Chop tail off in the hover??

[Mutley1013]

Left and right yaw followed by nose up and down and then tail chopped. That’s a dramatic sequence from what I understand to be an OGE, albeit low level, hover. Serious over controlling or could turbulence from the tree tops be wholly responsible?


https://atlantic.ctvnews.ca/pilot-decided-not-to-land-moments-before-deadly-newfoundland-helicopter-crash-1.5343237

[zhishengji751]

The report is here
https://www.tsb.gc.ca/eng/rapports-reports/aviation/2020/a20a0027/a20a0027.html

They've highlighted LTE, presumably as they cleared the trees tail rotor entered the vortex from the main rotor blades

[Robbiee]

I don't get it?

Your friend decides to not land there because of the winds, so you decide to land there?

[Hot and Hi]

Nah, TTRW < 150. On type < 100. Nil HRS past 90 days.

I wouldn’t say he ”forgot” how to fly because at that hours he hadn’t ‘learned’ yet to fly.

Plus all the other signs of attitudinal incompetence: no medical (3 yrs expired) no flight log entries, ...

[Mutley1013]

More money than sense. He was not so much PIC, more like DHIC.

[ShyTorque]

Rules, regulations and common sense obviously didn’t apply to this pilot.

His medical was two and a half years out of date so he was unlicensed and presumably therefore uninsured. I feel sorry for his unknowing passengers.

[[email protected]]

The report states he was only 130 lbs under gross max weight at the time of the accident and this was when he was going for a refuel - what was his take-off weight when they started the trip then? Full fuel (110 litres)is just over 200lbs.

130lbs is only 5% below max gross and, adding in the relatively high temperature, he will have been working the aircraft quite hard to get into an OGE hover, let alone then climb vertically.

I wouldn't be surprised if he drooped the Nr trying to lift out of the confined area, slowing down the TR by default and reducing its effectiveness. Then, panic at the prospect of a non-existent TR malfunction led to some serious overcontrolling.

A very inexperienced pilot trying to do things way beyond his capabilities - again!

Shame the TSB muddies the waters by banging on about LTE - this clearly wasn't.

[aa777888]

It was not hot at 23.6C (74.5F). It was not high, CCW5 is 350 ft MSL. Weight is 2370. That is well within the OGE hover performance limits of the R44.
https://cimg3.ibsrv.net/gimg/pprune.org-vbulletin/618x935/capture_c759d0960ee24714da0291f063474720584adec7.jpg

Full fuel is 47.7 USG or 180 liters assuming bladder tanks (it would be a hair more with the old tanks). Assuming there was room in the tanks for all of the 130lbs available that would be 21.6 gallons, or almost half tanks. However those numbers are probably meaningless because the report does not discuss the fuel state of the aircraft. But theoretically if he added 20 gallons that would give him well over an hour of additional flight time. Conservative planning for an R44 RII at max. gross, near sea level, 90KN, is about 15 gal/hr. That might have been exactly what he was seeking.

The weather conditions including winds were well within the limits of the machine. The max. performance take-off at max. gross would have required maximum pilot effort, though, if the trees are as high as reported.

It is unfortunately that this pilot did not choose to come in over the water above ETL with the wind on his right. Or make an approach to the water into the wind and hover taxi with a right crosswind up onto the paved ramp. Perhaps the paved ramp was full, or that he was untrained/unfamiliar with crosswind landings, or the fuel drums were in the confined area. Either way, a little unanticipated yaw, which is certainly possible, should not have lead to such wild pilot-induced oscillations that the tail was cut off, but no doubt I state the obvious.

[Bell_ringer]

What robbies are missing in the poh, is a chart that shows the average OGE pilot performance :}

[172510]

What robbies are missing in the poh, is a chart that shows the average OGE pilot performance :}
That should be part of the training. The instructor should demonstrate that for the same manœuvre the students needs more power than the instructor. And explain why.

[Hughes500]

Just because the manual says the aircraft can doesnt mean your aircraft can. Please remember that the manual is derived from test pilots using a new helicopter with perfectly clean blades and a brand new engine, there ability is obviously beyond the majority of pilots with the manufacturer trying to make his machine's performance look really good

[Bell_ringer]

Certification takes the responses of the average bloke, or gal, into consideration.
There is always a margin for error.

[[email protected]]

aa777888 - when you say 'well within' you should qualify that with 'inside the limits of the performance graphs' since you can't tell how much spare performance there might or might not be from the graph, only that you reach the max gross weight line before you hit temperature or DA limits.

Just having OGE performance isn't enough for proper confined area operations like this with tall trees - you need to have a thrust margin of at least 5% and ideally 10% to allow for the manoeuvring and any turbulence/wind shear/recirculation.

My point about the fuel - and I took the 110litre fuel capacity from the Robinson site without realising there was an aux tank giving 180 - was that to get to where they planned to refuel, they would have used quite a lot and in all likelihood got airborne from Reeds Pond in excess of gross weight. It adds to the expired medical in terms of attitude to aviation.

[aa777888]

aa777888 - when you say 'well within' you should qualify that with 'inside the limits of the performance graphs' since you can't tell how much spare performance there might or might not be from the graph, only that you reach the max gross weight line before you hit temperature or DA limits.How about this: the aircraft was capable of an OGE hover per the POH at approx. 4800 ft pressure altitude under the stated conditions, but it was landing at an altitude of 350 MSL. In my book that is "well within", others may have a different opinion.

Just having OGE performance isn't enough for proper confined area operations like this with tall trees - you need to have a thrust margin of at least 5% and ideally 10% to allow for the manoeuvring and any turbulence/wind shear/recirculation.Even stipulating that, it would not have been an issue in this case, both on paper and as someone who regularly flies an R44 at max. gross.

