COMFAA 3.0 Beta
Federal Aviation
Administration
Demonstration and
Hands-On Training
Presented to: VIII ALACPA Airport Pavement
Seminar & VI FAA Airport Pavement Workshop
Buenos Aires, Argentina
By: David R. Brill, P.E., Ph.D.
Date: 2 September 2011
Acknowledgments
• Gordon Hayhoe, Rodney Joel and Jeff
Rapol, FAA.
• Ken DeBord and Mike Roginski, Boeing
Commercial Airplane Co.
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Outline
• Brief review of ACN/PCN system and ICAO
definitions.
• FAA guidance on PCN calculation.
• Draft AC 150/5335-5B and computer programs
(COMFAA 3.0 and new support program).
• Flexible example using COMFAA 3.0.
• Rigid example using COMFAA 3.0 for a large
hub airport.
• Using COMFAA 3.0 additional features.
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The ACN/PCN System - General
• Aircraft Classification Number (ACN) is specified as
a standard by ICAO in Annex 14 to the Convention
on International Civil Aviation.
– Aircraft manufacturers are required to publish properly
computed ACN values for all of their aircraft.
• Pavement Classification Number (PCN) procedures
are given in the ICAO Aerodrome Design Manual,
Part 3, Pavements.
– The PCN procedures in the manual are for guidance only and
a great deal of latitude is provided.
– Airport operators are responsible for determining and
publishing PCN values for runways.
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ICAO Documents
Annex 14 to the Convention on
International Civil Aviation
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ICAO Aerodrome Design Manual
Part 3 – Pavements
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ACN/PCN System - Definitions
• ACN – A number expressing the relative effect of an
aircraft on a pavement for a specified standard
subgrade strength.
• PCN - A number expressing the bearing strength of
a pavement for unrestricted operations.
• Therefore, if a particular aircraft at a given weight
has an ACN less than, or equal to, the PCN of a
particular pavement (ACN  PCN), then no
restrictions need to be placed on operation of that
aircraft on that pavement.
• Special provisions for overload evaluation.
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ACN Computation
• ACN is computed as the ratio of a computed
(derived) single-wheel load to a reference singlewheel load.
– Flexible: Based on the US Army Corps of Engineers ESWL
CBR method of design using alpha factors adopted by ICAO
October 2007. Thickness is computed for 10,000 coverages.
– Rigid: PCA Westergaard interior stress method of design.
Thickness is computed for 10,000 coverages.
• These are fixed, standard procedures. Other design
procedures or traffic levels cannot be substituted.
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Subgrade Strength for ACN Computation
• Flexible: The CBR of the subgrade soil.
• Rigid: The k-value at the top of the support,
including all subbase layers.
– It is not the same as the k-value of the subgrade
soil.
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PCN Reporting Format
• PCN values are reported in a coded format
using 5 parts separated by “/”
Sample 39/F/B/X/T
• Information includes:
–
–
–
–
–
Numerical PCN Value (39 in this example)
Pavement Type (F = Flexible, R = Rigid)
Subgrade Strength Category (A, B, C or D)
Allowable Tire Pressure (X  1.5 MPa = 218 psi)
PCN Evaluation Method (U = Using, T = Technical)
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Proposed Change to ICAO PCN Tire
Pressure Limits (Flexible Only)
Tire Pressure
Category
Current ICAO
Designations and Limits
Proposed ICAO
Designations and Limits
W
High: no pressure limit
Unlimited
X
Medium: pressure limited
to 1.50 MPa (217.6 psi)
High: pressure limited to
1.75 MPa (253.8 psi)
Y
Low: pressure limited to
1.00 MPa (145.0 psi)
Medium: pressure limited
to 1.25 MPa (181.3 psi)
Z
Very low: pressure limited
to 0.50 MPA (72.5 psi)
Low: pressure limited to
0.50 MPA (72.5 psi)
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PCN – Using Aircraft Method
• Find the ACN of all of the aircraft regularly
using the pavement and pick the largest
ACN to be the PCN of the pavement.
• But see page 3-27 of the ICAO manual:
“Support of a particularly heavy load, but only rarely,
does not necessarily establish a capability to support
equivalent loads on a regular repetitive basis.”
