Federal Aviation 

Administration 

Presented to: 

By: 

Date: 

Continuous Lower 

Energy, Emissions and 

Noise (CLEEN) Program 

Aircraft Technology -

CLEEN Update 

REDAC Environment & Energy 

Subcommittee 

Levent Ileri 

FAA CLEEN Program Manager 

March 8, 2018 
Outline 

• CLEEN Program Overview 

• CLEEN Phase II Overview 

• CLEEN Phase II Technologies 

• CLEEN III Notional Timeline 

• Summary 

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CLEEN Program Overview 

• CLEEN is FAA’s principal environmental effort 

to accelerate development of new aircraft and 

engine technologies and advance the 

introduction of alternative jet fuels. 

• Helps achieve the Next Generation Air 

Transportation System (NextGen) goal of 

attaining environmental protection that allows 

sustained aviation growth. 

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CLEEN Program Overview 

CLEEN Phase I (2010-2015) 

– Industry partners: Boeing, General Electric, Honeywell, Pratt & 

Whitney, Rolls-Royce 

– Federal Funding: $125M (1:1 minimum cost share is required) 

CLEEN Phase II (2015-2020) 

– Industry partners: Aurora Flight Sciences, Boeing, 

Delta/MDS/America’s Phenix, General Electric, Honeywell, Pratt & 

Whitney, Rohr/UTC Aerospace Systems, and Rolls-Royce 

– Federal Funding: $100M (1:1 minimum cost share is required) 

CLEEN Fact Sheet (updated 2/12/18) 

– https://www.faa.gov/news/fact_sheets/news_story.cfm?newsId=22534 

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CLEEN Phase I Benefits: 

Demonstrated technologies that reduce noise, emissions and fuel burn 

Boeing 

Adaptive Trailing Edge 

~ 2% fuel burn reduction 

~ 1.7 EPNdB cum in some single and twin aisles 

CMC Acoustic Nozzle 

~ 1% fuel burn reduction 

~2.3 EPNdB cumulative noise margin to Stage 4 

General Electric 

TAPS II Combustor (entered fleet in 2016) 

> 60% margin to CAEP/6 LTO NOx was achieved 

FMS/Engine and FMS/ATM Integration (Entered 

into service - LEAP engine on B737MAX, Airbus 

A320 Neo aircraft, and GE9X engine on 777X) 

0.7-1.0% fuel burn reduction 

Open Rotor 

~26% reduction in fuel burn (re: 737-800) 

~15-17EPNdB cumulative noise margin to Stage 4 

Honeywell 

Fuel Burn Technologies 

CLEEN technologies contributed to ~5% fuel 

burn reduction as part of a 15.7% fuel burn 

reduction engine package Rolls Royce 

Ceramic Matrix Composite Turbine Blade Track 

CMC blade tracks offer > 50% reduction in cooling 

flow and component weight. 

Rolls-Royce – Dual Wall Turbine Airfoil 

Dual Wall turbine airfoils provide > 20% reduction in 

cooling flow and increased operating temperature 

capability. 

Pratt & Whitney 

Geared Turbofan Technologies 

CLEEN techs expand design space for engine 

with ~ 20% fuel burn reduction, > 20 EPNdB 

cumulative noise margin to Stage 4 

For more information: http://www.faa.gov/go/cleen CLEEN tech will provide ~1% fuel burn reduction 
CLEEN & Boeing EcoDemonstrator 

• Boeing Quiet Technology Demonstrator Program 

(2001 & 2005) 

• CLEEN I began in 2010 

• “EcoDemonstrator Program formally began in 2011 

in cooperation with American Airlines and the FAA” 

(Boeing Backgrounder – June 2017)

http://www.boeing.com/resources/boeingdotcom/principles/environment/pdf/Backgrounder_ecoDemonstrator-2017.pdf 

– 2012: Boeing/CLEEN I flight demonstration of Adaptive Trailing Edge 

(ATE) system on pre-delivered American Airlines 738-800 

– 2014: Boeing/CLEEN I flight demonstration of Ceramic Matrix 

Composite (CMC) engine nozzle on 787. 