My point about the fuel - and I took the 110litre fuel capacity from the Robinson site without realising there was an aux tank giving 180 - was that to get to where they planned to refuel, they would have used quite a lot and in all likelihood got airborne from Reeds Pond in excess of gross weight. It adds to the expired medical in terms of attitude to aviation.Looking at the distances involved, which even in a straight line without screwing around with the reported stops due to fog, is on the order of 340+ NM. That is beyond the no-reserve range of the helicopter which is 300NM (per the book). They would have had to stop for fuel during one or more of the stops they made as they scudded their way down the Labrador coast. If that was the case, then he probably wasn't over gross. But the report doesn't provide that level of detail. So we can't be sure. Nevertheless, over gross was not a factor in this accident.

Regardless, one cannot but agree that there was a significant lack of airmanship demonstrated.

[staticsource]

Lazy feet and probably looking at the trees, then possibly gripping the throttle too tightly. With that kind of wind, weight and altitude, the 44 shouldn’t end up the way it did.

[Hughes500]

Bell ringer i think you find it doesnt and it certainly doesnt take into account an aircraft which is not new !

[gulliBell]

The performance charts I'm familiar with are always based on a zero engine. If you have a positive margin engine the chart will also accommodate this. If you have less than a zero engine you're off the chart, you can't fly, and maintenance is required. But that's for turbine engines. I don't know if engine trend monitoring is done on piston engines, or whether performance charts take into account the performance margin of the piston engine.

[[email protected]]

How about this: the aircraft was capable of an OGE hover per the POH at approx. 4800 ft pressure altitude under the stated conditions, but it was landing at an altitude of 350 MSL. In my book that is "well within", others may have a different opinion. But you don't know how far within and what level of power margin it gives you - that is my point. Just having OGE performance isn't enough for confined area work. And his DA was about 1200'.

If you were doing a long transit like that in uncertain weather conditions, wouldn't you fill it to full (if you could keep within max gross). The report doesn't mention previous refuel stops but they had to go beyond where they originally planned to refuel so the chances of it being quite empty are higher and may explain why he chose to try and get in where he did.

It would be interesting to know if he did any pre-flight performance planning.

Poor airmanship, poor decision making and ultimately poor handling are the causes here - an inexperienced pilot biting off more than he can chew.

[[email protected]]

Military turbines have a Power Performance Indicator graph (PPI) and on the Sea King, the performance graphs were based on 94% PPI so as long as your engines were better than that, you were on the safe side of the line - very important for prolonged high hover work when winching.

[aa777888]

But you don't know how far within and what level of power margin it gives you - that is my point. Just having OGE performance isn't enough for confined area work. And his DA was about 1200'.Practically all my hours are in Robinson products. I can assure you that he had boatloads of margin. Plus, I find it hard to believe that if you looked at any OGE performance chart for any helicopter and saw a 5000ft DA differential between where it was operating and where it could operate OGE, as there was in this case, that you would not automatically believe that not only was there sufficient margin, but that there was a lot of it. Seriously, is there any helicopter that you know of or have flown that would not have provided sufficient margin under those conditions? And no corner cases like it was a hurricane or something. Just a plain old nice flying day like they had.

If you were doing a long transit like that in uncertain weather conditions, wouldn't you fill it to full (if you could keep within max gross). The report doesn't mention previous refuel stops but they had to go beyond where they originally planned to refuel so the chances of it being quite empty are higher and may explain why he chose to try and get in where he did.Didn't argue that, and still not arguing that. But it does stand to reason they had to refuel somewhere in Labrador for the trip to be possible. It would have been nice to see that information in the report, and also to know how the other helicopter managed fuel and payload, too, especially since the other helicopter never did refuel at the accident site.

Poor airmanship, poor decision making and ultimately poor handling are the causes here - an inexperienced pilot biting off more than he can chew.Again, not arguing, totally agree. But I am much more focused on the inadvertent yaw induced panic that ultimately did him and his passengers in. That might have happened nearly anywhere in this trip with similar results, without the distractions of fuel state or confined landing spaces, but those things definitely contributed and ultimately made the situation worse.

[[email protected]]

Seriously, is there any helicopter that you know of or have flown that would not have provided sufficient margin under those conditions? And no corner cases like it was a hurricane or something. Just a plain old nice flying day like they had. No, simply because we operated with a minimum of a 10% thrust margin whenever possible, especially for high power scenarios like confined areas, mountain flying and any OGE hovering.

You can calculate your thrust margin by looking at the max weight on your OGE graph - for them 2500lbs and reducing that by 10% - ie 250lbs which is 120 lbs lighter than he was at the time of the accident.

His DA was around 1200' given the temp and elevation so he was further up the graph than you imply.

The example in the R44 POH of weight and balance shows full fuel isn't available with 3 POB and a small amount of kit - how much baggage would they have for a fishing trip? And the example uses 170 lbs per pax which is light by anyone's estimation, especially in outdoor gear.

Given the layout of the HLS and the wind direction he should actually have had a reasonably clean airflow, certainly above the treetops even though the report cites mechanical turbulence from the low buildings and the trees (with a max estimated of 20 kts, I feel this is unlikely.

Not sure why you think the yaw induced panic could have happened anywhere on the trip - the proximity of the trees was what seemed to panic him.

[aa777888]

No, simply because we operated with a minimum of a 10% thrust margin whenever possible, especially for high power scenarios like confined areas, mountain flying and any OGE hovering.

You can calculate your thrust margin by looking at the max weight on your OGE graph - for them 2500lbs and reducing that by 10% - ie 250lbs which is 120 lbs lighter than he was at the time of the accident.That's how YOU operated. Unfortunately, in the world of light helicopters, in order to get any real work done, only loading to 90% of max. gross is usually a dream.

His DA was around 1200' given the temp and elevation so he was further up the graph than you imply.Not at all. If you enter the chart at the 2370lb line, move upwards to where it intersects the 23.6C line (interpolate as required, of course), then across to the left, you will see he can operate at up to a pressure altitude of over 5000ft at 23.6C, i.e. a density altitude of over 7000ft. There is no problem here. Again, he had tons of margin. Not in your book, or the way you fly for the military, but tons in any light helicopter operator's book.

