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Tire Pressure
?? psi
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Transportation Systems Workshop
April 23, 2008
Federal Aviation
Administration
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• Official ACN values are provided by the Aircraft
Manufacturer
Airplane Characteristics for Airport Planning
ACN/PCN System – Official ACN
• Airplane Characteristics
manual report official
center of gravity and
max gross load for ACN
calculation.
• Tire pressure (used in ACN
calculation) is also reported
for standard configuration
ACN/PCN System
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Transportation Systems Workshop
April 23, 2008
Federal Aviation
Administration
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FAA Guidance on ACN-PCN
AC 150/5335-5A STANDARDIZED METHOD OF
REPORTING AIRPORT PAVEMENT STRENGTH – PCN
• AC introduces the COMFAA program.
• COMFAA can be used to calculate ACN values for any
airplanes.
• Manufacturer’s have provided CG and max load data for
ACN determination.
COMFAA 2.0 Program
COMFAA 2.0 Program
Select desired aircraft group
Select desired airplane
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Transportation Systems Workshop
April 23, 2008
Federal Aviation
Administration
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COMFAA 2.0 Program
The internal aircraft library in
COMFAA contains the
manufacturers data for ACN
determination.
Coverages is set to 10,000
per ICAO procedure.
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Transportation Systems Workshop
April 23, 2008
Federal Aviation
Administration
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COMFAA 2.0 Program
In ACN Computation mode, ACN values are calculated for 4
standard subgrade conditions using the identified airplane data
Flexible Rigid
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Transportation Systems Workshop
April 23, 2008
Federal Aviation
Administration
28
ACN-PCN SYSTEM – PCN Values
• PCN values are reported in a coded format using 5
parts separated by “/”
Sample 39/R/B/W/T
• Information includes
• Numerical PCN Value
• Pavement Type
• Subgrade Category
• Allowable Tire pressure
• Method used to determine the PCN value
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Transportation Systems Workshop
April 23, 2008
Federal Aviation
Administration
29
ACN-PCN SYSTEM
• PCN Numerical value is a relative indication of the load carrying
capacity of a pavement in terms of a standard single wheel load 181
psi (1.25 MPa)
• PCN value derived from the ACN value of the most demanding
airplane.
• PCN values can be determined in two ways
• Using Aircraft
• Technical Evaluation
39/R/B/W/T
PCN Numerical value
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Transportation Systems Workshop
April 23, 2008
Federal Aviation
Administration
30
ACN-PCN SYSTEM
• Pavement may be either Rigid (R) or Flexible (F)
• Rigid – Single Stiff Layer to support and distribute load
• Flexible – Multiple flexible layers to distribute load
• Composite pavements (overlays etc.) are reported as the type which
most accurately reflects the structural action
39/R/B/W/T
Pavement Type
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Transportation Systems Workshop
April 23, 2008
Federal Aviation
Administration
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ACN-PCN SYSTEM
39/R/B/W/T
Subgrade Category
Subgrade
Strength Category CODE
RIGID
k-Value* pci (MN/m3)
FLEXIBLE
CBR-Value
High A 552.6 (150) 15
Medium B 294.7 (80) 10
Low C 147.4 (40) 6
Ultra Low D 73.7 (20) 3
*Effective k-value
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Transportation Systems Workshop
April 23, 2008
Federal Aviation
Administration
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ACN-PCN SYSTEM
39/R/B/W/T
Allowable Tire Pressure
Category Code Tire Pressure Range
High W No pressure limit
Medium X Pressure limited to 218 psi (1.5 MPa)
Low Y Pressure limited to 145 psi (1.00 MPa)
Very Low Z Pressure limited to 73 psi (0.50 MPa)
Recent request to ICAO have proposed modifying this table to increase
allowable tire pressures
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Transportation Systems Workshop
April 23, 2008
Federal Aviation
Administration
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ACN-PCN SYSTEM
PCN values can be determined in two ways
• U =Using Aircraft
• Simply select highest ACN from all airplanes using facility
• T = Technical Evaluation
• PCN based on technical study of pavement structure and traffic
data.
39/R/B/W/T
Method used to determine PCN
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Transportation Systems Workshop
April 23, 2008
Federal Aviation
Administration
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