7.0 PAVEMENT DATA

7.1 General Information

7.2 Footprint

7.3 Maximum Pavement Loads

7.4 Landing Gear Loading on Pavement

7.5 Flexible Pavement Requirements

7.6 Flexible Pavement Requirements, LCN Conversion

7.7 Rigid Pavement Requirements

7.8 Rigid Pavement Requirements, LCN Conversion

7.9 ACN-PCN Reporting System: Flexible and Rigid Pavements

MDC K9099OCTOBER 2002

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OCTOBER 2002MDC K9099

MDC K9099

7.0 PAVEMENT DATA

7.1 General Information

A brief description of the following pavement charts will be helpful in their use for airport planning.Each airplane configuration is shown with a minimum range of five loads imposed on the main landing gear to aid in interpolation between the discrete values shown. All curves for any single chart represent data based on rated loads and tire pressures considered normal and acceptable by current aircraft tire manufacturer's standards.

Section 7.2 presents basic data on the landing gear footprint configuration, maximum design taxi loads, and tire sizes and pressures.

Maximum pavement loads for certain critical conditions at the tire-ground interfaces are shown in Section 7.3.

Pavement requirements for commercial airplanes are customarily derived from the static analysis of loads imposed on the main landing gear struts. The chart in Section 7.4 is provided in order to determine these loads throughout the stability limits of the airplane at rest on the pavement. These main landing gear loads are used as the point of entry to the pavement design charts, interpolating load values where necessary.

The flexible pavement design curves (Section 7.5) are based on procedures set forth in Instruction Report No. S-77-1, "Procedures for Development of CBR Design Curves," dated June 1977, and as modified according to the methods described in FAA Advisory Circular 150/5320-6D, "Airport Pavement Design and Evaluation," dated July 7, 1995. Instruction Report No. S-77-1 was prepared by the U.S. Army Corps of Engineers Waterways Experiment Station, Soils and Pavements Laboratory, Vicksburg, Mississippi. The line showing 10,000 coverages is used to calculate Aircraft Classification Number (ACN).

The following procedure is used to develop the flexible pavement curves:

1. Having established the scale for pavement depth at the bottom and the scale for CBR at the top, an arbitrary line is drawn representing 6,000 annual departures.

2. Values of the aircraft gross weight are then plotted.

3. Additional annual departure lines are drawn based on the load lines of the aircraft gross weights already established.

4. An additional line representing 10,000 coverages (used to calculate the Aircraft Classification Number) is also placed.

OCTOBER 2002 7–1

MDC K9099

Rigid pavement design curves (Section 7.7) have been prepared with the use of the Westergaard equation in general accordance with the relationships outlined in the 1955 Edition of "Design of Concrete-Airport Pavement" published by the Portland Cement Association, 33 W. Grand Ave., Chicago, Illinois, but modified to the new format described in the 1968 Portland Cement Association publication, "Computer Program for Airport Pavement Design" (Program PDILB) by Robert G. Packard.

The following procedure is used to develop the rigid pavement design curves such as that shown in Section 7.7:

1. Having established the scale for pavement thickness to the left and the scale for allowable working stress to the right, an arbitrary load line is drawn representing the main landing gear maximum weight to be shown.

2. All values of the subgrade modulus (k-values) are then plotted.

3. Additional load lines for the incremental values of weight on the main landing gear are then established on the basis of the curve for k = 300, already established.

All Load Classification Number (LCN) curves (Sections 7.6 and 7.8) have been plotted from data in the International Civil Aviation Organization (ICAO) Document 7290-AN/865/2, Aerodrome Manual, Part 2, "Aerodrome Physical Characteristics," 2nd Edition, 1965.

On the same charts showing LCN versus equivalent single wheel load, there are load plots for airplane Model MD-90-30 showing equivalent single wheel load versus pavement thickness for flexible pavements and versus radius of relative stiffness for rigid pavements.

Procedures and curves provided in the ICAO Aerodrome Manual – Part 2, Chapter 4 are used to determine equivalent single wheel loads for use in making LCN conversion of rigid pavement requirements.

Note: Pavement requirements are presented for loads, tires and tire pressures presently certified for commercial usage. All curves represent data at a constant specified tire pressure.