The example in the R44 POH of weight and balance shows full fuel isn't available with 3 POB and a small amount of kit - how much baggage would they have for a fishing trip? And the example uses 170 lbs per pax which is light by anyone's estimation, especially in outdoor gear.Where are you getting your numbers? Basic empty weight of a Raven II is 1510lb. Full fuel is 287lb. Max. takeoff is 2500lb. That leaves 703lb for people and stuff. Few R44s are that light. Let's say he's got 20lbs of options on board (which is very conservative, it didn't have a lot of options (https://www.aircraft.com/aircraft/74801841/c-fpbl-2012-robinson-r44-raven-ii)). Call it 683lbs. That's three 200lb guys and 80lbs of cargo. And that's about right, because the only place to put that much stuff is piled on one of the seats. You can't fit it in the stupid little cargo areas under each seat. Again, I'm not seeing any problems here. In fact, this all but proves he was not over gross at any time during the flight unless his cargo was gold bars or him and his passengers were huge, both an unlikely state of affairs.

Given the layout of the HLS and the wind direction he should actually have had a reasonably clean airflow, certainly above the treetops even though the report cites mechanical turbulence from the low buildings and the trees (with a max estimated of 20 kts, I feel this is unlikelyAgreed!

Not sure why you think the yaw induced panic could have happened anywhere on the trip - the proximity of the trees was what seemed to panic him.I'm basing my assessment on the following passage from the report: "When the helicopter cleared the tree tops, it began to slowly yaw to the right. The pilot applied left anti-torque pedal input; however, the helicopter continued to yaw and the yaw rate increased. The pilot then deflected the anti-torque pedals to the right and back to the left several times to check for pedal response while the helicopter continued the right yaw. The pedal inputs did not arrest the right yaw.As the pilot was trying to control the yaw rate, alternating nose-up and nose-down pitch excursions began with increasing amplitude. After at least 2 full rotations to the right the main rotor severed the tail boom as the pitch excursions increased beyond a controllable range."

[Two's in]

Any trip is only as good as your planning. Weights, fuel, endurance, weather are the staples of planning and shouldn't reveal any surprises. What seems to have surprised this guy, as a relatively low-time inexperienced pilot, were the planning considerations that are needed to operate safely in and out of a confined area. When you're grizzly and ugly, a confined area is rotor span plus 2 feet. When you are just starting, an open football field can be a confined area. The accompanying aircraft with him got uncomfortable and threw it away, this guy didn't realize he'd run out of ideas until he was over committed to the landing. He was obviously thinking of getting home and maybe what a great fishing trip this had been, instead of thinking what 'gotcha's' were lining up for him. It's a tale as old as time, if you change the plan, change the thinking.

[Hot and Hi]

A78, there is no “your world” vs crab’s military world (at least not this time round).

I admire your patience. You are of course 100% right. And crab didn’t read the book.

The MTOW (of 2500 lb) is not a power limit. The power margin is not the difference between the actual weight and MTOW, but between the actual weight and the weight the engine could lift under the current circumstances (disregarding MTOW restrictions). Or as you correctly pointed out, by the difference between the current PA and the OGE ceiling at the current circumstances (which was massive).

The only limit was the pilot’s lack of skill and recency.

[[email protected]]

And crab didn’t read the book. Mea Culpa, that's what comes of rushing things when the rugby is on - doh. The example in the POH has 4 POB not 3.

What was I thinking - questioning aa777888?, the font of all Robinson related knowledge:)

[FC80]

Mea Culpa, that's what comes of rushing things when the rugby is on - doh. The example in the POH has 4 POB not 3.

What was I thinking - questioning aa777888?, the font of all Robinson related knowledge:)

Surely he makes a good point?

Taking procedures from (relatively) powerful twin turbine aircraft and applying them to R44s is not a practical or realistic way to operate.

[[email protected]]

Taking procedures from (relatively) powerful twin turbine aircraft and applying them to R44s is not a practical or realistic way to operate. For those earning a living using the aircraft as a tool - probably not, but they are likely to be more experienced and better trained and therefore far more likely to anticipate problems and be better placed to deal with them if they occur..

Those with PPLs and low time would be better served to give themselves as much safety margin as possible.

Operating into confined areas at close to max gross weight is something to be done very carefully and progressively.

[Robbiee]

Operating into confined areas at close to max gross weight is something to be done very carefully and progressively.

Hmm,...that was basically every day training in the R22. :E

[[email protected]]

Hmm,...that was basically every day training in the R22 Clearly I am talking about proper confined areas like the one in this accident, very limited on space and requiring OGE hover and vertical descent, not just something you have to make a slightly steeper approach into.

[Robbiee]

Clearly I am talking about proper confined areas like the one in this accident, very limited on space and requiring OGE hover and vertical descent, not just something you have to make a slightly steeper approach into.

So am I :ok:

[John R81]

My PPL(H) training was into a site surrounded by trees, requiring OGE hover and about 100ft vertical descent / ascent to leave. Same site was used on my PPL(H) skills test.

[[email protected]]

And are you both typical of the PPLH trainees? Do you think all PPLH trainees operate out of such sites?

What is taught regarding performance planning on Robbies regarding confined areas?

[Robbiee]

And are you both typical of the PPLH trainees? Do you think all PPLH trainees operate out of such sites?

What is taught regarding performance planning on Robbies regarding confined areas?

Well, I don't know what the "typical" training is, as I am not a CFI.

However, the way I was taught to handle off-airport landings is to crawl it in, basically just riding that vibration down at around 150fpm. So before committing I'd pull it back to pretty much a hover (while still high enough to abort) then check my MAP to see how much I have between what I'm pulling and what my takeoff limit is. If there's at least an inch and a half, or two (depending on just how steep and how high the takeoff will need to be) go for it.

Now I can't speak for other schools, but I went to one of those "CFI Factories" that pumped out CFIs like Tic-Tacs.

