Back in the late 80's or early 90's I wrote an article for our club newsletter about engine noise and specifically referenced a: "decibel (dB) level guideline set by the AMA”. In that article I also specifically stated: “AMA’s dB specifications, state that an airplane at running full throttle at ground level should not exceed 96 dB measured at 3 meters”.

I decided to do an updated/reprint of this article and just spent an hour over on the AMA web site looking for specific wording regarding engine noise and couldn’t find anything other than noise specs for contest. (which don't match the numbers I printed way back when)

So I searched this forum and found threads where the brain trust says an engine noise guideline/rule or whatever basically never existed in the AMA.

Am I losing my mind? Seems something must have existed in the general rules/guidlines at one time, I'm not capable of making stuff like that up.
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There is no "hard and fast" rule, per se. All the AMA recommends is that clubs adopt a policy where mufflers are required, with a set db limit. Contests do have a set db limit on noise.

Yeah, the noise issue is deferred to the clubs, since it's really their butts on the line when it comes to noise complaints. Some clubs out in the middle of nowhere could care less about noise, aside from health concerns.

Not all "Contests". Certain events have such in their specific event rules. However at most such events I have attended, that rule is ignored, so if concerned, check with the event management prior to arriving.

And for BillyGoat, I don't think you are losing it. Back in the '80s there were so many recommendations, changing like the weather, who could stay up with stuff? Definitely not me!! AMA document 535B has this but it is simply a suggestion, a model from which clubs can modify for themselves. "FLYING SITE OPERATIONAL RULES" as a suggestion for a club: "3. Mufflers are required on all models. (db limit recommended). " Again, just something for a club to think about.

According to then Sound Committee Chairman Howard Crispin, in AMA pub SOUND AND MODEL AERONAUTICS A handbook for model clubs, 1991, "Some time ago the AMA Executive Council voted to approve a standard of 90 dBA at nine feet as a recommended figure for clubs to use for operations." It was adapted from a figure used widely in Europe (82 dBA at seven meters) with a change to measurement distance and units, and is essentially the same when the difference in spreading loss due to distance is accounted for.

You aren't losing your mind, but the keyword is "recommended." It may be a reasonable ballpark figure for many clubs sites, but not a panacea. Two most significant shortcomings are 1) not all flying sites are equidistant from neighbors that are potentially impacted by the noise, and 2) it lacks a nexus to cognizant authority. Local (county, city) political subdivisions are the controlling authorities that establish and enforce noise abatement standards, not AMA.

Sound committee? They need a whole committee to figure out sound DB' limits? Do they have a hall monitor also.....

The only ones I know that still get into all that is IMAC

cj_rumley and Hoss if I understand your post correctly, the AMA did publish engine noise standards but it was in the form of a handbook or recommendations to Clubs?

I'm even more perplexed then. Reading the article that is nearly 20 years old and thinking back... I was nothing more than your standard AMA member with no access to information beyond what was mailed to every member. So I surely would have thought the numbers I quoted would have been part of general AMA membership info???

So guess I’ll put this down as one of those things in life that I can’t explain why I did what I did and rewrite the article without the reference to the AMA.

If the neighbors are complaining.....It's to loud........if they arn't then run it!....easy!

BillyGoat-

In the cite from the handbook that I quoted, Crispin referenced action by the EC that had occurred years before. He had a monthly column in MA, certainly this standard was mentioned there long before the handbook was published. I know I was well aware of it at least as far back as ca 1985 when I was involved in establishing a new flying field in a particularly quiet neighborhood, and it must have come from the MA articles (actually, some of my work there is cited by Crispin in the handbook).

FWIW, I think it would be more productive to research local ordinances and tailor standards at your field to meet them than to dwell on this early recommendation from AMA that has been superseded. The AMA recommendation was changed to "comply with local community noise abatement standards" before Dave Brown disbanded the committee and assigned its role to the Flying Site Assistance Committee, and AFAIK it still stands. Joe Besher or Wes De Cou ought to be able to tell you if there have been any developments since.

There is good information to be found in MA archives on how to go about establishing standards for your field, with traceability to applicable community standards. Look for the Sound Committee's quarterly column "Sound Advice" published 1998-99, usually the 1st article in the AMA News section.

The noise 'patrol' at our field will only check your dB ratings if they don't like you! []

cj_rumley, much thanks for the information.

Didn't they appoint Richard Simmons or Jane Fonda the head of the Db Patrol?


It's unimaginable that any man would take such a job........[:'(]

jody powell, i think it was.

How many clubs have dB meters?  Are these things expensive?

Our club has one, but so do I

Sound Pressure Level meters (SPL meters) are availble at Radio Shack for about $40. I believe they offer an analog and digital version. They're both sufficient for environmental noise measurements, includiing gas engines. IMO, the analog version is better suited for dynamic noise measurements because the meter is much easier to read.

The Radio Shack meters are fine for measuring instantaneous levels near the source. Good inexpensive device for testing models for compliance with club standards, once such standards have been established. For measurements needed to set club standards traceable to the applicable codes and ordinances in the locality, an integrating/recoding meter is needed, for a couple of reasons. Ordinances usually specify allowed maximum levels at the noise sensitive sites (residence, school, et al) usually at the property line, at an 'equivalent' dB level, that is an average over some specified time period, usually one hour. The RS meter doesn't have the sensitivity (lowest range is 60 dB) to monitor typical ambient levels and noise abatement ordinance-specified levels at the impacted (i.e., receiving) locations, nor the ability to record a running average of measured levels over some interval. A sound meter up to that task is too expensive to warrant purchase by a club, but can be rented for the short time (a day or two) needed to conduct a reasonable sound survey. The whole point of the survey is to be able to demonstrate, in exactly the same measurement units and at the same locations as specified in community standards, that those standards are being met when your club standards for source levels are being adhered to.