View Full Version : Failed Open T/R on Stratus
Scrub
08-08-2005, 04:44 PM
I have (had) an open T/R gear box on my Stratus. It had the latest shaft/gear assembly (not pinned). The assembly had less than a dozen flights on it. I was flying around when all of a sudden the tail let go and piroed out of control. Here's a few pics of the broken shaft.
http://www.helifreak.com/album_mod/upload/606fc222cc6d3fa6d448d4843d1dc09f.jpg
http://www.helifreak.com/album_mod/upload/632b4f406c248a8962e5ac6dcf621a83.jpg
bono1
08-08-2005, 05:15 PM
That does not look good at all. Hope that you were able to minimize the damage with an auto. I have two extremes with closed boxes and have considered the open boxes, mostly because of the new factor, but I have decided to wait and see what the final 'new and improved version' looks like. Does (had) mean that you have gone to the closed box?
Sam
WayneBrown
08-08-2005, 05:23 PM
MA has recalled the open boxes for all GAS powered machines. They will replace at no cost an open box with a closed gearbox provided you have a VALID serial number for your Spectra G.
This has been implemented for a week or two already, so all you need is to send it in.
Did you get the machine on the ground without further damage?
Scrub
08-08-2005, 06:18 PM
The T/R was from my Spectra but after all the failures I read about them I swapped it. So now, my Spectra G has a Closed T/R case and my Stratus has (had) the newest version of the open T/R case. I think I've had it with the Open T/R and will be switching back to the closed style.
I did get the bird down with no damage. I wish I had a video of it. I was about 20 ft from the ground and just entered into a tight funnel when the tail let go. The heli went inverted and spun out of control. I hit throttle hold (don't you love that switch ?) and flipped it right side up just in time to make a very gentle landing. The next thought in my mind was "thank God".
WillJames
08-08-2005, 07:09 PM
Did you get in touch with MA about this Scrub? I know they are VERY concerned about this issue.
kthane
08-08-2005, 08:51 PM
I wonder if this gear box you "had" on your stratus had any flight time on your spectra? :shock:
ChrisS
08-08-2005, 09:04 PM
Hey Scrub
Give us a call tomorrow and we'll take care of this...glad you got it down without any further damage.
Chris
Scrub
08-08-2005, 09:19 PM
The t/r did not have any time on the gasser. I sent it to MA a few weeks back to have the new gear put on. But instead of putting it back on the Spectra I decided to put it on the Stratus.
Thanks Chris, I'll give you a call tomorrow.
EricLarson
08-08-2005, 10:25 PM
Good save man.
OK so now the pinned shafts are starting to break too ? what can us mortals do with the open gear box ?
im starting to think this isnt a shaft problem but there might be something else in the box causing pressure to break these shafts ?
capebob
08-09-2005, 04:33 PM
I too think this is getting to be a big problem. I have had good luck with my gear box but one of my flying friends has broken two shafts by merely dragging in an auto over grass. He is very unhappy.
Bob
"two shafts by merely dragging in an auto over grass"
I have seen this happen as well with two of them up here in Colorado. Both autos were not the best but the hits were relitivly soft and the tail blades and remainder of the saft went flying. What is going on with these???
Joel Mann
08-15-2005, 06:58 PM
Great save!!
Ive broken 2 already. I replaced one shaft took it to the field spooled it up and it broke in the same place. i put another in and flew about two cases and broke yesterday in a spool up. both shafts were the rolepin version. i dont have any vibe problems this on my stratues. anyway i hope tim fixes the problem. i might put my closed box back on sence im not the only one with this problem.
How about making tail output shafts without the middle hole?… then building the boxes FAI style, tail rotor on the RHS. Should fix the problem…..It will require a bit of re-work on the Stratus frames to move the servo to the other side, but looks very doable.
DavidH
08-16-2005, 09:15 AM
It will require a bit of re-work on the Stratus frames to move the servo to the other side, but looks very doable.
No re-work at all required to move the tail servo to the right side of the Stratus frames. The Stratus is available for a right side and left side tail servo setup.
David
wattybotts
08-16-2005, 03:39 PM
I have seen this happen to the same person's helicopter twice- which makes me think that it could be a setup problem? Maybe a tail vibration issue?
Scrub
08-16-2005, 03:56 PM
Bobby, Great observation! Prior to the failure I did have a severe vibe from the tail. The t/r assembly worked flawlessly for about 5 flights. Then all of a sudden my 601 wasn't holding anymore. I narrowed it down to a vibe in the tail. I adjusted the mesh and the vibe went away and the 601 held as normal. The following week, two flights later, the shaft breaks.
Can this be the cause of the failures?
WayneBrown
08-16-2005, 06:15 PM
It's been said that vibration is the source of the breakage, and that it is more pronounced in gassers due to the weight of the rotating engine assembly.
If you have a fan that's out of balance and/or runout, even slightly it can duplicate this 'harmonic vibration' in glow powered choppers. Any vibration is bad, period. If you notice any, and have a problem finding it quickly, it'd be best to swap for the closed gearbox while you search it out, rather than keep flying it and have a failure.
I'm sticking with the closed box.