Flyng Dragon PCP Air Tube Failure

[cosmic]

Borrow a magnetic rake for  roofing nail pickup and try that to locate the tube, or a strong magnet on a rope in the water..

[Kailua]

So this is the bottom line for me and correct me if I am wrong or add any thoughts.
This incident did happen but probably will never be solved.
If threading in the tube and tolerances feel adequate (not to much wobble 1/4" in) and the ends are square (no taper).  As mentioned through mass production there may be a bad apple in the bunch.  So with a little checking of part or parts on hand.  I will feel confident on using this rifle as designed under 1500 psi.  JMO

[Nathan]

I don't own one of these rifles, so I have "no dog in the fight" as they say. If you feel, after some inspection of your rifle(s) that they're safe to use at a given fill PSI, great. Shoot and enjoy your rifle. Some people may never trust this gun design at any pressure even after an inspection and get rid of them. If they feel that is the safest thing to do, great. Do it.
One gun failed, we know that. One gun out of maybe dozens, hundreds or many more converted so far. There may never be another failure like this or any other type in one of these guns, ever. The missing airtube may never be found and even if it is, they may not be enough information to conclusively determine that cause(s) of the failure.
Each individual is going to have to choose. If they own one or more of these rifles, if they want to continue pressurizing and shooting it/them. If they don't own one, if they want to purchase a new or used model  or not.
If someone makes a choice different from yours or what you think they should, so be it. Don't say anything negative about them.
Just my $0.03 (adjusted for inflation) and not directed at any one poster/person.

Nathan

[Motorhead]

Has anyone thought of doing a magniflux on the receiver?
Bill 

That won't work best I understand how magniflux works .... Part must be Steel, Ferris iron able to be magnetized by current applied which then shows breaks in the magnetic field created along fractures of part edges.
The Iron particles then get attracted to where this field gets broken etc ...
Cast or billet aluminum I don't think can be subjected to a magnetic field and test the same as irons ??

Could be wrong tho 

[Privateer]

https://www.pegasusautoracing.com/productdetails.asp?RecID=1207

[Rocker1]

I have checked  iron, aluminum, titanium  just about everything on a racing engine, different dust for different type metals.  David

[OleTomCat]

Very interesting, can't wait to see what comes of it, I will be shooting my FDPCP this weekend, only fill to 1500 psi, lets see what happens....

[ronbeaux]

Just a thought.

We had a 1/2" thick 20" pipeline rupture and fling sections of pipe over 200yrds in three directions that was transporting methane. It was idle at the time and only had 600 psi contained. It was a 2200 psi rated line. After gathering and analyzing the pieces we found , it was determined that a corrosion pit that reached 70% of the thickness was the intitial cause of failure. Since the pipe contained a gas the rupture was many times more violent than one containing liquid. A Chevron pattern pointed to the intial point of failure.


Sooo. What if the gun had moisture in the tube and sat long enough in one place to start the corrosion and when it failed it failed so dramatically that the section of threads were not "pulled free" but instead simply deformed enough to loose contact.

And looking for one piece is why you are not finding multiple pieces instead? We found 13 individual pieces.

Very interesting 7 pages of info here. Just haven't seen this line of thought.

The pieces we found looked like torn paper and it was 1/2" steel.

Just thinking out loud here, no real experience in this type of work, but wouldn't the fact that it was in a gun case and the hole in the case shows that a single point of exit was made indicate your idea that it fragmented not logical. ps without searching all of this thread, I may have seen the photo of the gun case from the yellow link.

The pic I saw here showed tearing of the material inside of the gun case and not a 'clean' exit hole. The case is layed open and there are tears on each side of it and there is not evidense that the zipper still works. It could have ruptured into pieces, tore the inside material, and broke the zipper evenly along the threads. Once the threads of the plastic zipper failed it would just lay open.

Sure would like to see the tube

[BigTinBoat]

It could have ruptured into pieces, tore the inside material, and broke the zipper evenly along the threads. Once the threads of the plastic zipper failed it would just lay open.

If this happened, I wonder how the alum barrel band was apparently untouched? Did the tube just break apart on each side of it?

[Booger]

It could have ruptured into pieces, tore the inside material, and broke the zipper evenly along the threads. Once the threads of the plastic zipper failed it would just lay open.

If this happened, I wonder how the alum barrel band was apparently untouched? Did the tube just break apart on each side of it?

+1 on the barrel band.

[Geoff]

here is 1 image that Bob posted where I cropped, lightened and sharpened the image

[BigTinBoat]

here is 1 image that Bob posted where I cropped, lightened and sharpened the image

So not being able to see the opposite side of threads...what if the tube to receiver threads where on the "loose" side and when the gun was put into the vehicle the tube was "knocked" against something on it's right side? (or if it was sitting still and something else was dropped or shoved against it?) causing the end of the tube to move to the left and "disengaging" the threads we can see. Could the tube then get ejected from the receiver only damaging the threads we can't see?
In this pic the threads we can see do not look "damaged", but some look to have some pieces of "debris" on them.

[bradyman1]

Can we get a pic of the other side of the threads?

[BigTinBoat]

Can we get a pic of the other side of the threads?

Didn't realize one had been posted towards beginning of thread, but looks like the other side is in "decent" shape. Hard to tell from the quality of pic (a bit blurry), but it doesn't seem like much of the Alum threads are damaged on either side. I would think it would look quite a bit different if the tube had "scraped" along any of the threads while "exiting".

The receiver separating (expanding) , via a possible crack, seems like the most plausible explanation at this point.

[bradyman1]

I saw that pic but it is not very clear or telling.

Does Grumpy still have the gun or is it on its way to Mike?

[William]

It is obvious that the threads gave out, could have been tube to small/receiver hole too big/ or badly cut threads. That receiver did not crack, it would be obvious if it was, due to as the threads on the tube forced their way out, it would have spread open the breach and a crack would be obviously seen.

I have seen a lot of threads give out on tubing and other types of threaded items, that picture shows the same thing, threads not holding for some reason.

I'm no expert but anyone should be able to look at that and tell what happened and it was not from over filling.


William

[avator]

WOW  that's the first picture of the stock I've seen. That shows some energy that I didn't have a mental image of before.

[rsterne]

My understanding is that the tube went straight out through the end of the case, and therefore straight out through the barrel band, which is why it wasn't damaged.... The damage to the stock and the sides of the case are presumably from the sudden air blast when the tube parted company from the receiver.... There was no parts of the air tube found inside the truck, nor was it damaged, so I think it extremely unlikely that the tube fragmented.... If I get any more details or photos, you can rest assured I will post them....

Bob

[bradyman1]

Partial information and minimal photos lead the masses to speculate. That doesn't help anyone. It doesn't help the owners of the fdpcp and it sure doesn't help Mike.

Mike is a good guy and does a lot for the airgun community and the GTA!

[Big Bore Bart]

 IMHO the photos and other evidence point to a spiral failure of the thread root.    The tube is quite possibly hanging in a tree, the threads having turned into a Slinky(Tm).   I have seen this type of failure in low pressure steam and HP water piping, the pipe corrodes and erodes from the inside until only the threads are left.   The pipe is then removed simply by pulling on it( if it hasn't already removed itself)  The damaged thread tops is the main indicator for my diagnoses.