Confined area power check - tips and techniques
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Confined area power check - tips and techniques
I am interested in hearing your tips and techniques for confined area power checks (before making the decision to land if we have enough power to hover and get back out).
I have been shown a few methods during my training, the one being the OGE Hover, Power Check on Startup (MAP, or Torque/Temp margin) if in the same area (and ambient conditions).
I have been reading the other thread about approaches, and thought this would be a good compliment.
Discuss.
I have been shown a few methods during my training, the one being the OGE Hover, Power Check on Startup (MAP, or Torque/Temp margin) if in the same area (and ambient conditions).
I have been reading the other thread about approaches, and thought this would be a good compliment.
Discuss.
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For Pistons(R44 and R22) we teach - 53kts S+L over the site carb cold. Compare your MAP to your 5min rating. If you have 6"(R22) or 8"(R44) spare your have power to spare and can hover OGE. Wouldn't recommend going into a confined area with less. For departure, 2ft IGE hover and compare MAP with 5min rating, if more than 2" it will lift vertically. 1 1/2" and you could get away with a towering. Remember to actually pull your 5min rating(before approaching) at some point to make sure you can attain that power without rotor droop.
Check out this... http://www.pprune.org/rotorheads/401...mb-only-2.html
The first on the list...
It's a technique I came accross that the Aussies use... and is the simplest that I have found
The first on the list...
It's a technique I came accross that the Aussies use... and is the simplest that I have found
Confined Landing:
Do the P.A.W.S. check:
Power
Draw a horizontal line across the graph from point B (IGE Hover) to point C, which is X speed in straight and level flight. Point B and point C both use the same power. The trick is to know what the speed at point C is. To find this, when lifting off, stabilize into an IGE hover and read what power is being used. Now, using that same power, establish a S&L flight +-500 above your IGE hover alt. Read what speed that particular aircraft gives at that IGE power setting.
Now when you come to land at a different LZ, reverse the process. Fly at the speed you obtained earlier, as you are approaching the LZ at +-500 agl, and check what power you are using. This will give you an idea for what you will be using for an IGE hover at that LZ.
Obviously, the graph shifts according to altitude, temperature, etc, but it is an easy way of figuring it out instead of having to add/subtract Tq/MAP to give an IGE power required.
Area
Wind
Wires
Way in/Way out
Size
Shape
Sun
Surroundings
Slope
Do the P.A.W.S. check:
Power
Draw a horizontal line across the graph from point B (IGE Hover) to point C, which is X speed in straight and level flight. Point B and point C both use the same power. The trick is to know what the speed at point C is. To find this, when lifting off, stabilize into an IGE hover and read what power is being used. Now, using that same power, establish a S&L flight +-500 above your IGE hover alt. Read what speed that particular aircraft gives at that IGE power setting.
Now when you come to land at a different LZ, reverse the process. Fly at the speed you obtained earlier, as you are approaching the LZ at +-500 agl, and check what power you are using. This will give you an idea for what you will be using for an IGE hover at that LZ.
Obviously, the graph shifts according to altitude, temperature, etc, but it is an easy way of figuring it out instead of having to add/subtract Tq/MAP to give an IGE power required.
Area
Wind
Wires
Way in/Way out
Size
Shape
Sun
Surroundings
Slope
Last edited by Flyting; 12th Feb 2010 at 04:13.
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The performance section of your RFM should be able to tell you whether you have hover OGE capability at the relevant weight, altitude and temperature.
As a rule of thumb, give yourself a 10% thrust margin for confined area - ie make sure your AUM is 10% less than the max for the altitude and temp for hover OGE.
Obviously, include this in your planning before takeoff, 'cos you dont want to be looking through the graphs in flight!
Do the manufacturers recommended engine power checks before take off, or check that you can pull to your aircrafts max continuous torque and takeoff power settings without topping out on Ng or temp (if we are talking turbines) or whatever other limitations you have in piston engines (manifold pressure?/temp?) at the altitude of the LS on the day.
As a rule of thumb, give yourself a 10% thrust margin for confined area - ie make sure your AUM is 10% less than the max for the altitude and temp for hover OGE.
Obviously, include this in your planning before takeoff, 'cos you dont want to be looking through the graphs in flight!
Do the manufacturers recommended engine power checks before take off, or check that you can pull to your aircrafts max continuous torque and takeoff power settings without topping out on Ng or temp (if we are talking turbines) or whatever other limitations you have in piston engines (manifold pressure?/temp?) at the altitude of the LS on the day.
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This topic has been beaten to death, revived, then beaten again elsewhere, but it's one that is worth figuring out (if for no other reason that CFIs think it's a good idea to teach something like this). Nobody taught me a "power check" during my training--beyond noting my hover power on pick up and checking my POH performance data--and there's nothing about it in the RHC Maneuver Guide. I looked at all the VR threads on the topic, and the advice was muddled and inconsistent at best. One school owner made an interesting comment: an examiner started asking his students who cited these rules of thumb to point out their sources.
Anyway, I tried to assimilate all I've read about it in this lesson plan. What I don't understand is why your published performance data aren't good enough, especially in a training environment. With a little pre-planning, you can guesstimate your fuel, LZ elevation, and temperature before the rotors even turn, and you'll know where you can land and where you shouldn't try landing. At your LZ, you can check your actual conditions to see how far off your expected condition is from your actual. For example, if the charts say you can land at 4500 MSL, is it reasonable for a <1000 hr CFI to take a student out and try landing there? Or even 4200 MSL? Seems like a lesson on ADM and understanding (performance, weather) minimums would be better for a student pilot rather than a rule of thumb.
Anyway, I tried to assimilate all I've read about it in this lesson plan. What I don't understand is why your published performance data aren't good enough, especially in a training environment. With a little pre-planning, you can guesstimate your fuel, LZ elevation, and temperature before the rotors even turn, and you'll know where you can land and where you shouldn't try landing. At your LZ, you can check your actual conditions to see how far off your expected condition is from your actual. For example, if the charts say you can land at 4500 MSL, is it reasonable for a <1000 hr CFI to take a student out and try landing there? Or even 4200 MSL? Seems like a lesson on ADM and understanding (performance, weather) minimums would be better for a student pilot rather than a rule of thumb.
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WikiRFM - Not really. There are many instances where a pilot has incorrectly calculated a weight/wind/pax which will mean that the aircraft is out of limits.
Look on youtube....there are scores of f*ckups to prove it
Before you land......check your weight and power.
you may get away with it for a couple of years.....but wait!
Look on youtube....there are scores of f*ckups to prove it
Before you land......check your weight and power.
you may get away with it for a couple of years.....but wait!
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"What I don't understand is why your published performance data aren't good enough, especially in a training environment"
Leaving aside whether you have a min spec engine, and if your weight is calculated correctly, none of this tells you what the effect of down flowing or up flowing air is at your landing area. Assuming a training environment, where weight is not be added to leave the confined area, you want to shoot an approach to the imaginary platform above your confined area, and before you slow below translational, determine what torque/temp/gas producer margins you have to get in and back out. Depending upon the up flow or down flow, you may be able to take more or less than the charts say.
Mel Schiller, instructor extraordinaire at Canadian Helicopters, has a whole program on confined areas developed there, that I can't do justice to, that combines wind finding, checking power and assessing the spot. This is just part of the whole procedure. It starts with the high recce, where he looks at 4 S's: size, shape, sun, starting point. Then he goes to the low recce and wind finding, the overshoot and option to land, maneuvering in the confined area and the departure.
Leaving aside whether you have a min spec engine, and if your weight is calculated correctly, none of this tells you what the effect of down flowing or up flowing air is at your landing area. Assuming a training environment, where weight is not be added to leave the confined area, you want to shoot an approach to the imaginary platform above your confined area, and before you slow below translational, determine what torque/temp/gas producer margins you have to get in and back out. Depending upon the up flow or down flow, you may be able to take more or less than the charts say.
Mel Schiller, instructor extraordinaire at Canadian Helicopters, has a whole program on confined areas developed there, that I can't do justice to, that combines wind finding, checking power and assessing the spot. This is just part of the whole procedure. It starts with the high recce, where he looks at 4 S's: size, shape, sun, starting point. Then he goes to the low recce and wind finding, the overshoot and option to land, maneuvering in the confined area and the departure.
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This is a very simple way to check wether your power will be sufficient for a landing.....
1. Approach the area and bring the helicopter down to the obstacles.
2. Before reaching your area, reduce airspeed as much as possible, but keep it above translational lift-airspeed (mostly 18-25 knots)
3. Keep the heli with that speed straight and level (Vario=0) when flying over the are.
4. Check Torque/Power.
If your power leaves a minimum of 10% to max torque available, you can safely land (regarding to the wind...) and climb out of the area again....
1. Approach the area and bring the helicopter down to the obstacles.
2. Before reaching your area, reduce airspeed as much as possible, but keep it above translational lift-airspeed (mostly 18-25 knots)
3. Keep the heli with that speed straight and level (Vario=0) when flying over the are.
4. Check Torque/Power.
If your power leaves a minimum of 10% to max torque available, you can safely land (regarding to the wind...) and climb out of the area again....
The value of the power check is that it tells you what you need to know in the situation you find yourself in. And if you do one for the aircraft you fly: the source of the values is no mystery
Stand to be corrected, but what is really clever about the power check is that the values work irrespective of DA and weight: that is you need x% torque or x" MAP margin to guarantee a particular manoeuvre. Depending on your weight and DA, wind etc, you will either have that margin or not.
Again, I may be wrong, but the values should work across aircraft types, ie. be the same for SE pistons such as R22, R44, H269. This is where 3" over hover power for a vertical take off has come from.
I have seen several different lists handed down by instructors to students and many have some form of error or another because the reasoning behind the chart has got lost. e.g Take-off = +1 is manifest rubbish. If you can hover, you can take-off: so hover power is take-off power (minimum for IGE normal hover height). More is nice to have. Lists with values so generous that there would never be an issue with power don't really help define the point where available take-off and landing techniques is limited.
TT
Stand to be corrected, but what is really clever about the power check is that the values work irrespective of DA and weight: that is you need x% torque or x" MAP margin to guarantee a particular manoeuvre. Depending on your weight and DA, wind etc, you will either have that margin or not.
Again, I may be wrong, but the values should work across aircraft types, ie. be the same for SE pistons such as R22, R44, H269. This is where 3" over hover power for a vertical take off has come from.
I have seen several different lists handed down by instructors to students and many have some form of error or another because the reasoning behind the chart has got lost. e.g Take-off = +1 is manifest rubbish. If you can hover, you can take-off: so hover power is take-off power (minimum for IGE normal hover height). More is nice to have. Lists with values so generous that there would never be an issue with power don't really help define the point where available take-off and landing techniques is limited.
TT
hueyracer - your technique has so many variables that it cannot be reccommended. 10% torque in hand does not equate to a 10% thrust margin which is a sensible performance level to keep when operating into CAs. Use your performance graphs to calculate OGE hover, anything else is guesswork. Unless your RFM has a graph for level flight performance at a specific speed that can then be equated to a power margin for landing, then the OGE graph is the only way and, as suggested earlier, taking 10% from the calculated max AUM will give you sufficent performance to deal with light turbulence/windshear etc.
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kneedwondean
I would be wary of doing this "carb cold", in a 22!
Ive always taught and been taught, to do it carb hot.
If you were carb cold, alone 53kts S&L that would take you below 18" manifold, which, as the gauge says "Full Carb Heat" applied.
Just a wee pointer. If i am wrong please tell me.
HJ
Ive always taught and been taught, to do it carb hot.
If you were carb cold, alone 53kts S&L that would take you below 18" manifold, which, as the gauge says "Full Carb Heat" applied.
Just a wee pointer. If i am wrong please tell me.
HJ
Last edited by Heli-Jock; 12th Feb 2010 at 09:17. Reason: no name
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Like all "rules of thumb" my above mentioned statement does not have to be right for every situation and every helicopter.
For the last 15 years, i have been flying 205īs and 212īs in various countries-and the military.
After doing all the checks before landing, the "flying over" as described above gives you the last decision check wether to land or not...
I do not apply to be correct for all kinds of operations-but doing "confined area landings" is my daily business......but i have never flown a piston A/C.....so i donīt know about their performance...
Within Bell helicopters, 10% are more than enough to clear a confined area again-if the conditions stay the same for landing AND for take-off....
For the last 15 years, i have been flying 205īs and 212īs in various countries-and the military.
After doing all the checks before landing, the "flying over" as described above gives you the last decision check wether to land or not...
I do not apply to be correct for all kinds of operations-but doing "confined area landings" is my daily business......but i have never flown a piston A/C.....so i donīt know about their performance...
Within Bell helicopters, 10% are more than enough to clear a confined area again-if the conditions stay the same for landing AND for take-off....
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My question for this situation - why are we continuing to put up with the dreadful level of information provided to us?
Turbine engines that are above spec lead us to not trust the charts, because the performance is better than expected. Turbine engines that are below spec get us into trouble. But at least with a turbine engine there is a way to know whether the engine is above or below spec.
Piston engines have no such check, but surely someone could develop one - Just to name one problem, piston engines can have poor compression, and the pilot wouldn't be aware of it till it's too late.
And none of the charts take into account wind.
Civil charts only publish one hover height for in-ground effect hover, and many out of ground effect charts are based on flying in to the hover, as opposed to climbing up to it.
So why are we putting our lives on the line for such poor information, when the technology surely exists to give us better, more clear and easily understood data???
Answers on a postcard please!
Turbine engines that are above spec lead us to not trust the charts, because the performance is better than expected. Turbine engines that are below spec get us into trouble. But at least with a turbine engine there is a way to know whether the engine is above or below spec.
Piston engines have no such check, but surely someone could develop one - Just to name one problem, piston engines can have poor compression, and the pilot wouldn't be aware of it till it's too late.
And none of the charts take into account wind.
Civil charts only publish one hover height for in-ground effect hover, and many out of ground effect charts are based on flying in to the hover, as opposed to climbing up to it.
So why are we putting our lives on the line for such poor information, when the technology surely exists to give us better, more clear and easily understood data???
Answers on a postcard please!
Shawn...I guess until the industry demands such knowledge, it will not be given. It would be my guess that it has to do with liability---but I'm sure you knew that huh?
As for rule of thumb..I use the mountain flying technique that I learnt from Larry Doll, (former chief instructor at Rocky Mountain Helicopters). This technique supposedly works for all Bell products---I routinely land my L4 upto 10k and occasionally upto 12K during fire season and it works.
On final approach, flare the aircraft to a slight nose up attitude, (be slow and methodical with most of you power already applied), to be a little short and 100ft above any obstacles on your path---hold the slight flare till speed falls through ETL and you will feel a slight shudder, level, apply the last of the power and note:
1. Pedal position
2. N1
3. TOT
To hover IGE it will take an ADDITIONAL:
1. One inch of left pedal
2. 12% N1
3. 35 degrees TOT
To hover OGE will take and ADDITIONAL:
1. One and Half inches of left pedal
2. 15% N1
3. 50 degrees TOT
IF you do not have the additional pedal, N1 or TOT available before hitting any red line limits, you are in a position to nose forward and fly away.
If you have the available pedal, N1 and TOT, you can continue the approach in a nice controlled manner all the way to the ground. The mark of a perfect approach is to hold the collective in one position, the aircraft will settle all the way and "kiss" the ground and then lift off again to about 2 feet as ground effect kicks in.
I have tested this "rule of thumb" at most weights, lots of Alt/Temp variations and it works for me. The biggest thing to learn, if this is not your standard procedure, is the slow/methodical approach.
As for the original question of having enough power to get out---this comes down to being at "one" with you aircraft and understanding all the performance. I am lucky in that I fly the same aircraft most of the year---I know all of her quirks. By using the above technique, and having a cheat sheet in the aircraft, I am able to make a reasonable determination of whether I can get out or not.
As for rule of thumb..I use the mountain flying technique that I learnt from Larry Doll, (former chief instructor at Rocky Mountain Helicopters). This technique supposedly works for all Bell products---I routinely land my L4 upto 10k and occasionally upto 12K during fire season and it works.
On final approach, flare the aircraft to a slight nose up attitude, (be slow and methodical with most of you power already applied), to be a little short and 100ft above any obstacles on your path---hold the slight flare till speed falls through ETL and you will feel a slight shudder, level, apply the last of the power and note:
1. Pedal position
2. N1
3. TOT
To hover IGE it will take an ADDITIONAL:
1. One inch of left pedal
2. 12% N1
3. 35 degrees TOT
To hover OGE will take and ADDITIONAL:
1. One and Half inches of left pedal
2. 15% N1
3. 50 degrees TOT
IF you do not have the additional pedal, N1 or TOT available before hitting any red line limits, you are in a position to nose forward and fly away.
If you have the available pedal, N1 and TOT, you can continue the approach in a nice controlled manner all the way to the ground. The mark of a perfect approach is to hold the collective in one position, the aircraft will settle all the way and "kiss" the ground and then lift off again to about 2 feet as ground effect kicks in.
I have tested this "rule of thumb" at most weights, lots of Alt/Temp variations and it works for me. The biggest thing to learn, if this is not your standard procedure, is the slow/methodical approach.
As for the original question of having enough power to get out---this comes down to being at "one" with you aircraft and understanding all the performance. I am lucky in that I fly the same aircraft most of the year---I know all of her quirks. By using the above technique, and having a cheat sheet in the aircraft, I am able to make a reasonable determination of whether I can get out or not.
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It works the same way, when you plan to load weight...
As a rule of thumb (in Bell helicopters), you can subtract for each person (app. 100 kg including baggage) 0.1 kp/cm2 (Torque) which equals 3% Torque...
So-if you have 15% Power to Max left when overflying the area, you can just subtract the expected pax-weight and see, if you have enough power left for T/O BEFORE you land in that area.....
As a rule of thumb (in Bell helicopters), you can subtract for each person (app. 100 kg including baggage) 0.1 kp/cm2 (Torque) which equals 3% Torque...
So-if you have 15% Power to Max left when overflying the area, you can just subtract the expected pax-weight and see, if you have enough power left for T/O BEFORE you land in that area.....
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Off Site Power Checks
You can plan based on where you're going and what the weather is, but you can bet that it'll change by the time you get there.
I'll do all the planning I can before I go, but I've found the off site power check is a good way to make sure you've still got the power before you commit to the approach. I use it with confined area/ridge line approaches and rappel ops, and I do it before every approach, even if I've been going in there all day.
When I set up on a long final I slow the helicopter to an OGE hover while I still have sufficient power to fly out of it, if I find I don't have the power. If I have the power to hover out there I should have the power in the hole. Keep in mind that things can change when you get close to the trees or the ridge. Winds defy physics some times, and the wind that's been helping you above the trees can drop to zero or shift to a quartering tailwind below the tops.
Departing a confined area I'll depart vertically until I'm above the obstacle so that if there's a problem I can go back down to a known spot instead having to bleed speed to land short of the trees.
I'll do all the planning I can before I go, but I've found the off site power check is a good way to make sure you've still got the power before you commit to the approach. I use it with confined area/ridge line approaches and rappel ops, and I do it before every approach, even if I've been going in there all day.
When I set up on a long final I slow the helicopter to an OGE hover while I still have sufficient power to fly out of it, if I find I don't have the power. If I have the power to hover out there I should have the power in the hole. Keep in mind that things can change when you get close to the trees or the ridge. Winds defy physics some times, and the wind that's been helping you above the trees can drop to zero or shift to a quartering tailwind below the tops.
Departing a confined area I'll depart vertically until I'm above the obstacle so that if there's a problem I can go back down to a known spot instead having to bleed speed to land short of the trees.