Presented to:By:Date:

RPD 147

Aircraft Braking Friction

REDAC Subcommittee

Joseph Breen

April 1, 2015

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Aircraft Braking

April 1, 2015

BASIS OF AIRCRAFT BRAKING RESEARCH
        - Project Initiated in Response to NTSB Safety Recommendation
        - NTSB Issued Safety Recommendations to the FAA, Dated Oct. 16, 2007, in Response to the SWA Airplane Accident
        - The Following Recommendation is Included in the NTSB Document:

	“Demonstrate the technical and operational feasibility of outfitting transport-category airplanes with equipment and procedures required to routinely calculate, record, and convey the airplane braking ability required and/or available to slow or stop the airplane during the landing roll.  If feasible, require operators of transport-category airplanes to incorporate use of such equipment and related procedures into their operations. (A-07-64)”

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Aircraft Braking

April 1, 2015

Aircraft Braking Friction Challenges
        - Anti-Skid Braking Systems of Commercial Transport Aircraft Are Not Optimized to Interact with Contaminants Offering Low Maximum Mu’s, anticipated during landings on Winter Weather Contaminants.     
        - Maximum Mu’s Offered by the Winter Weather Contaminants of Snow, Slush, and Ice are Not Known. 
        - Performance of Anti-Skid Braking Systems on Winter Weather Contaminants Is Also Not Known. 

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Aircraft Braking

April 1, 2015

Mu-Slip Curve Defines Tire-Pavement Interaction
        - Mu:

     Drag (Friction )Force Divided By Vertical (Ground) Force
        - Slip:

     Percentage Loss of the Rotational Speed     

     of a Braked Wheel

Mu

% Slip

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Aircraft Braking

April 1, 2015

Variables Determining Mu-Slip Curves 
        - Aircraft Ground Speed
        - Tire

       - Specific Tire

       - Tire Pressure

       - Vertical Load
        - Pavement Condition 

       - Dry, Wet, Snow, Slush, Ice

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Aircraft Braking

April 1, 2015

Research Project Objectives
        - Effective utilization of onboard aircraft data generated with Test Aircraft (B727) during braking conditions on contaminated runways to determine maximum available braking friction.
        - Establish variables common to B727 and Commercial Aircraft which would allow for calculation of Mu developed during landings on contaminated runway surfaces.
        - Develop algorithm to translate onboard aircraft data into Mu developed during landings on contaminated runway surfaces. 

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Aircraft Braking

April 1, 2015

Aircraft Parameters Related to Braking Friction 
        - To be Measured by B727 During Testing with Main Gear Brakes.
        - Measurable by Commercial Transport Aircraft 

          - Ground Speed

          - Wheel Speed

          - Pressure Differential Across Anti-Skid 

            Valve

          - Electrical Current to Anti-Skid Valve

          - Deceleration of Aircraft

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Aircraft Braking

April 1, 2015

FAA B727 Braking Capability
        - All Four Main Gear Wheels Are to be Equipped with an Upgraded Anti-Skid Brake System (ASBS) Comparable in Performance to Contemporary Civil Transport Aircraft (Mark III Advanced).
        - The Two Inboard Main Gear Wheels Are Equipped with an Alternate Programmable Braking System Which Can Generate Complete Mu-Slip Curves.

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Aircraft Braking

April 1, 2015

B727 Aircraft Braking Friction Testing
        - Testing to be conducted on ACY Runway on natural snow at speeds up to 100 knots.
        - Braking on Natural Snow will initially use Programmable Valves controlling hydraulic pressure to the Inboard Main Gear Brakes.  Pilot to then Apply Maximum Braking to all Four Main Gear Brakes through the Anti-Skid Valves.
        - Testing to be conducted on FAA Ramp on Manufactured Snow at speeds up to 45 knots.
        - Braking on Manufactured Snow will be applied with the Programmable Valves controlling hydraulic pressure to the Inboard Main Gear Brakes. 

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Aircraft Braking

April 1, 2015

B727 Nose Gear Braking on Dry, Wet, and Manufactured Snow as Placed on PCC Pavement, FAA Ramp, ACY, 2013, 2014

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Aircraft Braking

April 1, 2015

Mu-Slip Curve Generated on Manufactured Snow Demonstrating Proof-of-Concept of a Programmable Braking System, Using the Nose Gear Wheels – A Technical First

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Aircraft Braking

April 1, 2015

Mu-Pressure Relationship Demonstrates Potential of Recorded Aircraft Parameters Determining Mu

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Aircraft Braking

April 1, 2015

Calculation of Braking Friction Based on  Parameters Measured on Commercial Transport Aircraft 
        - Algorithm to be Developed that Can Process the Measured Aircraft Parameters.
        - An Onboard Laptop Performance Computer (OPC) Can Use the Algorithm to Calculate Main Gear Wheel Braking Mu.
        - OPC of Follow-on Aircraft can Use the Mu in Its Aircraft Landing Performance Calculation.  

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Aircraft Braking

April 1, 2015

Project Schedule

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Aircraft Braking

April 1, 2015

Recent Project Accomplishments with B727
        - Installed Programmable Servo Valves and Diverter Valves to allow for Controlled Application of Hydraulic Pressure to Inboard Main Gear Brakes Independent of Application of Brake Pedal Pressure.
        - Installed New Motion Controllers for Control of Programmable Valves on Both Nose and Main Landing Gears.
        - Development/Installation of Upgraded Hydro-Aire Mark III Anti-Skid Brake System is Ongoing and to be Completed by June 10, 2015. 
        - Installed Wheel Speed Transducers on All Four Main Gear Wheels.
        - Installed Infrared Temperature Sensors on All Four Main Landing Gear Brakes with Display in Aircraft Cabin.

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Aircraft Braking

April 1, 2015

Recent Project Accomplishments with B727 (Continued)
        - Recalibrated Main Landing Gear Strain Gauges
        - Installed Radial Tires on Main Landing Gear.
        - Working to Make Aircraft Engine and Auxiliary Power Unit (APU) Fire Detection and Fire Suppression Systems Fully Operational.
        - New Aircraft Pilot Acquired with Airline Transport Pilot (ATP) Rating and Type Rating on B727 and Global 5000.  Pilot Has 21 Years as a Test Pilot for the FAA R&D.
        - Procured Hand-Operated Instrumentation for the Classification of Winter Weather Contaminants. 

AIRCRAFT BRAKING FRICTION (RPD 147)

Contract Funds ($K)

TOTALS:
        - Aircraft Braking Research Work

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Aircraft Braking

April 1, 2015

Cooperative Research and Development Agreements (CRDA’s)
        - Team Eagle of Ontario, Canada, Developing Braking Availability Test (BAT) Vehicle.
        - ESCO Zodiac Aerospace of Logan Township, NJ, in Testing of Braking Action Safety System (BASS) Using the FAA Global 5000. 

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Aircraft Braking

April 1, 2015

Questions?