Where is the line between “regular” and
overload operation?
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PCN – Technical Method
• The ICAO manual covers in detail a very
broad range of methods, including:
– Any rational design procedure developed specifically
for airport pavements but applied in reverse for
pavement evaluation.
– Pavement surface deflection measured under the
load from a representative aircraft.
– Non-destructive test results with backcalculation.
– Allows for design and evaluation procedures not in
use when the manual was written.
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FAA Guidance on PCN Calculation
• The FAA is responsible for certifying all
commercial airports in the U.S. and is the
organization generally responsible for
complying with international agreements on
aviation.
• Well defined procedures are therefore
required for determining and publishing
PCN values for runways at all commercial
airports in the U.S.
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AC 150/5335-5A (2006)
Standardized Method of Reporting Airport Pavement Strength – PCN
• Complete rewrite of AC 150/5335-5.
• Standardized the procedures for computing and
reporting PCN values for inclusion in the 5010
database.
• AC 150/5335-5A is based in large part on the
procedures described in Boeing Report D6-82203
“Precise Methods for Estimating Pavement
Classification Number,” 1998.
• D6-82203 is, in turn, based largely on
recommendations contained in the ICAO
Aerodrome Design Manual.
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Draft Advisory Circular 150/5335-5B
• AC 150/5335-5A, PCN,
to be replaced by AC
150/5335-5B.
• Draft AC was posted
for comment October
2009.
• Comment period has
ended.
• Copy of draft AC is
included on the CD.
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AC 150/5335-5B
STANDARDIZED METHOD OF REPORTING AIRPORT PAVEMENT
STRENGTH - PCN
• The Pavement Classification Number (PCN) field has
been added to FAA Form 5010 and data collection is
underway.
• During each airport inspection, the airport owner will
be asked to provide runway PCN information.
• WHY?
– With release of AC 150/5320-6E, the “design aircraft” concept
has been replaced.
– This means the Aircraft Gross Weight fields on the 5010 will no
longer be used to describe load carrying capacity of runways.
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AC 150/5335-5B …PCN
Gross Weight data
may transition.
PCN data request now part
of all airport inspections
•
•
The Master Record is required to be updated periodically.
PCN is now mandatory and Gross Weight data will possibly be
phased out with time.
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Draft AC 150/5335-5B
- Changes from AC 150/5335-5A
• The procedure for selecting the critical aircraft has
been substantially revised.
• The procedure for computing equivalent departures
has been replaced by a new procedure based on
cumulative damage factor (CDF).
• Except for obtaining the structure and aircraft
properties, the procedure has been completely
automated in a revised version of the computer
program COMFAA (COMFAA 3.0).
• A spreadsheet application has been developed to
facilitate determining the evaluation thickness.
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Draft AC 150/5335-5B
• The design procedures recommended in the new
AC are:
– CBR ESWL with the new alpha factors for flexible pavements.
– Edge stress Westergaard as implemented in AC 150/5320-6C
and -6D.
– The PCA center stress method can also be selected in
COMFAA 3.0.
• These were selected for backward compatibility
with established methods and compatibility with
the ACN computation procedure.
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New PCN Methodology
• The current methodology (-5A) finds the critical
aircraft and then finds the ACN of that aircraft at
the maximum allowable gross weight. That ACN is
then the PCN.
• The new methodology is the same except that the
ACN at maximum allowable gross weight is
calculated for all of the aircraft in the mix. The CDF
procedure is used for equivalent coverages.
• The largest ACN value is then selected as the PCN.
• There is a need to eliminate “occasional or
overload” aircraft from the mix.
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ACN-PCN – Technical Evaluation
7 Basic Steps to Determine Pavement
Classification Number in AC 150/5335-6B:
1.
2.
3.
4.
Identify pavement features and properties.
Determine traffic mixture.
Convert traffic to equivalent traffic of “critical” aircraft.
Determine allowable operating weight of critical
airplane.
