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AV8ORJWC
Joined: 13 Jul 2006
Posts: 1149
Location: Aurora, Oregon "Home of VANS"
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 Posted: Mon Jun 07, 2010 10:45 am Post subject: RV-10 losses against the finite pool of insured's |
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A few of us were Hangar talking on a soggy dark day a little while ago about what is now the 4 total loss of a finished RV-10s against the fleet of over 300 successful ones. Now owners are beginning to pay increasing premiums to cover those losses. It is some Real Money charges passed back onto the remaining pool with a dwindling number of companies wanting to insure us. After the resent loss of an Alternate Engine RV-10 in Georgia, it was mentioned that 50% of those losses were these (an alarming percentage of the Alternate RV-10 Fleet) and a question raised at what might be a short list of some of the various conditions to look for. There is seldom a simple answer and always lots of discussion which can be a good thing or frustrating. I don't think it’s the Alternate Engine choice.
As an EAA Tech Advisor, occasionally I am asked about Vans coiled aluminum lines, B nuts, ferrules and the like. Also I am asked as to the merits and costs of Bonaco pre-fabricated products. Attached herewith is an excellent post on hydraulic lines, It just as easily could have been "Fuel" lines on one of our RV-10s. (Note: The PDF attachment is 290K for our bandwidth restricted brethren). Too often, the builders of Experimental Built/Amateur maintained aircraft are yet to get up to speed on the latest fabrication techniques, effective flushing of an installed system and proper torqueing of B nuts. Much is the result of poor preparation and brutal torqueing forces by operators. Kinks, chafes, constrictions , FOD and distorted mating surfaces came to light. Quality Control and a second set of eyes can certain not hurt.
I doubt we will ever hear that such a boring subject actually contributed to the loss of the most recent RV-10. Hopefully a few builders out there may find value in a road traveled by an earlier builder with fabricated lines. The pictures drive home what we are looking for in a successful Tech inspection. Some value may be applied to future RV-10 operations.
Just fanning the fumes of controversy before packing up for the pilgrimage to OSH. Our prayers remain which those who travel before us and contribute to the pool of our aviation experiences. <<Anatomy of a Hydraulic LeakR3.pdf>>
John Cox
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jdriggs49(at)msn.com
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| Posted: Mon Jun 07, 2010 1:38 pm Post subject: RV-10 losses against the finite pool of insured's |
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John,
Nice article. i've made a hard copy to keep in the basement to refer for torque values. I'm replacing the few aluminum lines I've already installed with SS as I believe they are much better. I'm really "anal" about torquing and then marking every nut and bolt installed. However, one brake line that I had previously installed didn't even have a flare on it. How the heck did that happen???  Must have been those dang elves that work on my plane at night forgot to put a flare on. I'm gonna have words with them! Thanks again. Dan
Subject: RV-10 losses against the finite pool of insured's
Date: Mon, 7 Jun 2010 11:38:04 -0700
From: johnwcox(at)pacificnw.com
To: rv10-list(at)matronics.com
RV-10 losses against the finite pool of insured's
A few of us were Hangar talking on a soggy dark day a little while ago about what is now the 4 total loss of a finished RV-10s against the fleet of over 300 successful ones. Now owners are beginning to pay increasing premiums to cover those losses. It is some Real Money charges passed back onto the remaining pool with a dwindling number of companies wanting to insure us. After the resent loss of an Alternate Engine RV-10 in Georgia, it was mentioned that 50% of those losses were these (an alarming percentage of the Alternate RV-10 Fleet) and a question raised at what might be a short list of some of the various conditions to look for. There is seldom a simple answer and always lots of discussion which can be a good thing or frustrating. I don't think it’s the Alternate Engine choice.
As an EAA Tech Advisor, occasionally I am asked about Vans coiled aluminum lines, B nuts, ferrules and the like. Also I am asked as to the merits and costs of Bonaco pre-fabricated products. Attached herewith is an excellent post on hydraulic lines, It just as easily could have been "Fuel" lines on one of our RV-10s. (Note: The PDF attachment is 290K for our bandwidth restricted brethren). Too often, the builders of Experimental Built/Amateur maintained aircraft are yet to get up to speed on the latest fabrication techniques, effective flushing of an installed system and proper torqueing of B nuts. Much is the result of poor preparation and brutal torqueing forces by operators. Kinks, chafes, constrictions , FOD and distorted mating surfaces came to light. Quality Control and a second set of eyes can certain not hurt.
I doubt we will ever hear that such a boring subject actually contributed to the loss of the most recent RV-10. Hopefully a few builders out there may find value in a road traveled by an earlier builder with fabricated lines. The pictures drive home what we are looking for in a successful Tech inspection. Some value may be applied to future RV-10 operations.
Just fanning the fumes of controversy before packing up for the pilgrimage to OSH. Our prayers remain which those who travel before us and contribute to the pool of our aviation experiences. <<Anatomy of a Hydraulic LeakR3.pdf>>
John Cox
The New Busy is not the too busy. Combine all your e-mail accounts with Hotmail. Get busy. [quote][b]
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ecurington
Joined: 26 Feb 2010
Posts: 1
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| Posted: Thu Jun 10, 2010 10:59 am Post subject: Re: RV-10 losses against the finite pool of insured's |
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John,
Your article was very timely for me as I am just starting on my fuel system on my, -10 and it struck me as needing torque values for the flare fittings. I am currently running the vent tubing inside the tanks. I ordered the crowfoot adapter for the torque wrench after reading your post. However, the article did leave me with a couple of questions.
Should I be making double flare connections? I have the roto flare tool but do not have the double flare adapters. Does anyone have experience using the roto tool and double flare adapters?
Are the torque values listed in the article the same for double flares?
Thanks,
Eulice
RV-10 Wing Tanks
Serial # 40596
| | - The Matronics RV10-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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AV8ORJWC
Joined: 13 Jul 2006
Posts: 1149
Location: Aurora, Oregon "Home of VANS"
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| Posted: Thu Jun 10, 2010 11:37 am Post subject: RV-10 losses against the finite pool of insured's |
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Wrench tightening was on page 2 of 7 in the attachment. A flare or 12pt
crows foot works better than a standard two contact points. Torqueing
is critical.
During fabrication, some do not cut the tubing perpendicular, some leave
burrs or blemishes. A deburr wheel lightly applied can make a big
difference. Get a 10X inspection lens (you should have one for
sparkplugs anyway) and look with light at the workmanship before
applying the flare. Single flare is most common. Smaller tubes such as
1/4" 0.250" will sometimes get a double for additional flare strength.
The torque values are the force to be applied to the B nut. Most damage
incidents after fabrication are the application of 125%, 150% and
GoodNTight overtorqueing. You would be amazed how many times Foot Pounds
rather than the specified Inch Pounds are applied. that is 1200% Duh!
Pictures demonstrate what deformation the flare incurs when placed under
such abuse. Occasionally the coil tubing vs. the straight tubing can
demonstrate weakness of seams and associated failures.
Good luck with the build. Become familiar with the AC43.13 on the
subject. Bend Radius of rigid tubing, flex tubing and wiring are all
fascinating for the more anal types. (No Side comment requested or
required Rick).
John
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