The ACN-PCN system (Section 7.9) as referenced in ICAO Annex 14, “Aerodromes,” 3rd Edition, July 1999, provides a standardized international airplane/pavement rating system replacing the various S, T, TT, LCN, AUW, ISWL, etc., rating systems used throughout the world. ACN is the Aircraft Classification Number and PCN is the corresponding Pavement Classification Number. An aircraft having an ACN equal to or less than the PCN can operate without restriction on the pavement. Numerically, the ACN is two times the derived single wheel load expressed in thousands of kilograms, where the derived single wheel load is defined as the load on a single tire inflated to 1.25 MPa (181 psi) that would have the same pavement requirements as the aircraft. Computationally, the ACN-PCN system uses PCA program PDILB for rigid pavements and S-77-1 for flexible pavements to calculate ACN values. The method of pavement evaluation is left up to the airport with the results of its evaluation presented as follows:

7–2 OCTOBER 2002

MDC K9099

PAVEMENTTYPECODE

RIGIDFLEXIBLE

RF

SUBGRADE CATEGORYCODE

HIGH(k = 150MN/M3)(OR CBR = 15)MEDIUM(k = 80MN/M3)(OR CBR = 10)LOW(k = 40MN/M3)(OR CBR = 6)ULTRA LOW (K = 20MN/M3) (OR CBR = 3)

A

B

C

D

TIREPRESSURECATEGORYCODE

HIGH(NO LIMIT)MEDIUM(LIMITED TO 1.5 MPa)LOW(LIMITED TO 1.0 MPa)VERY LOW (LIMITED TO 0.5 MPa)

W

X

Y

Z

EVALUATION METHODCODE

TECHNICALUSINGAIRCRAFT

TU

PAVEMENTCLASSIFI-CATIONNUMBERPCN

(BEARING STRENGTHFOR UN-RESTRICTEDOPERATIONS)

(s)

This document has been partially revised to incorporate key information for the MD-90-30ER with a maximum ramp weight of 168,500 lbs (76,430 kgs). Due to the fact that there were only two aircraft delivered in this higher weight configuration when production of the model ceased, only limited charts in this section have been revised for the MD-90-30ER. The modified/new charts are limited to the following:

7.2 Footprint7.3 Maximum Pavement Loads7.4 Landing Gear Loading on Pavement7.9.3 Aircraft Classification Number - Flexible Pavement (168,500 lbs)7.9.4 Aircraft Classification Number - Rigid Pavement (168,500 lbs)

Contact Airport Technology for any additional data needed for this high weight model at:

Attention: Airport TechnologyTelephone: 425-237-0126Fax: 425-237-8281Email: AirportTechnology@Boeing.comWebsite: www.boeing.com/airports

7–3OCTOBER 2002

MDC K9099

7.2 FOOTPRINT MODEL MD-90-30/-30ER

168,500 LB (76,430 KG)

26 x 6.6 12 PR

160 PSI (11.3 KG/CM )2

H 44.5 x 16.5 — 21 26 PR

190 PSI (13.4 KG/CM )2

20.6 IN. (52.3 CM)

77 FT 2 IN. (23.5 M)

28.1 IN. (71.4 CM)20 FT 4.8 IN.

(6.22 M)

16 FT 8.2 IN.(5.09 M)

14.0 IN.(35.6 CM)

MAXIMUM DESIGNTAXI WEIGHT

PERCENT OF WEIGHT ON MAIN GEAR

NOSE TIRE SIZE

NOSE TIRE PRESSURE

MAIN GEAR TIRE SIZE

MAIN GEAR TIRE PRESSURE

MD-90-30ERMD-90-30

157,000 LB (71,214 KG)

SEE SECTION 7.4 SEE SECTION 7.4

26 x 6.6 12 PR

170 PSI (11.9 KG/CM )2

H 44.5 x 16.5 — 21 26 PR

193 PSI (13.6 KG/CM )2

7–4 OCTOBER 2002

MDC K9099

7.3

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OCTOBER 2002 7–5

15,3

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63,3

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MDC K9099

7.4 Landing Gear Loading on Pavement

To obtain the airplane weight on the following pavement charts, an equivalent main landing gear weightmust be determined.

In the example shown for the MD-90-30 in Section 7.4.1, for a gross weight of 105,000 lb at 96.48% weight on main gear, the equivalent weight on the main landing gear is 101,200 lb.

7–6 OCTOBER 2002

MDC K9099

7.4.1 LANDING GEAR LOADING ON PAVEMENTMODEL MD-90-30

PERCENT OF WEIGHT ON MAIN GEAR

130

80 85 90 95 100

120

110

100

90

80

70

60

150

140

WEI

GH

T O

N M

AIN

LAN

DIN

G G

EAR

(1,0

00 L

B)

AIR

PLAN

E G

RO

SS W

EIG

HT

(1,0

00 L

B)

70

60

50

40

30

AIR

PLAN

E G

RO

SS W

EIG

HT

(1,0

00 K

G)