[[email protected]]

That's not performance planning, that's a reasonable technique for confirming the performance you have is sufficient for want you have planned to do.

[Robbiee]

That's not performance planning, that's a reasonable technique for confirming the performance you have is sufficient for want you have planned to do.

Hmm,...guess you're right. What can I say, most of my off-airport landings are of the, "hey lets land there" variety.

I'm sure there's some pre-flight performance stuff they taught me, but I'd have to go look for it (think its on my kneeboard), as I haven't actually "planned" to land off-airport since my checkride.

[[email protected]]

I'm sure there's some pre-flight performance stuff they taught me, You don't need much - the OGE hover ceiling vs gross weight chart in the POH is the place to start having worked out your pressure altitude and expected gross weight.

You need at least OGE performance and ideally some extra - unfortunately there are no graphs to tell you how much extra you have got.

Hot and High is correct that the MTOW isn't a power limit but taking 5 or 10% off the weight would guarantee you a thrust margin of probably more than you need if the weight line is the first limit you hit rather than the OAT or Pressure altitude.

If you have the performance on the chart then you just need to confirm it before committing to landing - I'm sure you check your hover MAP against the placard to make sure it is correct before transitioning.

Once in the vicinity of the landing area, pull to your calculated max take off MAP - ie your max continuous plus 2.8 to make sure it is available without Nr decay or exceeding any other limits.

One problem is that the OGE graph is based on 5 min take off power and not the max continuous MAP which may pass people by if they are not paying attention - the problem being that if you need 5 min power to achieve OGE, you have no spare to deal with turbulence or any unexpected rate of descent - hence my advice - especially if you are hot and high, to have a thrust margin.

Now a 5% thrust margin was defined in various military Operating Data Manuals (same as POH) as sufficient to overcome light turbulence or manoeuvre gently in the hover - in a couple it quantified a vertical rate of climb of between 100 and 200 ft/min so it is not a huge amount of excess power.

Clearly such advice doesn't exist in the POH but you could experiment to see what difference 1 inch extra MAP gives you from an OGE hover - it will at least give you an idea of the difference between Sea Level at plus 23 degrees and 5300' at plus 23 degrees since the max continuous MAPS are only about 1.4 ins apart from the placard.

[John R81]

R44 Raven II POH is available online (https://robinsonheli.com/r44-ii-poh/) from Robinson. Section 5.5 (Performance) contain the graph of weight / OGE Hover, Take-Off power, Nil Wind at Density Altitude.

In addition, relevant to the actual Tread topic, Section 4 contains the checks that should be done after every engine start, and the hover checks - which includes "note MAP"

Craab - you make a good point. Don't recall being taught in PPL lessons "performance planning" for the confined area flight we were going to undertake. General planning for a flight (weight & balance, performance, fuel, route and diversions, etc) but not specifically planning ahead for this. Certainly was taught - as Robbie notes - how to assess the site, check available power for OGE and descent / climb-out, and how to approach and get into the site. That is not the same thing, as you say. There is therefore room for a training improvement there.

Training did include "artifically lowered" power so that you had to decide not to go in, or once in artificially lowered margins to show what might happen you now had to get out with less power than you might have wanted. This included towering but also restrictions so tight that you could not get out - as a means to showing you how to take responsibility for stopping and rethinking, rather than pressing on until you hit a tree.

I thought (still do) that the technical training was good and it left me with with this. The site we used in training for confined area was very (by my standards) tight. When first shown it from above, my reaction was "I appreciate the skills and training, but I am never going into a site like that when I have my license". I have stuck to that decision ever since, and take the view that "just because I can" doesn't mean that I should. There is, in reality, no justification for me to act otherwise as I only fly for pleasure. I do use these techniques - icluding OGE hover and descent into a lawn surrounded by Scots Pine trees, but the space is more than 3x larger than my old training area.

I would add; some years after getting my PPL the airfield stopped the use of that confined site and instead provided one surrounded by low bushes & shrubs and actually open on one side. Nothing like as challenging, and though technically "safer" to learn in I don't think it provides as good a training experience. Doing annual LPCs at that field, using that site is pretty much a non-event to me, and I think the risk is that you don't see the value of making all the right checks and asking the right questions as then you land on something that is "less difficult" than some of the Heli Pads provided on the airfield (close buildings giving recirculation issues, for example).

[aa777888]

You don't need much - the OGE hover ceiling vs gross weight chart in the POH is the place to start having worked out your pressure altitude and expected gross weight.

You need at least OGE performance and ideally some extra - unfortunately there are no graphs to tell you how much extra you have got.Exactly right.

Hot and High is correct that the MTOW isn't a power limit but taking 5 or 10% off the weight would guarantee you a thrust margin of probably more than you need if the weight line is the first limit you hit rather than the OAT or Pressure altitude.Those margins simply don't exist in the real world of Robinson helicopter operations. R22 useful load is 490lb. With two 170lb people inside that's less than full tanks, or less than two hours endurance. Raven II useful load is already discussed below and is equally challenging with 4 people and stuff on board and a desire to get real work done. If you are in a Raven I, or a fat pig of an R44 like a Clipper II (aka Raven II with pop-outs) with air conditioning, now you have lost 100lbs of useful load. The bottom line is that these machines are nearly always flying at near max. gross when full.

The only time you have the sort of margin you are talking about is when you are flying an R44 with only two people on board (or an R22 with one). If you want a "rocket ship", two people and half tanks. And the performance difference is dramatic. That makes for safer initial training, but ultimately one must learn to fly the machine the way it will really be used, and that means at max. weight. In the R22 that happens by default. In the R44, at least at the school I attend, that happens by finding two other erstwhile individuals to fill the back seats and endure max. performance takeoffs, confined space landings, and ham handed auto's without puking (screaming is allowed). Normally these are more students and it's actually quite a bit of fun as each student rotates through the pilot's seat. The repartee meter does get pegged!

