GT 500 tail explodes again

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Assembled and balanced everything just off the ground and the tail explodes.Luckily not too much damage,replaced entire tail upgrading to metal.After about 10 flights just off the ground and this time the tail rotor grip flies apart and drive gear is stipped.I must be missing something here.Everything seemed ok,this could be very dangerous not to mention it's getting expensive.I've just stepped up to 500's from 450's not real familiar with them yet.Can anyone give me a pointer here?

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trevpez Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum (AU) USERID: 387362 HobbyKing aficionado Joined: 28/Dec/2009 Location: C.Coast NSW Online Status: Offline Posts: 291	Quote Reply Topic: GT 500 tail explodes again Posted: 26/Feb/2011 at 7:16pm
	Assembled and balanced everything just off the ground and the tail explodes.Luckily not too much damage,replaced entire tail upgrading to metal.After about 10 flights just off the ground and this time the tail rotor grip flies apart and drive gear is stipped.I must be missing something here.Everything seemed ok,this could be very dangerous not to mention it's getting expensive.I've just stepped up to 500's from 450's not real familiar with them yet.Can anyone give me a pointer here?

Demon Members Profile Send Private Message Find Members Posts Add to Buddy List Gold (UA) USERID: 86578 HobbyKing aficionado Joined: 09/Mar/2009 Online Status: Offline Posts: 339	Quote Reply Posted: 26/Feb/2011 at 9:24pm
	There is plenty of info on this happening all over the internet but there is 2 things you need to do: Replace the tail blade grip screws (the ones that screw into the hub) with some Grade 12.9 screws (M2x8 i think). and also, the slider assembly on the plastic case sometimes touches the tail case because of over-travel leading to the tail case "exploding". i will be doing a Bulletproofing guide on the HK500GT in a few weeks time so look out for that. Good luck, Demon

trevpez Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum (AU) USERID: 387362 HobbyKing aficionado Joined: 28/Dec/2009 Location: C.Coast NSW Online Status: Offline Posts: 291	Quote Reply Posted: 27/Feb/2011 at 6:05am
	Thanks for the tips Demon. I'd say your oh the money with the weak bolts,both times I haven't found the blade's with the grips still attached.Steve Irwin[crocodile hunter] was killed by a stingray barb thru the heart,I don't want to join him with a tail blade thru mine. Do you think the same should be done to the main blade grips?A main blade would be more like being impaled by a javelin.I'm comfortable with a 450 but feel a little intimidated by it's bigger brother.

Blind Vision Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum (DK) USERID: 52464 Forum Admin ADMIN Joined: 21/Oct/2009 Location: DK/Denmark, AMC Online Status: Offline Posts: 3804	Quote Reply Posted: 27/Feb/2011 at 6:28am
	can the tail lock-up ?, and the servo crushes the bladeholders... - seen it could happen on a Align (to much throw on the servo)
	Doing some guerilla gardening... take a peek; http://www.facebook.com/groups/416558261701047/ lokal bustop infront of my flat

Demon Members Profile Send Private Message Find Members Posts Add to Buddy List Gold (UA) USERID: 86578 HobbyKing aficionado Joined: 09/Mar/2009 Online Status: Offline Posts: 339	Quote Reply Posted: 27/Feb/2011 at 7:53am
	As far as i am aware it isnt the screw securing the blade to the blade grip - it is the screw securing the blade grip to the centre hub. From what i have heard the screws securing the main blade grips are fine (or at least, i have not heard of any failing). There is a bug with the plastic tail (on the 500GT) that at max throw it does indeed lock up (the metal sliding arm touches a part of the plastic tail housing) and that is what causes the " Exploding tail syndrome". what you can do to stop it is putting a shim between the slider and the tailbox to prevent the servo from being able to hit max throw mechanically... Or go to the HK metal tailbox and change the screws out. The tail screws failing is not a problem limited to the HK500GT and if you look around the same thing happens to alot of the original ALIGN 500 and 550 size helicopters. Hope that helps, Demon

trevpez Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum (AU) USERID: 387362 HobbyKing aficionado Joined: 28/Dec/2009 Location: C.Coast NSW Online Status: Offline Posts: 291	Quote Reply Posted: 27/Feb/2011 at 9:52am
	I'm talking about the screws securing the grip to the hubs,not the blade retaining bolts.The first time travel may have been a factor as the plastic case split apart and a blade went into orbit.The second go I replaced the assembly with metal, the case itself handled it, again a blade complete with grip in orbit resulting in bent tail shaft,stripped belt a stripped set of drive gears.I don't have a spare tail shaft instock to be able to check out all travels.I will however straighten the bent shaft, only to see if travel is a contributing factor. Thanks again,I'll keep you informed as to the results

hairykarts Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum (NZ) USERID: 424820 Hobbyking Addict Joined: 24/May/2010 Location: auk nz Online Status: Offline Posts: 455	Quote Reply Posted: 27/Feb/2011 at 1:32pm
	I havn't had any problems with the tail since I checked the travel of the tail blades, but I check this regularly and make sure there is no binding at full throw in both directions. Change the various nuts and bolts, make sure you use locktite, Its worth the effort as the 500 is much more impressive than the 450. Rob
	I must remember .... when inverted .... down is up and up is down .

Demon Members Profile Send Private Message Find Members Posts Add to Buddy List Gold (UA) USERID: 86578 HobbyKing aficionado Joined: 09/Mar/2009 Online Status: Offline Posts: 339	Quote Reply Posted: 27/Feb/2011 at 4:21pm
	Hi Trav, What you are saying sounds pretty much spot on. The plastic tail is known for exploding as a result of over travel and the metal slider bracket contacts the slider arm on the tailbox and binds (see pics below). Even if the builder spots this and puts a shim in place to prevent it - Then the screws will fail eventually. The metal tailbox doesn't have the same problem with binding but has an increased risk of the screws failing due to the extra weight of the metal tail grips. Hope that helps, Demon

trevpez Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum (AU) USERID: 387362 HobbyKing aficionado Joined: 28/Dec/2009 Location: C.Coast NSW Online Status: Offline Posts: 291	Quote Reply Posted: 27/Feb/2011 at 5:59pm
	I found that 450 class, the aligh shafts are harder to bend, not to mention the pityful attempt with the belt drive gear.Sometimes cheap isn't cheap when you have to do a complete rebuild due to componant failure.Once you get the hang of things everything seems to fall into place

trevpez Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum (AU) USERID: 387362 HobbyKing aficionado Joined: 28/Dec/2009 Location: C.Coast NSW Online Status: Offline Posts: 291	Quote Reply Posted: 27/Feb/2011 at 7:55pm
	Demon Have just done a complete strip down type autopsy.It would appear we are on the money.It doesn't look like the slider can blind on the metal version, so bolt failure seems to be the culprit.I'll have to wait now 'till I can get me grubby little fanny scratchers on a new shaft. Thanks for your help Trev