Hi All,
I recently had a close call with my 1974 Cessna 180J. I had flown in to a backcountry strip near Ramah, NM, and just as I was taxiing to depart, by left rudder cable broke. About mid fuselage there is a pair of pulleys that change the direction of the rudder cables about 10 degrees as they run from the peddles to the tail. It broke just forward of the pulley. There was nothing rubbing on the cable and it had not displaced from the pulley. This is a 3/16" cable that when fully intact should be able to suspend a Volkswagen for chrissake! The only thing my mechanic and I could figure that caused the break was work-hardening.
Anyone else ever hear of such a thing? I've since replaced the right rudder cable as a precaution, and sure enough that one had 1 strand that had already broken too. Thank God this happened on the ground!

NMXWinds wrote:Hi All,
I recently had a close call with my 1974 Cessna 180J. I had flown in to a backcountry strip near Ramah, NM, and just as I was taxiing to depart, by left rudder cable broke. About mid fuselage there is a pair of pulleys that change the direction of the rudder cables about 10 degrees as they run from the peddles to the tail. It broke just forward of the pulley. There was nothing rubbing on the cable and it had not displaced from the pulley. This is a 3/16" cable that when fully intact should be able to suspend a Volkswagen for chrissake! The only thing my mechanic and I could figure that caused the break was work-hardening.
Anyone else ever hear of such a thing? I've since replaced the right rudder cable as a precaution, and sure enough that one had 1 strand that had already broken too. Thank God this happened on the ground!

Find a new mechanic. That's a mandatory inspection item, though it's not that easy to inspect, so often overlooked.

MTV

Friend of mine had some flight cables get cut in flight... Was messing around in his Cessna 140 and a whip style antenna that he had laying loose in the back of the airplane entered the battery box and contact the positive post, the left rudder, down elevator and trim cable.... Was able to fly it to the airport and land... It did ground loop to the left and pull the gear out and bent the wing tip.... Airplane was repaired.... A few years later the right rudder cable broke at the front pulley, also in flight... Was able to land with no other damage that time... Lucky guy... By the way, he is an A&P and did his own inspections...

Brian

We have had the same issue, in the same place, with the Rans S-7. Again, everything sized correctly, and minor direction change, I now replace mine every 700 hrs. When inspecting, I of course flex the cable the opposite direction it normally is worked, this is the way to inspect it best, learned that flying hang gliders and ultralights .

I got my brother to run me up to Monroe City, Missouri on his Harley Davidson to get a lease Pawnee I was taking to NM in March to spray in the Rio Grande valley. It had no primer. I pumped like crazy to flood the carb so it would start in the cold. The throttle cable broke. Only two of the nine strands were fresh brake. Seven had rust where they broke. Some other poor sole had sprayed the prior season in Missouri with a two strand throttle cable. I had to ride on the back of that cold Harley all the way back to SW Missouri where I got a different Pawnee.

I should have mentioned in the original post that as part of the repair I had the A&P cut two new holes in the cabin floor near where the cable broke and install inspection covers so that from now on ALL of the cable can be inspected with ease. This should never be a problem again. I still don't know for sure what caused the cable to break since it wasn't abrading against anything.

Send it in for analysis and do an SDR. Very suspicious. Anything about cables in the logs? Seems like a counterfeit install?

MIL-DTL-83420 3/16" 7X19 Breaking strength GAL 4200 LBS , SS 3700 LBS

Hmmm...

Strong word of advice:

pull the door post pulleys and inspect the cables in that location. 

Shit, if it was my bird I would do all the cables before further flight.

One if the first 100 hour inspections I performed years ago on a 135 float 185 all went well. The pilot owner went out to fly and the forward down flap cable failed at the small pulley no one looks at. Said operator never used me again but you can bet in the following eighteen years it is one place I get up close and personal with, well that and all the other problem cable locations.

Last winter I found a single wire poking out of my galvanized 182 aileron cable pulley at the lower doorpost location: I changed ALL the flap and aileron cables. I also promised myself I would do the rudder and elevator cables at this years annual. It is not cheap but sure is worth a hell of a lot less then my life or those I care enough to let ride around with me.

Having the right mechanic and really doing the annual and 100 hour inspections will save your life. I have seen a stainless cable go from perfectly serviceable looking (debatable) to three strand rats nest in 100 hours under a Beaver floorboard and only found because the fuel tank was leaking like a sieve. This is where the accumulated experience comes into play while keeping in mind that no matter how good your A&P is there is always something out there to humble us.

A photo would be great!  

Galvanized or stainless?

Thanx for sharing, you never know when someone's dilemma posted here will inspire another pilot to dig a little deeper into his own bird and save their ass.

Rocket

Courierguy, why did you choose 700 hours as the interval for replacing the cables? Say, as opposed to 600 or 1000?

Rocket, the cable that broke was galvanized. I replaced both rudder cables with stainless. Good advice to check the other primary flight control cables for wear as well. The next time I'm at the hangar I'll take a photo of the broken cable and see if I can figure out how to post it to this forum.

NMXWinds wrote:Courierguy, why did you choose 700 hours as the interval for replacing the cables? Say, as opposed to 600 or 1000?

I found the few broken strands at about 900 hrs., and like I said, it was a long way from failing, literally 2 or 3 strands burred up, replacing every 700 seems about right. Either that or I need to quit using the rudder so much.

As far as the stainless/galvanized choice, I've always heard that unless you are operating in a marine enviro., OR are going to be handling the cable (like hang glider pilots, they all use stainless, keeps the sail clean) galvy is the way to go. Cheaper plus doesn't work harden as quick. One of the few times less expensive is actually a better choice.

I know a mechanic that just changed cables on a Supercub that was in for annual and the first time he inspected it. They were stainless and he went back with galvanized. He said if not in a corrosive environment, use galvanized.