Paragraph 6 Adjustment of flight test results

(1)

Differences between test conditions and reference conditions must require that adjustments be made to the measured L_AE figures for two different effects—

(a)

variations in propeller tip Mach number and hence source noise;

(b)

variations in microlight aeroplane height over the noise measurement position and hence in noise path length.

(2)

The adjustments must be made in accordance with sub-paragraphs (3), (4), (5) and (6).

Adjustment for Propeller Tip Mach Number

(3)

An adjustment for propeller source noise Δm must be added to the measured sound exposure level L_AE_measwhere—

Δ m = 85 \log ((T - 0.0065 H) / 298)

and T is the absolute temperature in degrees Kelvin at the height of the microphone on the test day, and H is the height in metres of the microlight aeroplane over the microphone.

(4)

For microlight aeroplanes described in paragraph 1 of Section 1, if the propeller tip Mach number measured statically is less than 0.7, the adjustment Δm must be taken to be zero.

Adjustment for Noise Path Difference

(5)

Noise measurements made for microlight aeroplane heights over the noise measurement position different from 150m (492 ft) must be adjusted to 150m (492 ft) by adding a correction ΔH1 to the measured sound exposure level L_AE where—

Δ H 1 = 14 \log (H / 150)

and H is the height in metres of the microlight aeroplane over the microphone.

(6)

Reference day sound exposure level (L_AEref) must be obtained from—

L_{A E r e f} = L_{A E m e a s} + Δ m + Δ H 1

where L_AEmeas is the measured value of L_AE.