700E catastrophic tail blade failure causing complete destruction

[Hank79]

Hello friends, i thought it would be a good idea to give you the heads up before this could happen to you. My 700e only had 40 fights before a defective socket screw sheared off the tail rotor hub which as a result
the tail blade grip and tail blade flew off in mid air. This caused a tail failure that totally destroyed the whole helicopter. There was no way that the helicopter could be recovered once all control of the tail was lost.The Heli started pirouetting on a 45 degree angle uncontrollably. After it was clear the Heli was not recoverable I pressed the throttle hold button on the tx to minimize the damage. However, despite this the Heli is a ****ing write off, with it being virtually 95% destroyed. I have been flying for about a year, I have owned a 450 and 500 and this has never happend. I do not fly 3D and therefore do not put big loads of stress on the helicopter parts, i fly more circuits and scale. I loctite all the screws, I do not over tighten screws, I do regular servicing so my helicopter is in good condition. This helicopter has cost me $3000 to get into the air and one defective screw breaking/sheering off the tail hub worth maybe less than a dollar has caused this. The other aspect is that the helicopter has never had a tail blade strike of any kind which may have weakend the components in the tail.The rear torgue tube gears are in perfect condition proving the rear tail gear components was not at fault. The reason I know it was 100% a rear tail blade grip and tail blade failure is I saw it happen right in front of me, only 20 metres away. All i saw was the rear tail blade grip and blade fly off at tremendous speed from the high rpm of the tail. So im 150% sure this caused the crash. This crash was not due to any other failure as all the servo's and engine were able to function after the crash. To say im pissed is an understatment

As you can see from the picture below, the socket screw has sheared right off. Two thirds of the
screw is still lodged inside the thread. Please take the nessesary action in putting stronger socket screws that hold the blade grips to the rotor hub.











This is the heli in happier times, man i loved this thing, best heli i'v ever had

[terrybeb]

I'm very sorry to hear that and to see the pictures. Bert Kammerer and Bobby Watts had mentioned this in one of their Smacktalk Video's but your photo's have reinforced their statements to replace those bolts with aftermarket ones. I think I'll use the Lynx Spindle bolts on the head as well, just to be safe.
You may not have been able to save your heli but you may have been instrumental in saving other's heli's including mine.

[heli21]

I replaced my spindle bolts with the Lynx Spindle bolts and I replaced my tail grip bolts with 3x10-class 12.9-blue coated steel bolts.
Sorry to hear about your helicopter
Rob

[litespeed]

Originally Posted by heli21

I replaced my spindle bolts with the Lynx Spindle bolts and I replaced my tail grip bolts with 3x10-class 12.9-blue coated steel bolts.
Sorry to hear about your helicopter
Rob

Sorry for your loss Hank79......


Since I'm not really sure what these bolts are your speaking of can you post a link. For piece of mind I'd just assume replace mine now.


Tom

[ghost400]

Sorry to hear about that fatal defective .

Please could someone post a link where to buy those aftermarket tail grip bolts?

[Shef]

I'm soooo sorry to hear about your crash...I feel your pain, had a near re-kit crash last week. Hopefully your electronics survived.

Anyway you cut it, crashes (no matter how minor) can do some insane amount of damage because the weight of the bird. But when a crash is due to a bad part, it's beyond frustrating! Sorry again.

[heli21]

I use Mcmastercarr Part # 91303A012 for tail grip bolts.
I've got some extra ones and I'd be glad to hook you guys up with some.
If your going to Ircha Stop by the Esprit Models tent and ask for Rob McQuillen.
Rob

[f22warzone]

Dude that's bad.... feel sorry for your loss

on a happier not tho at lest your batteries didn't catch fire resulting in a total lose of electronics to.

Man thos main blades were beautiufl, at lest I now know they wont come apart

Hope to see you back up in the air again, and its very frustration when a stock part cant hold up to stock performance.

[kshelton]

I have a friend that this occurred on a nitro 700. After I saw this we all switched to plastic instead of alumn tails. I think it is a combination of bad bolts and alumn tail grips.

Kevin

[Mystic3D]

Sorry for your loss, I know it's heart breaking. Just don't give up, A rekit might be a cheaper alternative.

