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Front gear failure - Sting S4

Posted: Wed Oct 24, 2018 10:24 pm
by Warmi
Well, as soon as I got done swapping the oil tank and fixing the leaking fuel line I discovered another challenge - a silent failure of my upper front landing gear.

It literally looks like the front upper leg separated clean at the welding point without any other damage whatsoever up or down the landing gear.
There was no dramatic landing or frankly any particular precipitating landing event that I can think of - after an uneventful flight I simply noticed a bit more play in the front gear and subsequently discovered the issue.

I have no idea what happened and given that there is no other damage anywhere and the leg was being held firm by the lower attachment assembly, I am thinking this was some kind of issue with the original weld and after 300+ landings it finally gave out.

I got the replacement part ordered ( $480 + shipping ) and it will be here in about a week , so ultimately not that big of a deal but still, I got lucky that I caught this issue early on before the subsequent failure of the lower attachment ( which would eventually fail without the upper support ) - it kind of underscores the fact that anything can happen and importance of preflight inspections.

Here is how the part supposed to look ( with the weld highlighted - factory picture ) - firewall side view with lower attachment assembly.

LegLocation.jpeg
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And here how it failed on my plane - inside cockpit view

Leg2.jpeg
Leg2.jpeg (234.22 KiB) Viewed 2214 times



Interestingly, I got a few pictures from about 3 or 4 months ago of that strut that were taken for different purpose… to me it looks like the weld was already developing a crack.

strut1_June..jpg
strut1_June..jpg (128.7 KiB) Viewed 2214 times

Re: Front gear failure - Sting S4

Posted: Thu Oct 25, 2018 6:45 am
by Sling 2 Pilot
Warmi, so glad you caught that. It could have led to more expensive repairs.

Re: Front gear failure - Sting S4

Posted: Thu Oct 25, 2018 4:06 pm
by Jim Hardin
Glad you caught it!

It is interesting... I would not expect cracking or failure from a part that doesn't suffer from hot cold cycling like exhaust systems do.

Did the factory express any interest in examining the part? I would have if I had my name on it :D Actually we did have to stamp our identifier on every weld where I worked.

Re: Front gear failure - Sting S4

Posted: Thu Oct 25, 2018 5:05 pm
by TimTaylor
Probably the result of some hard landings over the past 6 years.

Re: Front gear failure - Sting S4

Posted: Thu Oct 25, 2018 5:52 pm
by Warmi
I haven’t really had a chance to talk to the factory – I mean, B. Canino was very appreciative of rather extensive photographic documentation I provided for him but that’s about it.
As far as hard landings, I am sure these didn’t help and I had a few firmer ones myself but nothing really bad that would warrant this.
I actually have talked to a few Sting owners ( including Rich of Sting Flight who had a very hard landing at Lake Tahoe a few years back ) and all of them indicated completely different pattern of failure related to either hard or side loaded landings.
It is all about bending/crushing damage at certain points ( indicated by the arrows) which to me kind of makes sense - I always inspect the gear looking for any signs of slow, progressing , landing induced failure, like stuff slowly bending etc ...

parts.jpg
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Anyway, my personal theory is that this is more related to takeoffs because, ever since I bought the plane , I always had this nasty front gear rattle with every takeoff – I was told at SportAir that it was related to unbalanced front wheel but I could never get anyone to balance that wheel to get rid of it.
To me , the clean break on this weld looks like some kind of vibration induced failure ( combined with a weak weld to begin with ) – I am gonna make sure that when we start replacing the strut , will check every bolt and nut and see if we can find anything loose ( this stuff is very hard to get otherwise as it is hidden deep in the cockpit side of the firewall)

Re: Front gear failure - Sting S4

Posted: Thu Oct 25, 2018 6:37 pm
by TimTaylor
Nose wheel shimmy is pretty common. Probably the result of past hard landings. You'll never know what transpired before you bought the airplane.

Re: Front gear failure - Sting S4

Posted: Thu Oct 25, 2018 6:51 pm
by Warmi
On the subject of TL Ultralight looking at my broken strut .. I guess they would rather spend their time more productively , like for instance making/releasing videos like this one https://youtu.be/ZO0h8bh9JVQ
:D

Re: Front gear failure - Sting S4

Posted: Thu Oct 25, 2018 8:52 pm
by ShawnM
TL Ultralight? Who? Were there airplanes in that video? All I saw were boobs! :mrgreen: :mrgreen:

Re: Front gear failure - Sting S4

Posted: Thu Oct 25, 2018 9:11 pm
by Warmi
ShawnM wrote:TL Ultralight? Who? Were there airplanes in that video? All I saw were boobs! :mrgreen: :mrgreen:


Yeah, their booths at European aircraft shows are like ...really odd mix of high end , carbon fiber manufacturing themes ....and a cheap Titty Twister style go-go club ( but unlike the namesake in the movie, with crappy music ) .. whatever works ..

Re: Front gear failure - Sting S4

Posted: Thu Oct 25, 2018 9:21 pm
by TimTaylor
I suggest you take down those videos. They are not appropriate for this site.

Re: Front gear failure - Sting S4

Posted: Thu Oct 25, 2018 9:29 pm
by Warmi
Well, one is the official promotion video of a plane manufacturer in Europe and the other is just a minute or two from a high grossing Quenteen Tarantino movie ... nothing really that a well brought up adult with classical education trained mind can’t handle imho :D

But I took the other one down - I guess anyone can look up for themselves what a Titty Twister bar theme looks like ( the music themes in that bar was awesome though )

Re: Front gear failure - Sting S4

Posted: Thu Oct 25, 2018 9:40 pm
by TimTaylor
Maybe, but this is not an adults only forum. There are also women here who may not appreciate the videos. I'm not a mod, of course, so it doesn't matter what I say or think.