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Heads up for QQ Yak (ARF) owners!

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Heads up for QQ Yak (ARF) owners!

Old 04-23-2006, 01:03 PM
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patternjockey
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Default Heads up for QQ Yak (ARF) owners!

Hi folks

A heads up for QQ Yak 54 ARF owners.......

I just witnessed a buddies 85 inch QQ Yak 54 flame out on the climbout. The plane was poorly positioned for a return and unfortunately broke up after it landed short of the field. The aircraft was inspected in search of clues to the power loss. It turns out that the fuel tubing inside the tank had swollen and come off causing fuel starvation and the subsequent flame out. The fuel tubing provided in the kit, although it looks like it, is not fuel proof!

I strongly suggest all these kit's fuel tanks be inspected for this problem before flight and at a minimum, the fuel pickup tubing replaced with a reputable brand (i.e. Tygon).

My buddy is a little upset to say the least but has contacted the company to advise of the problem.

I have one of these ARF's and absolutely love how it flys so I would hate to see anyone else lose a ship for a piece of tubing!

Safe flying & building,

Dave
Old 04-23-2006, 03:50 PM
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Jleyland
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Default RE: Heads up for QQ Yak (ARF) owners!

Was the tubing secured with a tie wrap or wire of some sort? I'm using the stock tubing with no problems, it must be either tie wrapped or clipped in order to stay on. All gas fuel tubing I've dealt with expands.
Old 04-23-2006, 03:52 PM
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Jleyland
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Default RE: Heads up for QQ Yak (ARF) owners!

Copied from GSAL.org

Fuel tubing:
Glow fuel tubing is not compatible with gas fuel, the gas will eat the fuel line so use tubing designed for gas, Tygon is one brand.

One thing to remember here is that the line will expand when in contact with gas..
This means that you have to use some sort of clamp to hold the line to the fittings, either a spring clip or some other suitable device.
This is really important, especially in the tank on the clunk line where the clunk is always pulling on the line.
Old 04-23-2006, 05:31 PM
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tail strike
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Default RE: Heads up for QQ Yak (ARF) owners!

Thank you, thank you, thank you, thank you, thank you, thank you, thank you, thank you.

after reading this post I pulled my gas tank and even tho I had belled the end of the brass tube the tygon just pulled right off very easily.
Needless to say I have ti wraps on it now.

I am watching you
Larry
Old 04-23-2006, 06:56 PM
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Maudib
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Default RE: Heads up for QQ Yak (ARF) owners!

Whenever working with gas, the tank should be plumbed with Tygon (or other gas proof line), and zipties, fuel barbs or fuel line clamps used to secure the line.

The supplied clear tubing is only for glow installations and will certainly fail if used in gasoline installations.

Tygon (and most other gas approved lines), while gas proof, does stiffen and slightly loosens over a short period of time. It is common practice to do these things.

Many take it to the next step and solder Dubro fuel barbs to the tubes:



I don't see this as a "tank defect" but rather a lack of experience on the builder's part.

Did your friend use Tygon for the fuel line? If so then he MUST have been aware that silicone is not gas proof and that the clunk line should have been plumbed with Tygon as well.

I'm sorry for your buddy's loss, it sucks to lose any plane, and especially because of an error like this. But I reckon this is the first time someone has lost a QQ 85" Yak due to not plumbing the tank properly for gasoline.
Old 04-23-2006, 07:36 PM
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rctestpilot1
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Default RE: Heads up for QQ Yak (ARF) owners!

So the supplied tank fuel tubing is not gas fuel proof huh? I wish it said that in the instructions before I put the tank together as the instructions are written for "gassers" specifically the 3W or DA.

With regards to the following posted comment:

"I don't see this as a "tank defect" but rather a lack of experience on the builder's part.

Did your friend use Tygon for the fuel line? If so then he MUST have been aware that silicone is not gas proof and that the clunk line should have been plumbed with Tygon as well".

Yes I did use Tygon on all the connections exiting the tank and NO I was not aware that the tank line was silicone and not gas proof. Why would it be included in the kit when the airplane is designed for gas application. That doesn't make sense to me at all. Lack of experience doesn't cut it for me when the wrong type of fuel line was supplied for a gas power designed airplane.

Mark
Old 04-23-2006, 08:09 PM
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Maudib
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Default RE: Heads up for QQ Yak (ARF) owners!

I'm not trying to be combative... and maybe the instructions could have been more clear, I dunno.

I'm also not SURE the included line ISN'T gas proof as there are materials that are both... in this case it doesn't appear the line caused the crash... but rather it slipped off because it wasn't properly connected. Tygon would have done the same thing, and even your external lines could JUST have easily come off instead. I just automatically replace any supplied line with Tygon because I KNOW it's gas proof. ALso because it's stiffer and will not let the clunk flop to the front of the tank.

Anywho... I was more eluding to the fact that the tank isn't faulty... perhaps the manual isn't clear on that topic, but then again, most manuals cannot possibly contain every specific step there is... like loctiting servo screws, but not Karbonite geared ones, no metal to metal contact vibration, etc... the manual would be a tome.

Something also to consider is that it's also possible your engine died because it was too lean and the crash caused sufficient inertia on the clunk to have pulled the line off the tank... tho it is more likely the lack of a ziptie, clamp or barb was the culprit.

It's a shame you didn't partake in the QQ 85" Yak thread... lots of experienced guys there that are glad to answer questions... and are always willing to help people new to gas.

