Indeed cables are prone to maintenace error and suffer from lack of maintenance which was basically my point.
Crossing control rods, not impossible hence the Enstom which rolled over at Oxford a number of years ago when the internal mast rods were crossed.
However control checks will always show up a crossed rod, whereas double crossed cables often only show when they break. Realistically crossing rods is difficult.
Misrouting cables over structure, other cables, over guard pins, wear on seized pulleys e.t.c requires vigilance at installation and maintenance.
Cables and rods all have there place in aircraft construction, but for me rod systems are safer. Cables tend to be more flexible in both senses and lighter. I suppose that you pay your money and take the choice. However I would put money on more aircraft losses are down to cable failure than control rod failure.
Last crossed cable I saw was 2 years ago. An aileron cable on a factory new Boeing 737.
The cables had been incorrectly fitted at the outboard aileron quadrant and were a long way thru. In this particular design crossing the cables at this point does not alter the control output and is extremely difficult to see as the cross point is behind the quadrant, tight against the spar. If the factory can get it wrong so can anyone.
As a matter of interest the cables I found "just holding on", were on an S76 where they exit the cabin and pass under the main transmission. No apparent reason other than wear and tear and poor inspection work. Just revisiting this if one cable had snapped the flight loads would have passed to the other (Nick Lappos)
but given the condition of both cables was equally bads would the second cable have survived for long?
Last edited by ericferret; 27th Mar 2007 at 11:10.
Reason: more info