Maintenance items

[Mercuriell]

Notes on S-Diabolo maintenance can be found here


Had a few Diabolo repairs to do along the way:

Cause: TAil belt loose causing unlocked in tail
Effect: did emergency auto with a low HS boom strike - bent mast, spindle, chipped 1st stage gear

Cause: Incorrect tail assembly with thrust bearing in the middle rather than the outside of the radial bearings.
Effect: Lost tail all together and tipped into some palms. Bent spindle, mast, boom, damaged lipo, Jive and blades.

Cause: Stripped splines in FUtaba servo arm (T-arm)
Effect: Had to land with 1/2 stick aileron - no damage

Cause: Lost tail just after take-off due to stripped thread in tail pulley rendering set screw ineffective.
Effect: Stripped all 3 cyclic output arms. Bent tail spindle, bent spindle. Notchy tail rotor radial bearing needed replacing.

Cause: Broken thrust bearing race
Effect: Inconstant tracking and momentary control loss

Cause: Probably running 753 blades too fast
Effect: Bent main grip bolts - probably better for them to bend rather than brake

So a bit of a pot-pourri of maintenance - tail belt needs an eye keeping on for first dozen flights or so as it does stretch.

Tail rotor thrust assembly a real PIA as it caused $1000 worth of damage

Tail pulley set screw stripping thread a surprise - I'm careful with assembly - anyway drilled a new hole and tapped it out to M4.

Not sure about the heavy duty Futaba arms - maybe too soft but at least they saved the servo gear. Have ordered some Mikado glass filled plastic to try.

Not sure about the head thrust bearing either - could be a bad bearing, could be too high HS on 753s or could be due to the tumble - probably a bit of each !

So my advice:

Check the tail rotor radial bearings if you prang the tail

Be very careful with the set screw in the tail pulley.

Check the tail belt tension after every session.

If you have tracking issues tear down the head and check the bearings.

Oh and last but not least - I love this heli - it is the testing bed for torture testing of a prototype ESC and for speed runs and has had some extreme stresses

[sunnyville]

Love this heli too. One thing about the stripped thread for the set screw in the tail pulley: happened to me too (have one of the very early diabolos from
Last year). The thing is it stripped while in use my while I was rebuilding.

I ordered a replacement pulley - they now come with 2 set crews. So less force on the one set screw. Just thought that "improvement" was noteworthy.

[abanihani]

Thanks John for this valuable advise, it is really highly appreciated to take sometime to write up your personal experiences and pitfalls that others may have. I will definitely use these tips as I will be building my Diabolo kit soon

[kevinbj]

I heard it several updates done to the manual is there a certain site to get the latest one that has the correct way to assemble the tail?

[smsodhi]

The online manual on the minicopter site is up to date.
Also check here https://www.helifreak.com/showthread.php?t=386378

[kevinbj]

Originally Posted by smsodhi

The online manual on the minicopter site is up to date.
Also check here https://www.helifreak.com/showthread.php?t=386378

Ok.. Thank you

[seanq222]

The set screw on my tail pulley backed out - it was not striped - but perhaps not enough locktite? I ended up loosing control of the tail and the tail shaft worked its way out of one of the bearing, but got it down in one piece. One of the tail shaft bearings was toast and there was a fair amount of aluminum shavings around the pulley!

I also tend to slowly bend the skid arms on both the joker and diabolo from less than ideal autos - the stance just gets more aggressive :-)

[helicraze]

Sheesh all this makes me nervous!!!

I only found the tail belt to stretch and need slight retension!

I think you run the heavy blades with too much RPM John LOL! It did fly well though!

I always replace servo arms after a prang, they are easily damaged even in tip over

[smsodhi]

Seeing as the bird is down I thought I would take the opportunity to check things over. I noticed slightly more play in the main shaft and main gear where the M4 bolt attaches.
The bolt seems to have worked its self lose a bit. Maybe I did not tighten it enough, maybe grease got into it, who knows? The hole in the main gear hub has ovaled a bit.
John mentioned this in my build thread that there is some play in the shaft and he put a 0.3mm slot in the hub to pinch the shaft getting rid of play.
John have you had any problems here after your mod?
Well I guess it may be wise to keep an eye on this guys.

[Mercuriell]

I haven't had any problems, I was a bit concerned that play on the gear would oval the hub hole and that seems to have happened with yours. If if keeps on raining here I'll have a peek at mine see if it's ovalled too.

[helicraze]

I had the same issue. I think gerd now puts a slot in it (as indicated in manual) every other heli manufacturer does.

It needs a slot!!

[headhunter]

Originally Posted by helicraze

...I think gerd now puts a slot in it (as indicated in manual) every other heli manufacturer does.

It needs a slot!!

You're right. Got my kit about a month ago and it has a slot.

[Mercuriell]

Just checked my prototype slotted one - NO fore or aft play

[smsodhi]

I wonder why Gerd did not offer to change it for those of us who got the kit before the mod as he has done with other things I.e rotor head? Or inform us of the potential problem and the subsequent fix?
Just paid 10eur in postage for stuff, had I known I could have had it sent also.

[smsodhi]

I have tightened the M4 bolt tight. There is no play. I will keep an eye on it now maybe after a few flights.
Will probably order the updated part in the future when I order more stuff if it continues to loosen.

[smsodhi]

On another maintenance note. I mentioned that I wanted more snap in the heli in another thread. I ordered another set of medium and hard dampers. I noticed that after around 90-100 flights the medium dampers installed feel softer than the new medium dampers.
I suspect that is why I was feeling that the heli was getting soft. I have put the hard ones in now and will probably get my neck snapped off !!!!

So worth keeping an eye on this also, like all helis.

I was wondering if the medium and hard dampers could be mixed i.e one medium and one hard on each side, and if the order installed will make a difference?

[marcosp]

Since dampers are mentioned, do hard dampers do well at 1500rpm?

[helicraze]

I got new dampers and oring carriers. Put them in, its heaps tighter. I had done 50 flights.

[smsodhi]

Hmmm. Maybe it's worth changing them every 50-60 flights as a routine.

[helicraze]

Depending on how you fly yes i would