10 15 20 25 30 35

160

130

120

110

100

90

80

70

60

150

140

160

40

NOTE: UNSHADED AREAS REPRESENT OPERATIONAL LIMITS

–10 –5

PERCENT MAC

96.48

C.G. FOR ACN CALCULATIONS

MAXIMUM DESIGN TAXI WEIGHT 157,000 LB

50

OCTOBER 2002 7–7

MDC K9099

7.4.2 LANDING GEAR LOADING ON PAVEMENTMODEL MD-90-30ER

PERCENT OF WEIGHT ON MAIN GEAR

WEI

GH

T O

N M

AIN

LAN

DIN

G G

EAR

(1,0

00 L

B)

AIR

PLAN

E G

RO

SS W

EIG

HT

(1,0

00 L

B)

AIR

PLAN

E G

RO

SS W

EIG

HT

(1,0

00 K

G)

NOTE: UNSHADED AREAS REPRESENT OPERATIONAL LIMITS

OCTOBER 20027–8

-5 5 10 15 20 25 30-10 0

80 85 90 95 100

150

140

130

120

110

100

90

160

40

45

50

55

60

65

70

160

90

100

110

120

140

150

130

170

75

170

C.G. FOR ACNCALCULATIONS

93.96

PERCENT MAC

MAXIMUM DESIGN TAXI WEIGHT 168,500 LB

MDC K9099

7.5 Flexible Pavement Requirements -- U.S. Army Corps of Engineers Method (S-77-1)

The following flexible-pavement design chart presents data for 5 incremental main-gear weights at a constant main-gear tire pressure of 200 psi (14.1 kg/cm ).2

In the example shown for the MD-90-30, for a CBR of 7.0, a main-gear load of 100,000 lb, and an annual departure level of 6,000, the required pavement thickness is 24.5 inches.

The line showing 10,000 coverages is used for ACN calculations (see section 7.9).

The FAA design method uses a similar procedure using total airplane weight instead of weight on main landing gear. The equivalent main gear loads for a given airplane weight can be calculated from Section 7.4.

7–9OCTOBER 2002

MDC K9099

7.5.1 FLEXIBLE PAVEMENT REQUIREMENTSU.S. ARMY CORPS OF ENGINEERS/FAA DESIGN METHOD

MODEL MD-90-30

(CENTIMETERS)

NOTES: � H44.5 x 16.5–21, 26 PR TIRES� TIRE PRESSURE CONSTANT AT 200 PSI (14.1 KG/CM )

SUBGRADE STRENGTH (CBR)15 25

WEIGHT ON MAINLANDING GEAR

(SEE SECTION 7.4)

151,500 (68,720)140,000 (63,500)120,000 (54,400)100,000 (45,400)80,000 (36,300)

LB (KG)

ANNUALDEPARTURES

1,2003,0006,00015,00025,000

10,000 COVERAGES(USED FOR ACN CALCULATIONS)

* 20-YEAR PAVEMENT LIFE

15 25

10 15 20 25 30 40 50 60 80 100 120

MAX POSSIBLE MAINGEAR LOAD AT MAXDESIGN TAXI WEIGHTAND AFT C.G.4

INCHES

FLEXIBLE PAVEMENT THICKNESS

2

3 4 5 6 7 8 9 10 20 30 40 50

3 4 5 6 7 8 9 10 20 30 40 50

OCTOBER 20027–10

MDC K9099

7.6 Flexible Pavement Requirements, LCN Conversion

To determine the airplane weight that can be accommodated on a particular flexible airport pavement,both the LCN of the pavement and the thickness (h) of the pavement must be known.

In the example shown for the MD-90-30, the flexible pavement thickness is 30 inches and the LCN is 70.For these conditions, the weight on the main landing gear is 110,000 pounds.

If the resulting aircraft LCN is not more than 10 percent above the published pavement LCN, the bearing strength of the pavement can be considered sufficient for unlimited use by the airplane. The figure of 10 percent has been chosen as representing the lowest degree of variation in LCN which is significant. (Reference: ICAO Aerodrome Design Manual, Part 2, "Aerodrome Physical Characteristics," Chpt. 4, Para. 4.1.5.7v, 2nd Edition, 1965.)

Note:

7–11OCTOBER 2002

MDC K9099

7.6.

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PAV

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40

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5060

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CN

)

4030

5060

7020

1580

9010

0

510203040

EQUIVALENT SINGLE WHEEL LOAD (1,000 KG)• H

44.5

x 1

6.5-

21, 2

6 PR

TIR

ES• T

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PRES

SUR

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ON

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140,

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120,

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100,

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80,0

00

(68,

720)

(63,

500)

(54,

400)

(45,

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(36,

300)

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90 80 70 60 50 40 30 20 10

EQUIVALENT SINGLE WHEEL LOAD (1,000 KG)

OCTOBER 20027–12

MDC K9099

7.7 Rigid Pavement Requirements, Portland Cement Association Design Method

The following rigid-pavement design chart presents data for 5 incremental main-gear weights at a constant main-gear tire pressure of 200 psi (14.1 kg/cm ).2

In the example shown for the MD-90-30, for an allowable working stress of 400 psi, a main-gear load of 127,000 lb, and a subgrade strength k of 150, the required rigid-pavement thickness is 12 inches.

