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WTF * Weird noise coming from the main rotor


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While i was on the ramp the other day a 300 on final caught my attention.. it was making a fairly loud noise that was completely unusual. While they were running down i asked one of our instructors to come out and listen to see if i was just hearing things.. he heard it too. On post flight we found this little piece of a plastic bag stuck to the leading edge of one of the blades.. to me it sounded mechanical, but clearly wasn't.

 

the pilot in this case said that he couldn't feel the difference in flight, although he could HEAR the difference and remembered hitting the bag on final.

 

Another instructor told me that he had once hit a styrofoam cup and a piece of it had done the same thing, stuck to the blade, and in this instance he thought the helo would shake apart (it didn't).

 

just to let you all know what can happen and what the issues might be.

 

in the photo of the 300 in flight you can see the bag stuck to the blade!!!

 

dp

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Seen that happen to an R22 doing hover practice. This plastic bag came rolling and bouncing along, up into the blades. The handle from the bag got caught on the edge of the main rotor and unleashed a terrific noise, like the loudest zipper you can ever imagine. Pilot landed and shut down, said there was no ill affect to the controls. Apart from the unreal noise it made there was no indication something was different.

 

On our S76's some blades have a lot of tape on the leading edge... kinda like a hockey stick. In hard rain the tape starts to peel off and the torn edges make a funny noise too. Can't hear it inside, but outside it sounds like a little dog barking with every rotation of the blade.

*Yip-Yip-Yip-Yip*

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On our S76's some blades have a lot of tape on the leading edge... kinda like a hockey stick. In hard rain the tape starts to peel off and the torn edges make a funny noise too. Can't hear it inside, but outside it sounds like a little dog barking with every rotation of the blade.

*Yip-Yip-Yip-Yip*

 

Haha funny you mention that. I was just going to say that I have seen the abrasion tape bubble slightly and it was letting air through it.. Made a pretty weird sound too.

I also saw a plastic bag come rolling through the ramp when we had about 7 helicopters turning. Went though a MR and just blasted to bits. Nothing done to the blade of course. :)

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Yeah, no harm will be done to the aircraft in most of these cases. All it will do is make a small helicopter sound like a big one. :D Heads will turn and then be a little disapointed to see it's an R-22. Just kidding, but it is loud and sure gets your hair to stand up for a second until you realize what it is.

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Yeah, I wasn't flying, but was sitting PNF in a 500 that hit a bag while hovering. The whole bag stuck to the blade, and I tell you it added some serious vibrations to the heli. We set her down, put the throttle in idle, and the bag fell off, ran her back up and everything was good after that. The sound just kind of sounded like a loud swoosh, almost like a wave crashing on the beach and that was it. I think it really depends on size of the bag, how much sticks to the blade, and location (outboard, inboard).

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Hey Dennis, did it sound like grinding metal, or maybe a zipper? I'm curious because you said it sounded mechanical.

 

Later

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Hey Dennis, did it sound like grinding metal, or maybe a zipper? I'm curious because you said it sounded mechanical.

 

Later

 

 

Hey Witch,

 

it sounded like a grinding when it was on final, about 1/4 mile away, but as it got closer it was clear that it was a single main blade. i was thinking it had delaminated near the tip. one of our A&Ps thought the screw had come off the tip cap, or the whole cap had come off.

 

you gonna make the expo?

 

dp

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Naw, I'm broke, unemployed, and can't afford to pay attention. See what happens when you don't take part in a recession?

 

Really, I can't afford to do much at this point. At least I can stay current. I'm working on a plan to have the State pay for part of my edumication through a Dislocated Worker kind of program, so hopefully that'll go through.

 

Out of curiosity, have you ever had the ship shake so bad that you thought the rotor was out of balance, and it gets worse during the cool-down?

 

Later

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Out of curiosity, have you ever had the ship shake so bad that you thought the rotor was out of balance, and it gets worse during the cool-down?

 

Later

 

 

I did. It was in a ship that had been oversped awhile before I flew it. I took off with a student and no sooner than 3 minutes into the flight the helicopter started shaking like mad and the cyclic was all over the place. Couldn't even make it out, the cyclic was so blurry from moving so much. requested a quick return to the airport. Turned out to be the bearings up top. No suprise there. Yes, it had been inspected post overspeed.

 

JD

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