Federal Aviation Administration, DOT

Pt. 36, App. K

Section K4 Noise Limits

takeoff weight (mass) of 176,370 pounds
(80,000 kg) or more, in VTOL/Conversion
mode, 108 EPNdB, decreasing linearly with
the logarithm of the tiltrotor weight (mass)
at a rate of 3.0 EPNdB per halving of weight
(mass) down to 88 EPNdB, after which the
limit is constant. Figure K4 illustrates the
flyover noise limit as a dashed line.
(c) At the approach flight path reference
point: For a tiltrotor having a maximum certificated takeoff weight (mass) of 176,370
pounds (80,000 kg) or more, in VTOL/Conversion mode, 110 EPNdB, decreasing linearly
with the logarithm of the tiltrotors weight
(mass) at a rate of 3.0 EPNdB per halving of
weight (mass) down to 90 EPNdB, after which
the limit is constant. Figure K4 illustrates
the approach noise limit as a dash-dot line.

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For a tiltrotor, the maximum noise levels,
as determined in accordance with the noise
evaluation in EPNdB and calculation method
described in section H36.201 of Appendix H of
this part, must not exceed the noise limits as
follows:
(a) At the takeoff flight path reference point:
For a tiltrotor having a maximum certificated takeoff weight (mass) of 176,370 pounds
(80,000 kg) or more, in VTOL/Conversion
mode, 109 EPNdB, decreasing linearly with
the logarithm of the tiltrotor weight (mass)
at a rate of 3.0 EPNdB per halving of weight
(mass) down to 89 EPNdB, after which the
limit is constant. Figure K4 illustrates the
takeoff noise limit as a solid line.
(b) At the Flyover path reference point: For a
tiltrotor having a maximum certificated