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**marcusofcotton** · 08-22-2016, 10:45 PM

Galvanized for all with the possible exception of Stainless for rudder cables if you plan on saltwater operations.

**Bdflies** · 08-22-2016, 11:11 PM

Stainless or Galvanized? My $0.02 worth; Think about which concerns you most. Corrosion, from environmental conditions or abrasive wear. Jared's wear is extreme and rapid, but not typical. I suspect, as has been theorized, that Jared's wear is the result of a geometry problem. A problem he likely fixed, as evidenced by the minimal tension variance now vs before. If Jared's plane had the harder galvanized cables, would something else have been damaged or stressed by the tension variance? If the cable hadn't worn, might the problem have manifested itself in some more precarious manner? Don't know and can't say.
The situation that Jared encountered, is a 'textbook example ' of why we do the extensive annual condition inspections. I'd much rather fly in a plane that was inspected by the guy who built it and flies it! The system worked because he performed a good, careful inspection of his aircraft. This thread, is an example of the tremendous value that this forum provides the whole Bearhawk community. I bet everyone who read this thread will pay a bit more attention to cable rigging. I know I will! Further, I'll bet that everyone with a flying Bearhawk takes a real close look at their control cables, at the next condition inspection, if not sooner! This forum allows information to be shared and ideas discussed. Isn't this great! But, I'm venturing into the weeds...
Personally, my Patrol will fly with stainless cables. I'm about 30 miles from salt water and humidity is rarely less than 80%. I'm more concerned about corrosion.

Bill

**Sebastian** · 08-23-2016, 01:08 PM

I think there are some very strong arguments for galvanized cables especially if you are not around the salt air of the coast. Like Bill I live close to the salt water so I guess I will stay with the stainless and resign myself to very close inspection of my control cables. It is our attention to detail on our planes that keep us and out family's safe.

**whee** · 08-23-2016, 04:30 PM

I can think of three BHs, including Jareds, that had to replace SS cables at around 200hrs. All those guys replaced them with galvanized and two of them have over 1000 hrs on their planes now.

The airplane my dad and I restored 10 years ago had the original 50y/o galvanized cables that were still airworthy. That plane had spent its entire life in the Portland, OR. When we bought it it had spent 20yrs sitting in a field and had moss growing on it.

My opinion is that SS cables cables will fail from wear before galvanized cables fail because of corrosion. It's great to have options and have the opportunity to decide what these kind of things for ourselves. I'm using galvanized cables throughout.

**Battson** · 08-23-2016, 05:23 PM

I just think stainless cable is a bad idea.

I have seen wear in places others haven't, and vice versa, Jared is seeing wear in places I don't have it... It seems to take only a couple of hundred hours. There seems to be no predictability.
From a maintenance point of view, that random failure mode is a nightmare. I have have almost 500hrs on my plane now, and I am wondering whether there is a cable wearing out somewhere that I can't see. They are just bad news.

**Mark Goldberg** · 08-24-2016, 08:12 AM

Just a little context here - my BH has almost 1200 hours on stainless cable and none has been replaced or had significant wear. I would still now recommend the galvanized. But my luck with the stainless cable has been better than what has been mentioned on this thread. Mark

**Bdflies** · 08-24-2016, 06:43 PM

When I consider the minimal loads imposed on our control cables, relative to the strength of those cables, I have a hard time wrapping my head around the degree of wear that we're talking about. Hearing of cables worn, to the point of replacement, in 200 hours, the hairs on my very bald head perk up! I'm not going to venture into a tyrade of anecdotal evidence, but I could. My experience with stainless cables, mimicks Mark's.
Before loading the flamethrower, grant me this; If one Bearhawk can fly 1200 hrs, with no significant wear and another has cables worn to the point of replacement in 200 hours, is it possible that there's something awry in the system of the latter? Are we talking about worn cables in elevator, aileron or rudder systems? Or, all 3? I have a suspicion that the problem resides in a specific system. NOTE: I've been wrong before! Further, I suspect that the problem is one that's easily overlooked, or the correction is not intuitive, otherwise the conciseness builders would have spotted the issue. Whee, could you tell us which system(s) wore so quickly, in the Bearhawks you spoke of? My interest here is purely to prevent or correct potential hazards. I don't sell stainless cables or own stock in Thyssen, Sandvick or other producer of high alloy metals.
I completely understand the arguments for galvanized. I even agree that galvanized cables should outlive stainless, in most regimes. Properly installed (correctly sized pulleys, minimal deflection through fairleads, no off-axis deflection through pulleys, proper tension, careful attention to bellcrank geometry, etc..) I'm certain that either material is perfectly fine. Another thought bounced through the void that is my mind: If either material carried catastrophic deficiencies, I have ultimate faith that our FAA would take great pleasure in banning its use. Their purpose IS to help, ya know!
Now, bring on the flamethrowers! I just love a lively discussion, even when I'm wrong, which is usually the case. And when this one is beat like a bad dog, I'm thinking of starting a thread about the RIGHT way to weld 4130!

