Jump to content

Throttle Friction Block


Fly Boss

Recommended Posts

When we picked up the plane in Miami (CTLS 860LS) the throttle lever slid forward and back using one finger.  Obviously it didn't hold where you set it and needed constant attention in flight.  Upon arrival home, we tightened the friction block bolt to remove unnecessary slippage.  This worked pretty well but after 5 hours of flight had loosened up again and caused creeping. The lock bolt can handle tightening each time without issue.  Arian (FD) indicated he had never heard of a friction block actually wearing down and that perhaps the lock nut had simply lost some of its plastic locking material. Inspection of the friction block doesn't show the nut is actually loosening, which suggests the friction block may indeed be in need of attention. Has anyone else suffered similar experiences with different solutions?

 

Danny

Link to comment
Share on other sites

I have never heard of one wearing out and once tightened stay where they are set. Is it possible you aren't tightening it correctly?

Maybe a dab of "Torque-Seal" to see if the nut is turning?

 

If it is, either a fresh lock nut or a second nut over the first if there are enough threads showing? If not, maybe some LocTite on the existing threads?

Link to comment
Share on other sites

Is there no flight adjustable throttle friction? I though most planes had them.

 

Nope it just works fine until it doesn't and then you default to full throttle and choke off.  Works fine for me in cruise.  Makes for a surprise startup if you don't notice the wrong throttle lever position.

Link to comment
Share on other sites

Is there no flight adjustable throttle friction? I though most planes had them.

 

If you mean more than 50% when you say most, then most have them. On the other hand there are quite a few airplanes that don't have pilot adjustable friction locks. The Citabria I learned to fly in. The J-3 I bought to do sport pilot instruction initially. The A model Taylorcraft. The Champs I instructed in. The Thorp I flew to Oshkosh.

Link to comment
Share on other sites

I remember when the Bellville washers were the topic of discussion, but I never picked up any to install. IIRC someone had bought a bunch and were sending them out if requested, but that may have been a different website and a different airplane part.

Link to comment
Share on other sites

I remember when the Bellville washers were the topic of discussion, but I never picked up any to install. IIRC someone had bought a bunch and were sending them out if requested, but that may have been a different website and a different airplane part.

 

They are easy to find: https://www.google.com/search?q=Bellville+washers&rlz=1C1CHFX_enUS506US506&oq=Bellville+washers&aqs=chrome..69i57&sourceid=chrome&ie=UTF-8#q=belleville+washers

 

Dunno the size

Link to comment
Share on other sites

If you mean more than 50% when you say most, then most have them. On the other hand there are quite a few airplanes that don't have pilot adjustable friction locks. The Citabria I learned to fly in. The J-3 I bought to do sport pilot instruction initially. The A model Taylorcraft. The Champs I instructed in. The Thorp I flew to Oshkosh.

 

 

Tom,

 

You're of course right - I don't recall either Citabria of mine having throttle frictions.

 

But having one you can adjust in flight is very handy - I'm kinda spoiled by the one in my Sky Arrow - the knurled knob on the right that tightens the friction on both the throttle and choke:

 

27141626026_23e8d3b25f_z.jpg

 

Admittedly it does tend to loosen up on its own sometimes, and needs a little nudging to get back where I like it.

Link to comment
Share on other sites

You can get the belleville washer at Ace Aviation (Ace Hardware).

 

Seasonal changes usually only occurs in the cold climates. 0-20F in the inter and then 75-100F in the summer. The belleville washer should help relieve that problem.

Link to comment
Share on other sites

I have never heard of one wearing out and once tightened stay where they are set. Is it possible you aren't tightening it correctly?

 

I think it is being tightened properly.  A look at the parts manual shows the block as one piece.  It appears on mine that the thin sliver on the right side of the throttle lever is broken off the rest of the block.  It is only being held in place by the bolt and lock nut.  You don't really see it unless you move the lever forward and backwards. I suspect that because of this that no matter how it is tightened or locked down, the broken piece has lost its leverage to maintain the friction properly. Does anyone have a friction block for the CTLS by any chance? Seems hit or miss when I call FD for parts.

 

Danny 

Link to comment
Share on other sites

Mine needed a bit of adjustment for a couple of years (partly because I was playing with different amounts of friction), but the last year or so has not crept at all and has a good feel, light but sticky enough to maintain a setting.

 

Eddie, the ground adjustment is easy and takes about five minutes.  I keep the necessary tools in the airplane just in case, but in practice if it starts to slip a little you can manage it easily for several flight hours before it becomes a real nuisance.  I always keep my hand on the throttle, and with a fixed pitch prop there is no "set it and forget it" anyway.   :)

Link to comment
Share on other sites

I think it is being tightened properly.  A look at the parts manual shows the block as one piece.  It appears on mine that the thin sliver on the right side of the throttle lever is broken off the rest of the block.  It is only being held in place by the bolt and lock nut.  You don't really see it unless you move the lever forward and backwards. I suspect that because of this that no matter how it is tightened or locked down, the broken piece has lost its leverage to maintain the friction properly. Does anyone have a friction block for the CTLS by any chance? Seems hit or miss when I call FD for parts.

 

Danny 

 

If you don't have any luck with Flight Design USA. you might try Lockwood or Airtime Aviation. They might have a recycled unit from a damaged airplane.

 

Another option would be to remove the part and have a machine shop make a new one out of Delrin.

Link to comment
Share on other sites

You can make these blocks. They are made from PVC. The slots for the levers are made with a table saw (you can see the marks left by one).

 

If I was making one and it was going in an E-LSA, I might try making it from phenolic.  It will wear better and be stronger than the stock part.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...