Brief Description: Aircraft Control Cable - What is it?
Talked with Bob M. about cable, posted this to matronics.
Today I called my mentor and asked about stretch in the cables. After much listening I came away with the realization that I won't be conducting a pre-stretch because that has already happened in the manufacturing process.
He did however maintain that checking the tension periodically is necessary. The major factors effecting the tension are temperature variation from the last check and wear of the fair leads/pulleys.
Comparing the expansion coefficients of both:
Aluminum 12.3 Steel 7.3
You can see Aluminum expands and contracts 5 times that of Steel. So if you tension your cables on an 80 degree day you can bet they will need it again on a 0 degree day in the winter. Just some thoughts.
I checked the cable I got from ACS and it is MIL-DTL-83420 with a red and gold filament.
Wire rope used as flight-critical aircraft control cable must meet MIL-DTL 83420 (latest revision). It is estimated (Defense Daily Network July 27, 2005) that less than 2% of "aircraft control cable sold in the world today meets MIL-DTL-83420. Most of it is what you would find in your local hardware store." Tests performed on non-MIL-DTL-83420 cable concluded that the fatigue strength requirements were rarely met.
If your log book entry or sales receipt uses the term "aircraft control cable" then you might be implying that the cable is MIL-DTL-83420 when it is not.
There are two easy identification methods that may help you identify aircraft control cable:
(1) All MIL-DTL-83420 contains a two-color tracer filament embeded within the cable that identifies the manufacturer, (2) All MIL-DTL-83420 cable sold on a shipping real must contain the identification number of the manufacturing reel. (All MIL-DTL-83420 cable is lubricated with a corrosion inhibiter.)