VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics


Go Back   VAF Forums > Model Specific > RV-12/RV-12iS
Register FAQ Members List Calendar Today's Posts

Reply
 
Thread Tools Search this Thread Display Modes
  #31  
Old 11-22-2011, 07:18 AM
vernhendershott vernhendershott is offline
 
Join Date: Dec 2007
Location: Spruce Creek, FL
Posts: 370
Default

I agree with BigJohn, and Marty may have a good part of the answer. My first RV-12 had the original throttle set and you had to lock the friction control to stop throttle movement, if you did not have it locked it would move forward when you removed your hand, say to pull on flaps and this made it a little hard to use in the pattern. It made formation flying all but impossible and that has made the aircraft a lot less popular here. I do not know how the second RV-12 will turn out, still waiting for avionics, but I am buying the springs so that after a trial with the newer throttle set we can change the springs if this one is as bad as the last one. This is a good reason to think about the fuel injected modification as it may permit the return to what most of us think of as normal operation of the throttle, where it can be moved at any time and it does not have to be hard locked to keep it from moving on its own.

Best regards,
Vern


Quote:
Originally Posted by BigJohn View Post
I've been lurking, watching this thread with interest, and now I feel inclined to comment. Marty, Tony, and John B. are all friends of mine, and I respect their opinions on everything RV-12. However, my experience has been different than theirs. I have over 50 hours on my '12, and the throttle creep is a constant annoyance. In cruise in order to hold a power setting I have to crank the friction knob down as hard as I can, to the point I am afraid of breaking something. With this much tension the throttle it is impossible to move. On landing approach, I can't keep the engine down to idle unless I do the same, setting up a bad situation if I need power in a hurry.

When Joe got his first batch of replacement springs I had him send me a set, but I did not want to install them until I gave myself sufficient time to get used to the original springs and for the mechanism to "break in". After watching this new thread I have decided to install the weaker springs. I think I have given the originals a fair trial.

My advice to newer builders is to live with the originals for a few hours before changing. Your installation may have different characteristics than mine and be trouble free.

Joe, as always, thanks for your thoughtful analysis of this issue, and for your research in finding a replacement spring that can be adapted to our use.
Reply With Quote
  #32  
Old 11-22-2011, 08:21 AM
Mich48041 Mich48041 is offline
 
Join Date: Apr 2008
Location: Riley TWP MI
Posts: 3,070
Default

Quote:
Joe, add me to the list of those wanting throttle springs. I think $10 is more than a fair price, considering the hassle you have to go through to handle.
Walt Shipley
Walt,
I am not buying this batch of springs. Tom Odehnal aka todehnal is. I assume that he will read your request. I have no financial interest in this issue, just trying to help others by sharing my success.
Joe Gores
Reply With Quote
  #33  
Old 11-22-2011, 08:54 AM
KRAUSEGB KRAUSEGB is offline
 
Join Date: Oct 2008
Location: CAMARILLO, CALIFORNIA
Posts: 119
Default springs

I would like to get on the list for springs. I am having the same problem as others.
Where and how do I get on the list?

Thanks,

Gary Krause
N117GB
Reply With Quote
  #34  
Old 11-22-2011, 03:51 PM
Ausflyer Ausflyer is offline
 
Join Date: Jun 2008
Location: Byron Bay, NSW
Posts: 104
Default Safety issue

From the stories that are now coming forward, it is clear to me that throttle creep is a safety issue for many RV-12 pilots. I think Vans needs to investigate this and come up with an engineered fix for aircraft with the fault. I hope they add it to the list.
Rod
Reply With Quote
  #35  
Old 11-22-2011, 04:00 PM
RVnoob RVnoob is offline
 
Join Date: Sep 2009
Location: London
Posts: 167
Default

just in case anyone who is planning on the mod, but has not read this...
http://www.ch701.com/webmaster/Jon/d.../jon_crash.htm
Reply With Quote
  #36  
Old 11-22-2011, 06:20 PM
Mich48041 Mich48041 is offline
 
Join Date: Apr 2008
Location: Riley TWP MI
Posts: 3,070
Default

Quote:
just in case anyone who is planning on the mod, but has not read this...
Thanks for reminding everyone of the danger. I had read similar warnings that made me apprehensive on the test flights with the weaker springs. The Zenith 701 builder mentioned that strong springs are needed to overcome a binding cable. I had not thought of that, but was only thinking about a cable breaking. Regardless of which throttle springs are used, it would be a good idea to loosen the friction nut during the pre-flight inspection and make sure that the throttle is pulled fully forward. The weaker springs still pull my throttle all of the way with the friction nut loose. The 701 builder did not mention the pulling force of his springs or how he chose them. I spent lots of time reading spring catalogs to find the one that I wanted: 4 pounds of tension compared to 8 pounds for the original springs. The accident airplane had 2 1/2 hours. I have 30 hours on my weaker springs with lots of touch & goes. A couple of other RV-12 builders have even more time on their springs. Of course there could be failures in the future. It is scary deviating from what is known to work. But so far, so good.
For those who still intend to replace the springs with Century Spring part number 6049, here is some advice:
The springs must be shortened. They come with extended hooks on both ends. Since an extended hook is only needed on the top end, the bottom hook can be cut off and a new hook formed. Be careful bending with pliers so as not nick the wire. Doing so will create a weak spot.
The nice thing about springs is that they stretch. It is better to make the spring too short rather than too long. The spring needs to remain in tension even when the throttle is in the fully open position.
The final length measured from inside of hook to inside of hook should be less than 1.75". Shorter is definitely better than longer. The springs have plenty of stretch; it will not hurt to have them on the short side. If you make them too short, it is better to leave it rather than bending back and causing metal fatigue. After bending, you will need to cut off excess wire to make room for installing the spring. Do NOT use heat. The springs do NOT require heat treating after bending. The long end goes up. Proceed with caution.
Joe Gores
Reply With Quote
  #37  
Old 11-22-2011, 06:53 PM
Mich48041 Mich48041 is offline
 
