News:


  • April 27, 2024, 12:05:52 AM

Login with username, password and session length

« previous next »
Pages: [1]   Go Down

Author Topic: How long will Brodak bellcranks last?  (Read 727 times)

Offline bfrog

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 291
How long will Brodak bellcranks last?
« on: June 23, 2009, 08:13:40 PM »
Last weekend I made up a new set of lines for my Vampire (36 profile carrier plane). After I was done I noticed that there was a hitch in the action, when exercising the up and down movement at one point there was a bit of a snag. When I looked at the plane it was obvious what was happening. The bellcrank is under the wing and fits is a slot in the fuselage. The bellcrank had developed some slop and was tilting up and down more that it had before thus causing it to tip enough that it hit the side of the opening in the fuse. The base of the bellcrank was still solidly mounted to the plane but the slop was in the slider/bearing area.

This bellcrank/airplane has about 4 seasons worth of flights, not really that many. I would hope that it would last longer than that.

My question(s) are, has anyone else had a problem with the bellcrank becoming sloppy like this? Is there a way to relliably fix it? I am concerned that if it gets too loose it could come apart in flight, not a good thing. I am also afraid that if I try to stake the bearing or slide it will not be reliable and smooth.

Any help?
Logged
Bob Frogner

Offline dale gleason

  • 23 supporter
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 842
Re: How long will Brodak bellcranks last?
« Reply #1 on: June 23, 2009, 08:22:06 PM »
The most and just about only wear on my bellcranks has occurred on my Class II. The in/out action of the throttle control has got some tilt, but it doesn't impinge on anything. The holes where the line clips go on the bellcrank started to enlarge quite a bit- I took brass eyelets and inserted them into the holes and pounded them flat with a hammer, no visible wear since then. I'm thinking this plane has about 200 flights on it in all. If I ever find there is even a hint of a problem, I will replace the bellcrank.     dg
Logged

Offline Paul Smith

  • Moderator
  • Trade Count: (0)
  • Admiral
  • *****
  • Posts: 5801
Re: How long will Brodak bellcranks last?
« Reply #2 on: June 23, 2009, 08:51:13 PM »
I wore out a J.Roberts inverted bellcrank and had to replace it.  The "tilt" of the UP-Down bellcrank was beyond excessive.  It looked like it could roll over completely on the next pull test or hard flight.  I have no idea how many flights.

The proiblem now is how to get another of this style?
« Last Edit: June 24, 2009, 11:31:51 AM by Paul Smith »
Logged
Paul Smith

Offline eric conley

  • 2018 Supporter
  • Trade Count: (0)
  • Commander
  • *
  • Posts: 174
Re: How long will Brodak bellcranks last?
« Reply #3 on: June 23, 2009, 09:43:01 PM »
     I have had pretty good luck with all of my 3-wire bellcranks (all purchased from Brodak's). The ones that are 6-7 years old have gotten a little loose (they rock back and forth) the same way that Bob is describing but don't appear to be coming apart. As one of my flying buddies Say's "Eric thats why we put test these things".
     Now having said that, I do have a concern about some of the newer Brodak 3-wire bell cranks that have what appears to be an anodized aluminum base plate instead of the blued steel base plate. The bellcranks with the aluminum base plate are "REAL" loose to begin with and on the planes that I've used them on I have to open up the area that these bellcranks function in or they come in contact with the plane. I don't understand why they would go to an aluminum base plate when you think about the pull tests that are made on some of these carrier planes (up to 100 pounds).
     I like to put my bellcranks on the outside wing panel and run the lines through the fuselage using a slit just big enough to get the line through in case I have to change them out. My hopes are that if the BC ever fails the fuselage will trap it and the plane will not get away. Kind of a dumb thing to have to worry about?   eric
Logged

Offline don Burke

  • 2014 Supporters
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1027
Re: How long will Brodak bellcranks last?
« Reply #4 on: June 24, 2009, 09:23:52 AM »
Answer to why aluminum instead of steel. Simple, it's cheaper to manufacture that way!  The stamping dies last a very lot longer on alum than on steel.
Logged
don Burke AMA 843
Menifee, CA

Offline eric conley

  • 2018 Supporter
  • Trade Count: (0)
  • Commander
  • *
  • Posts: 174
Re: How long will Brodak bellcranks last?
« Reply #5 on: June 24, 2009, 12:02:31 PM »
     The thought did cross my mind that perhaps Brodak was finally running out of inventory they picked up when they purchased the rights (or what ever the did) to build and sell the bellcranks. Then again I'm not positive that they are aluminum, they could be steal, and instead of bluing them it was cheaper for them to use another type of covering. At any rate they seem looser (mine have been very smooth). I'm currently using some and have had no trouble with them so far.
     I don't think they are easy to produce, and not get them too tight or not tight enough and I have had my share of to tight so for now I guess should be happy.   eric
Logged

Advertise Here
Pages: [1]   Go Up
« previous next »
Tags:
 


Advertise Here