• “CLEEN is foundational element & enabler for 

ecoDemonstrator” (Boeing: Nov 2012 CLEEN I Consortium 

Public Session) 

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Assessment of CLEEN Technologies 

PARTNER Project 36 (Georgia Tech) 

• Environmental Design Space (EDS) used to provide 

independent assessment of technologies (leveraged 

PARTNER Project 14 and NASA efforts) 

• Modeled most, but not all CLEEN Technologies. Did not 

model all GE technologies 

– Open rotor engine 

– Engine control/flight management system integration 

– Flight management system/air traffic management integration 

Follow-on Efforts 22 billion gallons of 

cumulative jet fuel saved 

• ASCENT Project 10 (GeorgiaTech- - 1.7 million cars off road 

between 2025 and 2050 Stanford-Purdue) – evaluating all - $2.75 billion annual 

savings to airlines CLEEN technologies for CO2, NOX 

and noise 

• ASCENT Project 37 (GT) CLEEN 

II Technology Evaluation 

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 7 PARTNER Project 36 report can be downloaded at: 

http://partner.mit.edu/sites/partner.mit.edu/files/PARTNER-Project-36-final-report.pdf 
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Evaluation of Noise Reductions through 

CLEEN Technologies 

• Adapted from PARTNER Project 36: EDS Assessment 

of CLEEN Technologies 

• CLEEN-funded technologies as well as other public 

domain and proprietary industry technologies 

potentially available in the CLEEN timeframe, including 

NASA N+1 and N+2 technologies 

Scenario Description 

Evolutionary ‘Normal’ technology evolution. Conservative inclusion of 

(Baseline) CLEEN technologies in N+1. 

Aggressive Represents higher rate of technology development. 

Includes all CLEEN Techs in N+1 

Note: 

Additional analysis details and results were given to REDAC in August 2016 in 

briefing given by Grandi and Dorbian (2016 Aug 30 1:45 pm timeslot) 

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Impact on Population Exposure to DNL 65 

• 20 and 26% decrease in population exposure between 2012 and 2030 for 

65 dB contour for baseline and aggressive technology scenarios, 

respectively. 

• 8.5% difference between Baseline and Aggressive Technology in 2030. 65 dB DNL Population Exposure (Normalized) 

1 

0.8 

0.6 

0.4 

0.2 

0 

Year 

Baseline 

Aggressive Technology 

Note that only 2012 and 2030 were computed 

2012 2014 2016 2018 2020 2022 2024 2026 2028 2030 

Note: 

Additional analysis details and results were given to REDAC in August 2016 in 

briefing given by Grandi and Dorbian (2016 Aug 30 1:45 pm timeslot) 

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CLEEN Phase II Overview (1 of 2) 

• Purpose: 

– Mature previously conceived noise, emissions and fuel burn 

reduction technologies for civil subsonic airplanes from 

Technology Readiness Levels (TRL) of 3-5 to TRLs of 6-7 to 

enable industry to expedite introduction of these technologies into 

current and future aircraft and engines 

– Assess the benefits and advance the development and 

introduction of “drop-in” alternative jet fuels, including blends 

• CLEEN II technologies expected to be on a path for 

introduction into commercial aircraft by 2026 

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CLEEN Phase II Overview (2 of 2) 

CLEEN Phase II Program Details: 

• Reducing environmental impacts via aircraft technology and alternative jet fuels 

• Five year effort to accelerate technology maturation (2015-2020)

• 50% cost share; total FAA budget: ~$100M

CLEEN Phase II 

Program Goals: 

• 32 dB1 cumulative noise 

reduction 

• 70%2 landing/take-off 

NOx emissions reduction 

• 40%1 fuel burn reduction 

Conducting ground and/or flight test 

demonstrations of certifiable aircraft 

technologies with entry into service 

by 2026

Based on 5-year cost share 

agreements with industry 

1 Common baseline with CLEEN I goals 

Awardees: 

• Aurora Flight Sciences 

• Boeing 

• Delta Tech Ops, America’s Phenix, MDS Coating 

Technologies 

• General Electric (GE) Aviation 

• Honeywell Aerospace 

• Pratt & Whitney 

• Rolls-Royce 

• Rohr, Inc. / UTC Aerospace Systems 

2 70% reduction in landing and take-off NOx relative to CAEP/8 standard. Relative to CLEEN I baseline of CAEP/6 this is a 75% reduction. 

