Ballistic cable cutters on helo winches

[Wooly]

I need some factual information to back up research being conducted into the need for ballistic cable cutters.. .Could anyone who has experienced an inadvertent or uncommanded cutter activation, or who has needed to cut the cable to save the aircraft, please contact me by email, or post on this forum.. .Much appreciated any and all contributions. :)

[heedm]

It wasn't me but happened on one of our helicopters. Lost power during a ship hoist due to salt water causing a salt buildup on compressor blades resulting in compressor stall. Man still attached to cable, so it was cut to prevent yanking him off the boat and into the rotors.

Hoisting into tall trees in mdt turbulence (crashes always seem to happen in bad weather), cable wrapped around tree branch. With man on the hook, the cable was too tight to do much. Man on hook swung to tree, climbed up a bit and unloaded cable, moved helicopter to free cable. Very nearly had to cut that cable.

Another incident that very nearly resulted in cutting the cable. Hydraulic hoist started random rapid moevements while man on high (>100') hoist. Barely able to get him to the ground. Once on ground (he hit hard), excess cable peeled out so cutting unneccessary. If cable didn't peel out, man could have been yanked off harshly only to be smacked into the ground yet again.

Small price to pay, low weight, don't know why you wouldn't have one.

[syd_rapac]

Roll back to the 1st December " uncommanded winch squib firings " and all will be revealed.

Syd

[heedm]

Thanks for that link, I see where this is going.

Wooly, if you are truly researching the need for a ballistic cable cutter, then the reliability of the system shouldn't be a concern. The need should be based on possible negative outcomes of having cable hanging from the aircraft.

If you determine there is a need, then it would be worth examining the reliability. If there is no system that is sufficiently reliable, then a risk assessment needs to be done. Choose which is more dangerous, not having a cutter or having a cutter that may operate uncommanded.

If a cutter is unreliable then rather than dropping it, fix it.

[Too Cloudy]

Has this anything to do with what is happening at Careflight in Sydney presently?

[Nick Lappos]

Wooley,. .The problem with using anecdotal evidence of uncommanded cable cuttings (due to faulty equipment) is that there is no objective evidence to tell that the system failed, rather than that an inappropriate command was given.

In studies of cowl openings, I found tons of stories of dual latches that somehow popped open, and when ran to ground, all were shown as a high probability of error during pre-flight inspection.

We humans are quite reluctant to admit (or perhaps even remember) our failures. Recall the Audi experience here in the States, where dozens of auto-throttle accidents were reported, virtually all mythical.

[Mark Six]

It probably won't help your research but I do remember one incident of an accidental cable cut from my RAN Wessex days. Prior to departing for a SAR check it was normal for the crew to check the functioning of the hoist and cargo hook. The cargo hook was checked by having the observer/aircrewman lie on the floor in the back with his head outside the door so he could see under the aircraft belly and observe the opening of the cargo hook. On this occasion the observer assumed the appropriate position, and instructed the pilot to open the cargo hook using the electrical release button. The pilot duly obeyed, only problem was he hit the cable cut instead of the cargo hook release. The cable cut worked as advertised, with the result that the severed winch hook landed on the back of the observer's head as he peered expectantly at the cargo hook. Fortunately he was wearing a helmet.