5. Determine ACN of critical airplane at allowable weight.
6. Repeat with each airplane as the critical airplane.
7. Report PCN.
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AC 150/5335-5B Computer Programs
• COMFAA 3.0 Program
• Support Spreadsheet for COMFAA (Excel)
Input Support:
– Flexible Layer Equivalency Worksheet
– Rigid Pavement k-Value Worksheet
Output Support:
– Output Data Parsing
– Rigid and Flexible Chart Creation
– FAA Form 5010 Preparation
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COMFAA Support Spreadsheet
Flexible Layer Equivalency
– The equivalent pavement
has three layers:
• 5 in. P-401,
• 8 in. P-209,
• P-154.
– The spreadsheet
determines the maximum
thickness for the
equivalent pavement
based on the userdefined layer equivalency
factors.
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COMFAA Support Spreadsheet
Flexible Pavement Input
• ENTER (or confirm)
layer equivalency
factors.
– Refer to Table A2-1.
• ENTER all existing
pavement layers
starting at the surface
of the pavement.
• ENTER the subgrade
CBR value.
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2 September 2011
Reference Guidance AC 150/5335-5B Appendix A-2
Fig. A2-2 Figs. A2-1, A2-2
Flexible Pavement
Convert
Convert
Structure Items
to P-209
to P-154
1.4
1.5
P-401 and/or P-403 1.6
P-306
1.2
1.3
1.4
P-304
1.3
1.4
1.5
P-209
P-208 and/or P-211
P-301
n/a
P-154
n/a
Equivalent Thickness, in.
Existing
Flexible
Pavement
Layers
Existing
Layer
Thickness
1.6
1.8
1.9
2.0
ENTER P-401
2.0 and/or P-403
6.0 in.
1.2
1.6
1.7
1.8
1.6 ENTER P-306
0.0 in.
1.2
1.6
1.7
1.8
1.6 ENTER P-304
0.0 in.
1.0
1.2
1.3
1.4
1.4 ENTER P-209
12.0 in.
1.0
1.3
1.4
1.5
ENTER P-208
1.3 and/or P-211
0.0 in.
1.0
1.1
1.2
1.0 ENTER P-301
0.0 in.
1.0 ENTER P-154
13.0 in.
ENTER Subgrade CBR
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9.0
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COMFAA Support Spreadsheet
Flexible Pavement Output
COMFAA Evaluation Criteria
Evaluation CBR = 9.0
PAVEMENT TO BE
EVALUATED IN COMFAA
•
•
Equivalent Pavem ent
P-401
P-401
5
Evaluation thickness t = 33.8 in.
P-209
10
Depth from Surface, in.
Recommended PCN Codes: F/B/W or
Recommended PCN Codes: F/B/X
Existing Pavem ent
0
P-209
15
20
P-154
25
P-154
30
35
Subgrade
CBR 9.0
Subgrade
CBR 9.0
The spreadsheet determines and consolidates COMFAA software
input values and recommends three of five necessary PCN codes.
The spreadsheet updates the graphical representation of the existing
and equivalent pavement.
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Using the COMFAA 3.0 Program
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COMFAA Input
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Aircraft Window – COMFAA Input
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Main Window - COMFAA Input
Click
“PCN Flexible Batch”
Click “CBR” – Enter
9.0 in the dialog box.
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Enter the evaluation
thickness = 33.8 in.
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COMFAA Output
Click “Details” to view
the detailed output.
Message “Flexible
Computation Finished”
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COMFAA Detailed Output Screen
Summary Aircraft Table
with -6D Thickness
Requirements
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COMFAA Output – Details (I)
COMFAA generates an aircraft ACN table.
CBR 9 indicates B subgrade designation.
• PCN based on using aircraft ACN can be reported as
54.
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COMFAA Output – Details (II)
COMFAA generates a table based
on the CDF method. For each
aircraft, allowable gross weight
and corresponding PCN are
identified.
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CBR 9 indicates B
subgrade designation.
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COMFAA Output – Details (III)
• CDF method identifies (3) aircraft that contribute
substantial structural damage based on pavement
structure: 727-200, 747-400, and A300-B4.
• PCN based on technical CDF method can be
reported as the highest PCN of these aircraft = 73.
