Forums: Skydiving: Gear and Rigging: Re: [sooperswooper] Cutaway cable cleaning mistake: Edit Log


JohnSherman  (D 2105)

Apr 23, 2013, 7:53 AM

Views: 3538
Re: [sooperswooper] Cutaway cable cleaning mistake

In reply to:
I just realized it might be a bad idea since I saw that contains some petroleum derivates.
After spraying it on the cable I wiped multiple times so that it didn't go in the housing wet.

The Yellow coated cable is coated in pure Nylon and requires lubrication on a monthly basis at minimum. I recommend weekly as stated in the Racer manual. We Skydive on a weekend basis and the end of the month could come in the middle of the week.
The recommended lubricant is petroleum, silicone is acceptable but it hydrolyzes in Nylon in about a week requiring reapplication. If you don’t have any 3 in 1 oil handy just wipe the oil from your dipstick with your fingers and apply it to the last 7 or 8 inches of the cable. This is to make sure you lube the part of the cable which goes through the nylon locking loop.
Test: This test should be part of the “Jumpmaster or Pin check” before boarding. Pull one or both of the cables out of the riser channel and run it between your fingers. If it “Squeaks” like freshly shampooed hair go back and oil it. There should be no resistance or “Squeak” from the cable.
If you have a Red coated cable it is coated in pure FEPT Teflon and requires no maintenance or lubrication.
A general word about 3 ring cables and housings: The black “goop” which you see on some of your cables is good. It is the residue from the cutting oil used in the housing manufacture. It is a lubricant albeit with high viscosity. Many people worry about dirt sticking to the cable because of the stickiness of the oil and try to remove it. This is misguided and not a problem. One military orginization wiped the cable clean every 90 days for several years before they got all of the cutting oil off of the cable and out of the housing. Then they began having cutaway problems. They now lubricate every 90 days.
Test: With a cable and housing separate from a rig. Oil the cable until is drips with oil then drag it through the dirt and sand. Fill the housing with dirt and sand. Insert the cable and coil the housing to its minimum diameter. Pull the cable out and observe the effort.
The worst thing you could have on your rig is a dry cable.
The point of loading is the nylon loop. Loop tension effect is doubled with a dry cable.
I know all of this because I have had a “No Cutaway” from a 3 ring. It occurred many years ago shortly after the Yellow cable was released to replace the clear cable. The Yellow cable was touted, by the supplier, in writing, as being Teflon impregnated and requiring no lubrication. This was not accurate. It had no Teflon was pure Nylon and it required lubrication as above. Because of this bad info we stopped lubricating new rigs. After my experience I tested some 30 rigs which were ready for shipment. Two of us did the test. One held the rig and one held the risers with tension. The one with the rig pulled the cable or should I say TRIED to pull the cable. None would release. We oiled each in turn and they all worked find.
This experience led to a series of extensive test where we built a simulator for the configuration. From those test we learned the relationship between the cable, housing and oil and developed the procedures reported here.
BTW: The only damage petroleum does to nylon is to stain it, which can be removed . There is no loss of integrity.


(This post was edited by JohnSherman on Apr 23, 2013, 8:11 AM)


Edit Log:
Post edited by JohnSherman () on Apr 23, 2013, 8:11 AM


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