I been thinking to myself, "self I must read this thread thru and contribute something, seeing as how that low level is where I have lived for the last forty years and check and training of survival in the small survivable areas of it is second nature to me, and many have come back and thanked me for getting them out of the poo at times".
I would like to keep it simple. At the end of it all I encourage people to think why it is not a good idea to be in an impossible to do a safe auto area, say hovering at 80 feet. They simply must come away from these exercises thinking how they will change their mustering or LL techniques when between 20 and 250 feet to always involve a safe airspeed.
1. As Nick Lappos says discussions and training in these aspects encourage us the think. The Robinson safety course is an excellent example in stimulating thinking in their explanation of energy management during autorotation; I assume other factory courses to be the same.
Thought process one, all helicopters are designed and tested for certification to sustain the inactivity of a brainless pilot for at least a second without further control adjustment once the power source becomes silent, one doesn't need to be violent. So entry is to position the A/C in a good auto flight or termination mode and you will drop quite a-ways doing that if starting from a low or zero airspeed.
Thought process two, my ab-initio instructor (ex Brit army) encouraged me to think along these lines. "There may be any number of reasons why you have to quickly enter autorotation. Upon noticing that things are not right you are to firstly, rationalise the problem - solve with your solution - then ACT. Because you're a blasted country bumpkin I'll give a full quarter of a second to start acting, any more and I'll thump you, which he would." A later debrief would explore my thought processes and actions.
2. Of the very many emergencies I have experienced all bar one were at LL and thanks to my ex Brit army mate I always had a spot in sight, it’s amazing what you will fit into at times.
Thought process three, always but always pick spots and plan your approaches to them as you are tooling along.
3. During my early check and training experience, in fact when I was getting checked out to conduct C&T having by then done a bit of it by one CASA man (or whatever the fed agency was called then) Holga Von (something long name, ex Oz army), he says to me. "You seem to be teaching autos at cruise speed 8 feet, 50 feet or 500 feet, or hovering autos at 300 feet, why not is it that you do not teach them at 40 knots and 250 feet where you seem to operate mostly all day?"
Thought process four, Jawohl! We quickly found some error inducement in pilots doing autos at 250 feet had they been conditioned to do them at 50 feet say and at high cruise settings. That error was to fairly quickly bring the cyclic back thus leaving one with no airspeed at a most uncomfortable height. (Not enough thought process)
There seem to me to be four parts of an auto; 1, entry, 2, decent during auto (range chasing if needed) 3, the termination area - say one knot of airspeed must equal one foot of height 50 /50 is nice where one begins to flare, then 4, the touchdown. It matters not how far one will fly in descent if at all, the main game is to arrive at a nice 'termination area', and the rest should follow. A good entry will easily facilitate this and it is where this discussion started so that brings me to what I do now which is to check out several regimes of our LL practices.
a) Fast cruise at super low level where one will bring a whole lot of pain if the cyclic is brought back too early and slams the T/R into something solid beneath, one first must give the collective a quick flick up, then down again as a small cyclic zoom climb is performed as part of a quick stop technique to arrive comfortably in the 'termination area'
b) More than 50 knots at say 50 feet where one simply enters a quick stop routine, collective going down smoothly as the cyclic aft is being applied to arrive at the same height and now established in the 'termination area'. Less than 50 knots down to say 25 knots, leave the A/S where it is until you intercept a 'termination area' further down, but that collective must be got down smartly.
c) At 50 to 250 feet and between thirty and seventy knots, under no circumstances do I want to see a quick check back on cyclic, cos it may hurt you when I thump you and me if it turns real and you have run us right out of airspeed in that nasty height area.
d) Normal cruising at a higher height as between 40 knots and above, checking back on cyclic is not necessary as it may condition you to a bad mistake in tighter circumstances, refer point 1 para 2.
e) Very slow A/S or hover at LL. This procedure is checked at 300 feet after demonstration and follow thru, and at lower heights it is demonstrated only with power recovery and always positioned to reach a target spot. Here I use the point process. Point everything you got brother at your spot, collective, cyclic and right pedal. The RRPM will not decay too much and can be easily got back in hand after about 80 to 120 feet which is where the A/S will again be approaching 60 knots. Do not check back on cyclic until the aircraft is pointed downwards, then I will calmly say, “60 knots attitude please - not 600”, it is then quite a large check back. First couple of demos as hands off I ask them to strongly monitor both the RRPM and A/S. it only takes a second to get down that first bit with the cyclic forward and the RRPM will be still be in the green.
I often use the analogy of the F/W being a bit high on finals; one can simply quickly dive off the extra altitude without increase of speed to arrive a nicer height, so too do we dive off height with the point process to arrive at a safe 'termination area' with enough inertia still in our M/R. You may even be lucky enough to have picked up a small extra airspeed which can be flared off to help arrest ROD. In all slow entries either maintain or increase your A/S if possible. I.E. Do not check back on cyclic at entry.
In all instances I talk a lot about ROD being at the very minimum you can achieve at ground level as high ROD is what will kill you.
It is incredibly important that the auto RRPM must be set up as the Manufacturer describes in the manual. If it is too high ground the A/C as it is too easy to slam the collective down and increase the ROD too much, and I have the back to prove it.
There are four items that need to be completed and checked when an entry to auto is required; 1. collective down RRPM in the green, 1. Set the A/C attitude for max range A/S or the desired A/S under the circumstances, 1. Safe to reach a spot or already turning into wind. 1. Get a mayday out.
Note the generic priority, one doesn’t need to psyche oneself to think about a mayday, just hold the blessed xmit button down while you are briefing others or whatever. Any person listening to a radio is an attentive person, they will do something to help.
Autos from higher heights can induce errors in a pilot's range assessment if auto flight is continued after joining needles. The glide path then changes, so when joining needles at say 300 feet fly away and look away.
Please fly a little higher and a little faster if possible and no passengers while doing Air-work.
None of the above is a recipe for survival or designed as a pissing contest from a predicted height A/S combination say, as every A/C and day is different. It is amazing how easy it is on a very cool, windy day and, lightly loaded compared with a muggy, hot day with a heavy A/C.
MERRY XMAS tet.