Helicopter drops large air conditioning unit onto Oakland street 10Jan2021
 

I don't really know, but that does not look like a snapped cable???? Or the hook was released???

News video

Pressed the hook release instead of the PTT button?🤷‍♂️ If that’s even possible on one of those machines? It is on the 350

I wonder if they'll still charge them for the helicopter rental after splattering the load?

Hopefully all ground crew escaped unharmed

I fly for fun, not work, so have never seen a pickle. I would think the pilot must be instantly ready to release the load, but that the switch itself would not be overly sensitive so you couldn't drop the load by being a bit anxious. How much effort does it take to pickle?

On all types I’ve flown the load release button is very similar to switches used for trim release/SAS disengage or floats actuation but they are guarded by a flip type cover.

Some switches are actuated by pressing the guard which is flipped over through 180 degrees.

One type I flew (S-76) had the float actuation switch in the place on the cyclic where the load release was on the previous type I’d flown most (Puma). I had to think carefully when carrying out USL work.

It looks pretty windy there what are the flying limits for a job like that. Done a few A/c moves in/out buildings but all with a rented crane, not a chopper.

Interestingly, the rotor coning and blade tip water separation instantly terminate, the millisecond the load is out.

The "windy" conditions you see is the rotorwash from the helicopter.
It could have been a hook failure, an accidental release or a commanded release. I don't see anything that would suggest a reason to purposefully punch off the load. I have seen hooks not lock completely and fail in this manner after taking load for a short amount of time. I have also seen hooks just plain break and drop a load. Or they hit the button accidentally. This ship had been on fire contracts with a tank for the majority of the year, and maybe during reconfiguring it, people forgot what switch did what?

This is one of the reasons I was taught to never turn my back to a helicopter/load, and minimize or eliminate time under a load.

One event of a load release was caused by a transmission being made on HF radio, load dropped onto a freeway, no one hurt or vehicles damaged.

Correct me if I'm wrong but on the Skycranes isn't the load controlled by an operator sitting behind the pilots facing the load. Would he or she not have control of the load release button?

What ever the cause of the release; that strop is WAY too short!

I at first thought that it may have been a vortex ring state event due to the surrounding buildings; however, in the video, I didn't see any settling of the helicopter as it was picking up the load.

At least it looks to have been an expensive incident instead of a painful (or fatal) one.

Cheers,
Grog

There aren’t many rookie lift pilots on the sky crane fleets. Maybe they actually know what they’re doing?

Rotor wash
 

LTP90 is very correct about the rotor wash. Years ago I was landing a C172 at the local strip and one of these Skycranes was adjacent to the runway near the approach end. It was running with the rotor disk turning but firmly on the ground. Even with the blades at fine or flat pitch (ie not pulling pitch) there was enough rotor wash that in the flare as I was landing I thought for a split second that I was going to cartwheel and crash as the right wing flipped up about 20 degrees. It felt like 50-60 so I'm guessing at 20 but it was a serious gust when not at all expected.

Agree. For real precision, its best to be as close to the load as possible. You can't see your ground crews fingers from the top of a 100' line.

Reminds me of when the Navy first got the Wessex to replace Whirlwinds....first practice landing from Albion on to Lulworth Cove area, full Commando plus us CDO Gunners; my command post Landrover took a dive into the sea when the LH seat pilot said "What's the time" and the RH seat pilot replied "1005" but pressed the hook release instead of the PTT, because they were the opposite way round from the Whirlwind's. That was his story, anyway.

Not really. Most down town lifts with the crane are done on short strops. Part of it has to do with safety zones. We have to have a safety zone typically radius of 1.5 times the maximum eight of the aircraft. If you use a 100' line, that adds 150' radius to your safety zone, and that gets expensive when paying for the cops to close more streets.

Typically these are done at first light on Sunday mornings as there is less people around.

Not always, but in this case you may be right. FYI, that "operator" is a pilot and is able to control the whole aircraft from that seat.

Our company's underslung load insurance is .01/lb, that's right, a penny per pound, so not as expensive as one might think for the helicopter company, unless your including the cost to their reputation.

Thank you Gordy for a sensible answer. Not being there I am not aware of local ordnances affecting these type of lifts. Although they appear to be lifting from an intersection, it is still like trying to fly in a Canyon in amongst those tall buildings. I still maintain that technically, the strop is WAY to short.