Robinson marketed the R44 Cadet to address this issue, but it's just such a dumb choice on so many levels. Few small schools will buy one because they need a machine they can use for more than just training. And it actually offers too much performance and does not prepare one for the real world of a regular 44 loaded to the gills.

If you have the performance on the chart then you just need to confirm it before committing to landing - I'm sure you check your hover MAP against the placard to make sure it is correct before transitioning.If you mean check your hover power vs. the 5-minute max. on the placard, of course. That is (should be) taught and is a no-brainer. It's generally taught that if you've got 2" MP below 5 minute max. you can make a max. performance takeoff. This was well and thoroughly taught to me, with innumerable exercises involving artificial power limits. During my private and commercial training there was a lot of emphasis placed on "making it out safely", including such things as shuttling partial loads to a spot where a max. perf. was not necessary and other techniques.

Once in the vicinity of the landing area, pull to your calculated max take off MAP - ie your max continuous plus 2.8 to make sure it is available without Nr decay or exceeding any other limits.Actually the landing power check, if you even need one (you did plan it, right?), is generally as follows: assume level flight 500ft above the landing altitude at Vy, then see if you've got 6 or 8" of MP margin (depending on who you talk to) against 5 minute power (don't forget to check OAT, pressure altitude and the placard!) If you do then you are probably OK for OGE hover. This is poorly taught in my experience. At least it was where I learned. We did spend a lot of time exploring the lack of OGE hover using artificial power limits in a run-on landing environment, but never for spot landings, which I felt was an unfortunate hole in the instructional repertoire. I have since developed that experience after the commercial check-ride, but I feel it should have been sooner. In the school's defense it can be difficult to train if you don't live in a hot/high environment, and the potential for a training accident is high.

One problem is that the OGE graph is based on 5 min take off power and not the max continuous MAP which may pass people by if they are not paying attention - the problem being that if you need 5 min power to achieve OGE, you have no spare to deal with turbulence or any unexpected rate of descent - hence my advice - especially if you are hot and high, to have a thrust margin.Welcome to the wonderful world of very light helicopters where those margins are razor thin if they exist at all.

Now a 5% thrust margin was defined in various military Operating Data Manuals (same as POH) as sufficient to overcome light turbulence or manoeuvre gently in the hover - in a couple it quantified a vertical rate of climb of between 100 and 200 ft/min so it is not a huge amount of excess power.

Clearly such advice doesn't exist in the POH but you could experiment to see what difference 1 inch extra MAP gives you from an OGE hover - it will at least give you an idea of the difference between Sea Level at plus 23 degrees and 5300' at plus 23 degrees since the max continuous MAPS are only about 1.4 ins apart from the placard.Again we have the rules of thumb for MP margins as discussed above, that are admittedly not in the POH, to go by. They have proven themselves over the many decades that Robinson helicopters have been in service.

Regarding confined space operations: I can't speak to other schools. The school I use is a pretty good school in this regard. Like any school they are obviously focused on getting people to pass the FAA checkride. But they will train you just as hard and thoroughly as you can safely be trained. Not every student learns at the same rate, not every student wants to be an accomplished helicopter pilot (e.g. wealthy guy in a hurry--just make me good enough--one major reason for the Robinson accident rate). But for folks who have the drive to train more comprehensively, this place will take you way, way beyond paved runway to paved runway and Farmer Jone's field. During my commercial training surprise landings were as common as surprise auto's. Instructor says "See that hole? Put me in there. See that pinnacle? Put me on top." One of the more challenging sites is a mountaintop transmitter site that is very popular with the instructors. It's a forest of guy wires and tall pine trees and a 15ft square gravel pad on a jaunty slope. Really great stuff.

One does see quite a bit of this sort of thing on the schools who like to publish on Youtube. Mischa Gelb's stuff, for example. One would like to think that all schools are teaching the same stuff to the same level, but of course that is not true.

[[email protected]]

So you'll be able to tell me what extra performance 1.4 inches of MAP gives you in an OGE hover then?

[aa777888]

So you'll be able to tell me what extra performance 1.4 inches of MAP gives you in an OGE hover then?
Give me a procedure to follow and maybe I can make that measurement.

[[email protected]]

Actually the landing power check, if you even need one (you did plan it, right?), Planning it and having it are two different things - if you pull to the take-off limit before you commit to a high hover, you know you have what you planned for - inherently safer than flying somewhere between 6 and 8 inches (not exactly precise) below 5 Min Max and approximating that you might have enough power before discovering you haven't as the RoD builds up from your attempt at OGE hover. How difficult is it to take 5 seconds to PROVE you have the performance available?

What you do as a commercial pilot doesn't concern me, you should be old and ugly enough to deal with limited power - my concern is the PPLH like the guy in the accident who has neither the skills or experience - he doesn't have to work with razor thin margins and if he does he is likely to come unstuck. Strangely enough I am trying to help.

As for checking the performance added by each inch of MAP - just establish an OGE hover, check the MAP and add an inch to see what rate of vertical climb it gives you. You can then try 2 inches - at least then you have an idea of what sort of RoD you might be able to recover from if your OGE hover is a bit wobbly.

But I've only been flying and teaching confined area ops for 38 years day, night and NVD in singles and twins so I probably don't know what I'm talking about.

[aa777888]

But I've only been flying and teaching confined area ops for 38 years day, night and NVD in singles and twins so I probably don't know what I'm talking about.And a few people who fly Robinsons are telling you what the industry teaches about flying Robinsons. The whole industry, pretty much. They can't all be wrong. Or even substantially incomplete. Or not know what they are talking about. There might even be more than one way to skin a cat. It might be safer to look at MP margins at Vy than try to come to an OGE hover if conditions don't allow it.

These differences in methodology may be a mil vs civ thing, or even a UK mil vs USA civ thing. Or an R44 vs. big turbine thing. Or some combination of the above.

