The current Version of the HeliArtist BO-105 and UH-1 fuselages, have a plastic, smooth guide pulley, in the elevated tail assembly, that has been found to wear and come apart.


To prevent your elevated tail model from having a tail rotor failure, you should perform this modification to your model!

Parts needed:
6mm or 15/64" Drill Bit
2x Flanged Bearings 3x6x2.3mm or 3x6x2.5mm or 3x6x3mm
2x 3mm ID Washer
1x TREX Tail Rotor Shaft w/Gear (For Tooth side of Belt, lower Guide Pulley)
1x EFLH1464 E-Flite Blade 400 Tail Drive Belt Guide Pulley/Tensioner: B400 (For smooth side of belt, upper Guide Pulley)
4x M2x6mm Socket Head cap Screws
Dremel Tool
Sand Paper
Thread Lock

1. Disassemble the Elevated Tail assembly. Using the four M2x6mm screws, assemble the two side plates together.


2. Drill a 6mm hole into the side plates. Smooth out rough edges with sand paper.


3. Install the Flanged bearing into the side plates, with the flange oriented to the inside.


4. Partially assemble the Elevated Tail, and determine where to cut the tail rotor shaft.
Remove any burrs and rough edges from the cut shaft.



5. Install a 3mm washer to each side of the tooth guide pulley, shim as necessary.
Re-assemble the elevated tail assembly and replace the plastic upper guide pulley with the metal guide pulley.
Thread lock all nuts and bolts.

More info...

Using the flanged bearings I found that about .7 or so gap needed to be filled in on each side. While finding a .7mm washer is rather hard...you can get some Tamiya 53585 shims to make up the gap (they are cheaper from just about anywhere other than TamiyaUSA). They come 10 each of .1, .2, and .3mm, and are small enough that they wont hit the outer races of the bearings. Here's a pic of my mod, I used a .5mm washer in there along with the shims, but just a pile of shims should work the same.

Very good info and nice work

May be HeliArtist could beta test their products by you guys before marketing the products. I'd say they should at least copy your modification and implement the change into the production line immediately.

look pretty and solid, thanks

Nice work BT.

Originally Posted by ecat

look pretty and solid, thanks

Thanks for bringing it to my attention, before I found out the hard way!

BTW, HeliArtist said that they have already made a fix.
I have not heard if they are going to offer a recall replacement kit.
I don't know when the fixed kits will be on the shelf.

I'd say they should offer up a free fuselage of our choice to those that did this Beta testing for them. Heck, just for the engineering support they receive here they should give us 2 of them!

Originally Posted by BlackTitanium

Thanks for bringing it to my attention, before I found out the hard way!

BTW, HeliArtist said that they have already made a fix.
I have not heard if they are going to offer a recall replacement kit.
I don't know when the fixed kits will be on the shelf.

Good result of our voice out
BTW, can HA make some fuselage mould adjustment for the BO105 too if
not too copyright violating?

This problem can be tackled a lot easier and simpler, involving less cost:

Parts needed: 4 bearings 6 x 2 x 2.5 mm

Tools needed: Drill (preferrably 5.9 mm, but 6 mm is OK)
When drilled with 6 mm, it can be necessary to secure the bearings with some loktite or similar. When drilled with 5.9 mm, the bearings need little force to be pushed in place but will stay there without further securing

Just drill out both guidepulleys with 6 mm (or 5.9 mm) and install TWO bearings 6 x 2 x 2.5 mm bearings in each pulley. Shorten the plastic distance bushings accordingly and with a minimum of fuss your chopper is airborne again, with the same results.
The toothed pulley is nice but not a must have, provided the belt is tensioned as loose as flying allows.

It helps to keep headspeed to a sensible max 2000 RPM (for a fourbladed head this is sufficient even for non stabilized flight), and when shortened mainblades of a Blade mCPx are used as tailblades, tail authority will be dramatically improved compared to even original tailblades together with a headspeed of 2500 plus.

BRGDS, Bert

"Shorten the plastic distance bushings accordingly" can u please explain this procedure or supply a picture of what you meant by shorten the plastic distance?

I attempted to shorten the original plastic spacers on the idler pully so I could use the metal Blade 400 pully - I never got the end of the spacer shaped right to allow the pully to run perfectly centered.

I dug around my spare parts box and here is what I came up with: 2 bearings
size 2.5 x 5mm and two washers.(Trex 250 parts) It fit perfectly with no drilling or other drama.
YMMV

If you want a photo just PM me - the RCG server isnt allowing photo upload right now.
Trent

Hey Blunight i did the same thing with my UH-1 i put a B400 inside and used the metal pulley to take the place of that plastic one and that was over a Year ago and i have put a holeeeee lot of flights with no problem from it

someone needs to clone it useing good qual.ity plastic, and make it worth the price they want for it!.

Originally Posted by theone2007

"Shorten the plastic distance bushings accordingly" can u please explain this procedure or supply a picture of what you meant by shorten the plastic distance?

Sorry, Internet access (at least "unlimited" access) has been "out of reach" for me for a couple of months

How difficult is that? I did not say "shorten the plastic distance", but said "shorten the plastic distance bushings"....

Original set-up: length of two "distance bushings" + "width of the single bearing in the pulley" equals the distance between the side plates.

If you're going to install 2 bearings in the pulley, the bushings have to be shortenend in order to keep the pulley centered between the sideplates, because two bearings together are wider than one single bearing.

Brgds, Bert

PS: as for durability: I have not yet had one single problem with the pulleys or the belt. So far, problems with keeping belt tension constant seems to be the biggest problem, the slop in the tail control pushrod (bowdencable) the second. But the belt holds up no problem, the guide pulleys hold up no problem, and the heli flies well (for a 450 scaler)

The HA upgrade kits are just a few bucks. I bought seveal for the 450-size helis. I think I paid 5 or 6 bucks. I got mine from Flying-Hobby, but I have also seen them on E-bay. Mine came with two new FRP side-plates, two flanged bearings and a belt pulley. Significant improvement. Big thanks to BT for thinking this thru.......and HA for the f/u....