Gyro packed up mid flight.

[Granpappy]

The gyro on my Trex 450SE V2 just seemed to pack up mid flight this evening. I've never come across this before. On my first flight I noticed the tail was starting to drift in heading hold. I just compensated on the stick until the battery was done.

I landed, changed the battery and tweaked up the heading hold setting on the transmitter. I took off and it held in the hover. I turned right and moved forward and the tail started to drift. I compensated on the stick and it turned the drift into a spin and crashed. It broke the main blades, bent the feathering shaft, split the rubber dampers and sheared the M2 12mm bolt that holds the head on. Deep joy.

After doing an assessment at home and stripping the heli down, I ordered the bits I needed and then had a look at the gyro. When I powered up, the gyro seems to have lost all its settings that I programmed into it.

I guess I am now looking at getting a new gyro unless I can determine what caused this. Anyone had this problem before? The gyro is a Logitech LTG-2100T.

Cheers.

[trillian]

I never tried the Logitech. The good news is that you can get the best tail gyros ever made for next to nothing these days.

[Granpappy]

I never tried the Logitech. The good news is that you can get the best tail gyros ever made for next to nothing these days.

I guess you mean on the second hand market. I just looked at new prices and thought 'Wow'.

I was just testing the Logitech I've got fitted and it had reset the end points, the sensitivity and reversed the servo direction. Not impressed....

[Raptormad2]

Get yourself a spartan quark really great little gyro for the money and easy to set up and they work great.

[trillian]

I guess you mean on the second hand market. I just looked at new prices and thought 'Wow'.

I was just testing the Logitech I've got fitted and it had reset the end points, the sensitivity and reversed the servo direction. Not impressed....

Yes, 2nd hand. All the high-end gyros that used to be very expensive, the Spartans, CSM 720, Futaba 601 and 611 etc. can now be found super cheap because everyone went FBL.

[Granpappy]

Yes, 2nd hand. All the high-end gyros that used to be very expensive, the Spartans, CSM 720, Futaba 601 and 611 etc. can now be found super cheap because everyone went FBL.

Cheers. I'll have a look to see what's out there.

[hedge]

Sure its not the tail servo? Sounds exactly like what happens when they over heat and seize. Should be able to check this on the bench, plenty of stick twerking for 5 mins.

[trillian]

As Hedge mentions, definitely check the tail servo as they get worked pretty hard and maybe if the servo was putting an extra high load on the connections to the gyro it could cause the gyro to freak out as well (just thinking out loud).

If you want to try a good gyro on there I have a Spartan 760 I can send you to play around with. I would recommend testing the tail servo on the bench by plugging it directly into the RX and see if it gets hot or acts strange.

[Planehazza]

I've a gy401 you could have for a tenner of its any good?

[Granpappy]

As Hedge mentions, definitely check the tail servo as they get worked pretty hard and maybe if the servo was putting an extra high load on the connections to the gyro it could cause the gyro to freak out as well (just thinking out loud).

If you want to try a good gyro on there I have a Spartan 760 I can send you to play around with. I would recommend testing the tail servo on the bench by plugging it directly into the RX and see if it gets hot or acts strange.

That is very kind of you. I guess I need to do a bit of fault diagnosis to find out what caused what. If I need to replace the gyro then I will be in touch. Thank you.

[trillian]

That is very kind of you. I guess I need to do a bit of fault diagnosis to find out what caused what. If I need to replace the gyro then I will be in touch. Thank you.

No problemo, I have a couple of them sitting around here doing nothing and they have always been extremely good on my helis.

[scallybert]

IIRC, the Logitech LTG-2100T wasn't a bad gyro. Not as good as the Spartans, though.

[Granpappy]

Well I just removed the MR Head and swashplate and TR Blades and ran it to check that the main shaft wasn't bent. Main shaft was fine but the TR servo was twitching a lot and after two minutes was really hot. I disconnected the TR servo from the pitch change link rod and noticed that pitch change mechanism on the tail rotor was quite stiff. It hasn't been greased since the old king died. I ran it up again and the TR servo got warm with all the twitching but not hot. The servo is a futaba digital micro S3154. I'm guessing the twitching was because of ground vibes with the motor running. I switched to rate mode and it still twitched.

So I know what one problem is....stiff TR pitch change linkage. As for twitching and still getting warm...I don't know. I might just overhaul the TR pitch change linkage and run it again and see what happens. Or I could just say the hell with it and change the servo and gyro. Dunno.

[trillian]

Ideally we always want the pitch linkage to be as smooth and free as possible. The twitching though, it's hard to say without know how much it's moving.

What happens if you plug the servo directly into the RX?

Well I just removed the MR Head and swashplate and TR Blades and ran it to check that the main shaft wasn't bent. Main shaft was fine but the TR servo was twitching a lot and after two minutes was really hot. I disconnected the TR servo from the pitch change link rod and noticed that pitch change mechanism on the tail rotor was quite stiff. It hasn't been greased since the old king died. I ran it up again and the TR servo got warm with all the twitching but not hot. The servo is a futaba digital micro S3154. I'm guessing the twitching was because of ground vibes with the motor running. I switched to rate mode and it still twitched.

So I know what one problem is....stiff TR pitch change linkage. As for twitching and still getting warm...I don't know. I might just overhaul the TR pitch change linkage and run it again and see what happens. Or I could just say the hell with it and change the servo and gyro. Dunno.

[scallybert]

Possibly worth noting that this gyro can (IIRC) run in 760 or 1520 modes.