I've never had an ex. mil. instructor. Only 200-500 hour civilian-only CFIs, one 2000 hour civilian-only CFI, and one 10,000+ hour civilian-only CFI. All of whom evolved in the Robinson-based training ecosystem. They can't all be wrong.

It's not going to happen, but it would be very, very interesting to know what your feedback would be if you jumped into an R44 for 10 hours or so to observe the performance of the design first-hand, and also to observe the performance of the instruction available to you first hand.

[[email protected]]

Again, what am I thinking? How could I possibly question such an experienced God of the air who flys pleasure trips for a living?

I must have a word with myself and point out to the rest of the helicopter world, mil and civ that the Robinson way is the way to do it!

I had the R22 on my licence (ATPLH) in 1992 and re-taught a private owner with 120 hours how to fly because he was scared of the aircraft and what would happen if the engine failed - I am quite aware of the power and performance issues with a single-engined piston helicopter thank you.

It might be safer to look at MP margins at Vy than try to come to an OGE hover if conditions don't allow it. You are not listening - it is safer to confirm that you have take-off power available before committing to the hover rather than relying on a hand-me down approximation which seems to vary - is it 6 or 8? very scientific and professional.

[nomorehelosforme]

Again, what am I thinking? How could I possibly question such an experienced God of the air who flys pleasure trips for a living?

Crab, once again aa777888 and his delinquent sidekick want to pick a fight, quite frankly I can’t understand why they aren’t prepared to enter into a sensible discussion that might be beneficial to all parties and indeed many others. Instead they just resort to the same BS on every thread... getting boring.

I must have a word with myself and point out to the rest of the helicopter world, mil and civ that the Robinson way is the way to do it!

Lol Please don’t do that, I only have a 100 hours as a pax ... and have never accepted a Robinson as an option for my personal travel, yes may sound like a snob... and guess what if I couldn’t afford the alternative would happily take a ship, train or taxi.. just saying

[aa777888]

I'm no sky god. I am only as good as my training, which is what I report on here. I don't pretend to be a test pilot or any other sort of authority. But I can accurately report on my training and its efficacy, which has so far been adequate to keep things in one piece.

​​​​​​Discourse on this website has been a valuable adjunct to that training, but you don't do much to make the process at all pleasant.

Instead of the last two posts you just offered why don't you explain why testing an OGE hover is better and safer than maintaining LTE at Vy and looking for a given margin?

[Robbiee]

Well, I AM a sky God! So bow down and kiss my skids!

[[email protected]]

Instead of the last two posts you just offered why don't you explain why testing an OGE hover is better and safer than maintaining LTE at Vy and looking for a given margin? You still aren't listening.

You pull to your max power BEFORE you get anywhere near the OGE hover ie at the same speed you would be assessing your inaccurate Vy MAP somewhere between 6 and 8 inch power margin.

Instead of relying on an approximate assessment of power available, you have proved that what your charts require and what you have planned is in fact available in the conditions of the day - all while flying quite safely above ETL.

Your way isn't backed up by any empirical evidence or accurate power assessment - my way confirms the POH figures, provided by Robinson, are available - which do you think is more accurate and therefore safer?

Discourse on this website has been a valuable adjunct to that training, but you don't do much to make the process at all pleasant. Right back at you with that one.

Just understand that the Robinson training system is not the be all and end all of helicopter training - it does what it was designed for, getting people into Robinson helicopters. Plenty of people on this forum have been trained to far higher standards in many disciplines.

[[email protected]]

nomorehelosforme - I try to offer advice where I can - their noise won't distract me from that.

[aa777888]

You still aren't listening.
Actually I am listening, or reading, very carefully and precisely. As a result I have identified a number of factual errors throughout this topic.

You pull to your max power BEFORE you get anywhere near the OGE hover ie at the same speed you would be assessing your inaccurate Vy MAP somewhere between 6 and 8 inch power margin.
This is the first time you've written that this max power test occurs at Vy. Since that was not explicitly stated I had erroneously understood that it was part of an OGE hover test.

Instead of relying on an approximate assessment of power available, you have proved that what your charts require and what you have planned is in fact available in the conditions of the day - all while flying quite safely above ETL.
If I understand this correctly, this can be broken down into two concerns:

1. That the engine is capable of obtaining a given, indicated MP.
2. That the helicopter climbs at some vertical speed.

Your way isn't backed up by any empirical evidence or accurate power assessment - my way confirms the POH figures, provided by Robinson, are available - which do you think is more accurate and therefore safer?
With respect to (1) above, that is true. However if an engine has a problem producing power under those conditions it will be known long before then due to the way the engine is derated and the way that derating is respected by means of the MAP chart.

With respect to (2), there are no numbers in the POH that say if you can obtain a given vertical speed at max power and Vy then you can safely attain OGE hover performance at that density altitude. Thus a given vertical speed reading becomes the same sort of rule of thumb that the 6-8" of MP margin is. Both methods are empirical by definition.

Absolutely willing to be wrong here...

[[email protected]]

This is the first time you've written that this max power test occurs at Vy. i didn't think I had to explicitly state it since I was talking about doing the power check before committing to a hover - it doesn't have to be done at Vy, it can be done at pretty much any speed, you are simply proving the engine.

With respect to (1) above, that is true. However if an engine has a problem producing power under those conditions it will be known long before then due to the way the engine is derated and the way that derating is respected by means of the MAP chart. If you didn't pull to full take off power at any stage previously in the flight, how do you know it will produce it? Coming to the OGE hover short of power because your engine is starting to show its age or has a niggly fault is not clever, especially into a confined area.

It's just a power check - plain and simple - but you have proven the engine so you know it will perform as advertised. You are going to put yourself in a hazardous position, possibly well inside the HV curve if you are using OGE hover to get into a deep confined area - why wouldn't you want the confidence that the engine will perform as it should?