There are also threads here on RCU about "New to gas... what should I know" That discuss many things including, tank plumbing.

In any case, feel free to participate now and ask questions all you want. Often guys will post pictures of their installs and ask "Does this look right?" Or even to share their handywork.

Hope your next experience is better than this one...
Old 04-23-2006, 08:16 PM
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Maudib
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Default RE: Heads up for QQ Yak (ARF) owners!

Also curious... your buddy PatternJockey mentioned he has one of these ARFs... and loves the way it flies... what did he do differently that his tubing hasn't "failed"?
Old 04-23-2006, 08:21 PM
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patternjockey
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Default RE: Heads up for QQ Yak (ARF) owners!

Folks,

The intent of my post was to identify a potential problem with the ARF based on the components provided. I love the plane and look forward to a long fun experience flying it.

Now for the record I did not use any attachment method, (wires, clips etc.) as I was under the impression that Tygon does not expand and swell from gasoline. If it does swell and you must have additional wires, clips, solder nipples etc then obviously I too am caught with the potential flame out scenario like others. Live & learn.

If by looking at the tank and finding this same problem, I have saved someone some grief then my post is worth the time I took to write it.

BTW I removed my tank this afternoon and also found the tubing swollen and lose. (Glad I checked!) The tubing is yellow and appears to be Tygon type tubing. See attached photo:

Dave



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Old 04-23-2006, 09:40 PM
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rctestpilot1
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Default RE: Heads up for QQ Yak (ARF) owners!

It looks like I'm not alone on this issue. I guess if my misfortune saves other pilots from losing their aircraft then my loss is worth every penny I invested as knowledge cannot not be measured in dollars. Kinda sounds like a MasterCard commercial huh?

85" gas airplane "X" dollars
Da Engine "X" dollars
Top of the line flight system "X" dollars

Crashing your aircraft due to the wrong type of fuel tubing that was supplied with the kit.................PRICELESS!


Mark
Old 04-23-2006, 09:49 PM
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Default RE: Heads up for QQ Yak (ARF) owners!

All the tanks I've bought, DuBro or Sullivan all supply silicone tubing with their tanks but it doesn't mean it's OK to use with gas. I don't think any tank manufacturer supplies Tygon tubing with their tanks, regardless how big the tank is.
Old 04-25-2006, 06:05 AM
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randy racer
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Default RE: Heads up for QQ Yak (ARF) owners!

i built my first gasser last fall, AM35%Yak and used the right fuel line with out any clamps. around flight #6 it came off and i missed the runnway. broke the prop,cowl,engine box and fire wall, distroyed the gear. AM's manuel didn't say anything about clamping the fuel line.
all is fixed now and like you, i gained knowledge. in wish the manuel would include tips for the first timers, but i'm sure no one can think of every way i can screw up a build. live learn and fly with a smile.

randy
Old 04-25-2006, 07:02 AM
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Maudib
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Default RE: Heads up for QQ Yak (ARF) owners!

Hmmm some posts disappeared...

Just so it's clear to anyone reading this thread later... the fuel tubing supplied with the plane is indeed Tygon and IS gas proof.

It is a common practice to use ziptied/clamps or fuel barbs . This MUST be done to insure that the tubing does not come off... the iside OR the outside.

I'll suggest that the manual gets clarified on this step to hopefully prevent anyone else from making the same mistake.




ORIGINAL: rctestpilot1

It looks like I'm not alone on this issue. I guess if my misfortune saves other pilots from losing their aircraft then my loss is worth every penny I invested as knowledge cannot not be measured in dollars. Kinda sounds like a MasterCard commercial huh?

85" gas airplane "X" dollars
Da Engine "X" dollars
Top of the line flight system "X" dollars

Crashing your aircraft due to the wrong type of fuel tubing that was supplied with the kit.................PRICELESS!


Mark
Old 04-25-2006, 08:30 AM
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rctestpilot1
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Default RE: Heads up for QQ Yak (ARF) owners!

Just a quick note to say Quique Aircraft Company and I have come to an agreeable conclusion on this issue. I agree that there should be some sort of instruction to avoid improper instalation of tubing in all manufactueres kits especially when using gas.

Anyway, thanks to Quique I will be in the air soon.
Old 04-25-2006, 08:40 AM
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shakes268
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Default RE: Heads up for QQ Yak (ARF) owners!


ORIGINAL: Maudib

Hmmm some posts disappeared...

RCU had a database corruption problem last night and had to restore from backup.
Old 04-25-2006, 08:46 AM
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Maudib
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Default RE: Heads up for QQ Yak (ARF) owners!

Awesome!

I'm sure they'll be making an addendum to the manuals to cover this.


ORIGINAL: rctestpilot1

Just a quick note to say Quique Aircraft Company and I have come to an agreeable conclusion on this issue. I agree that there should be some sort of instruction to avoid improper instalation of tubing in all manufactueres kits especially when using gas.

Anyway, thanks to Quique I will be in the air soon.
Old 04-25-2006, 11:22 AM
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patternjockey
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Default RE: Heads up for QQ Yak (ARF) owners!

Folks,

I think it's only fair to wrap this thread up on a high note. As noted above, a replacement Yak 54 aircraft is on the way to rctestpilot as I type this. QQ personally e-mail him and they came to a mutually satisfactory resolution to this situation.

Special thanks to QQ and his company for supporting both its customers and products to a very high standard. Just one more reason to get this ARF kit!

Now on to other stuff... were can we find an IMAC contest?

Safe building, charging & flying,



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