Strange sound in a boom block...what the h..!

[saeed09]

Hi...

I noticed that at spooling up i get a strange sound coming from the boom block. Its dificult to explain but it souds like ''grkr gkr gkrkr gkrrr..."

I removed the main blades and tried to rotate the head by my hand. Rotating the head slowly the sound is noticed but when you rotate faster, the sound disapear. I disassembled the whole boom block and to me i assume nothing was wrong with either the gears or the bearings. I grease the black gears so the sound is heard just inside the boom block, its not a gear friction sound. The whole tail is new!

Am worried..i dont like to crash becouse of mechanical feilure. Is this sound normal?

Guys can you please check your helis for this sound and feed me back on what is in there?

[saeed09]

Every one sold their velocity 90's or? No one is interested to comment!

[im4711]

Most likely not but in myncase I have not experienced such noise.
Possible issue could be TT gear need to work in a bit but hard to say.

[saeed09]

Thanks for your response. I believe other fellows will also try to rotate there helis to check for this sound and post here so that i can comfirm this is/not a sound to worry about. I think six soft flights on these gears already. Should i be worried too much with this sound? Am not sure if the sound was there since i replaced the gears or it started after some few flights..

[saeed09]

Thanks again im4711 for your post, at least you took your time to look into my problem.

I wonder why no one could atleast look into their helis as i requested and just feed me back if that sound was normal or not. Perhaps my English is broken thats why no one understood what my problem is . Other wise the +200 views were from non V90 owners except one!

Ok then becouse i normally apriciate when am helped, i like to help too especially when i know that thing.


The sound came from the boom block but i wasnt sure so;

1.I removed the tail boom and checked the torque tube, every thing was ok.
2.I then removed the main blades so that i can rotate the head easily.
3.Sound was still there so i dis assembled the boom block and everything was ok. I tightened the 4 screws on the boom block reasonably and then checked for smoothness on the gears, everything seemed ok.
4.When i fixed back the boom block on the frame without the 12 screws, the was no sound. Then i equally tightened the 12 screws holding the boom block, the sound was loud and anoying.
5. I then removed the outo rotation and main gear to see the behaviour of the front end gears when the boom block is tightened with the 12 screws on the frame.
6. When i tried to rotate the gears....! GOT IT!! the gears were so tight at one point such that stripping was to happen at any time. And that was the cause of that bad sound I think if I didnt use grease, with that tightness, i was to crash in the first flight. Thanks to the one who adviced me to use grease.

Solution;
I simply balanced the tightning of the 12 screws on the boom block. I applied very low torque just enough to hold but with red lock tight and the gears turned so smooth with no sound. Re assembled the tailboom, gears and main shaft and everything was clean but still a tinny notchy sound can be heared from the TT's i think they are not perfecly round. I will try with a new boom block to see if the one i have is a defected one from manufacturer.

My advice.....FOR THOSE WHO ARE STILL STRIPPING THE FRONT END BLACK GEARS ON THERE V90's, PLEASE CHECK THE SMOOTHNESS OF FRONT END GEARS WHEN THE BOOM BLOCK IS SECURED TIGHT ON THE FRAME AND WHEN THE TAIL BOOM, AUTO ROTATION AND MAIN GEAR ARE REMOVED FOR A WHILE.


This is just my opinion and my finding, i hope some other guys might have known this earlier. This will be my normal practice to fix the velo tails from now anyway!

[im4711]

Interesting observation.
I am sure quite a few others will look into that too.