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  #1  
Old 03-29-2018, 02:35 PM
Allan Stern Allan Stern is offline
 
Join Date: Jan 2006
Location: Cape Coral, Florida
Posts: 177
Default SB-18-03-06

I am curious about this service bulletin and why Van's has issued it saying to rectify the issue before flight or at next annual? My engine came from Rotax without any springs on the throttle shaft. Checking several other manufacturers with Rotax engines shows no springs on shaft. Secondly when I originally got my engine from Van's we were told to replace the original springs with a heftier one supplied with the engine.
Why hasn't Rotax said anything about throttle shaft springs if these are better than what we currently have.

I have ordered the springs and will look at them and see.

Allan Stern 2018 paid
RV 6A sold
RV 8A for sale
RV 12 out of phase 1
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  #2  
Old 03-29-2018, 02:52 PM
DaleB's Avatar
DaleB DaleB is offline
 
Join Date: Sep 2012
Location: Omaha, NE (KMLE)
Posts: 1,825
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Doesn't say before flight...

Quote:
At or before the next annual condition inspection or upon a part
failure of one of the previous spring types installed on the aircraft.
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Dale
Omaha, NE
RV-12 # 222 N980KM "Screamin' Canary" (bought flying)
Fisher Celebrity (under construction)
Previous RV-7 project (sold)
-=VAF=- 2017 dues paid
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  #3  
Old 03-29-2018, 03:28 PM
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 7,425
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This thread would probably be better in the RV-12 section if a moderator wants to move it. <<Done...ScrollF4>>

A couple of corrections -

- The time of compliance listed in the SB is At or before the next annual condition inspection or upon a part failure of one of the previous spring types installed on the aircraft.

So if you just did a condition inspection last week, you don't have to change until a year from now unless one of the current springs breaks.

- The springs you changed to when you got your engine were actually a lighter/weaker spring, not heavier.

The heavy tension spring originally supplied on the engine makes control of the throttle position more difficult and can cause unwanted throttle creep.
They are a universal / meant for all applications spring that is not necessarily ideal in for all situations (think of an Aircam with 12 foot long throttle cables with multiple bends, vs an RV-12)

The new spring has been introduced to resolve a breakage problem some RV-12's were having because of the low spring tension allowing a vibration mode that caused accelerated fatigue failure.

The new spiral torsion spring can not vibrate in the way the tension spring could , thus improving the longevity.

Having said all that, if someone has an E-LSA RV-12, they can ignore a service bulletin if they don't like it. There is nothing regulator to require you to install the new springs, but I would recommend that you do.

For S-LSA RV-12's, following SB's and safety alerts is required.
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Any opinions expressed in this message are my own and not necessarily those of my employer.

Scott McDaniels
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")

Last edited by scrollF4 : 03-29-2018 at 07:34 PM.
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  #4  
Old 03-29-2018, 07:01 PM
bob1393 bob1393 is offline
 
Join Date: Jun 2014
Location: Port Orchard, Wa
Posts: 82
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I just received the new throttle springs today from Van's. They are very very different than the ones we have been using. They are very short. Scott - will these stretch enough without breaking to fit? Also, they don't have a loop on either end of the spring - are we to bend the spring ourselves to make the loop so they can be attached?

Bob1393
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  #5  
Old 03-29-2018, 07:22 PM
bob1393 bob1393 is offline
 
Join Date: Jun 2014
Location: Port Orchard, Wa
Posts: 82
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Looking at the revised instructions on 50-05, it appears the new spring is put on differently than the old type.

Bob1393
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  #6  
Old 03-29-2018, 07:40 PM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
Join Date: Nov 2014
Location: Hinckley, Ohio
Posts: 815
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The old spring is an extension spring that is stretched linearly (lengthwise). The new spring is a torsion spring that slips over the throttle shaft. As the throttle shaft rotates to the closed position the torsion spring winds-up to provide the counter force.

Torsion springs are commonly used on motorcycle carburetor throttle plates. Well proven design.
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Jim Stricker
Hinckley, Ohio
PPL/ASEL 1970 Sport Pilot since 2004
80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC Jul 2012 - Bought Flying Oct 2015 with 48TT - Hobbs now 318

LSRM-A Certificate 2016
Special Thanks to EJ Trucks
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  #7  
Old 03-30-2018, 06:08 AM
Allan Stern Allan Stern is offline
 
Join Date: Jan 2006
Location: Cape Coral, Florida
Posts: 177
Default Throttle springs

Jim,

I know that a lot of motorcycles use those springs on carburetor so and are a proven design. However if this is so, than why doesn't the Bing carburetor factory or Rotax put them on the engines when they assemble them and ship the engines out? I have a hanger mate building an air-cam. Will be interesting to see if Lockwood aviation does anything?

If I get a SB that telling me to do something "at or Before next annual" then I kind of maybe self interpret "before flight" like that stabilator cracking. Which I took off and fixed along with the AST issue too.
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  #8  
Old 03-30-2018, 07:31 AM
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DaleB DaleB is offline
 
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Location: Omaha, NE (KMLE)
Posts: 1,825
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Allan,

The stabilator and anti-servo tab SBs both gave a time of compliance of, "Before further flight". That's pretty clear and unambiguous. This one doesn't say that it needs to be done right now, mor like "the next time you're in there anyway". And if you're flying an E-LSA, you don't have to do it at all.

We're going to be doing our CI soon, and will be pulling and disassembling the carbs for their 200 hour inspection, so it's good timing for us. Never mind that we have a set of brand new McFarlane springs on the shelf for backup... maybe I can find another Rotax owner who wants them.
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Dale
Omaha, NE
RV-12 # 222 N980KM "Screamin' Canary" (bought flying)
Fisher Celebrity (under construction)
Previous RV-7 project (sold)
-=VAF=- 2017 dues paid
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  #9  
Old 03-30-2018, 07:43 AM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
Join Date: Nov 2014
Location: Hinckley, Ohio
Posts: 815
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I did a little searching and it seems maybe Bing did use extension springs on their carbs and perhaps it was carried over by Rotax.
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Jim Stricker
Hinckley, Ohio
PPL/ASEL 1970 Sport Pilot since 2004
80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC Jul 2012 - Bought Flying Oct 2015 with 48TT - Hobbs now 318

LSRM-A Certificate 2016
Special Thanks to EJ Trucks
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  #10  
Old 03-30-2018, 12:10 PM
philrisl philrisl is offline
 
Join Date: Apr 2014
Location: Deltona, FL
Posts: 13
Default

The Aircam uses a different set up. The spring is relocated to close the throttle to idle.
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