7–13OCTOBER 2002

MDC K9099

7.7.1 RIGID PAVEMENT REQUIREMENTS,PORTLAND CEMENT ASSOCIATION DESIGN METHOD

MODEL MD-90-30

THE VALUES OBTAINED BY USING THE MAX LOAD REFERENCE LINE AND ANY VALUES OF k ARE EXACT.FOR LOADS LESS THAN MAXIMUM, THE CURVES ARE EXACT FOR k = 300, BUT DEVIATE SLIGHTLY FOROTHER VALUES OF k.

REF: “DESIGN OF CONCRETE AIRPORT PAVEMENT" AND "COMPUTER PROGRAM FOR AIRPORT PAVEMENTDESIGN -- PROGRAM PDILB," PORTLAND CEMENT ASSOCIATION.

18

16

14

12

10

8

50

45

40

35

30

25

20

PAVE

MEN

T TH

ICKN

ESS

IN.(CM)

20

6

800

700

600

500

400

300

60

50

40

30

20

ALLO

WAB

LE W

OR

KIN

G S

TRES

S

PSI (KG/CM )2

900

200

151,500 (68,720)140,000 (63,500)120,000 (54,400)100,000 (45,400) 80,000 (36,300)

LB (KG)

k = 75k = 150k = 300k = 550

MAXIMUM POSSIBLE MAIN GEARLOAD AT MAXIMUM DESIGN TAXIWEIGHT AND AFT C.G.

WEIGHT ON MAIN LANDING GEAR(SEE SECTION 7.4)

NOTES: � H44.5 x 16.5–21, 26 PR TIRES� TIRE PRESSURE CONSTANT AT 200 PSI (14.1 KG/CM )2

NOTE:

OCTOBER 20027–14

MDC K9099

7.8 Rigid Pavement Requirements, LCN Conversion

To determine the airplane weight that can be accommodated on a particular rigid airport pavement, boththe LCN of the pavement and the radius of relative stiffness must be known.

In the example shown in section 7.8.2, the rigid pavement radius of relative stiffness is 35 inches and theLCN is 70. For these conditions, the weight on the main landing gear is 115,000 pounds.

Note: If the resulting aircraft LCN is not more than 10 percent above the published pavement LCN, thebearing strength of the pavement can be considered sufficient for unlimited use by the airplane. Thefigure of 10 percent has been chosen as representing the lowest degree of variation in LCN which issignificant. (Reference: ICAO Aerodrome Design Manual, Part 2, “Aerodrome Physical Characteristics,”Chpt. 4, Para. 4.1.5.7v, 2nd Edition, 1965.)

7–15OCTOBER 2002

MDC K9099

7.8.1 RADIUS OF RELATIVE STIFFNESS(REFERENCE: PORTLAND CEMENT ASSOCIATION)

RADIUS OF RELATIVE STIFFNESS ( )VALUES IN INCHES

WHERE: E = YOUNG’S MODULUS = 4 x 106 PSIk = SUBGRADE MODULUS, LB/IN.3d = RIGID-PAVEMENT THICKNESS, IN.µ = POISSON’S RATIO = 0.15