Join Date: Apr 2008
Location: Riley TWP MI
Posts: 3,070
Default

Look at the picture of the springs in the accident airplane.
http://www.ch601.org/stories/Croke%20Crash/Springs.JPG
Notice how much smaller the replacement spring is in both coil diameter and wire diameter compared to the original spring next to it.
Now look at this picture of the springs that I am using.
https://lh6.googleusercontent.com/-I...0/DSCN4567.JPG
It is hard to tell much difference between my replacement spring and the original on the left, even though it is only about half as strong. It would be interesting to know the properties of the throttle springs in the accident aircraft.
Joe Gores
Reply With Quote
  #38  
Old 11-22-2011, 07:32 PM
yankee-flyer yankee-flyer is offline
 
Join Date: Jun 2009
Location: Dayton, OH
Posts: 838
Cool Joe's springs-- I'd like more too

I have about 50 hours on the weaker springs (78 total). I still have to use the friction lock; the weaker springs will pull the throttle open all but the last 1/4 inch or so of cable travel. If you forget and take your hand off the throttle it will still increase the engine RPM but it doesn't SNATCH it all the way forward the way the original springs did. I was concerned about two things-- inadvertant WOT during ground operation and same when trying to bring flaps up for increased braking in short field operations. It's still a concern but much less of one now. Whoever is doing the order list, please put me downh for a "spare pair".
Wayne 12o241 143WM
Reply With Quote
  #39  
Old 11-22-2011, 08:05 PM
Andy J Andy J is offline
 
Join Date: Mar 2007
Location: Minden, NV
Posts: 145
Default

I think if I were having this trouble I would investigate why the throttle friction won't hold, after all this throttle and cable assembly was made for this engine alone and seems to work fine on some of our planes. I haven't heard of different springs coming from Rotax, so I see the throttle as the variable here. Maybe there have been changes in materials, or defects in assembly of these throttle controls?

Has anyone contacted the manufacturer of the throttle cable assembly? I think mine is a Mcfarlane. The stock springs are strong for a good reason, and the throttle control can hold them if it is working correctly. Seems like a lot of folks are working around the real problem.

Just my opinion of course.
__________________
Andy Johnson
RV-12: Oshkosh 2012 "Outstanding Workmanship"
RV-6: Bought Flying - "She's a good ole bird"
-PAID 2014-
Reply With Quote
  #40  
Old 11-22-2011, 09:32 PM
Jetguy's Avatar
Jetguy Jetguy is offline
 
Join Date: Aug 2008
Location: Texas, Fort Worth
Posts: 1,237
Thumbs up Throttle Creepy!

This seems to be a case that should be reported to Van Engineering. My serial Number is 120079. I have noticed that my throttle is different than from later models. My friction lock works fine with the original/stock springs that came on the Rotax. If the later version of the throttle does not lock when the friction is applied then this should be reported to Vans. Even though we are talking about it here doesn?t mean they know about it. So everybody who?s friction lock allows the throttle to creep please send a email to Vans asap.
Email: engineering@vansaircraft.com Also there is,?already a specific process in place (required by the ASTM for S-LSA certification) for submitting a service difficulty or report a safety issue via Mail, Fax, or E-mail. Look in Chapter 17 of the Maintenance Manual?. As quoted by Scott McDaniels in previous posts. So I?ll go one better, here is a reprint of the page for all to see and use. Sound off on this thread after you send in your report.

Rev.1 4/16/10
17-1
CHAPTER 17 - FEEDBACK &
REPLACEMENT PARTS
FEEDBACK

To maintain the highest level of safety the FAA requires and Van?s Aircraft Inc.
requests notification of any safety of flight issue, service or maintenance difficulty that
could compromise airworthiness of the RV-12 aircraft. A feedback form is provided in
the Supplement section of this manual.
A valuable description will include:
?Specific flight condition if applicable.
?List of the parts identified as affected by the anomaly.
?Description of the apparent condition of the parts prior to the anomaly (de-burred,
primed, modified, etc.)
?Statement as to whether the aircraft has remained within the operating limitations
defined in the POH.
?Brief description of the type and frequency of aircraft use (may include; runway
conditions, flying conditions, storage methods, etc.)
REPORTING METHODS
Mail to:
ATTN: RV-12 Safety Alert
Van's Aircraft, Inc.
14401 Keil Road, NE
Aurora, OR 97002 USA
Fax to:
'RV-12 Safety Alert' (on cover page)
503.678.6560
Hours: 24 hours per day
E-mail to:
'RV-12 Safety Alert' (in subject line)
engineering@vansaircraft.com
__________________
John
RV12 N1212K
Flying Since June 2010
1020 Hours as of 9/30/2017
Johnrv12@icloud.com
RV14 Wing, arrived and building at Rdog's new Hanger at 16X
S/N 140014
Reply With Quote
Reply



Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 05:18 AM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.