11 Federal Aviation 

Administration For more information: http://www.faa.gov/go/cleen 
CLEEN Phase II 14 Technologies 

– Aurora Flight Sciences: D8 Double Bubble Fuselage 

– Boeing: Structurally Efficient Wing (SEW) 

– Boeing: Compact Nacelle – Short Inlet 

– Delta Tech Ops/MDS Coating 

Technologies/America’s Phenix: Leading Edge 

Protective Blade Coatings 

– GE: TAPS III Combustor 

– GE: FMS Technologies 

– GE: More Electric Systems and Technologies 

for Aircraft in the Next Generation (MESTANG) 

– GE: Low Pressure Ratio Advanced Acoustics 

Uncoated Coated 

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– Honeywell: Compact Combustor System 

– Honeywell: Advanced Turbine Blade Outer Air Seal 

(BOAS) System 

– Pratt & Whitney: High Pressure Compressor AeroEfficiency Techs 

– Pratt & Whitney: High Pressure Turbine AeroEfficiency & Durability Techs 

– Rolls Royce: Advanced RQL Low NOx Combustion 

System 

– UTAS: Thrust Reverser Technology 
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CLEEN Phase II Goal Impact 

Goal Impact 

Technology Fuel Burn Emissions Noise 

Aurora Flight Sciences: D8 Double Bubble Fuselage  

Boeing: Structurally Efficient Wing (SEW) 

Boeing: Compact Nacelle – Short Inlet 

Delta Tech Ops; MDS Coating Technologies; America’s 

Phenix: Leading Edge Protective Blade Coatings 

GE: TAPS III Combustor 

GE: FMS Technologies 

GE: More Electric Systems and Technologies for Aircraft 

in the Next Generation (MESTANG) 



GE: Low Pressure Ratio Advanced Acoustics 

Honeywell: Compact Combustor System  

Honeywell: Advanced Turbine Blade Outer Air Seal 

(BOAS) System 

Pratt & Whitney: High Pressure Compressor AeroEfficiency Techs 

Pratt & Whitney: High Pressure Turbine Aero-Efficiency 

& Durability Techs 

Rolls Royce: Advanced RQL Low NOx Combustion 

System 

UTAS: Thrust Reverser Technology  
Technology & Emissions Reduction 

• Visible smoke emissions have been eliminated 

DC-8, Boeing 787, 

1958 2012

• 50% reduction in CAEP Nitrogen Oxides (NOx) 

emissions standard since 1995 

• CLEEN Program - Low NOX Combustors 

• GE TAPS II Combustor, 

LTO NOx: 55% below most recent CAEP std 

PM: 90% below CAEP visibility smoke limit 

• CLEEN II combustor development ongoing 

with GE, Honeywell, and Rolls Royce 

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CY2015 CY2016 CY2017 CY2018 CY2019 CY2020 

Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q 

4 

Q 

1 

Q 

2 

Q 

3 

Q 

4 

Preliminary CLEEN II 

Tech. Fleet Assessment 

Final CLEEN II Technologies Fleet 

Assessment & Benefits Comparison 

Interim CLEEN II Tech. 

Fleet Assessment 

Demonstrating New Technologies Under CLEEN Phase II 

CY2016 CY2017 CY2018 CY2019 CY2020 

Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 

CLEEN II 

Kickoff 

Meetings 

CY 16 Tests: 

5 Rig, 0 Engine, 0 Flight 

CY 17 Tests: 

16 Rig, 1 Engine, 0 Flight 

CY 18 Tests: 

14 Rig, 1 Engine, 0 Flight 

CY 19 Tests: 

14 Rig, 4 Engine, 4 Flight 

CY 20 Tests: 

0 Rig, 5 Engine, 0 Flight 

0 Techs @ TRL 5 

0 Techs @ TRL 6 

0 Techs @ TRL 7 

3 Techs @ TRL 5 

1 Techs @ TRL 6 

0 Techs @ TRL 7 

4 Techs @ TRL 5 

3 Techs @ TRL 6 

0 Techs @ TRL 7 

5 Techs @ TRL 5 

5 Techs @ TRL 6 

1 Techs @ TRL 7 

1 Techs of 13 @ TRL 5 

11 Techs of 13 @ TRL 6 

1 Techs of 13 @ TRL 7 

All CLEEN Techs reached TRL goals 

Number of technologies at TRL 5, 6 or 7 in each year 

Number of technology demonstration tests occurring in each year 

Milestone Success Success Milestone Complete Criteria Criteria 

Complete 

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CLEEN II Technologies – TRL Milestones 

