Thanks for the info rotorhead, the spectra lines however do not degrade with uv as kevlar does, the color will infact bleed out of it but the strength remains. They use spectra on tugs and and fishing boats, have left one of these lines outside lying in the sun for a year and when retested still had the same strength(breaking). I know a company that used kevlar 12 years ago and lost a helidrill and when the dust settled it was caused by the kevlar breaking down. I wouldn't use kevlar to lift anything, maybe good for bulletproof vest where is covered but thats it.
Dirt is definetly bad as not only does it have the conductivity problem but it gets in the fibres of the rope which act to break the rope down. It should be inspected for white powder like substance as sign of breaking down. To my knowledge fuel, water and such do not bother it as well. Spectra(amsteel blue) is one excellent product but heat and dirt are its nemisis. So keep it covered, don't use tiewraps to attach the electric cord to it and be extremely careful around heat. Some pilots land with the longline behind them, this practice is extremely hazardous for two reasons, one it is light and can be blown up into the t/r, the other especially around the 500 is the heat from the exhaust can cause breakdown of the line.
As mentioned before it seems strange that the heat hasn't bothered these lines one fires more than it has. Perhaps the sheathing acts to insulate the line.