Bill

**Battson** · 08-24-2016, 07:08 PM

Originally posted by Bdflies View Post

When I consider the minimal loads imposed on our control cables, relative to the strength of those cables, I have a hard time wrapping my head around the degree of wear that we're talking about. Hearing of cables worn, to the point of replacement, in 200 hours, the hairs on my very bald head perk up! I'm not going to venture into a tyrade of anecdotal evidence, but I could. My experience with stainless cables, mimicks Mark's.
Before loading the flamethrower, grant me this; If one Bearhawk can fly 1200 hrs, with no significant wear and another has cables worn to the point of replacement in 200 hours, is it possible that there's something awry in the system of the latter? Are we talking about worn cables in elevator, aileron or rudder systems? Or, all 3? I have a suspicion that the problem resides in a specific system. NOTE: I've been wrong before! Further, I suspect that the problem is one that's easily overlooked, or the correction is not intuitive, otherwise the conciseness builders would have spotted the issue. Whee, could you tell us which system(s) wore so quickly, in the Bearhawks you spoke of? My interest here is purely to prevent or correct potential hazards. I don't sell stainless cables or own stock in Thyssen, Sandvick or other producer of high alloy metals.
I completely understand the arguments for galvanized. I even agree that galvanized cables should outlive stainless, in most regimes. Properly installed (correctly sized pulleys, minimal deflection through fairleads, no off-axis deflection through pulleys, proper tension, careful attention to bellcrank geometry, etc..) I'm certain that either material is perfectly fine. Another thought bounced through the void that is my mind: If either material carried catastrophic deficiencies, I have ultimate faith that our FAA would take great pleasure in banning its use. Their purpose IS to help, ya know!
Now, bring on the flamethrowers! I just love a lively discussion, even when I'm wrong, which is usually the case. And when this one is beat like a bad dog, I'm thinking of starting a thread about the RIGHT way to weld 4130!

Bill

Both Jared and I have QB kits - so they are standard design. Only the operational use is specific. The wear is in different places on each. Mine wore out at the rudder cable fairleads in the tail and at the rear seat. Jared's at the pulley on the elevator cables.

Any kind of control cable can wear out, at any point in it's life. There any many reasons why that wear could happen, slow or fast. Anecdotal evidence and the science suggests that stainless wears out faster than galv.

This is why inspecting the full length of all control cables each 100hr inspection is so important - every pulley, fairlead, rib pass-through, any place they could be touching anything needs to be looked at carefully. The hardest place to see is inside is the wing strut. I also don't enjoy pulling my floorboards.

**Bcone1381** · 08-24-2016, 10:09 PM

Originally posted by Bdflies View Post

.....Properly installed (correctly sized pulleys, minimal deflection through fairleads, no off-axis deflection through pulleys, proper tension, careful attention to bellcrank geometry, etc..) I'm certain that either material is perfectly fine....

Bill

This appears to be a pretty good list of why a cable might experience premature wear. Are there any other reasons? How about a Manufacturer deficiency?

**Collin Campbell** · 08-26-2016, 09:11 AM

From reading the comments, I don't believe we are all on the same page regarding the "cable geometry" thing. I have attached a crude drawing (not to scale and exaggerated for effect) that shows the difference between good and bad geometry. This could be a big contributing factor in the cables wearing out so soon. Tried to explain this before, but maybe you can see what I am talking about. I know this works, as I have just been reminded as I am currently rigging the cables for the trim system on my LSA project. The bellcrank arms (trim lever and trim bellcrank in the tail) are both different dimensions. If you don't rig them the way I have shown in the bottom drawing, you will see cables go from "guitar string" tight to sloppy loose as the trim lever is moved throughout it's range. Something to think about...

Collin

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