Aircraft Classification Number and Pavement Classification Number Method

The LCN is airfield-specific and aircraft must comply with it. Subsequently, ICAO introduced a new classification system, known as the aircraft classification number (ACN), which represents the tire-loading limit, and another system that represents the airfield pavement-strength limit, known as the pavement classification number (PCN). Both numbers must be the same to operate at an airport without any restric­tions. However, the LCN method is still in use and conversion is needed to use the ACN/PCN method. This book uses Figure 7.13 to obtain the LCN.

The ACN/PCN method is described in [9]. According to the design manual, the ACN/PCN method is intended only for publication of pavement-strength data in the Aeronautical Information Publication (AIP). It is not intended for design or

Table 7.4. A380 Data

Maximum Ramp Weight = 592,000 kg (1,305,125 lb) Maximum Landing Weight = 427,000 kg (941,365 lb) Zero Fuel Weight = 402,000 kg (886,250 lb)

Tire size and pressure

Maximum load per strut*

CG position

Nose-gear tire size = 1,400 x 530R23 40PR Nose-gear tire pressure = 11.8 bar (171 psi) Wing-gear tire size = 56 x 22R24 40PR Wing-gear tire pressure = 13.6 bar (197 psi) Body-gear tire size = 56 x 22R24 40PR Body-gear tire pressure = 13.6 bar (197 psi)

77,100 kg (169,975 lb) (at 10 ft/s2 braking) 112,500 kg (242,025 lb)

168,750 kg (372,025 lb)

Forwardmost

(at 36% MAC)

Aftmost

(at 42.8% MAC)

Aftmost

(at 42.9% MAC)

Note:

* Maximum load is at maximum ramp weight and at the limiting CG positions.

evaluation of pavements, nor does it contemplate the use of a specific method by the airport authority for either the design or evaluation of pavements. The ACN/PCN method is more elaborate and involved. Parameters like the California Bearing Ratio (CBR) for subgrade-strength soil tests are required to determine tire pres­sure. The LCN method is still in use and can be converted to the ACN and PCN. According to the AIP, “The ACN of an aircraft is numerically defined as two times the derived wheel load, where the derived single wheel load is expressed in thou­sands of kilograms.”

The author was able to locate the Airbus publication for the largest passenger­carrying aircraft, the A380-800F model; pertinent data are listed in Table 7.4. The weight per wheel is distributed relative to the wheel arrangement (see Figure 7.11). The braking deceleration is 10 ft/s2. The horizontal ground load is calculated at a brake coefficient of 0.8. The main landing gears can take as much as 95.5% of the weight.

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