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COMFAA Detailed Output Screen
Copy and paste data into
COMFAA support
spreadsheet.
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COMFAA Support Spreadsheet
Data Parse
• Copy/Paste output
data into Cell B5
• Click “Create
Flexible Pavement
Charts”
• Airplanes are
ordered by PCN
number, with the
aircraft at top giving
the highest PCN
when treated as
critical.
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COMFAA Support Spreadsheet
Flexible Charts
1,200
Most Demanding Aircraft in Traffic Mix
Rigid Pavement Thickness
35 in.
1,000
30 in.
800
25 in.
20 in.
600
15 in.
400
10 in.
200
5 in.
0 in.
```
DC8-63
767-200
ER
0
777-200 A300-B4 747-400
Airplane Gross Weight, lbs. (thousands)
AC 150/5335-5B Example
727-200
1. 6D thickness at traffic mix
GW
25.7
25.7
25.5
27.5
28.8
23.1
2. CDF thickness at max.
GW
33.2
31.4
31.9
29.5
29.3
27.5
3. Evaluation thickness from
equivalent pavement
33.8
33.8
33.8
33.8
33.8
33.8
4. Max.Allowable Aircraft
GW from CDF
378,158
365,739
646,354
443,728
992,902
253,830
5. Aircraft GW from traffic
mix
370,000
330,000
600,000
370,000
820,000
185,000
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Thickness
Comparison
• Compare
thickness and
gross weights.
• When CDF
thickness (yellow)
is less than
evaluation
thickness (red),
excess PCN is
available.
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COMFAA Support Spreadsheet
Flexible Charts
AC 150/5335-5B Example
73
71
68
PCN= 70
2,500
57
57
PCN= 60
PCN= 50
45 47
49
51
52
54
48
2,000
1,500
PCN= 40
PCN= 30
1,000
PCN= 20
500
PCN= 10
PCN= 0
PCN
Comparison
3,000
PCN= 80
Annual Departures
Subgrade code= B at CBR= 9.0, t= 33.8
3,500
Most Demanding Aircraft in Traffic Mix
PCN= 90
• PCN needed for
using traffic is 54.
• PCN based on
CDF analysis can
be reported as
high as 73.
0
767-200
ER
DC8-63
777-200
A300-B4
747-400
727-200
1. Aircraft ACN at traffic mix
GW
45.2
48.8
51.3
52.4
53.9
48.2
2. Calculated PCN at CDF
max. GW
46.6
56.7
57.0
68.3
70.6
72.8
3. Annual Departures from
traffic mix
2,000
800
300
1,500
3,000
400
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Technical Method Example – Case 1
• International hub airport.
• Rigid pavement.
• Large number of narrow-body, dual-wheelgear aircraft.
• Example courtesy of Rodney Joel.
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2 September 2011
CASE 1
Traffic Data
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39
ACN
gear
Operating
Weight, lb
Gear Load.
lbs.
Wheel
Load, lbs.
Avg Annual
Departures
Total
Coverages
20 yrs
DC-9-30/40
D
109000
51775
25888
8
44
B717-200
D
122000
57950
28975
301
1701
A318-100 std
D
124500
59138
29569
654
3593
A319-100 std
D
142500
67688
33844
13,002
70663
A320-100
D
151000
71725
35863
15,280
79583
MD-80/83/88
D
161000
76475
38238
739
4322
MD-90
D
168500
80038
40019
213
1283
B727-200 basic
D
185200
87970
43985
111
760
B737-700
D
188200
89395
44698
18,133
96709
B757-300
2D
271000
128725
32181
10,079
51555
DC-8-60/70
2D
358000
170050
42513
79
472
A300-b4 std
2D
365750
173731
43433
831
4579
B767-300
2D
413000
196175
49044
2,521
14006
DC-10
2D
458000
217550
54388
115
622
B787-8
2D
478000
227050
56763
32
169
A330-200 std
2D
509000
241775
60444
88
936
A340-300 std
2D
608000
243200
60800
179
1884
MD-11
2D
633000
245288
61322
44
240
B747-400
2D
877000
208288
52072
754
4358
A380 (2D)
2D
1235000
469300
117325
59
309
255075
Federal Aviation
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AIRCRAFT
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B777-200 base
3D
2 September 2011
537000
5153 40
CASE 1
Existing
Pavement
Data
Effective k at top of
base = 323 psi/in
17″ PCC, R = 775 psi
8″ CTB
k-value = 160 psi/in
The original design based on procedures in AC
150/5320-6D called for 16.3 inches of PCC. This
value was rounded to 17.0 inches.