Incidentally, I am endorsed for sling loads, and lost my own helicopter and pilot, plus my business, because of a botched up sling load many years ago.

Any Skycrane drivers out there who can say when the handover from the rear facing pilot to the front facing pilot happens on a job like this? I just wonder if it was at that crucial point that the release/failure happened.

Normally I would agree, but in this case, they are using that hook that can swivel the load around to align it correctly on the roof, without having to use lines with people pulling the load to the correct position. They have 4 lines on the unit and making them too long, would probably twist them.
I think they knew what they were doing, regarding the rigging ... until the moment all went wrong, but I don't think the length of the strop is the problem.

so if the result was just bent sheet metal I guess its ok

Somehow I don't think the building engineers would agree with your assessment. Depending on what part of the system was dropped it might contain electrical and or pressurized equipment

Going by the video in post #1 , I say it was a release , not broken cable , because if you pause at 0:30 it shows the loop is intact .

Would there not be two separated cable ends if it broke ??



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https://cimg2.ibsrv.net/gimg/pprune....6ed56fb06b.jpg

If you listen carefully there is a distinct change in the engine noise signature immediately after the load release. Sounds like one engine spooling up, so I wonder if there was a power loss and it was deliberately pickled?

Could just be that the sudden loss of load and reduction in pitch resulted in a transient increase in engine rpm.
There was no discernable decrease in engine noise post-lift.

https://cimg3.ibsrv.net/gimg/pprune....92bf7cbbdd.jpg
Isn't one line broken?

skadi

From the video, it looks like everything from the aircraft cargo hook downwards fell away.

Hopefully there is a company procedure in place to preserve evidence regarding switch and guard positions. Very lucky it all fell away in possibly the one place where collateral damage was little or none.

Facing backwards
 

Just idly thinking about flying a helicopter while facing backwards, presumably the controls are reversed so that pulling back on the cyclic actually makes the machine move forwards, and right cyclic makes it roll left.

This machine is equipped with an Anti-rotation device, the jettisonable part of which is attached directly to the Airframe Cargo Hook. This maintains the position of the load in relation to the helicopter and is used for precision construction placement. Prior to the first take-off of the day, the Cargo hook is physically tested in both electrical and manual release modes. Prior to flight, all hook releases are placed in the ARM mode. There is no means of determining if the Load is electrically released, other than functionally testing it after the event. In my experience, virtually all inexplicable Cargo Hook releases are caused by improper rigging setups, eyes hung up on the load beam, sitting on the keeper and slipping off (unless keeperless hooks), or lastly and very rarely, finger trouble.

In this instance, the jettisonable part of the anti-rotation device is released from the hook. It looks intact. There is no visible line or equipment failure.

These instances do happen, but pretty rarely for professional specialty lift operators. The fact that it is worthy of discussion is precisely because of its rarity and the fact it was captured on video.

bksmith
Depending on what part of the system was dropped it might contain electrical and or pressurized equipment
I am in the middle of installing a small airco. Indoor unit contains some nitrogen. Outdoor unit
contains pressurised R290 (=propane). Large commercial units will be different or empty.
Too cold for me to work outside & verify.

esa-aardvark I understand that I was replying to Rotorookie in post #25 who commented that it was only sheet metal so it was ok.

Give it more thought I’d suggest!

212,,when operated by the`man in the boot`,it is logical that `his`. controls should be operated with reference to his position only......

Yes, so they can still move in the same direction as the ones in the cockpit. By facing aft the cyclic has effectively been reversed anyway - his forward is the pilot's aft etc. Just think about sitting in that capsule, looking down and rearwards, and what you would do with the cyclic to hover. The aircraft doesn't know who is controlling it and what references are big used! The control inputs will be the same.

You are right 212.

As I have had explained to me - thanks John - the rear facing pilot doesn't have mechanical controls but has a system giving 10% AFCS authority.

Anyone familiar with the Sea King AHT (auxiliary hover trim) will understand the idea.

As with the AHT, there is a verbal handover of control with the forward pilot following through on the mechanical controls while the load is positioned/lifted and then taking control for the transition.

So it is pretty certain the forward pilot was flying when the load dropped off.