Replies to This Discussion

Permalink Reply by Jonathan Porter on February 17, 2009 at 6:37am

We fit a positive back stop to the throttle using 2 small pieces of aluminium angle, 2 rivets and a bolt. A hole in one piece and a slot in the other allows adjustment. Note the silicone in the end of open tubes to avoid insects and other nasties hiding in the tubes or making their homes there!!!

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Permalink Reply by Chris Aysen on March 24, 2009 at 11:22am

Good tip on the throttle stop. I will use it.

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Permalink Reply by Thomas Richardson on March 24, 2009 at 12:26pm

Hello to you both..... At the risk of sounding ignorant and not being able to find the post you replied to,,,, What is the purpose of the positive back stop to the throttle? Thanks

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Permalink Reply by Jonathan Porter on March 24, 2009 at 3:39pm

If you look carefully, when you pull the throttle back the 'stop' is on the Bing Carb. Look a LITTLE closer and see how soft it is. Next fly with somebody who is strong who like to PULL the throttel and - you will see BENT back stops on the carb. THEN your low revs is wrong - or you may even get a lean cut - especially on final, about a quarter mile out!!!

SO, I wonder, "am I the only one" so I read the ROTAX manual and it says 'FIT A POSITIVE BACK STOP'. Dont be surprised lots of people dont and lots of manufacturers dont. Also, I didn't until I had a student bend the carb stops which led to a lean cut on taxiing. Now I set the back stop so that I can just pass the standard 'normally in most people pocket'slip guage (a dollar or cedis or euro note or similar) between the carb stop and the moving part on a new setup - since then all of our planes have nice carb stops that do not get bent and no more lean cuts on finals!!!! This is also a good way to set a pretty good mechanical balance on a NEW engine (but it wont work later - you will HAVE to use pneumatic balancing...) - set it so that the throttle belcrank is on the physical backstopb (get somebody to keep about 1kg pull force on the throttle) - now adjust the two carbs to just have the note slip system working equally both sides - I can almost guarantee a smooth first start and a near perfect pneumatic check - which equals satisfaction!!!

Be safe and remember that "Safety is NO accident"

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Permalink Reply by Thomas Richardson on March 24, 2009 at 3:57pm

Thanks for the input as mine will be a brand new 912 installation.

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Permalink Reply by Dan Wilde on March 16, 2009 at 9:40pm

To cut the thin .016 skins you can use a good pair of scissors. They especially are good for following curved lines. On straight stuff it sounds like the Olfa knife is the way to go.

Dan Wilde

PS - DO NOT USE YOUR WIFE's SCISSORS!

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Permalink Reply by Thomas Richardson on March 24, 2009 at 3:11pm

Found a neat little trick for lining up the location of the pivot pin on the fuselage. Take a laser pointer pen (available at target and just about everywhere) , point it through the out board hole on the inboard flaperon bracket until it goes through the inboard hole and have someone mark it on the fuselage with the sharpie. I found that the 1/4 in rod tends to sag some in the middle making it a litlle harder to locate the hole precisely. this is on a 701. I think this might be handy for alot of things like setting cable pulley angles from the floor to the outlets at the rear

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Permalink Reply by Jonathan Porter on March 25, 2009 at 5:33am

PErsonally, I think that the positive stop should be a formal part of all aircraft - it is a safety feature. For the cost of two bits of angle, two rivets, a bolt, two washers and a nut it could save a life! (it is also peace of mind that when you 'yank' back the power it is going to stay alive. I once knew an Ag pilot who insisted on being able to lean cut from the throttle - somebody else flew the plane and it scared them half way to the upper place!!!

How did you do yours? Any photos?

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Permalink Reply by Chris Aysen on March 25, 2009 at 9:30am

The stop would also preserve cable integrity. Less stretching (you can't completely stop stretching) and having to sync carbs (talking about Rotax 912 of course). I like the idea and will probably mount a stop on both sides of the engine compartment firewall stopping the lever on both ends.

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Permalink Reply by Jonathan Porter on March 25, 2009 at 1:39pm

There is no need to mount both ends, since both cables are from the same place (see pics). Only thing to be gained is reduction in torsion in the control ass'y - it is a personal choice!

It looks like your mount is already in flight - so simply fit it to the current stop point.

Take care.

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Permalink Reply by Stephen R. Smith on March 26, 2009 at 10:05pm

I also have a Jabiru 3300 and my engine cut out on final on the second flight. I was about 1/4 mile out. Lucky for me it started right back up else I would not have made the numbers. My solution was a simple one. I added a b-nut to the cable. When you pull back on the throttle the b-nut contacts the outer cable and provides a positive stop. Its been working perfectly for almost two years. Here is a picture. Its a "down" view. The carb is just out-of-picture to the lower-right. The arrow points to the b-nut. The throttle is at idle in this picture.

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Permalink Reply by Chumphol Sirinavin on March 27, 2009 at 4:24am

Stephen,

This B-nut seems the most economical and the most practical for the job.
Thank you.

Champ

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