I have read on here about how loud the MU-2 is but have never been close to one. Today at KTPL in Temple, TX one taxied up next to me as I was climbing in my helo. I always leave my door open and helmet off while I start the engine. During his cool down it was deafening and once he pulled it to fuel cut off it seemed to get even louder for a second or two.

Makes a King Air sound like Blue Thunder in whisper mode. Even made my startup sound pretty lame.

They refurbish those things at my home field....deafening. Wickedly fast, built like tanks, but LOUD.

Peace,
Don

Heheheheheheh...

Every time I roll up and see all of you with your fingers in your ears I can almost hear myself laughing over the noise...

Almost.

Actually, it's surprisingly very quiet in the cabin.

Fingers in the ears, the Garrett Salute! I've gotten it in the Merlin, Turbo Commander and the MU-2. I always waive so they feel compelled to waive back.

Stupid loud on the ground, but a darn good airplane.

It's actually a feature - no conscious person walks into the props !

Apparently you've never been around a Rockwell 681 Commander either.

Dave

I wish.

4 fatal accidents from folks walking into props in MU2s. I know of at least one non fatal prop contact.

A high wing airplane is more susceptible to this.

My theory is that the MU2 is loud on the ground due to some sort of underwing resonance with the short engine exhaust. Other TPE331 airplanes have longer exhaust (Commanders, B100) or longer tail pies with overwing exhaust (Merlin, Conquest).

Once the prop develops thrust, that isolates the exhaust inside the prop wash and it gets much quieter after that. So in the air, the MU2 is no worse than any other typical turboprop and better than some (way better than Piaggio).

Mike C.

Try getting out of or in a commander with the right side engine running. Some real James Bond sh$t!

Yep, my 680V (which is a 681 for all intents and purposes) is just as loud. People squint and put both their hands in their ears as it passes.

Huh?

I can't year you.

We have regular MU-2 traffic. Reece Howell, MU-2 recurrent instructor brings his pilots to our field for practice and re-fueling. They have become a real nuisance. The noise is deafening. They are louder than the Lear 35 without hush kit also based on field.

Agreed at idle they are loud but as soon as they are pulling air into themselves, they are not. From an airport noise standpoint, they are quieter than the old stage III jets like a Lear 35.

According to the FAA, a B55 Baron is louder than the MU2 when it comes to overfly noise.

http://www.faa.gov/documentLibrary/medi ... 036-1H.pdf

The objectionable noise is taxiing on the airport. It is loud, but not really THAT loud.

This video captures the difference between flight and taxi noise:

https://www.youtube.com/watch?v=ihUXDW2Uy0s

Once you go to zero or near zero thrust and taxi RPMs, the MU2 develops a characteristic howl. The exhaust is no longer surrounded and isolated by prop airflow.

I wondered if making a new tailpipe with serrated trailing edge would reduce this noise. The theory is the howling is a resonance from the tailpipe length (much like a wind instrument) and by having a serrated trailing edge, it would detune the resonance.

Kind of like this:



Mike C.

It seemed to me as soon as he went to fuel cut off it actually got louder for a second or two as the engine started to spool down. There was one spot between us with me being off the end of the left wing.