16 

CY2015 CY2016 CY2017 CY2018 CY2019 CY2020 

Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 

Goal TRL 

Reached TRL Milestone TRL Milestone 

Reached Goal TRL 

6 

6 

5 6

5 6 

6 

5 6

5 

6 

5 

6 

6 7

5 

6 

6 

5 

3 4 5 6 

5 

6 
 

 

 

 

 

 

 

 

CLEEN Phase II Progress Highlights 

Highlights of completed milestones achieved to date 

• Aurora: Y-joint test demonstration 

• GE: TAPS III Combustor CLEEN II Technology Program completed 

1Q2018 and projected to meet or beat CLEEN II LTO NOx target of 65% 

CAEP/8 @ 55 OPR. A version of the TAPS III combustor is scheduled to 

enter into service on the GE9X engine / 777X aircraft in 2020. 

• Honeywell: Combustor rig testing is underway 

• P&W: Compressor Aero-Efficiency Technologies rig testing 

• Rolls Royce: Initial fuel spray nozzle and initial flame tube testing 

• UTAS: Achieved TRL5 for two acoustic technologies 

Highlights of progress anticipated in 2018 

• Boeing: SEW Wing Component Test Article, TRL 6 full-scale test 

demonstration (Q3 CY 2018) 

• Delta Tech Ops; MDS Coating Technologies; America’s Phenix: Flight 

Evaluation of Fan Blade Leading Edge Protective Coating 

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Actual timeline is in flux due to budget uncertainty 

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In Summary 

• CLEEN technology development and 

alternative fuels projects are progressing 

under second phase of CLEEN 

• Coming CLEEN Consortium Meetings: 

May 1-3; Chula Vista, CA 

Nov 6-8; Washington, DC 

• In the process of securing support for and initiating 

planning for 3rd Phase of CLEEN (2020-2025) 

• For more on CLEEN https://www.faa.gov/go/cleen 

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Backup 

Federal Aviation 

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CLEEN Goal in Relation to Noise Trends 

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Aurora CLEEN II Technologies 

Technology Goal Benefits and Application Key Milestones 

Impact 

29% fuel burn reduction and 16 • Y-joint test 

EPNdB cumulative noise 

D8 aircraft Fuel burn, 

fuselage: Noise demonstration –

reduction benefits for 2025 with Completed Advanced 

wing mounted engines. December 2017 composite • CLEEN II Efforts structure and 56% fuel burn reduction and Completed Y-joint 32EPNdB cumulative noise 

demonstration reduction benefits with 2035 

technology and integrated 

engines. 

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Boeing CLEEN II Technologies (1 of 2) 

Technology Goal Benefits and Key Milestones 

Impact Application 

Structurally 

Efficient Wing 

- enabled by 

advanced 

manufacturing 

and 

composites 

technologies 

Fuel Burn Lower weight, higher 

performance wing, 

reducing fuel burn by 

3.5% 

• CoDR – Completed 

March 2016 

• PDR – Completed 

January 2017 

• DDR – Completed July 

2017 

• Wing Component Test 

Article, TRL 6 full-scale 

test demonstration (Q3 

CY 2018) 

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GE CLEEN II Technologies (1 of 3) 

TAPS III Low- Emissions 65% of 

NOx CAEP/8 NOx 

Combustor @ 55 OPR – 

Development large twin 

aisle class 

aircraft 

Technology Goal Benefits and Key Milestones 

Impact Application 

• Combustion dynamics models developed 

& validated against rig data (April 2017) 

• Analytical screening (pre-test predictions) 

of alternate concepts completed (August 

2017) 

• Single-cup rig emissions and P4’ 

screening of the alternate concepts; TRL3 

review completed (November 2017) 

• TAPS III Combustor CLEEN II Technology 

Program completed 1Q2018; projected to 

meet or beat CLEEN II LTO NOx target of 

65% of CAEP/8 @ 55 OPR. A version of 

the TAPS III combustor scheduled to 

enter into service on the GE9X engine / 

777X aircraft in 2020. 

