[Andee]

Hi all,

I have a blade 400 which I am completely new with.

Yesterday, I was having a go. Just trying to get off the ground.
As this was happening it tipped to one side and the rotors dug into the ground.

Since then, when spinning the rotors up the whole body of the heli shakes!

Have had a look around the heli and nothing appears broken.
Tested all the flight controls and everything appears to work there too.

Am thinking that the rotors maybe off balance?
If I pitch the rotors (with t.hold on) it looks as if the pitch of one blade is more than the pitch on the other.

Jut wondering if you guys thin the shaking could be because of this or is there any other reasons?

Thanks in advance,

Andee

[popeyepete]

I'm no heli expert, but i'd say you have bent either the feathering shaft or the main shaft.

Heres a good web site that should help.

http://www.slyster.com/heli/b400bible.html

[Skidz]

You have definitely bent, at least, the feathering shaft (the shaft between the two main rotor grips). They don't survive tip strikes like the one you had. I'd also suggest the main shaft is bent too. Please don't fly the heli until you've replaced the bent bits. It will crash again but perhaps worse than already. Also check your blades to see if there is any damage. Sometime you can get small cracks near the blade root if if the strike was decent.

Remove both shafts and roll them on a hard flat surface like a glass table. If they have the slightest bend, they can't be used. You'll need to replace them. Learning to repair helis is part of the fun . Post back if you need to.

[brotherblonde]

I'm intimately familiar with the B400. Many many rebuilds have created a lovingly close relationship with her. I'll echo Peter & Dave's comments with an endorsement for the website Peter mentioned. That's what helped me with my 1st of many prangs.

Secondly, are you using a set of training gear?

Thirdly, don't try to "fly" it..even once it's fixed!...There are several steps you need to take to minimise the risks before flying.. There are other discussions on this subject on this site.

Fourthly, most spares are readily available from Hobbies in the Hills (Castle Hill), or RC Hobbies (Leichardt).

[Skidz]

If I pitch the rotors (with t.hold on) it looks as if the pitch of one blade is more than the pitch on the other.

Missed this in your post Andee. This is unrelated to the shaking issue. What you are seeing is a blade tracking issue. When the heli links are set up exactly the same, the tip of each blade should pass through the exact same space as the blade before. If this isn't corrected, you can get uneven lift when travelling foward.

It is best corrected by placing the heli flat on a table that is level. With the motor disconnected or throttle hold active (so the motor can't spin), move the collective/throttle lever to the mid point. This should be 0 deg pitch on both blades. Using a ruler (or pitch gauge), measure the height of the leading edge of any blade, then measure the trailing edge. If they measure the same, the pitch is 0 deg. Note the blade closest to being correct and then focus your attention on the other blade. It has to be blade with incorrect pitch (given both are different). Using the link from the mixer arm up to the rotor grip, unclip one end and rotate in full turns clockwise or anticlockwise until the leading and trailing edge measurements are exactly the same. It now must be 0 deg pitch and identical to the other blade.

Disconnect everything now. You should now be close to exact on the blade pitch at zero (mid throttle) and tracking.

[Per BB's post below: Go through this routine after you've replaced bent shafts]

Dave

[brotherblonde]

Dave, what you said is correct. The only issue is, if the feathering shaft is bent, it can rotate and cause different "incorrect" pitches at random. The pitch may be corrected as you instructed, but once up to speed, the feathering shaft could rotate and put everything out again.

Your post on checking the straightness of the shaft is still important.

[Andee]

I'm no heli expert, but i'd say you have bent either the feathering shaft or the main shaft.

Heres a good web site that should help.

http://www.slyster.com/heli/b400bible.html

That looks like a great site

Please don't fly the heli until you've replaced the bent bits.....Also check your blades to see if there is any damage. Sometime you can get small cracks near the blade root if if the strike was decent....Learning to repair helis is part of the fun

Definately won't fly it until it's sorted. I haven't really ever flown it. Had it for nearly a year. Have always been worried about crashing it :-) Have only spun it up. Has come off the ground but not for long.

Secondly, are you using a set of training gear?

Thirdly, don't try to "fly" it..even once it's fixed!...There are several steps you need to take to minimise the risks before flying..

Fourthly, most spares are readily available from Hobbies in the Hills (Castle Hill), or RC Hobbies (Leichardt).

I have a training gear from another dual rotor heli I bought age ago but never used them. Don't know if they are compatible with the B400. They have orange 'gears' on them.

I plan on getting an rc sim very soon. It' a shame this happened now but will be good to learn how to fix this anyways.

What you are seeing is a blade tracking issue.

Thanks Dave for your post. I will do this when I get the shafts sorted.

Thanks to everyone for your help!

[gbanger]

My advise Andee, if you want to learn to fly your heli safely and with minimal damage is to drop by our club and have a chat with some of our experienced heli pilots. There is not better way to start your flying than getting assistance from experienced guys who have already done the hard yards.
You will learn a lot faster and also keep the damage and repair costs to a minimum.
Gazz

[Andee]

My advise Andee, if you want to learn to fly your heli safely and with minimal damage is to drop by our club and have a chat with some of our experienced heli pilots. There is not better way to start your flying than getting assistance from experienced guys who have already done the hard yards.
You will learn a lot faster and also keep the damage and repair costs to a minimum.
Gazz

Hi Gazz - this is definately on my to do list. Have been meaning to come down for a while now.

[Lindamus]

Hi Gazz - this is definately on my to do list. Have been meaning to come down for a while now.

Common down, we dont bite.

I am a firm beliver that the B400 is the best ever heli to learn on. Got mine here on the bench...

I can almost repair it with my eyes closed.