With respect to (2), there are no numbers in the POH that say if you can obtain a given vertical speed at max power and Vy then you can safely attain OGE hover performance at that density altitude. Thus a given vertical speed reading becomes the same sort of rule of thumb that the 6-8" of MP margin is. Both methods are empirical by definition. I didn't say that at all - I was trying to point out that since you do have a lack of performance figures in the POH, you can give youself an idea of what the difference of one or 2 inches MAP makes in an OGE hover by trying it for yourself.

Go out at a weight that you know won't need take off power in an OGE hover, stabilise and check the actual MAP. Then see what rate of climb an extra inch of MAP - or 2 - gives you, it just allows you to calibrate your brain to how much or little performance you have left when you are pushing the limits of the aircraft. If you know you are only just below the max gross for an OGE hover then you will know you have to be super-careful if you have to go into a tricky confined area.

It's no different to checking the MAP in a low hover to see what your margin is before committing to a high vertical climb out of a confined area - you will effectively be doing the power check in the climb in that case if you hadn't done one before going into it.

In essence - 1. Make sure you have sufficient power available according to the POH ie you are inside the lines according to the graph at your intended gross weight, PA and temperature.

2. Confirm that the aircraft will actually produce take-off power at some stage of the flight before you put yourself in a condition where you are going to rely on it doing so.

[aa777888]

Go out at a weight that you know won't need take off power in an OGE hover, stabilise and check the actual MAP. Then see what rate of climb an extra inch of MAP - or 2 - gives you, it just allows you to calibrate your brain to how much or little performance you have left when you are pushing the limits of the aircraft. If you know you are only just below the max gross for an OGE hover then you will know you have to be super-careful if you have to go into a tricky confined area.
Done and past done, demonstrated and in every day use. I.e. the aforementioned 2" MP margin for max. performance and 6-8" for OGE hover. Rules of thumb, or brain calibrations if you prefer. Those guidelines work. No need to reinvent the wheel. Assuming a healthy engine, of course, which was the other major point you are making, I think.

[[email protected]]

Assuming a healthy engine, of course, which was the other major point you are making, I think Yes, exactly. Just combine the 'rules of thumb' with the confirmation of engine performance using a power check and you shouldn't go far wrong.

[Devil 49]

The accident event was initiated by an uncommanded yaw that the pilot could not stop, yes?
AFTER the accident aircraft had descended into the confined area, aborted and was in the vertical climb to exit, yes?
The theory is that this was an LTE event.
First, I have to say the theory of LTE is generally accepted, but in 48 years of flying, I never had one even though I landed up, down and both crosswinds thousands of times; in confined areas, natural and man-made, elevated (as in roof-top pads), with all knids of turbulence and none at all- I would guess that LTE is probably pretty rare and type specific- OH58 and 206B in particular... although thousands of my landings were in all wind conditions in 206s, Bs and Ls. They do have weakish tail rotors, is the R44 in that class?
The Aerospatiales I flew, the AS350 and 355 could turn tail into just about anything up to about 40 knots. Not that it is a good idea, the tail does get busy, especially in the it's near the upwind edge an blocky ledge, rooftop. I didn't want the pax exposed to the tail rotor.

The accident aircraft was in a vertical climb, exiting the confined area- it had sufficient power. As the accident aircraft ckimbed above, exited the terrain that was obstructing the wind, it became a 15-20 knot breeze from the left front. Yes, it fits the LTE pie chart.... But that is enough air that the aircraft should have experienced effective translational lift, and could have reduced power and continued a climb or accelerated into the wind, minimizing the demand on the tail rotor. But that's not what happened, apparently full pedal didn't stop the yaw, so the pedals were reversed (????) and the yaw developed into a spin.

The nose goes up and the nose goes down as the world goes round and round, you become disoriented. I know pilots who advance the idea of following the nose and accelerating out of it in a spiral- highly skilled professionals. I doubt the accident pilot had been trained in that and certainly did not consider it- or reducing power demand. I have had the technique demonstrated (never used it) and I don't think I could have done it after at least two revolutions in the spin, up and down, position over the ground is what I remember being aware of when the student botched the hovering auto- reducing power and the rotation rate, get the aircraft under control (well really, a chop and hovering auto, the student was locked in all other axis).

I was appalled at how little is actually required for a commercial much less a private when I was teaching. Maintaining the aircraft upright and intact, some theory and limited emergency training- success! Now go challenge the world without any limitations.
You teach them plan, fly the aircraft as slowly as possible into hazard and move slowly, abort at any point at which success is not assured. A slow climb into changing winds, even pausing and evaluating in the process, perhaps letting the tail streamline a little as you move into and as close as possible to the upwind barrier and when effective translation is achieved fly out and make a new plan.

You can demonstrate this once or twice, and maybe even talk the process in landings, takeoff. It's really not in any syllabus I was given. (I do talk the whole process constantly even when nobody's aboard- some habits are forever.) And then they get the ticket and learn that they can do all the hot dog yank and bank, see it modelled in real life and media...

[[email protected]]

Someone suggested earlier in the thread that the pilot could have been too tense on the controls and prevented the governor from doing its job - that could have caused reducing Nr and subsequent reduction in TR thrust.

Combine that with a little weather-cocking - I'm not convinced by the LTE pie chart - and he mis-diagnosed a TR malfunction, over controlled and crashed. Had he just used full left pedal and waited, he would probably not have ended up in the spin.

Interference between the MR vortex and the TR isn't a new piece of knowledge, we used to teach it specifically in a Max All Up Mass sortie on the Wessex 30 plus years ago - it certainly doesn't cause a spin, just a bit of twitching in yaw which goes when you change the heading in relation to the wind direction - the arc really isn't that big.

[Robbiee]

Once while hovering in an S300 I was practically standing on the left pedal, yet the nose just would not turn,...then I looked down and noticed the rpm was at the botton of the green. So, I rolled it up and the nose began to turn.

So, yeah, its possible this guy just had the death grip and overrode the governor? Its not like it hasn't happened before, as there is another video of a guy descending in a 44 due to low-rpm, because he had the death grip while flying through turbulence.

Still, we don't know for certain that this guy had full left pedal applied, so who knows?

[staticsource]

With that type of wind in that direction, the R44 will not run out of pedal. The type does not suffer from LTE, the tail rotor is extremely efficient. The aircraft can oscillate in the yaw axis as the tail rotor catches the vortices from the main rotor, but it’s controllable.

I would have thought the aircraft would want to weather cock into wind (nose to the left in this case) coupled with the increased power to climb out of the CA, was there a left yaw, which happened quicker than anticipated, which surprised the pilot?

However, if you’re heavy on the pedal inputs, you can droop the rrpm as the governor can lag.

[Aucky]

Assuming a healthy engine, of course, which was the other major point you are making, I think.
And that you have read the right altitude/temperature figures on the MAP chart, and appreciated that there is the section on the MAP chart labelled ‘full throttle’ when you are no longer gearbox/drivetrain/torque limited, but limited by the fact the engine won’t give anymore... i.e. instead of having a theoretical max, you will have an actual maximum engine power available with no specified figure (you won’t get the extra 2.8” take-off power), and you need to establish what that actual maximum power available is. Admittedly this is only an issue at higher altitude if you have a healthy engine/mags/gauge*, but that is precisely where it is really going to matter. It’s a wake up call when you start getting droop at 21” and you are used to being able to pull 25.5”, particularly if you are not prepared and expecting it!

[Hot and Hi]

You make it all look so difficult. I suppose there are one or two things one need to know on any given helicopter type.

There is a simple rule: The first 100 hours *after* you got your PPL-H don’t fly to go fishing, fly for practice. And don’t take pax, fly alone.

[Robbiee]

You make it all look so difficult. I suppose there are one or two things one need to know on any given helicopter type.

There is a simple rule: The first 100 hours *after* you got your PPL-H don’t fly to go fishing, fly for practice. And don’t take pax, fly alone.

As a former self-fly- hire just for fun Robby pilot I have to say, that the dumbest "simple rule" I've ever heard!

"Congrats kid, you're now a private pilot!,...now remember, only fly circles around the airport alone for the next 100 hours.". :hmm:

[aa777888]

The solution I chose was to immediately press on and obtain a commercial cert. I felt pretty comfortable with a fixed wing private in my hot little hands, but the helicopter private certificate felt more like a "license to get killed" ;)

Of course everyone's mileage will vary quite a bit on this one. But that's how I felt, FWIW.

[capngrog]

Although I have many hours of flying IN helicopters, I have never flown one. My flight experience is limited to fixed wing only. A tail rotor failure is just another possibility.

On 22 May, 2020, FAA Airworthiness Directive (AD) Number 2020-08-10 became effective and applied to certain Robinson R-44 series helicopters. This AD concerned possible tail rotor failure and required inspection for cracks.

Attached is a link to the AD; however, you may prefer to copy and paste to your browser the inactive link below.

https://rgl.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf/0/b1400c9f67bf3f828625854d0042cd8e/$FILE/2020-08-10.pdf

I would imagine that the loss of a tail rotor blade would cause loss of tail rotor effectiveness and could cause pitch oscillations and eventual separation of parts of the tail boom due to excessive vibration. Of course vibration due to loss of a tail rotor blade should have been immediately noticed by the pilot; however, he apparently made no mention of excess vibration in his statement to authorities.

Regards,
Grog

[Mutley1013]

It was 11hrs for me post GFT before I took my first passenger. It was my father, so at least it would have been a family matter if it went pear shaped! I also did the R22 safety course before taking him up. Considering that course was in 1998, I still remember aspects of it vivedly! Great course. The first 100hrs post GFT were taken up with 94 flights (I kept the heli off-field for some months whilst hour building and had to do some little hops to the local airfield to refuel) and 19 of them involved passengers and 28 confined area.

This accident highlights the 'pilot's attitude to flying as much as anything and maybe the instruction and initiation into the responsibilities of flying were lacking.

[Robbiee]

The solution I chose was to immediately press on and obtain a commercial cert. I felt pretty comfortable with a fixed wing private in my hot little hands, but the helicopter private certificate felt more like a "license to get killed" ;)

Of course everyone's mileage will vary quite a bit on this one. But that's how I felt, FWIW.

I didn't persue my commercial until I had over 200 hours of simply enjoying the freedom of flying, as I viewed my private as a "license to fly". I mean, no offense, but all that "license to learn"/"license to get killed" type of crap always erked me a bit.

,...but then, all the stupid things I've done as a pilot have all been in pursuit of commercial aviation not joyriding, so maybe I'm a bit biased?

[Robbiee]

It was 11hrs for me post GFT before I took my first passenger. It was my father, so at least it would have been a family matter if it went pear shaped! I also did the R22 safety course before taking him up. Considering that course was in 1998, I still remember aspects of it vivedly! Great course. The first 100hrs post GFT were taken up with 94 flights (I kept the heli off-field for some months whilst hour building and had to do some little hops to the local airfield to refuel) and 19 of them involed passengers and 28 confined area.

This accident highlights the 'pilot's attitude to flying as much as anything and maybe the instruction and initiation into the responsibilities of flying were lacking.


I've been through that course six times in the eighteen years I've been a pilot.

[[email protected]]

Capn Grog - the loss of a TR blade or the loss of TR drive or the complete TR would have been immediately obvious to the investigation team.

[capngrog]

Capn Grog - the loss of a TR blade or the loss of TR drive or the complete TR would have been immediately obvious to the investigation team.

You're absolutely right! I somehow skimmed over this sentence under the "Aircraft Information" section of the report: "Wreckage examination did not identify any pre-existing system malfunctions that would have played a role in the loss of control in this occurrence." My only defense is that perhaps I've become too used to FAA/NTSB reports wherein they routinely state words to the effect: "Control continuity was established from the (elevator, aileron, swashplate etc.)". Well, that's my excuse and I'm stickin' to it ... for now.

Cheers,
Grog