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I was just wondering if anyone is able to help me. I need to find out, what is the maximum decibel noise level of a stage 4 rated engine (as defined by the Federal Aviation Administration)?

Some more information: I need this information because the General Electric Honda HF120 engine has a noise level rating of stage 4. This is a small turbofan engine that is designed to be used on small business jets, such as the HondaJet. I have tried searching all day, but I cannot seem to find anything.

Thank you for your time and any help would be greatly appreciated.

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    $\begingroup$ First, the FAA certifies aircraft not engines. So the noise levels are measured for the entire aircraft at different points in flight and on the ground. Second, the testing parameters and weighting factors are ridiculously complex. There’s not a simple “X decibels” notation. Different frequencies are rated differently and by impulse time, etc. then the “Effective Perceived Noise Level” is calculated using some pretty hefty algebra. You can check it out here $\endgroup$ – TomMcW Mar 10 '18 at 23:39
  • $\begingroup$ @TomMcW Thank you for the reply. I have been looking into it further and your information has helped as a guide. Are the noise levels of the engines ever tested directly, or are the noise levels of the final aircraft only of concern? Thank you for the link as well. $\endgroup$ – M3DJ0 Mar 12 '18 at 16:10
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    $\begingroup$ The FAA wouldn’t be concerned with just the engine. For one thing, the airframe is a source of a lot of noise when flying. The manufacturer probably does tests on them to provide info to aircraft manufacturers that want to use them. You would most likely have to contact them for that info. $\endgroup$ – TomMcW Mar 13 '18 at 0:24
  • $\begingroup$ @TomMcW Thank you for the information. $\endgroup$ – M3DJ0 Mar 17 '18 at 9:53
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I have found an answer. This datasheet (easa.europa.eu) lists the noise levels for an aircraft with the engines and the stage 4 limits:

enter image description here

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    $\begingroup$ +1. And AFAIK the levels also change depending on the certified MTOW. $\endgroup$ – ymb1 Mar 10 '18 at 22:26
  • $\begingroup$ @ymb1 Thank you for the edited. Yes, I think you are correct that the noise level limits are dependent on the aircraft weight. $\endgroup$ – M3DJ0 Mar 12 '18 at 16:12

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