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Old 03-22-2016, 10:58 AM
Pat Stewart Pat Stewart is offline
Join Date: Jan 2005
Location: Granbury Texas
Posts: 1,116

I have had one break on the right side.
Built, RV 8, RV8A, RV 10, RV12, Purchased RV7A
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Old 05-16-2016, 08:33 PM
PilotBrent PilotBrent is offline
Join Date: Dec 2011
Location: Hackettstown, NJ
Posts: 426
Default Throttle spring break

Per Scott's note on this thread, I'll be putting in a report to Van's on this but thought I'd mention it here.

Installed Vernier Assist Throttle Control 3/2015 obtained from Van's with the new springs provided. At 107 hours, the right spring failed (noticed it after flying for several hours just before last flight of the day during a quick peak in oil door). Don't specifically remember looking at it at beginning of the day but I generally take a good look through door before the first flight of the day and obviously didn't notice anything. Throttle moves back and forth just fine without it so I wasn't even noticing an issue flying. If it had failed on left side, I might not have detected it until next oil change. Left side spring looks fine BTW.

Appears to be a relatively clean break just at the bottom of the coils. I'll hang onto it in case Van's wants to inspect it themselves.

Brent Connelly
Hackettstown, NJ
RV-12, N913BC

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Old 05-29-2016, 08:11 PM
Handclutch Handclutch is offline
Join Date: Feb 2015
Location: Bendigo, Australia
Posts: 59
Default Make that two

Found my right hand one broken over the weekend. Identical to the photo posted by Brent - snapped in exactly the same location. About 60 hours in service. Discovered recently that the prop had been installed without careful attention to equalising pitch. There was almost 1 difference! Now fixed but that may have been a contributing factor. Carbs have been well balanced from beginning (115 hours TT). Seems that more breakages are occurring on the right-hand side. If so, there has to be an explanation, but hard to imagine what it could be.

Like others I found that the aircraft still performed satisfactorily broken spring. Quite smooth at idle and above 5000 but noticeably rougher in the mid-rev range.

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Old 05-29-2016, 09:17 PM
bob1393 bob1393 is offline
Join Date: Jun 2014
Location: Port Orchard, Wa
Posts: 84

I called and talked to McFarlane. They told me it is usually the passenger side spring that breaks or falls off. They also said it could be due to propeller or engine vibration.

We had our propeller balanced, and have not had a broken spring in quite awhile. We also safety wired the bottom of the spring, and bent the top of the spring a little extra.

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Old 05-29-2016, 11:28 PM
RFSchaller RFSchaller is offline
Join Date: Oct 2010
Location: Phoenix, AZ
Posts: 2,201

I put in weak springs from Home Depot Four years ago after my frustration with throttle creep on the originals and one pair of HF springs that broke. They give vey smooth throttle action and no creep. I had to cut them to size. As I recall they are 0.375" coil and0.035 wire diameter.
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Old 05-30-2016, 05:39 AM
Mich48041 Mich48041 is offline
Join Date: Apr 2008
Location: Riley TWP MI
Posts: 2,603

I purchased Century Spring part number 5553. Coil Diameter: 0.375, wire diameter: 0.034, length: 3.63 inches, with extended hooks on both ends. I cut the springs shorter and formed hooks on the cut ends. My new springs have a fraction of the tension of the original springs. With the friction knob completely loosened, the throttle does not move unless the engine is running. Then the throttle opens with the help of vibration. These are the 4th Century part that I have tried and have finally found a winner. Century Spring has a $50 minimum order, so I had to buy many more springs than I will ever use.
At first I was apprehensive about experimenting, concerned about a spring breaking. But with all of the reports broken springs with no noticeable affect, not to worry.
Joe Gores
RV-12 Flying
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Old 05-30-2016, 10:28 AM
RFSchaller RFSchaller is offline
Join Date: Oct 2010
Location: Phoenix, AZ
Posts: 2,201

Joe, sounds like you are using a spring equivalent to the Home Depot one I use.

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Old 05-30-2016, 11:13 AM
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Piper J3 Piper J3 is offline
Join Date: Nov 2014
Location: Hinckley, Ohio
Posts: 849

I bought new springs from the local hardware store. Springs are full coils for entire length of spring. Wire diameter and OD are very similar to original springs. I had to shorten overall length and bend a new loop end being careful not to make sharp 90 degree angle to reduce stress riser. Spring wire can be bent cold without addition of heat for tempering.
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 333

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Old 05-30-2016, 11:14 AM
Ex Bonanza Bucko Ex Bonanza Bucko is offline
Join Date: Jul 2013
Location: San Diego, California
Posts: 291

I didn't see anyone here mention that the throttle springs have to be installed in accordance with the instructions that come with them -- i.e.. the hook has to be put into the eyes at each end as shown in the pictures or instructions.

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Old 05-30-2016, 10:14 PM
RFSchaller RFSchaller is offline
Join Date: Oct 2010
Location: Phoenix, AZ
Posts: 2,201


I'm not sure Iget what you're point is with regard to spring orientation. Is there something critical I'm missing?

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