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Has the FAA regulated yet the maximum dBs of noise an aircraft's engine is allowed to generate, and what the range of "safe operation" would be? If they have, what are their regulations on it?

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The answer can be found in Annex 16 of the ICAO, a copy including the noise limits can be found here (PDF).

Below a little excerpt from the annex:

(a) For acoustical changes to Stage 1 airplanes, regardless of the number of engines, the noise levels prescribed under § 36.7(c) of this part. What are the 'Chapter 2' and 'Chapter 3' aircraft noise classifications? Certificated noise levels for larger aircraft are classified by the ICAO 'Standards and Recommended Practices – Aircraft Noise: Annex 16 to the Convention on International Civil Aviation' into a) Chapter 2 types, characterised by the noisier, low bypass turbofan aircraft and early high bypass turbofan aircraft, and b) Chapter 3 types, characterised by the modern, quieter, high bypass turbofan aircraft. Under European legislation, since 2002, 'Chapter 2' aircraft (of over 34 tonnes maximum take-off weight or with more than 19 seats) have no longer been allowed to operate at European airports. There are separate noise certification schemes for small propeller aircraft and for helicopters.

(b) For any Stage 2 airplane regardless of the number of engines:

(1) Flyover: 108 EPNdB for maximum weight of 600,000 pounds or more; for each halving of maximum weight (from 600,000 pounds), reduce the limit by 5 EPNdB; the limit is 93 EPNdB for a maximum weight of 75,000 pounds or less.

(2) Lateral and approach: 108 EPNdB for maximum weight of 600,000 pounds or more; for each halving of maximum weight (from 600,000 pounds), reduce the limit by 2 EPNdB; the limit is 102 EPNdB for a maximum weight of 75,000 pounds or less.

(c) For any Stage 3 airplane:

(1) Flyover.

(i) For airplanes with more than 3 engines: 106 EPNdB for maximum weight of 850,000 pounds or more; for each halving of maximum weight (from 850,000 pounds), reduce the limit by 4 EPNdB; the limit is 89 EPNdB for a maximum weight of 44,673 pounds or less;

(ii) For airplanes with 3 engines: 104 EPNdB for maximum weight of 850,000 pounds or more; for each halving of maximum weight (from 850,000 pounds), reduce the limit by 4 EPNdB; the limit is 89 EPNdB for a maximum weight of 63,177 pounds or less; and

(iii) For airplanes with fewer than 3 engines: 101 EPNdB for maximum weight of 850,000 pounds or more; for each halving of maximum weight (from 850,000 pounds), reduce the limit by 4 EPNdB; the limit is 89 EPNdB for a maximum weight of 106,250 pounds or less.

(2) Lateral, regardless of the number of engines: 103 EPNdB for maximum weight of 882,000 pounds or more; for each halving of maximum weight (from 882,000 pounds), reduce the limit by 2.56 EPNdB; the limit is 94 EPNdB for a maximum weight of 77,200 pounds or less.

(3) Approach, regardless of the number of engines: 105 EPNdB for maximum weight of 617,300 pounds or more; for each halving of maximum weight (from 617,300 pounds), reduce the limit by 2.33 EPNdB; the limit is 98 EPNdB for a maximum weight of 77,200 pounds or less.

(d) For any Stage 4 airplane, the flyover, lateral, and approach maximum noise levels are prescribed in Chapter 4, Paragraph 4.4, Maximum Noise Levels, and Chapter 3, Paragraph 3.4, Maximum Noise Levels, of the International Civil Aviation Organization (ICAO) Annex 16, Environmental Protection, Volume I, Aircraft Noise, Third Edition, July 1993, Amendment 7, effective March 21, 2002. [Incorporated by reference, see § 36.6].

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  • $\begingroup$ By the way, the question is tagged FAA and you provided an ICAO answer. Does the FAA require compliance with the ICAO regulations that you have quoted? $\endgroup$ – Lnafziger Jan 17 '14 at 15:27
  • $\begingroup$ @Lnafziger I believe the FAA uses the same Stage 1 / Stage 2 / Stage 3 categories. (There are also some restrictions on operating Stage 2 aircraft buried in the regs.) $\endgroup$ – voretaq7 Jan 17 '14 at 19:57
  • $\begingroup$ @voretaq7 They do use Stage 1/2/3/4, but the regulations and limits might be different.... $\endgroup$ – Lnafziger Jan 17 '14 at 20:09
  • $\begingroup$ @Lnafziger FAR 36 Appendix B seems to match ICAO's numbers (but I've only given it a cursory spot check - reading regulations makes me stabby :-) $\endgroup$ – voretaq7 Jan 17 '14 at 20:16
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If it can be regulated it shall be regulated -- the relevant section of law is FAR 36 - NOISE STANDARDS: AIRCRAFT TYPE AND AIRWORTHINESS CERTIFICATION, with a number of advisory circulars as well.

These requirements are aimed mainly at Transport Category aircraft, and the absolute noise level limits are rather high (certainly nothing you'd want to be standing near without hearing protection).

What's probably of more interest to most people are the FAA's guidelines on Airport Noise, and specifically FAA Order 1050-1E, which deals with the noise you are actually exposed to on the ground (rather than what is generated by the plane's engines).
Order 1050-1E goes into great detail on what is considered "acceptable" noise levels for various types of land use around airports. Airport construction and/or expansion projects are evaluated against these criteria using computational models to ensure that noise levels will not exceed the FAA's guidelines.

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