COMFAA 3.0 Beta Demonstration & Hands-On Training
2 September 2011
CASE 1
Pavement thickness
requirements based
on actual annual
departures:
•FAA AC 150/5320-6D
•PCA method
• B737-700 appears to
be the “design”
airplane based on
5335-5A procedures.
• B737-700 is comprised
of several D gear
airplanes.
AIRCRAFT
ACN
gear
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Operating
Weight (lb)
41
Annual
Departures
-6D Edge Load
Thickness (in)
PCA Design
Thickness (in)
DC-9-30/40
D
109000
8
8.04
7.24
B717-200
D
122000
301
9.66
8.65
A318-100 std
D
124500
654
9.23
8.18
A319-100 std
D
142500
13,002
12.17
10.14
A320-100
D
151000
15,280
12.98
10.73
MD-80/83/88
D
161000
739
11.67
10.46
MD-90
D
168500
213
11.49
10.27
B727-200 basic
D
185200
111
10.92
9.81
B737-700
D
188200
18,133
15.47
12.71
B757-300
2D
271000
10,079
10.85
10.31
DC-8-60/70
2D
358000
79
10.05
9.72
A300-b4 std
2D
365750
831
10.78
10.62
B767-300
2D
413000
2,521
11.62
11.26
DC-10
2D
458000
115
9.52
9.21
B787-8
2D
478000
32
10.57
10.1
A330-200 std
2D
509000
88
10.84
10.28
A340-300 std
2D
608000
179
10.99
10.45
MD-11
2D
633000
44
10.65
10.27
B747-400
2D
877000
754
11.17
11.07
A380 (2D)
2D
1235000
59
10.60
10.13
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2 September 2011
537000
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9.46
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CASE 1 – Current Procedure
• Following 5335-5A procedures the B737-700
would become the “Critical Aircraft” due to
its individual pavement thickness
requirement.
• This is true for either the 5320-6D procedure
or the PCA center slab procedure.
• It was speculated that the B737 was
artificially elevated as the design airplane
due to high departure levels caused by
lumping several D-gear airplanes into one.
COMFAA 3.0 Beta Demonstration & Hands-On Training
2 September 2011
CASE 1
•
•
PCN values calculated
by following the
procedures in AC
150/5335-5A and
assuming that each
airplane is the “design
airplane.”
In this mix, the B737700 is comprised of
several D gear
airplanes, some with
lower operating
weights.
AIRPLANE
Federal Aviation
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ACN
gear
Allowable
Operating
Weight
Equiv.
