tight and loose conditions. 
Accelerometer mount 
Secured with safety wire 
NASA  Aviation Safety Program 
Preservation Oil Burn-off 
• Day 1 of VIPR testing was a 
“green engine run” (first time the 
test engine was run post-overhaul) 
 
• Provided an opportunity to 
evaluate the Emission Sensor 
System (ESS) during preservation 
oil burn-off 
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ESS Rig 
Preservation oil burn-off! 
NASA  Aviation Safety Program 
13 
Preservation Oil Burn-off Test 
NASA  Aviation Safety Program 
Engine 3 Preservation Oil Burn Off 
 Start up - ESS observed fast rise in concentrations 
 Exception – oxygen concentration dropped, as expected 
  ~2 min from start up - noticeable change and recovery 
 The high levels eventually tapered down to somewhat lower 
concentrations with the engine stable at idle   
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12/12/2011 - Engine  3 Preservation Oil Burn Off - 7205-31-100.002
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NASA  Aviation Safety Program 
VIPR I Highlights: Gas Path Diagnostic Testing 
Gas Path Diagnostic Test Objectives: 
• Collect engine performance data under nominal and 
faulty operating conditions 
• Evaluate ability of adaptive model to track engine 
performance 
• Evaluate ability of gas path diagnostic algorithms to 
detect fault conditions 
 
Engine Gas Path Fault Conditions Included: 
• Station 2.5 bleed failed full-open 
• Station 2.5 bleed schedule biased +10% open 
• Stage 14 bleed failed full-open 
 
Next Steps: 
• Continue post-test data analysis 
• Improve model transient and low power accuracy 
Station 2.5 
Stage 14 
F117 engine – bleed fault locations 
Power setting stair step 
2 minute accel/decel 
Jam accel/decel 
Event Test Sequence 
Station 2.5 and Stage 14 bleed fault signatures 
NASA  Aviation Safety Program 
VIPR I Post-Test Data Analysis 
(Preliminary Results) 
• Model-based performance estimation and diagnostics 
– Steady-state measurement residuals (faulty vs. nominal baseline) found to be in 
good agreement with model predictions for each fault type. 
 
– Model-based diagnostic architecture trained on a single baseline run and then 
used to analyze remaining runs. With training: 
• Model-engine residuals reduced on subsequent baseline runs. 
• Model-engine residuals exhibit increases on fault runs. 
 
– Future steps will be taken to: 
•  Improve model accuracy at specific power settings and during engine 
transients. 
• Evaluate the effectiveness of different machine learning techniques applied to 
capture engine-model mismatch.  
 
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NASA  Aviation Safety Program 
VIPR I Post-Test Data Analysis 
(Preliminary Results - continued) 
• Emission Sensor System (ESS) 
– Baseline emission levels established. 
– Discernable change in emissions observed during preservation oil burn-off. 
– Demonstrated system under nominal and seeded fault conditions. The ESS 
system in general tracked a wide range of varying engine conditions. 
 
• Microwave blade timing / tip clearance sensor 
– Successfully passed electro-magnetic interference (EMI) / electro-magnetic 
compatibility (EMC) checkout. 
– Cleared for actual on-engine use for future VIPR tests at DFRC. 
 
• Self-diagnostic accelerometer (SDA) 
– Four SDAs, attached at engine B-flange and gearbox, successfully 
completed first-ever demonstration in engine environment. 
– SDA able to successfully detect un-torquing (loosening) of accelerometer 
connection. 
 
17 
NASA  Aviation Safety Program 
Future Test Plans (VIPR 2 and VIPR 3 ) 
• VIPR 2 Test Objectives (2013) 
– Advanced sensors 
– Gas path diagnostic technologies 
– Miss-scheduled turbine case cooling 
– Fan response research 
 
• VIPR 3 Test Objectives (~2014) 
– Initial steps toward EHM sensor fusion with Advanced Sensors 
– Volcanic ash ingestion testing 
– Run engine to end of life 
 
18 


Vehicle Integrated Propulsion Research for the Study of Health Management Capabilities

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