Winchman trim or not?

[Nl_lynx]

Hi,
We are introducing a new helicopter (NH90 naval version) and we are currently evaluating our winching procedures. The increased downwash forces us to perform our hoist operations at higher hover heights (70' +) to avoid our own downwash. In the old days (Lynx) the hoist operator used to talk us to the hoist spot during the hoist. Since the NH90 is equipped with a winchman trim unit (joystick with a small FCS authority) he can actually steer the helicopter to the hoist spot after the helicopter has been put in a stable auto-hover by the pilot. This is no problem with wet winching, but we feel uncomfortable using this method when hoisting on a ship with moving obstacles/deck. The only way this could be done is with a hover well above obstacles (mostly 100' +) giving the pilot none or a very limited view on the ship and using a highline (nordic method). The workload on the hoist operator can become very high since he has to maneuver the helicopter, command the hoist and often hold the cable to control it from swinging under the helicopter...
So for the moment we are not using the winchman trim unit at all, which seems like a waste...
What are your experiences with hoisting from a big helicopter with a winchman trim unit?

Thx!

[ShyTorque]

The SAR SK-76s I used to fly had Auto Hover Trim (AHT). The crewmen were given time to practice AHT, picking up the drum from the water during wet drills. They found it very difficult, as you say, the workload is very high. Many was the time they reluctantly asked the pilot to take the aircraft back again and fly under their directions so we could pick it up and go home before we finally ran out of fuel.

On a moving vessel we never used it.

[louisnewmark]

Nl_lynx,

If the handling pilot can see the deck with sufficient references to hover accurately, why would you want to use hover / winchman trim? Just because it is there doesn't mean you have to use it.

On the other hand, if the deck is small and the pilot will lose references when approaching the overhead (eg a yacht with a tall mast) then you might consider using hover trim for accuracy and winchman safety - but it's busy for the crewman and should be practiced regularly to build experience and safety margins. If at all possible then (my advice) let the pilot fly the helicopter when winching to a deck and the crewman concentrate on the winch operation.

As you say, it's ideal for wet winching especially when it's a modern, non-doppler system. Not using it for unsuitable purposes isn't a waste, it's just sensible and appropriate use of the tools that you have available to you.

Veel geluk met de nieuwe helikopter.

Louis

[Redhawk 83]

Any comments from the S92 operators?

[[email protected]]

On the Sea King we use the HT/AHT for wet winching at night and sometimes for deck winching but only on a small vessel. We have used it at night on a 3 masted tall ship (sailing vessel) because the conditions were calm and the only hover reference for the pilot was the top of the 150 foot mast which was still moving around a lot.

I agree with Louisnewmark, if the pilot has adequate references he is better placed to respond to the vessels movement rather than give the winch op additional workload as he would have to control the winch as well as the HT in a fairly dynamic situation.

I think you have already come to the correct conclusion that HT is a great tool but not for all winching.

[Gene Genie]

Hi QSD

If the HP has the references he flies the serial, if he doesn't then the Winch Op flies it with HT/ AHT.

Crab and Louis have it spot on. Regular training (to a vessel with an open and clear stern area) and robust SOPs are key.

Cheers, Gene.

[C.King]

I tend to apply a simple rule of thumb.

If you feel the need to use the AHT for real, I would not use it for live winching unless its a wet lift or into something that the winchman will bounce off (liferaft/rib etc).

If you are struggling to winch to a larger vessel (such as a short yacht with a tall mast), the AHT can be used to allow the winchop to place a hi-line onto the deck, the caveat being that the hover height is above that of the highest obstruction. That way, if it goes pear shaped, no harm done, just get another hi-line.

Once the hi-line is on deck, the pilot should be able to fly the hover using the available references as the aircraft will be offset a few units, with the SOP being that he stops movement towards the vessel when he is approaching the limit of his visual references. The winchman can then be lowered/recovered using the hi-line to create the appropriate angle on the cable.

As suggested by the previous posters, success as always comes from practice.:ok:

[Gene Genie]

I've used HT/AHT in anger on both moving and stationary yachts as HP didn't have references. C King also has a good point and a Hi- Line is a good way of helping to skin this cat.

Don't know about S92, but on SK3A you have up to 15 or 25kts depending on FPC mode (crab will correct me I'm sure) or on SK3 above 10kts you need to do it Doppler out.

[Nl_lynx]

Thx for your comments!
They are more or less in line with what I was planning on doing. Still have to figure out the amount of (extra) flying hours we have to spend on training the use of the winchman trim since it is new to our hoist operators and pilots, and 95% of all hoists can also be done with the pilot doing the approaches.

[pasptoo]

S92 could use either VHold (Pilot controlled, AHRS Velocity based - not doppler) or CHov (Crew Equivalent). Let the Pilot "Fly" and the crewman winch. CHov is not a natural motion and can induce unwanted swing.

