GYRO TROUBLE

[Raptorite]

Hi Mo,

Im sorry to hear about your tail problems, now you have checked the tail servo and gyro, the only other thing it can be is something in the tail drive system.

If memory serves, the gears in the tail gearbox are both metal so it is unlikely to be these, the place I would start is the take off gears up front on the engine mount assembly, of one of these particularly the big one has even so much as a hairline crack it will cause loss of drive to the tail.

The plastic couplers on the tube drive itself are bolted to the tube so they are also unlikely to have broken free, it is worth checking them though.

If when you separate the frames to get at the engine, have a look at the alignment of the three gears, as having just replaced them my guess would be that something is slightly out of alignment causing the gear to be taken out.

One thing you could try is hold on to the rotor head with one hand and try turning the tail rotor with the other, if there is excessive backlash it may be that something is jumping a tooth which is the catalyst to the problem.

I hope you get it sorted soon.

Cheers,

Pete.

[mo]

Hello Peter. (WHERE HAVE YOU BEEN)
Thanks for your reply Pete',and I am sorry to say that I have scrutinised that helli for all of the faults that you think could have caused this problem.
All the gearing on the main motor drive was replaced after the peviouse bump, and fortunately appears to have survived the latest one, for everything still turns over very smoothly.
When I checked the electrics after the mishap they all worked perfectly so whatever it is must be intermittant.
I am happy once again after my Conquest flew O/K, so at least I am not grounded,so when my new parts arrive from midland (TWO UNDERCARTS), I will take both of my helli's to the field and it will be a case of crash one and fly the other.
I am sure that I will get there in the end, and intend to replace the gyro (AGAIN) with another new one (hopefully if I am nice to my wife) a GY 401.
Glad to see you back on the Forum Pete', it was getting very quiet and thought perhaps everyone was having early nights.
GOOD FLYING.
Mo.

[Raptorite]

Hi Mo,

I have known one other cause of this sort of problem, however it is associated with PPM receivers, I think you have a 149DP PCM receiver in the sport dont you?

With most futaba gyros, (Im not sure about any other brands) but I know that if these gyros are used with PPM receivers and they pick up more than three consecutive radio glitches it will reset the gyro's heading hold neutral point, thus causing the heli to behave as though the gyro had failed completely, in other words start pirrouetting out of control.

If however, you are using a PCM receiver as I suspect you are, the receiver will mask the glitches so the gyro never knows they have happened therefore this problem never occurs.

If the tail is suddenly just letting go and you have tried at least two different tail servo / gyro combinations, there has to be something else causing it.

Hang on a tick, I wonder if there is a build up of static electricity in the boom :idea:

I remember either seeing or talking with one of the guys at CSM, there was a problem with one of their gyros that they just couldnt sort out once, it turned out to be a build up of static in the boom which was causing the gyro sensor to go haywire and cause a gyro failure like problem.

Try taking a piece of wire and securing it from something like the back plate of the engine one end and the other end to the boom, it might discharge the static and stop the problem.

Give this a try and let me know how you get on, this is one problem I am determined to get to the bottom of one way or another

Cheers,

Pete.

[mo]

Hello Peter.
You are a most reliable chap when it comes to problems and believe me I do try the remedies you offer.
That one about the static build up appears interesting, but would that still apply when using a carbon boom that this helli is fitted with.
I had thought myself that it could be spurious signal related and I am going to try it with the canopy off next time.
You are quite right I am using PCM, and never had any trouble with PPM, so I am a little disappointed that I bothered to change my helli over to the supposedly better reception.
I will keep you up to date with developments Pete,and if I cannot get to the bottom of this fault,get prepared for me and that damn Moskito to turn up on your doorstep.(only joking)
GOOD FLYING.
Mo.

[Raptorite]

Hi Mo,

Yes, carbon is a good conductor of electricity, it also happens to be very good at interfering with radio signals, is the aerial wire routed anywhere near the boom?

If it is, it is worth while routing it a different way so it isnt so close to the boom and see what happens.

I would still try the earthing trick as well though.

Cheers,

Pete.

[mo]

Hello Pete.
Just a quick update on what I intend to try with my moskito problem.
The new undercarts arrived this morning and the helli is again back in one piece,I am going to put the CSM400 gyro back in, as this one only played about and did not let go completely,I am also going to earth the boom as you advised and fit another C cell 2500 milli amp battery pack in case it was a power drop under load.
If I get the same problem again I will be completely stumped, and will just have to purchase a new Futaba 401 gyro, for what else could it be.
GOOD FLYING.
Mo.

[mo]

PROBLEM SOLVED

Hi Guys.
I took that troublesome moskito to the field today and felt sure that one of the changes would have cured my problem.on lifting off the helli again started to give me tail problems, and again I attempted to cancel this out with the trims,but to no avail,I had anticipated having a good fly for the weather was great, and when this happened I was almost ready to give up, I then happened to notice the revs on the tail seemed to change speed,so I shut the helli down and found that if I turned the main blades I could stop the tail rotor from turning.

I took the helli home with the intention of another complete stripdown, but found the problem straight away in the rear box,the tail pulley had skewed itself into an inner and outer shell and this had obviously been the cause of all my troubles.

I had previously changed the belt and did not even notice the damage then,for just by looking, the pulley appeared to be in perfect condition.
I am pleased to have solved this problem, but I am p***d off that it has been such a s*d and taken so much time and effort.

To anyone interest enough I have put photo's in my gallery,and I would be very interested to hear if anyone has had the misfortune to have the same thing happen to them.
GOOD FLYING.
Mo.

[Raptorite]

Hi Mo,

I am really pleased the tail problem is sorted

I have had a look at the pictures in your gallery, it is difficult to make out exactly what happened with that tail pulley, but I can make out the jist of it.

I think all that remains to be done is to take it out and have some fun with it

Cheers,

Pete.

[mo]

CHEERS PETE', AND THANKS FOR ALL THE HELP YOU HAVE GIVEN ME.

GOOD FLYING.
Mo.

[antsis]

Mo.

Finally got to fly the super sport. Had a similar problem with the gyro. CSM400 which has been fine in my hawk. First hovers, the heli was yawing all over the place. I thought it was the wind as it was a tad gusty. Anyway found the gyro was hardly working at all. We had to reset the gyro again to get it to work. This was after the heli had already been test flown. I have now got a gy240 which will be fitted this weekend.

Ant

[mo]

Hi Antsis.
Took my overhauled mozzi sport to the field today, and the damn thing was all over the place,I had changed the gyro again in favour of the CSM 400, so it could be that perhaps like your's it might need resetting again.
It was very gusty at our field, but I have flown in far worse conditions with no problems, my fly today was more like a fight than a pleasure.
I think it would be a sensible move to bin the bl**dy lot and get some fun out of the hobby again by flying my conquest.
Tomorrow is another day,and weather permitting, I will once again be swearing my head off at our field when trying to fly that troublsome mozzi again after my latest attempt at a cure.
I WILL GET THERE IN THE END.
GOOD FLYING.
Mo.