Noise Signature 429 vs 135 vs 130

[KiwiNedNZ]

Have a friend who is looking at both 429 and 135 but am trying to find some info for him on the decibel readings of each.

Would any member here who what the decibel readings are for the 130, 135 and 429.

Thanks for your help.

[Windmill Wiz]

Good morning
You can find this data via the EASA Type Certificate Data Sheet for Noise:
Bell 429: https://www.easa.europa.eu/sites/default/files/dfu/EASA.IM_.R.506%20Issue2.pdf
EC130: https://www.easa.europa.eu/sites/default/files/dfu/TCDSN%20EASA.R.008%20Issue%2009.pdf
EC135: https://www.easa.europa.eu/sites/default/files/dfu/EASA.R.009%20Issue%2010.pdf
These are the EASA versions, the FAA equivalents can be found via FAA website.

[Tallguy]

I've sent you a pm...

[atakacs]

Mostly irrelevant but for some reason I can identify each type by ear almost 100% of the time 😜
Can't really say one is significantly louder but each have a fairly distinct sound.

[aa777888]

Interesting. Barely a dB difference between them. Form follows function follows regulation, I guess. Don't forget it takes a 10dB difference in SPL to sound twice (or half) as loud to human ears.

[casper64]

Mostly irrelevant but for some reason I can identify each type by ear almost 100% of the time 😜
Can't really say one is significantly louder but each have a fairly distinct sound.

Correct… tail rotor noise of the 429 is significantly louder than the fenestron, but side intake of new 135 is pretty loud as well..

[KiwiNedNZ]

Thanks for the help everyone - have passed on info to he who needs it.

[Hot and Hi]

Measurable differences is sound pressure levels while flying overhead aside, the H130 has by far the least obtrusive sound signature of the three.

[Tickle]

Measurable differences is sound pressure levels while flying overhead aside, the H130 has by far the least obtrusive sound signature of the three.

Definitely. And it's astounding how quiet its little EC120 sibling is also. I like to think I can hear any helicopter from far away but many times the EC120 has not been obvious until almost overhead.

[gipsymagpie]

Good morning
You can find this data via the EASA Type Certificate Data Sheet for Noise:
Bell 429: https://www.easa.europa.eu/sites/default/files/dfu/EASA.IM_.R.506%20Issue2.pdf
EC130: https://www.easa.europa.eu/sites/default/files/dfu/TCDSN%20EASA.R.008%20Issue%2009.pdf
EC135: https://www.easa.europa.eu/sites/default/files/dfu/EASA.R.009%20Issue%2010.pdf
These are the EASA versions, the FAA equivalents can be found via FAA website.

Be wary of these numbers. In a similar way to the Volkswagen diesel scandal, these figures are recorded in a very limited part of the flight envelope - I don’t think they give a particularly useful feel for loud a helicopter is in practice (its a huge driver of when a pilot or automatic system must increase NR for landing by the way). I live near a Bell 429 base and work around EC135 and the 135 is much quieter. You can hear the 429 coming from a long way away (mostly tail rotor from the pitch).

[Windmill Wiz]

Very true. How noise is perceived or how intrusive it is, has an element of subjectivity.
These figures are the certification noise data, warts and all: they are measured under set conditions, per prescribed procedures and verified by the certification authority; however, like performance data, real life can be different. For a real comparison, you would need to fly all three helicopters, on the same day, using the same profile.
Better data on noise signatures does exist, but not in the public domain.