6.06.57.07.5

8.08.59.09.5

10.010.511.011.5

12.012.513.013.5

14.014.515.015.5

16.016.517.017.5

18.019.020.021.0

22.023.024.025.0

31.4833.4335.3437.22

39.0640.8842.6744.43

46.1847.9049.6051.28

52.9454.5956.2257.83

59.4361.0262.5964.15

65.6967.2368.7570.26

71.7674.7377.6680.55

83.4186.2489.0491.81

26.4728.1129.7231.29

32.8534.3735.8837.36

38.8340.2841.7143.12

44.5245.9047.2748.63

49.9851.3152.6353.94

55.2456.5357.8159.08

60.3462.8465.3067.74

70.1472.5274.8777.20

24.6326.1627.6529.12

30.5731.9933.3934.77

36.1437.4838.8140.13

41.4342.7243.9945.26

46.5147.7548.9850.20

51.4152.6153.8054.98

56.1658.4860.7763.04

65.2867.4969.6871.84

22.2623.6424.9926.32

27.6228.9130.1731.42

32.6533.8735.0736.26

37.4438.6039.7540.89

42.0243.1544.2645.36

46.4547.5448.6149.68

50.7452.8454.9156.96

58.9860.9862.9664.92

21.4222.7424.0425.32

26.5827.8129.0330.23

31.4232.5933.7534.89

36.0237.1438.2539.35

40.4441.5142.5843.64

44.7045.7446.7747.80

48.8250.8452.8454.81

56.7558.6860.5862.46

20.7222.0023.2524.49

25.7026.9028.0829.24

30.3931.5232.6433.74

34.8435.9236.9938.06

39.1140.1541.1942.21

43.2344.2445.2446.23

47.2249.1751.1053.01

54.8956.7558.5960.41

19.5920.8021.9923.16

24.3125.4426.5527.65

28.7429.8130.8731.91

32.9533.9734.9935.99

36.9937.9738.9539.92

40.8841.8442.7843.72

44.6646.5148.3350.13

51.9153.6755.4157.14

19.1320.3121.4722.61

23.7424.8425.9327.00

28.0629.1130.1431.16

32.1733.1734.1635.14

36.1237.0838.0338.98

39.9240.8541.7842.70

43.6145.4147.1948.95

50.6952.4154.1155.79

23.3024.7426.1527.54

28.9130.2531.5832.89

34.1735.4536.7137.95

39.1840.4041.6142.80

43.9845.1646.3247.47

48.6249.7550.8852.00

53.1155.3157.4759.62

61.7363.8365.9067.95

29.3031.1132.8934.63

36.3538.0439.7141.35

42.9744.5746.1647.72

49.2750.8052.3253.82

55.3156.7858.2559.70

61.1362.5663.9865.38

66.7869.5472.2774.96

77.6380.2682.8685.44

d (IN.) k = 75 k = 100 k = 150 k = 200 k = 250 k = 300 k = 350 k = 400 k = 500 k = 550

�

4 Ed3=

12(1- µ2 )k424.1652 d 3

k= l

l

OCTOBER 20027–16

MDC K9099

7.8.

2 R

IGID

PAV

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T R

EQU

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, LC

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NM

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S ( l

)200

8010

0

4030

12050

6070

80

150

20

6050

102030405060708090100

EQUIVALENT SINGLE WHEEL LOAD (1,000 LB)

NO

TE:

EQU

IVA

LEN

T SI

NG

LE W

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L LO

AD

S A

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2, P

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.

4030

5060

7080

100

90

510203040

EQUIVALENT SINGLE WHEEL LOAD (1,000 KG)

• H44

.5 x

16.

5-21

, 26

PR T

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• TIR

E PR

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RE

CO

NST

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AT

200

PSI

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AIN

LA

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LB(K

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151,

500

140,

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120,

000

100,

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80,0

00

(68,

720)

(63,

500)

(54,

400)

(45,

400)

(36,

300)

INC

HES

MA

XIM

UM

PO

SSIB

LE M

AIN

GEA

RLO

AD

AT

MA

XIM

UM

DES

IGN

TA

XIW

EIG

HT

AN

D A

FT C

.G.

7–17OCTOBER 2002

MDC K9099

7.8.3 Radius of Relative Stiffness (Other values of E and l )

The chart of Section 7.8.1 presents l -values based on Young's modulus (E) of 4,000,000 psi and Poisson's ratio (µ of 0.15). For convenience in finding l -values based on other values of E and µ, the curves of Section 7.8 are included. For example, to find an l -value based on an E of 3,000,000 psi, the "E" factor of 0.931 is multiplied by the l -value found in the table of Section 7.8.1. The effect of variations of µ on the l -value is treated in a similar manner.

OCTOBER 20027–18

MDC K9099

7.8.4 EFFECT OF E AND µ ON l -VALUES

E, YOUNG’S MODULUS (10 , PSI)6

1.10

0

1.015

0 0.05 0.20 0.25

1.05

1.00

0.95

0.90

0.85

0.80

0

1.010

1.005

1.000

0.995

0

NOTE: BOTH CURVES ON THIS PAGE ARE USED TO ADJUST THE l -VALUESOF TABLE 7.8.1

FACTOR

E FACTOR

EFFECT OF E ON -VALUES

EFFECT OF µ ON -VALUES

1 2 3 4 5

l

l

µ

µ POISSON'S RATIO

7–19OCTOBER 2002

MDC K9099

7.9 ACN-PCN Reporting System: Flexible and Rigid Pavements

To determine the ACN of an aircraft on flexible or rigid pavement, both the aircraft gross weight and the subgrade strength category must be known. As an example, referring to Section 7.9.1, for an aircraft gross weight of 130,000 pounds and low subgrade strength, the ACN for flexible pavement is 39. Referring to Section 7.9.3, for the same gross weight and subgrade strength, the ACN for rigid pavement is 43.