Annual
Departures
43
5335-5A
PCN/R/B
DC-9-30/40
D
148600
739535
45.4
A318-100 std
D
181000
345027
46.1
B717-200
D
158900
386168
50.1
A319-100 std
D
189250
168314
52.1
A320-100
D
189500
125753
55.2
B737-700
D
201400
45167
59.8
MD-80/83/88
D
184000
92089
60.1
MD-90
D
189100
74317
61.4
B727-200 basic
D
222200
48463
65.7
B757-300
2D
385300
130968
68.7
A300-b4 std
2D
481000
32997
84.9
DC-8-60/70
2D
457500
36135
85.6
B767-300
2D
553000
20131
87.3
A330-200 std
2D
672000
9296
89.3
A340-300 std
2D
806000
10907
90.1
A380 (2D)
2D
1568000
20322
92.0
B747-400
2D
1148000
15972
92.8
DC-10
2D
653600
13572
93.0
B787-8
2D
608500
11612
96.4
MD-11
2D
820500
9462
100.6
B777-200 base
3D
920500
23190
115.2
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Assuming the B737-700
as the design airplane
per the procedures in
5335-5A
Calculated PCN
59.8/R/B
PCN = (60/R/B)
Airplane
ACN/R/B
A318-100 std
D
124500
29.5
DC-9-30/40
D
109000
31.3
B717-200
D
122000
36.5
A319-100 std
D
142500
37.2
2D
271000
41.4
A320-100
D
151000
42.2
B777-200 baseline
3D
537000
47.4
MD-80/83/88
D
161000
51.3
B727-200 basic
D
185200
52.7
MD-90
D
168500
53.5
B737-700
D
188200
55.2
DC-10
2D
458000
56.4
A300-b4 std
2D
365750
57.3
B767-300
2D
413000
57.4
DC-8-60/70
2D
358000
60
A330-200 std
2D
509000
61.2
61.4
B757-300
A340-300 std
2D
608000
B747-400
2D
877000
63
A380 (2D)
2D
1235000
65.8
B787-8
2D
478000
68.3
MD-11
2D
633000
69.6
COMFAA 3.0 Beta Demonstration & Hands-On Training
2 September 2011
Airplanes can operate
without restriction
ACN values for each
airplane
(from COMFAA)
Operating
Weight
AIRPLANE
Weight
Restrictions
CASE 1
Gear
type
for
ACN
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Case 1 – New CDF PCN Procedure
• The procedure for finding equivalent
coverages in AC 150/5335-5A is based on
gear equivalency factors and the ratio of
wheel loads.
• An alternative procedure based on
cumulative damage factors (CDF) gave
more consistent, and rational, results.
• The new procedure for finding equivalent
coverages has been incorporated in the new
AC 150/5335-5B.
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COMFAA 3.0 – Case 1
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COMFAA Support Spreadsheet
Rigid Pavement k-Value
– Each subbase layer
contributes to an improved
subgrade support k-value.
– ENTER all existing pavement
layers.
– ENTER the flexural strength
of the concrete and the
subgrade support k-value.
– The spreadsheet updates the
graphical representation of
the existing and equivalent
pavement.
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COMFAA 3.0 – Aircraft Window
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2 September 2011
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COMFAA 3.0 – Case 1 Results
Subgrade Category B
COMFAA 3.0 Beta Demonstration & Hands-On Training
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COMFAA 3.0 – Case 1 Results
Copy and Paste Data into
Support Spreadsheet
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COMFAA Support Spreadsheet
Case 1
Data Parse
• Copy/Paste output
data into Cell B5
• Click “Create Rigid
Pavement Charts”
• Airplanes are
ordered by PCN
number, with the
aircraft at top giving
the highest PCN
when treated as
critical.
• Next, click Rigid
Chart tab.
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COMFAA Support Spreadsheet
Rigid Charts – Case 1
AC 150/5335-5B Example
1,800
1,600
Rigid Pavement Thickness
16 in.
1,400
14 in.
1,200
12 in.
1,000
10 in.
800
8 in.
600
6 in.
400
``
4 in.
200
2 in.
0 in.
B747-400
B787-8
A330-200 A340-300
A380-Wing (Preliminar
std
std
y)
Thickness
Comparison
Airplane Gross Weight, lbs. (thousands)
Most Demanding Aircraft in Traffic Mix
18 in.
• Compare
thickness and
gross weights.
• When CDF
thickness (yellow)
is less than
evaluation
thickness (red),
excess PCN is
available.