Upto 50kts forward and 25kts side/aft. This should allow adjustments in .5kts increments.

Works well at any height for small vessels, life rafts (multi or single) or persons in the water.

P.

[Tight Anium]

As a user of Seahawk crew hover some years ago (as a winch op), it is invaluable for person in the water or life raft pickups.

For crew hover to be engaged, doesn't also radalt hold have to? If this is so (from my fading memory), won't this cause an upset as you move over the vessel? Best case it will initiate a climb but worse case the auto hover will drop out especially with a big mismatch.

[[email protected]]

Tight Anium - that depends on where your rad alt aerials are and how you set up the deck. For HT decks we would use a Left to Right configuration so the aircraft moves sideways into the overhead keeping the aerials (just under the nose) clear and avoiding lock-on.

[SARowl]

NL

As Crab and Tight Anium have stated, beware of rad alt climb/uncouple. Also all WTR systems are less responsive than manual flight which makes overshoots common; trying to hover over a liferaft in a high sea state is tricky. Make sure the target vessel is as steady as poss and choose your moment. Winch Op workload will be high whilst trying to maintain position and winching. Be careful when you select hover, all GPS hover systems maintain an excellent geographically stable hover, however, your vessel will be moving or subject to wind and tide and you can easily lose contact especially at night.

[[email protected]]

But most systems (even the Sea King 3A) allow you to beep in a vector(hvr/Hvr Trim) once hover has been selected so that shouldn't be an issue. The 139 shows you a pretty picture of your vector - green circle for the selected vector and a magenta line for the aircraft movement if memory serves.

[Turkeyslapper]

Close....magenta ring for velocity reference, green line for actual aircraft velocity.

The 139 wtr has 10 knots of authority around the " datum" the pilot gives him....interesting for the crewman if the pilot hasn't trimmed out the aircraft properly when he is given wtr, so when he gets over the spot and resumes what he thinks is a reasonably accurate relative hover (simply by pressing his trim switch) the aircraft doesn't perform as he expects and drifts accordingly:E

[pasptoo]

For crew hover to be engaged, doesn't also radalt hold have to?

Not on the S92, you need RadAlt to engage the Hover Modes, but once engaged you could select BarAlt hold or no hold at all. Also use any height (within reason up to winch cable limits) The collective is held by trigger in any case, so you could have ANY hold engaged and trigger for the required evolution, hold a manual height until requiring the Rad or Bar Alt Hold. At any stage without a hold you could re-acquire from PF or PNF.

"Flexibility is the Key to Air Power......"

[Thone1]

@QSD:

Our standard winching height in the Sea King is 40´. Working with a ship we´ll generally find ourselves at that height over the deck, if there are no larger obstacles.
Works fine with the downwash.

And we never use the Aux Hover Trim when working with a ship. Never.
Only use it for training to pick up a barrel or something from the water.
For live winching however it simply takes too long to get the programme to run down before you can engage AHT.

Tom

[[email protected]]

For live winching however it simply takes too long to get the programme to run down before you can engage AHT.It's only 78 seconds - it takes longer than that to brief the exercise/rescue and get the winchman ready.

[Thone1]

Well, we do brief, but generally don´t bother to wait.

As I said, we´ll have started the winching until then.
What do you brief for almost 80 secs?

And our aircrewmen are ready well before reaching the training- / rescue area.

[[email protected]]

What do you brief for almost 80 secs?Operating height, Hazards, heading, effect of downwash, method of rescue and execution, recovery, power and engine performance (SSE, flyaway or committed) and pre-winching checks.

For a drowning survivor these would be shortcut down to a few seconds during the run in but for a person in a dinghy or on a small vessel at night - brief it properly or end up looking stupid when something goes wrong or not as anticipated.

[Turkeyslapper]

Operating height, Hazards, heading, effect of downwash, method of rescue and execution, recovery, power and engine performance (SSE, flyaway or committed) and pre-winching checks.


Our organisation is in its infancy when it comes to this stuff (night wet winch operations/vessel transfers/automatic approaches and WTR). The stuff Crab mentions above is stuff we are trying to hammer home to our trainees at the moment.....better to take a minute and ensure your s&%t is in a sock and do it properly rather than rush into things with a likely cluster at the end. For us, particularly at the moment with reduced experience levels it works.:ok:

[cfr]

We never use AHT in our S76C+...
It is not a proper stick but a chinese hat.
It is very difficult for winch operator to trim because he has no doppler speed indicator. We've never used for real missions.

By the way, S76 autohover system is not good at all.
It works really good...when you don't need it.
Radalt mode (alt hold) works fairly well up to 3 meters high waves.
Higher than that, system "dances" up and down... (for a 4 meters swell it would be +/- 20' at 60' hover).
So when a really need it...that's when I have to change to Manual... :-P

VelHold, same thing.