Note: An aircraft with an ACN equal to or less than the reported PCN can operate on the pavement subject to any limitations on the tire pressure. (Reference: ICAO Annex 14, “Aerodromes,” 3rd Edition, July 1999.)

The following table provides ACN data in tabular format similar to the one used by ICAO in the "Aerodrome Design Manual Part 3, Pavements".

ACN FOR RIGID PAVEMENT SUBBRADES -- MN/m 3

ACN FOR FLEXIBLE PAVEMENT SUBGRADES -- CBR

AIRCRAFT TYPE

ALL-UP MASS/ OPERATING

MASS EMPTY LB (KG)

ON ONE MAIN GEAR LEG (%)

TIRE PRESSUREPSI (MPa)

HIGH 150

MEDIUM 80

LOW 40

ULTRA LOW

20

HIGH 15

MEDIUM 10

LOW 6

ULTRA LOW

3

157,000 (71,214)88,171 (39,994)

48.24 200 (1.4) 4925

5126

5327

5528

4221

4622

5024

5328

168,500 (76,430)89,059 (40,396)

46.98 193 (1.33) 5124

5325

5526

57 4420

4821

5224

5527

MD-90-30

27MD-90-30ER

OCTOBER 20027–20

MDC K9099

7.9.

1 A

IRC

RA

FT C

LASS

IFIC

ATIO

N N

UM

BER

-- F

LEXI

BLE

PAV

EMEN

T (1

57,0

00 L

BS)

MO

DEL

MD

-90-

30

(1,0

00 K

ILO

GR

AM

S)65

6055

5045

90

1010

011

012

013

014

015

016

0

AIR

PLA

NE

GR

OSS

WEI

GH

T, 1

,000

PO

UN

DS

NO

TES:

• A

CN

WA

S D

ETER

MIN

ED A

S R

EFER

ENC

ED

IN IC

AO

AN

NEX

14,

"A

ERO

DR

OM

ES,"

3R

D E

DIT

ION

, JU

LY 1

999

• TO

DET

ERM

INE

MA

IN-G

EAR

LO

AD

ING

,

SEE

SEC

TIO

N 7

.4

AIRPLANE CLASSIFICATION NUMBER (ACN)

2030405060

• H44

.5 x

16.

5-21

, 26

PR T

IRES

• TIR

E PR

ESSU

RE

CO

NST

RA

INT

AT

200

PSI (

14.1

KG

/CM

)N

OTE

S:

70

7–21OCTOBER 2002

(CB

R =

3)

(CB

R =

6)

(CB

R =

10)

(CB

R =

15)

SUB

GR

AD

E C

LASS

D -

ULT

RA

LO

WC

- LO

WB

- M

EDIU

MA

- H

IGH

2

MDC K9099

7.9.

2 A

IRC

RA

FT C

LASS

IFIC

ATIO

N N

UM

BER

-- F

LEXI

BLE

PAV

EMEN

T (1

68,5

00 L

BS)

M

OD

EL M

D-9

0-30

ER

AIR

PLA

NE

GR

OSS

WEI

GH

T, 1

,000

PO

UN

DS

• H44

.5 x

16.

5-21

, 26

PR T

IRES

• TIR

E PR

ESSU

RE

CO

NST

RA

INT

AT

193

PSI (

13.6

KG

/CM

)N

OTE

S:

OCTOBER 20027–22

170

9010

011

012

013

014

015

016

0102030405060 40

4565

AIRCRAFT CLASSIFICATION NUMBER (ACN)

5055

6070

75

2

NO

TES:

• A

CN

WA

S D

ETER

MIN

ED A

S R

EFER

ENC

ED

IN IC

AO

AN

NEX

14,

"A

ERO

DR

OM

ES,"

3

RD

ED

ITIO

N, J

ULY

199

9•

TO D

ETER

MIN

E M

AIN

-GEA

R L

OA

DIN

G,

S

EE S

ECTI

ON

7.4

• P

ERC

ENT

WEI

GH

T O

N M

AIN

LA

ND

ING

GEA

R:

93.9

6

(1,0

00 K

ILO

GR

AM

S)

(CB

R =

3)

(CB

R =

6)

(CB

R =

10)

(CB

R =

15)

SUB

GR

AD

E C

LASS

D -

ULT

RA

LO

WC

- LO

WB

- M

EDIU

MA

- H

IGH

MDC K9099

7.9.