0
MD11
1. 6D thickness at traffic mix
GW
11.1
10.8
11.1
10.6
10.5
10.6
2. CDF thickness at max. GW
15.0
15.0
15.0
15.0
14.9
14.9
3. Evaluation thickness from
equivalent pavement
17.0
17.0
17.0
17.0
17.0
17.0
4. Max.Allowable Aircraft GW
from CDF
1,076,982
657,683
785,764
1,558,981
590,004
792,982
5. Aircraft GW from traffic mix
877,000
509,000
608,000
1,235,000
478,000
633,000
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COMFAA Support Spreadsheet
Rigid Charts – Case 1
AC 150/5335-5B Example
Subgrade code= B323.0, t= 17.0
PCN= 100
PCN
Comparison
700
600
PCN= 80
63
96
92
91
87
87
85
PCN= 90
PCN= 70
800
Most Demanding Aircraft in Traffic Mix
61
61
66
68
70
PCN= 60
500
400
PCN= 50
300
PCN= 40
PCN= 30
200
PCN= 20
100
PCN= 10
PCN= 0
A330-200 A340-300
B747-400
std
std
0
A380Wing
B787-8
(Prelimina
ry)
MD11
1. Aircraft ACN at traffic mix
GW
63.0
61.2
61.4
65.8
68.3
69.6
2. Calculated PCN at CDF
max. GW
84.6
86.6
87.0
91.2
92.2
95.8
3. Annual Departures from
traffic mix
754
88
179
59
32
44
COMFAA 3.0 Beta Demonstration & Hands-On Training
2 September 2011
Annual Departures
PCN= 110
• 6 most demanding
aircraft in mix.
• PCN needed for
using traffic is 70.
• PCN based on
CDF analysis can
be reported as
high as 96.
• Next, click on
Form 5010 tab.
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54
COMFAA Support Spreadsheet
Rigid Charts – Case 1
Project info
FLEXIBLE PAVEMENT
Form 5010
MAXIMUM TIRE PRESSURE METHOD USED TO DETERMINE PCN
A Subgrade Category (CBR 15)
B Subgrade Category (CBR 10)
W Unlimited
Using Aircraft
X 218 psi
Technical
• Enter PCN Number.
• PCN can be reported as:
Y 145 psi
C Subgrade Category (CBR 6)
Z
73 psi
96/R/B/W/T
D Subgrade Category (CBR 3)
RIGID PAVEMENT
AIRCRAFT GEAR TYPE IN TRAFFIC MIX
S (single wheel gear)
A Subgrade Category (k 552 pci)
D (dual wheel gear)
B Subgrade Category (k 295 pci)
2D OR 3D (dual tandem OR triple tandem wheel gear)
C Subgrade Category (k 147 pci)
W/B (tandem gear under wing AND tandem gear under body)
D Subgrade Category (k 74 pci)
Enter PCN
96
FAA Form
Gross Weight
5010 Data
and PCN
Element
#35 S
100
#36 D
280
#37 DT
793
#38 DDT
#39 PCN 96 / R / B / W / T
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Case 1 – PCN Comparison
PCN calculated assuming each airplane is treated as the design airplane
120
D Gears
2D Gears
100
PCN or ACN
80
60
A380
B747
40
B757
20
B777
5335-5A PCN/R/B
5335-5B PCN/R/B
Airplane ACN/R/B
0
0
200,000
400,000
600,000
800,000
1,000,000
1,200,000
1,400,000
Reported Operating Weight, lbs. (not the weight used for PCN calculation)
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COMFAA 3.0 – Options
•
Batch
– Runs all airplanes in
succession.
– Automatically invoked by PCN
Flex and Rigid Batch function.
•
•
Metric
PCA Thick
– Equivalent coverages
computed with the PCA
interior stress design method.
•
PCA GW
– Maximum gross weight
computed with the PCA
interior stress design method.
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COMFAA 3.0 – Computational Modes
• ACN – Computes ACN at
indicated gross weight & strength.
• PCN – Computes PCN using
CDF-based procedure.
• Thickness – Computes by AC
150/5320-6D procedure.
• MGW – Computes maximum
gross weight for airplane.
• Life – Computes coverages to
failure for indicated thickness.
• Interior Stress
• Edge Stress
COMFAA 3.0 Beta Demonstration & Hands-On Training
2 September 2011
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COMFAA 2.0 Will Continue to be
Supported – Simpler and Old Alphas
COMFAA 3.0 Beta Demonstration & Hands-On Training
2 September 2011
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More Information
• Contact Dr. Gordon Hayhoe
– Gordon.Hayhoe@faa.gov
• FAA Airport Technology R&D Group
– www.airporttech.tc.faa.gov
– Click on “Downloads” then “Pavements”
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Questions?
COMFAA 3.0 Beta Demonstration & Hands-On Training
2 September 2011
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