Stuck Collective

[bugdevheli]

An item in Rotor and Wing regarding training for emergency situations, suggests that a machine can still be safely landed with a stuck collective. Any advice on how one would achieve this in a R22 assuming it was climbing when the collective jammed.?

[Hilico]

Whole subject discussed at length in this thread. (http://www.pprune.org/forums/showthread.php?s=&threadid=91465&highlight=stuck+collective)

[Axle]

I take it your not allready a pilot..... jammed collective is usually covered in your flight training isnt it??

[autosync]

Small piston helicopters are easy enough to get to the ground if a the collective is stuck and you have to loose power, put the carb heat on!
Or else, next time you are out hovering around, see how much power you can loose when you do lots of continuous small circular movements with the cyclic.

[RobboRider]

Its part of the syllabus if I recall.
All the above options plus try forward cyclic to get down in height, plus or alone careful decrease in throttle in small increments while watching the RRPM.

[Dynamic Component]

9out of 10 times the colective will get stuck at cruise power.
Have you ever slown the speed down gradualy at cruise power?
As the speed get lower(normaly below 40kts) you should start loosing hight(if you have not induced the "Baloon effect" by pulling back to quickly)Sometimes it happens before you feel that shuddering from losing translational lift.

Just my 2cents:}

[compressor man]

Obviously, it's not so complicated in a dual eng machine but I have heard of a few incidents recently with S-76. Apparently some were hydraulic related, others mechanical.

I'm not sure if these are within the realm of the emergency procedures checklist or more along the lines of a short burst of excitement injected into the daily routine for which we are paid so dearly.

take care out there

[Whirlybird]

I may already have posted about this on one of the previous threads, but we did it on my FI course. And tried it too. I thought slowing down would work, but it really doesn't. What did was to decrease the throttle, while turning, since turning will increase the rotor rpm. You gradually circle and come down, but as far as I remember, you have to be very careful near the ground, and get it just right. I think you straighten out at the right point and then do a run-on landing; can't quite remember. But it does work.

[Shawn Coyle]

So how many instances of stuck collective have happened? I'm being a devils advocate here, but are we training for something that happens extremely infrequently?
If it does happen frequently, do people report it on the Service Difficulty Reporting (SDR) system to make sure someone knows about this?

[SilsoeSid]

So how many instances of stuck collective have happened? I'm being a devils advocate here, but are we training for something that happens extremely infrequently?
I'd rather have thought about it over a coffee and given it a bit of practise if possible, than try and work it all out on a winters night come the 'unlikely' event.

Can I take it then Shawn, that you don't think of or train for any unexpected mishaps?

Then again, I suppose I was a boy scout and I like to 'be prepared'.

Reminds me of a saying always in the back of my head;

The thing about a helicopter pilot is; that he knows that if nothing is going wrong, it's just about to!

:ok:

[Shawn Coyle]

No, I'm not advocating not being prepared. What I'm advocating is being prepared for likely events - as an example, in one organization I was in, there are those who advocated practicing pedal failures in the hover where the pedal would go to maximum pitch (left). There was no hydraulic system in the pedals, and no possible way for the pedals to go to maximum left pedal pitch in any of the failure modes. The problem was that by introducing this false failure into training, it made people miss the point that the problem failure in the hover was loss of tail rotor drive - people were going to spend time trying to figure out if they had a stuck maximum left pedal or a loss of tail rotor drive (am I rotating left or right?) when it was pretty clear that if you started rotating rapidly in the hover, you needed to get rid of the power quickly.

The other thing I'm advocating is that if a stuck collective really does happen, then you ought to be reporting it. If you have something wierd like this happen, somebody in the aircraft manufacturer and someone in the certification authority should be told. The Service Difficulty Reporting system is set up for exactly that.
The helicopters are designed and tested so that these things should not be able to occur - if they do and enough of them do, then something will be done about it.
As an example, I've just seen an accident report on a helicopter that has a collective hold down system that (naturally) got engaged at the wrong time. I'm not sure how this model of helicopter still had this feature, as it was mandated to be removed in several countries as it had been implicated in several accidents / incidents.
And there has to be a limit to what failures we teach people about. "let's look at the failed pitch link failure..."
And just to show the other side, at least one country has mandated no intentional hydraulics off flight in one model of helicopter because of the problems of controlling the machine - this is perhaps unwise, because how do you train people to handle that emergency (which, in the model of machine concerned, happened with a significant frequency)?

[delta3]

Shawn

I'll follow you on the prevention logic. I tried what other people said on this and other tracks, and it looked awkward: trying to land a light R44 with excessive power looks like impossible whatever some people say. It takes a lot of trying just to get it to descend, what about landing it..., unless some of those pilots are used to fly with less than 80% rpm and land on a 747 runway.
No wonder the UH1 guys stood on the collective...

d3

[ec135driver]

I saw this in R&W today and tried out the "slow to the backside of the power curve" suggestion - trouble is we tend to fly around at max chat all the time to rescue fallen women and when that is over it's back to base for tea and medals.

Anyway at redline power the A/C just climbs and climbs and climbs and..........even at close to MAUW at zero airspeed. (failing one engine - if you have more than one, might help, but the T2 version of my A/C is a whizz even with one just taking up space)

Just to take up on SC premise about training for the unexpected, I often get the feeling we train and practice for weird and wonderful failures, just because we can. Also the RFM can be really blase about really horrendous failures.

The Bo105 FLM advice on tail rotor failures bears little relation to the AAIB findings in the simulator when they tried to replicate a fatal accident due to loss of tail rotor control

[Gaseous]

I have a reprort of a stuck collective occuring in my Enstrom from the previous owner. He warned me when I bought it that an object of some sort got stuck in the centre collective when the lever was not fitted. He could not free it and could not land.

Fortunately the pax, also a rated pilot, managed with difficulty to free it. I know he posts here occasionally, so come on Mark, fill us in with the details.

[Shawn Coyle]

Many years ago, the US Army did a study that showed that 75% of the emergencies in the FM had never happened, and that 50% of the emergencies that did happen weren't covered by the FM.
Go figure.

[belly tank]

Shawn,

Is it time for a revised emergency procedures suppliment!!!..but i guess this would cost dollars to implement!!...maybe surplus funds from comanche project may cover the investigation..(snigger)!!

Cheers