3 A

IRC

RA

FT C

LASS

IFIC

ATIO

N N

UM

BER

-- R

IGID

PAV

EMEN

T (1

57,0

00 L

BS)

MO

DEL

MD

-90-

30

(1,0

00 K

ILO

GR

AM

S)

AIR

PLA

NE

GR

OSS

WEI

GH

T, 1

,000

PO

UN

DS

AIRPLANE CLASSIFICATION NUMBER (ACN)

NO

TES:

• A

CN

WA

S D

ETER

MIN

ED A

S R

EFER

ENC

ED

IN IC

AO

AN

NEX

14,

"A

ERO

DR

OM

ES,"

3

RD

ED

ITIO

N, J

ULY

199

9•

TO D

ETER

MIN

E M

AIN

-GEA

R L

OA

DIN

G,

S

EE S

ECTI

ON

7.4

10

90

2030405060

100

110

120

130

150

140

160

7065

6055

5045

(k =

75

)(k

= 1

50)

(k =

300

)(k

= 5

50)

SUB

GR

AD

E C

LASS

D -

ULT

RA

LO

WC

- LO

WB

- M

EDIU

MA

- H

IGH

NO

TES:

• H44

.5 x

16.

5-21

, 26

PR T

IRES

• TIR

E PR

ESSU

RE

CO

NST

RA

INT

AT

200

PSI (

14.1

KG

/CM

)2

OCTOBER 2002 7–23

MDC K9099

7.9.

4 A

IRC

RA

FT C

LASS

IFIC

ATIO

N N

UM

BER

-- R

IGID

PAV

EMEN

T (1

68,5

00 L

BS)

M

OD

EL M

D-9

0-30

ER

(1,0

00 K

ILO

GR

AM

S)

AIR

PLA

NE

GR

OSS

WEI

GH

T, 1

,000

PO

UN

DS

AIRPLANE CLASSIFICATION NUMBER (ACN)

NO

TES:

• H44

.5 x

16.

5-21

, 26

PR T

IRES

• TIR

E PR

ESSU

RE

CO

NST

RA

INT

AT

193

PSI (

13.6

KG

/CM

)2

OCTOBER 20027-24

170

9010

011

012

013

014

015

016

0102030405060 40

4565

5055

6070

75

SUB

GR

AD

E C

LASS

D -

ULT

RA

LO

WC

- LO

WB

- M

EDIU

MA

- H

IGH

(k =

75

)(k

= 1

50)

(k =

300

)(k

= 5

50)

NO

TES:

• AC

N W

AS D

ETER

MIN

ED A

S RE

FERE

NCED

IN

ICAO

ANN

EX 1

4, "

AERO

DRO

MES

,"

3RD

EDI

TIO

N, J

ULY

1999

• TO

DET

ERM

INE

MAI

N-G

EAR

LOAD

ING

,

SEE

SEC

TIO

N 7.

4•

PER

CENT

WEI

GHT

ON

MAI

N LA

NDIN

G

G

EAR:

93.

96

MDC K9099

7.9.5 Development of ACN Charts

The ACN charts for flexible and rigid pavements were developed by methods referenced in ICAO Annex 14, "Aerodromes," 3rd Edition, July 1999. The procedures used to develop these charts are also described below.

The following procedure is used to develop the flexible-pavement ACN charts such as that shown in Section 7.9.1:

1. Determine the percentage of weight on the main gear to be used below in Steps 2, 3, and 4, below. The maximum aft center-of-gravity position yields the critical loading on the critical gear (see Section 7.4). This center-of-gravity position is used to determine main gear loads at all gross weights of the model being considered.

2. Establish a flexible-pavement requirements chart using the S-77-1 design method, such as shown on the right side of Section 7.9.6. Use standard subgrade strengths of CBR 3, 6, 10, and 15 percent and 10,000 coverages. This chart provides the same thickness values as those of Section 7.5.1, but is presented here in a different format.

3. Determine reference thickness values from the pavement requirements chart of Step 2 for each standard subgrade strength and gear loading.

4. Enter the reference thickness values into the ACN flexible-pavement conversion chart shown on the left side of Figure 7.9.6 to determine ACN. This chart was developed using the S-77-1 design method with a single tire inflated to 1.25 MPa (181 psi) pressure and 10,000 coverages. The ACN is two times the derived single-wheel load expressed in thousands of kilograms. These values of ACN are then plotted as functions of aircraft gross weight, as shown in Section 7.9.1.

The following procedure is used to develop the rigid-pavement ACN charts such as that shown in Section 7.9.2:

1. Determine the percentage of weight on the main gear to be used in Steps 2, 3, and 4, below. The maximum aft center-of-gravity position yields the critical loading on the critical gear (see Section 7.4). This center-of-gravity position is used to determinemain gear loads at all gross weights of the model being considered.