You had me sweating if I had replaced those bolts. The KDE Tail upgrade which I put on has Class 12-9 Bolts. The tail had a ton of slop which is the reason I did the upgrade, I did not know about the bolt problem.

[vanguy]

A similar thing happened to me with my 500 ESP last month but my bolt backed out instead of shearing off. However, my damages were not as bad as yours. It was my first mechanical failure in almost one year of flying. Unfortunately, most catastrophic failure is often the failure of a small cheap part.

[Speedy1661]

Originally Posted by heli21

I replaced my spindle bolts with the Lynx Spindle bolts and I replaced my tail grip bolts with 3x10-class 12.9-blue coated steel bolts.
Sorry to hear about your helicopter
Rob

Shit sorry to hear about that!

Do i understand that right, that the mainproblem are the cheap quality from the M3x8mm Socket Screw? So they broke and not the spindle bolt?

I think i have to change them too...

i never heard something about 12.9 class and so on...
when i buy new screws i think my dealer should have good onces no?

[PatrickH]

Thanks for the heads up. I went ahead and ordered some of the McMaster bolts mentioned above.

[Mystic3D]

Yes cheap bolts componded by the fact that the tail blade grips have some play side to side certainally does not help. I am sure cheap bolts to not have much shear strength.

[terrybeb]

Originally Posted by heli21

I use Mcmastercarr Part # 91303A012 for tail grip bolts.
I've got some extra ones and I'd be glad to hook you guys up with some.
If your going to Ircha Stop by the Esprit Models tent and ask for Rob McQuillen.
Rob

I'll take you up on that offer on thurs morning Rob.

[heli21]

I'll take you up on that offer on thurs morning Rob.

I'll be there thurs afternoon.
Seeyou then
Rob

[michael503]

Man, I am sincerely sorry for your loss.

I had watched the smacktalk video and Bobby mentioning this, but I had convinced myself that maybe it was nitro only, but after reading this, I put my butt in gear and went down to the local bolt store, "Alabama bolt", and they seem to stock everything. I got a small number of grade 12.9 bolts and plan to install them shortly. I took the liberty of doing some unscientific tests, comparing both of these bolts.

I found that...

-The Align bolt gets cut twice as deep with a file per pass.

-Cutting the bolts in two with a pair of electrical pliers with bolt shear holes, the Align bolt cuts easier and the new bolt cuts with a sharp snap vs a softer feel. There is more smearing on the Align bolt.

-Striking the bolt with a hammer 3 times produces slightly more deformity on the Align bolt, but not a significant amount.

the fuzzy pics below show the 2 bolts, the Align bolt is on the right.

Thanks for the heads up!

[heliwoodster]

+1 on the slop in the tail just put some quick uk grips on i had spare.

[Hank79]

Thanks for all the thoughts guys. At this point i have contacted the supplier and sent them and email and pictures. They forwarded them to Align to see if anything can be done. After reading the liability notice in the manual it seems i would not have a leg to stand on. I'm hoping i will be able to get another one soon but what worries me is the fact this crash was totally out of my control. This does not give me confidence in the next 700E i build as i do not know whether this will happen again. I would have prefered that i had made the mistake and crashed it, this way i could gain confidence that it wont fall out of the sky unless its my fault. On top of this ,its the time it takes to build and set the heli up, i think my friends and i put 40 or more hours into it. When i build the next one im going to put extra strenghth bolts through the whole Heli and the KDE tail upgrade. As pissed as i am, im not going to let this stop me flying these big birds as they are so worth the effort. This 700E is an incredible Heli, it flys far better than anything i have had before, its like a drug, once you fly it, you have to have it. I took the 500 out just yesterday, and boy did it feel like a little kitten by comparison. Its not even in the same leage as the 700, however it has not failed on me yet(touch wood)!

[im4711]

Sorry to hear about your loss. Actually Sunday I had a similar experience on the 700N. Tailblade holder flew off due to the same issue. The complete tail section was bent and finally cut off. I saved most of the heli by switching to throttle hold almost instantly. Still I have to replace the complete tail section, main blades, landing gear ... (total cost about 400 USD).
So I did read about the the bolds. Where would I get some decent once (would have to put them on the 700E and the 700N)? Any website where I could order them?
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