30 Questions
What is the primary purpose of using a Nicopress crimping tool?
To reduce the diameter of the sleeve and form a strong bond
What is the correct order of compression when using a Nicopress sleeve?
Centre compression, then nearest the thimble, then end of the sleeve
What is the purpose of applying a band of paint to the cable and sleeve?
To indicate if the cable has slipped during inspection
What is the minimum percentage of cable strength achieved by a Nicopress termination?
100%
How many Nicopress sleeves are used to join two lengths of cable?
Two
What is the purpose of the Nicopress gauge?
To check the compressions after installation
What is the purpose of applying a ring of brightly coloured paint around the end of the terminal and cable?
To indicate any subsequent slippage
What is the purpose of the Proof-Load Test after the cable is completed with the terminals?
To load the cable to 60% of its breaking strength
Where are cables most likely to wear or break?
When passing over pulleys or through fairleads
What is the primary method of inspecting cables for broken wires or strands?
Wiping the cable with a clean, dry rag
What should be done to inspect for corrosion in a cable?
Disconnect the cable and bend it into a loop
How often should cables be inspected?
At each scheduled inspection
What should you avoid doing when bending the cable during inspection?
Twisting it opposite its natural lay orientation
What is a critical fatigue area in aircraft control cable inspection?
The area where the cable runs over, under or around a pulley, sleeve or fairlead
Why is it necessary to use a cloth to inspect the cable?
To detect broken wires
What may indicate the presence of a broken wire in the cable?
A hairline crack in the wire
What is recommended to further inspect a suspected broken wire?
Using a powerful flashlight and a 7-power magnifying glass or greater
What publication recommends a procedure for inspecting aircraft control cables?
FAA publication, AC 43.13–1B
What is the recommended action for a cable assembly with a broken wire strand in a critical area?
Replace the entire cable assembly
Why is it important to wipe corrosion-resistant stainless steel cables with LPS-3, Boeshield T-9, or Dinitrol ML?
To prevent corrosion and lubricate the cables
What is indicated by external wear patterns on a cable?
The cable has moved a certain distance at that location
When should flexible and non-flexible cables be replaced?
When the individual wires in each strand blend together
What occurs internally in a cable as wear takes place on the exterior surface?
The same wear condition occurs internally
What causes the type of wear that occurs internally in a cable?
The relative motion between inner wire surfaces
What is the primary purpose of using rig pins in aircraft control systems?
To lock the control surfaces and major quadrants in place
What is the tool used to check the tension of control cables?
Cable tensiometer
What is the purpose of a cable tension compensator assembly?
To compensate for expansion and contraction of the airframe
What is the reading on the cable tensiometer scale?
An arbitrary reading for the particular riser
How are the risers on a cable tensiometer used?
To correspond to the cable diameter
What is the purpose of the pointer lock on a cable tensiometer?
To lock the reading on the scale
Study Notes
Nicopress Process
- Nicopress sleeves are compressed into a cable using a special crimping tool, reducing the sleeve diameter and forming an extremely strong bond.
- The cable is passed through the sleeve and around the thimble, with about 1/8 in. visible beyond the sleeve.
- Three compressions are made: centre compression, then compression nearest the thimble, and finally compression at the end of the sleeve.
- A Nicopress termination produces 100% of the cable strength.
Nicopress Gauge and Splice
- Compressions are checked with a special Nicopress gauge, which ensures the sleeve fits snugly in the slot.
- Running splices can be made to join two lengths of cable using two Nicopress sleeves.
- When two sleeves are used correctly, the splice is approved as having the full cable strength.
Safety Feature and Testing
- A band of paint is applied to the cable and sleeve to assist during inspection; if broken, it indicates the cable has slipped and further inspection is required.
- A spot of paint is applied to the cable against the sleeve, and a ring of brightly coloured paint is applied around the end of the terminal and cable after testing.
- The cable is tested by loading it to 60% of its breaking strength, with the load applied gradually and held for at least 3 min.
Cable Inspection Practices
- Cables are carefully examined at each scheduled inspection, especially where they pass over pulleys or through fairleads.
- Wear and corrosion are the two most common problems with control cables.
- Inspect for broken wires or strands by wiping a clean, dry rag over the cable, and move the controls through their full range to check for wear.
- Check for corrosion by disconnecting the cable, bending it into a loop, and using a torch and magnifying glass to inspect.
Cable Wear and Corrosion
- Critical fatigue areas are defined as the working length of a cable where it runs over, under, or around a pulley, sleeve, or fairlead, or where it is flexed, rubbed, or worked in any manner.
- Close inspection of these areas must be made by passing cloth over the areas to snag on broken wires.
- Visual inspection must be made to detect broken wires, which may show up as a hairline crack in the wire.
- Cables with one broken wire strand located in a critical area must be replaced.
Corrosion Prevention
- Corrosion-resistant stainless steel cable is used in seaplanes and agricultural aircraft, which operate in environments conducive to corrosion.
- It is recommended to wipe these cables with LPS-3, Boeshield T-9, or Dinitrol ML to protect and lubricate the cables.
Cable Tension
- Cable tension is checked with a cable tensiometer, which must be placed in a clear area of each section of cable, midway from any quadrants, bell cranks, or surfaces.
- The tensiometer reading is converted to tension in pounds using a chart.
- Most large transport aircraft are fitted with a cable tension compensator assembly, which compensates for expansion and contraction of the airframe and regulates control cable tension accordingly.
Learn about the Nicopress process for copper sleeves in aviation maintenance. Understand how to compress Nicopress sleeves onto a cable using a special crimping tool and create a strong bond.
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