.

2. Establish a rigid-pavement requirements chart using the PCA computer program PDILB, such as shown on the right side of Section 7.9.7. Use standard subgrade strengths of k = 75, 150, 300, and 550 lb/in. (nominal values for k = 20, 40, 80, and 15 MN/M ). This chart provides the same thickness values as those of Section 7.7.1.

3

7–25OCTOBER 2002

3

MDC K9099

3 Determine reference thickness values from the pavement requirements chart of Step 2 foreach standard subgrade strength and gear loading at 400 psi working stress (nominal valuefor 2.75 MPa working stress).

4. Enter the reference thickness values into the ACN rigid-pavement conversion chart shown onthe left side of Section 7.9.7 to determine ACN. This chart was developed using the PCAcomputer program PDILB with a single tire inflated to 1.25 MPa (181 psi) pressure and aworking stress of 2.75 MPa (400 psi.) The ACN is two times the derived single-wheel loadexpressed in thousands of kilograms. These values of ACN were plotted as functions ofaircraft gross weight, as already shown in Section 7.9.2.

OCTOBER 20027–26

MDC K9099

7.9.

6 D

EVEL

OPM

ENT

OF

AIR

CR

AFT

CLA

SSIF

ICAT

ION

NU

MB

ER (A

CN

) - F

LEXI

BLE

PAV

EMEN

TM

OD

EL M

D-9

0-30

ALLOWABLE WORKING STRESS (PSI)

REFERENCE THICKNESS, INCHES

AIR

CR

AFT

CLA

SSIF

ICA

TIO

N N

UM

BER

(AC

N)

1520

3040

500 10 20 20 40 50

AC

N F

LEXI

BLE

PA

VEM

ENT

CO

NVE

RSI

ON

CH

AR

T

CBR 3

CBR

6

CBR

10

CBR

15

NO

TES:

• H44

.5 x

16.

5-21

, 26

PR T

IRES

• TIR

E PR

ESSU

RE

CO

NST

RA

INT

AT

200

PSI (

14.1

KG

/CM

)2

MA

XIM

UM

PO

SSIB

LE M

AIN

GEA

R L

OA

D A

TM

AX

DES

IGN

TA

XI W

EIG

HT

AN

D A

FT C

.G.

WEI

GH

T O

N M

AIN

LA

ND

ING

GEA

R(S

EE S

ECTI

ON

7.4

)

(68,

720)

(63,

500)

(54,

400)

(45,

400)

(36,

300)

151,

500

140,

000

120,

000

100,

000

80,0

00

LB(K

G)

0 10 20 30 40 503

610

15

FLEX

IBLE

PA

VEM

ENT

REQ

UIR

EMEN

TS C

HA

RT

10,0

00 C

OVE

RA

GES

S-77

-1 D

ESIG

N M

ETH

OD

SUB

GR

AD

E ST

REN

GTH

, CB

R

7–27OCTOBER 2002

MDC K9099

7.9.

7 D

EVEL

OPM

ENT

OF

AIR

CR

AFT

CLA

SSIF

ICAT

ION

NU

MB

ER (A

CN

) - R

IGID

PAV

EMEN

TM

OD

EL M

D-9

0-30

AIR

CR

AFT

CLA

SSIF

ICA

TIO

N N

UM

BER

(AC

N)

NO

TES:

• H44

.5 x

16.

5-21

, 26

PR T

IRES

• TIR

E PR

ESSU

RE

CO

NST

RA

INT

AT

200

PSI (

14.1

KG

/CM

2 )80

6040

200

2020

1818

1616

1414

1212

1010

88

66

900

800

700

600

500

400

300

200

ALLOWABLE WORKING STRESS (PSI)

REFERENCE THICKNESS, INCHES

AC

N R

IGID

PA

VEM

ENT

CO

NVE

RSI

ON

CH

AR

T

MA

XIM

UM

PO

SSIB

LE M

AIN

GEA

R L

OA

D A

TM

AX

DES

IGN

TA

XI W

EIG

HT

AN

D A

FT C

.G.

RIG

ID P

AVE

MEN

TR

EQU

IREM

ENTS

CH

AR

TPC

A P

RO

GR

AM

PD

LB

WEI

GH

T O

N M

AIN

LA

ND

ING

GEA

R(S

EE S

ECTI

ON

7.4

)

(68,

720)

(63,

500)

(54,

400)

(45,

400)

(36,

300)

151,

500

140,

000

120,

000

100,

000

80,0

00

LB(K

G)

k =

75

k =

150

k =

300

k =

550

k =

75

k =

150

k =

300

k =

550

OCTOBER 20027–28