Noise levels

[raven2]

I have been granted planning permission for a heli pad and storage facility in a field near my home. One of the conditions of planning is that noise levels are not to exceed 55dBA over a 15minute period

Local residents have appealed the application and one of their arguments is

“It is feasible that the noise level could exceed 120 dBA at which a persons hearing would be damaged but on average over a period of 15minutes not exceed the 55dBA and would therefore not be in breach of planning permission. We also note that it is normal practice in industry for employees to wear ear protection at any noises over 80 dBA”

The helicopter is a R44 raven 2, and I would expect there would be 10 takeoffs and landings per week.

Can anybody advise on noise levels? Nearest residents would be 100 to 150 meters away.

They have also questioned safe approach’s etc but I am fairly OK on this.

Thanks

Raven2

[belly tank]

Raven,

we have received approval for a heliport here in Australia 12 months ago also, not sure about your requirements but we also had a EPENL [effective perceived noise exposure level] over the 15 min period, however our facility is somewhat 900+m away from a residential area.

it also depends on background noise and timed exposure levels for the period your planning to operate. we have approvals now for 7 days 6 am to 10pm with no limit on aircraft providing that they meet the required 85dba for a indusrtial area.

it took us 6 months to sort out our noise requirements and alot of headaches!, we actually sat down with our residents group and explained our operation and flight paths.

bearing in mind an industrial workshop has a average of 86-90dba rating for the 15 min period your talking about and an r44 is well below that.

it again depends on your location and frequency to the residents and note you said your going to do 10 movements a week, well this is nothing, here in OZ if you do 7 or less movements per week you dont need a council DA, this is for our state as i know it.

go speak to your residents grouo tell them about your operation, i found this to be invaluble and they see a face to the name so to speak.

noise exposures are a complex matter and you and i may think well its ok, but average joe who works nightshift and complains about helicopters waking him up during the day may think otherwise even though he lives next to a freight train line which make 3 times the noise!!

pm me i can dig out my files and have look if you need more answers.

remeber that helicopter noise is for short quick bursts and they dont neccesarily equate to a great deal of noise exposure.

cheers BT

[Helinut]

Noise is considered both in terms of absolute noise levels and the dose of noise received. Dose is level x duration of exposure.

A basic threshold for occupational noise levels is 80 dBa exposure on the basis of an 8 hour working day. It does not mean that this cannot be exceeded, but above this there is a risk of hearing loss, if someone was exposed over a long period (i.e. as someone would when working in a factory).

A level of 120 dBa is considered as a threshold at which hearing damage can be caused by a one-off short duration exposure.

Apart from damage to hearing, the other consideration is "noise nuisance". This is what is normally important in "neighbour disputes" like the one you have. It sounds to me like the local authority are trying to set (what they consider) a reasonable level that they can then measure to check for compliance. You don't say where the noise limit is to be measured, which is obviously pretty important.

From your very brief summary, it sounds to me like your neighbours have got hold of some fairly half-baked information about noise and are trying to use it to have their NIMBY way.

In responding to the points raised by your good neighbours:

1. The instantaneous noise level from an R44 will not exceed 120 dBa, even right next to the helicopter. If it did, anyone being near one without hearing protection would suffer hearing damage from a one-off exposure. It will probably exceed 80 dBa, but that is not significant, because the exposure time will be short (usually). Unless, of course you are the pilot and you don't wear a headset!!
2. The occupational requirement to consider hearing protection above 80 dBa is only when the exposure period approaches an 8 hour working day - It is not relevant to your situation because the exposure period from your operation will be short.

The number of take-offs and landings is not significant, in terms of the limit imposed by the LA, assuming that you don't squeeze all of them into a 15 minute period! As long as you separate each movement so that only one occurs in a 15 minute period, you only need to be able to show that the average noise level over any 15 minute period is less than 55 dBa. If you take a typical start-up and take-off, the noise levels would need to be measured from say engine start, warm-up, pre-flight checks, take-off and then departure through to the aircraft disappearing.

You can ease matters by keeping it as prompt as possible.

An approach and landing would be the same but in reverse. However, you would expect that to be quicker and less noisy.

There are meters that measure both the instantaneous and the dose/average levels over a period.

The best way to PROVE what is going on is to measure it with meters. It sounds like the LA might be wanting to do that anyway.


Hope that helps a bit. If you want you can PM me and discuss it some more..

[headsethair]

In your Raven II CAA paperwork is a noise certificate - which should contain a ratified figure that is way below the acceptable thresholds.
In my experience the worst noise from approaches and landings in R44s comes from the tail rotor. If you can keep your approaches & departures into wind for as long as possible, if you can do approaches with minimal power and blade slap, you will keep everyone happy.
I was in a very peaceful place last weekend with a group of 44s - and we felt guilty everytime we started up. But with some sensible planning for departures (max ROC, get the height and get away) and approaches (keeping out of blade slap, approaching into wind with minimal power) and only ground-running for the minimum possible time : we made way less noise.
On departures, the difference in noise between a machine being flown in accordance with the string and one that has its pedals in the wrong position is immense.

[Ascend Charlie]

You would be pushing it to measure 120dB anywhere other than a foot from a turbine engine.

Talk to the neighbours. Explain that the noise will be low for about 2 minutes on startup, moderate for one minute of run-up, a little more for another minute for takeoff, and 40 seconds later it is gone. On arrival, the level is low for a minute of approach, moderate for a minute of landing, low for two minute rundown. Less than 9 minutes of engine running per movement. Probably quieter than their vacuum cleaner, which they voluntarily run for 30 minutes twice a week, MUCH quieter than their lawn mower for 30 minutes, MUCH MUCH quieter than their circular saw some weekends.

A lot of the trouble is this: people feel they have no control over most noise (Hells Angels on their Harleys roaring down the road, the garbage truck at 3 am, the semi-trailers rumbling past their doors). Complaining about these will have zero result, so they don't bother.

BUT! If a neighbour gets a helicopter, a complaint will have a bigger result. So they do, even if it is quieter than the Angels.

There is also "perceived noise", where people associate the noise with wealth and jealousy. If they can't have a helicopter, you can't either.

So, talk to them. Take them for a ride to see their house from the air. Some of them will refuse to be nice, others will appreciate the gesture.

Lotsa luck.:ok: