[Rob L]

January 2019, Florida, video of Hughes 500 used to trail power cables over pylons.

"Because the area is rural and swampy, it was more efficient for lineworkers who were secured to the helicopter by rope to replace all 34 miles of this transmission line toppled by Hurricane Michael."

Linky

Scroll down for the Sikorsky delivering the new poles.

[aerial]

I wonder how they explain the risk to the person on the rope = anything goes wrong - you die!
Or perhaps I missed the failsafe?

[Colonel Panic]

In a similar vein, I have always thought that this video is quite good, almost poetical. Video quality is carp by today's standards though .

[Flyin'Dutch']

I share his fears, maybe a job waiting for me!

Very good thanks for sharing.

[eharding]

A while back I saw a crew maintaining the high-level electricity lines running alongside the old Severn Crossing, working from a cradle slung underneath a helicopter - I was on the Chepstow side, and I think they had a ground base on the other side as they would nip back across the estuary every so often.

The helicopter would get a reasonable turn of speed heading back across, and the cradle would reach a respectable angle trailing behind in the process. I did reflect that the crew should either be getting paid a significant sum for doing so, or they were actually adrenaline junkies who would gladly do it for free anyway.

[Kemble Pitts]

I led the team that designed, developed and certified that rig for National Grid.

The aircraft is equipped with vertical cameras for viewing the basket, the aircraft's speed is limited by the trailing angle of the basket; go any faster and the basket goes out of view of the camera.

When we carried out the flight testing, ballast first then real people, the National Grid chaps couldn't wait to get into the basket. During the first sortie around the aerodrome (Staverton) the guys in the basket ran to one end to induce it to spin. They then ran to the other end to get it to spin the other way and untwist the ropes!!

Watching this I was horrified but they were like puppies with their heads out of the car window...

Tried to load a photo but 'computer says no'. Too large apparently.

[Kemble Pitts]

[Kemble Pitts]

[Rob L]

My word, that looks dreadfully worse than the video!

(a single?)

[aerial]

@Kemble Pitts

Out of interest what were the mitigations in the case of engine failure - or did you just carry the risk?

[johnm]

Extraordinary and brilliant

[Lockhaven]

@Kemble Pitts

Out of interest what were the mitigations in the case of engine failure - or did you just carry the risk?

Two engines in twin squirrel helicopter.

[Dave W]

But would it maintain a high hover on one engine (many types wouldn't, at operating referred mass), or would it have to put the nose down and fly away forward, losing height? A tricky role, either way.

[Kemble Pitts]

One of the key factors limiting the underslung mass is the OEI performance of the AS355NP Twin Squirrel. Importantly what is known as 'drop down', rather than raw fly-away capability.

If you have an engine failure in the hover, before the remaining engine spools up, the aircraft will descend (or 'drop down'). This drop down distance is the factor that governs the underslung mass and it is more limiting than simple OEI hover performance.

Drop down had to be limited to less than the vertical distance between the bottom conductor and the ground and this limited the mass (otherwise the basket and crew would be crashed into the ground).

If you look at the largest cross-country power lines you will notice that the middle conductor set (of three per side) is further out from the pylon than the top and bottom ones.

So, to reach the bottom conductors with the basket you need to 'thread' the basket down 'inboard' of the middle conductor. So, if you have an engine failure when on the bottom conductor, you can't simply 'fly away' gaining forward speed and thus lift, you have to climb vertically (and very carefully) first.

It is a VERY demanding operation for the pilots, basket crew and ground crew - and the National Grid team are extremely well drilled in it.

[aerial]

This sounds like a good example of safety - and the proper management of risk - being used as an enabler to allow things to happen rather than an excuse to stop them.
Very impressive.