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GE CLEEN II Technologies (2 of 3)

Technology Goal 

Impact 

Benefits and 

Application 

Key Milestones 

Flight 

Management 

System (FMS) – 

Engine 

Integration 

Fuel burn Up to 1% fuel 

burn reduction 

• PDR (Q2 CY 2018) 

• DDR (Q4 CY 2018) 

• TRL 6 FMS & EFB 

prototype (Q1 2019) 

More Electric 

Systems and 

Technologies 

for Aircraft in 

the Next 

Generation 

(MESTANG) 

Fuel Burn Up to 3% fuel 

burn reduction 

for single-aisle 

aircraft 

PDR – Completed (May 

2017) 

DDR (Q1 CY 2018) 

Component tests (CY 

2018- 2019) 

TRL 6 system demonstration 

(CY 2020) 

 

 

 

 

 

 

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GE CLEEN II Technologies (3 of 3)

Technology Goal Benefits and Key Milestones 

Impact Application 

Low Pressure Noise 

Ratio Advanced 

Acoustics 

Alternative Jet Alternative 

Fuel Test and Fuels 

Evaluation 

Liner Noise 

Benefit 

~2EPNdB Cum 

Fan Noise 

Source Strength 

Reduction Noise 

benefit ~2+ 

EPNdB 

Testing of drop-in 

alternative jet 

fuels to support 

NJFCP and 

ASTM 

International 

approval 

• Fabricated Novel Liner 

Panels 

• Initiated Aeroacoustic 

Design - Q1 2018 

• Full Annular Rig tests; focus 

on operability impacts 

• NJFCP fuel (100% Gevo 

ATJ-SPK) - Completed; 

• 100% synthetic (HEFA SPK 

+ Virent SAK) (CY2018); 

• HFP-HEFA blend (CY2018) 

Federal Aviation 

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Honeywell CLEEN II Technologies 

Technology Goal Benefits and Key Milestones 

Impact Application 

Compact Combustor Emissions, +50% margin to • PDR Completed 

System Fuel burn ICAO CAEP/8 NOx • DDR (Q4 CY 

2018) 

Reduced weight, • TRL 6 engine 

emissions test (CY 2020) 

Advanced Turbine Fuel burn Contributes to • PDR Completed 

Blade Outer Air Seal package that • DDR (Q4 CY 

delivers 22% fuel 2018) 

burn reduction vs. • TRL 6 engine 

in service baseline test (CY 2020) 

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Pratt & Whitney CLEEN II Technologies 

Technology Goal Impact Benefits and Key Milestones 

Application 

Compressor Fuel burn 0.8-1.0% fuel burn • Rig tests (Q3-4 CY 

Aero- reduction 2016) Complete 

Efficiency • Redesign cycle (CY 

Technologies 2017) 

• Engine test (CY 2019) 

Turbine Aero- Fuel burn 0.8-1.0% fuel burn • Baseline rig tests 

Efficiency reduction ongoing 

and • Technology blade rig 

Durability tests (CY 2018) 

Technologies 

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Rolls-Royce CLEEN II Technologies 

Technology Goal Benefits and Key Milestones 

Impact Application 

Advanced 

Rich Quench 

Lean (RQL) 

Low NOx 

Combustion 

System 

Alternative Jet 

Fuel Test and 

Evaluation 

(Area A) 

Emissions 65% margin to ICAO 

CAEP/8 NOx 

Alternative 

Fuels 

Testing of drop-in 

alternative jet fuels to 

support ASTM 

International approval 

• Initial fuel spray 

nozzle and initial 

flame tube testing 

(Completed) 

• Full annular rig 

testing (CY 2017 – 

2018) 

• Engine test (CY2019) 

• Alternative fuels 

testing and 

demonstration; 100% 

synthetic (LanzaTech 

ATJ with Swift 

mesitylene aromatic) 

(CY 2017- 2019) 

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Rohr / UTAS CLEEN II Technologies 

Technology Goal Benefits and Key Milestones 

Impact Application 

Short, 

Integrated 

Fan Duct 

Thrust 

Reverser 

Fuel burn ~1.0% 

• Achieved TRL5 for two 

acoustic technologies 

• PDR (CY 2018) 

• DDR (CY 2018) 

• TRL 6 engine ground Advanced Noise ~2.5 EPNdB noise test (CY 2019) Acoustics reduction* 

* to offset short fan duct 

Legacy Thrust CLEEN II Thrust 

Reverser Fan Duct Reverser Fan Duct 

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Administration