Reserve of Power Bell 206
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Joined: Jun 2025
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From: Pune
Reserve of Power Bell 206
Why isn't there a Maximum power available vs Max power required graph in the Flight Manual of Bell 206?
Having flown the Lama for around two decades, it feels slightly inadequate to start a sortie without knowing the power margins and if the power used for hover (torque in the Bell) is within limits from the power required for the specific day's configuration.
Having flown the Lama for around two decades, it feels slightly inadequate to start a sortie without knowing the power margins and if the power used for hover (torque in the Bell) is within limits from the power required for the specific day's configuration.
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From: NYC
One difference between the two is the 206 lacks this lovely device.
http://www.alouettelama.com/photos/2...-040-1-07R.pdf
http://www.alouettelama.com/photos/2...-040-1-07R.pdf
Joined: Sep 2004
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From: Canada
Well, perhaps do a Power Assurance Check.
If the PAC is passed the performance charts should be valid.
Easiest way to think about the PAC chart is that it is a paper engine to compare against what your engine is doing.
If your engine is better you will have a power margin available.
Does this make any sense at all?
If your engine is below spec you want to find out why. Internal engine damage? Leaking bleed valve, dirty compressor.( in one case the problem was the wrong torque gauge… took a long time to find that one.)
If the PAC is passed the performance charts should be valid.
Easiest way to think about the PAC chart is that it is a paper engine to compare against what your engine is doing.
If your engine is better you will have a power margin available.
Does this make any sense at all?
If your engine is below spec you want to find out why. Internal engine damage? Leaking bleed valve, dirty compressor.( in one case the problem was the wrong torque gauge… took a long time to find that one.)
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From: Finland
Maximum power available vs Max power required graph is not part of the certified performance data. A manufacturer may supply such chart in additional performance figures, but I think there are very few that has it. But I can see how one might miss the graph, if used to work with a type that has it.
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From: yes
Max HIGE/HOGE GWT vs. actual GWT is your margin. In the case of operations at altitude/temperature combinations permitting HIGE/HOGE at maximum GWT, the margin is your actual hover power vs. the maximum torque per the chart.
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From: Florida
Thread Starter
Joined: Jun 2025
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From: Pune
No, didnt get it completely as the graph mentioned by him doesn't give torque values. So as of now i understand that Bell does not feel the need to make the pilot worry about the reserve of power as long as he stays withing the limitations of TOT, Nr, Torque and speed for take offs and landings.
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From: EGDC
If you calculate your max HOGE GWT for the conditions, subtract 5% from that to give a lower GWT and use that as a maximum, you are assuring yourself of a 5% Thrust Margin which gives you the ability to cope with light turbulence and a small vertical climb capability.
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From: Somewhere, Over the Rainbow
Two schools of thought I’ve learned over the years:
1. So long as you meet the power check appropriate to the performance chart you’re using, your aircraft will meet the lifting capability of the chart. Healthy transients allow you to feel comfortable at the limiting factor.
2. You can backwards engineer the performance charts to get some rough numbers for how much a degree of TOT or a % of Torque means in lifting. I don’t know where I have the 206 numbers written down, but in a 407 (for example), at 6-10k DA, a degree of MGT equals 8-9 lbs (depending on DA), and one percent of torque equals 25-27 lbs. Knowing when you’ll be torque limited or temp limited you can pretty closely estimate how much of the limiting power factor you’ll have left (plus any surplus power check temp on the engine limited scenarios).
Add in some general experience about how much power in addition to hover power you need to climb vertically, depart normally, etc and you can pretty accurately predict what your gauges are going to say and what margins you need off of the performance charts.
1. So long as you meet the power check appropriate to the performance chart you’re using, your aircraft will meet the lifting capability of the chart. Healthy transients allow you to feel comfortable at the limiting factor.
2. You can backwards engineer the performance charts to get some rough numbers for how much a degree of TOT or a % of Torque means in lifting. I don’t know where I have the 206 numbers written down, but in a 407 (for example), at 6-10k DA, a degree of MGT equals 8-9 lbs (depending on DA), and one percent of torque equals 25-27 lbs. Knowing when you’ll be torque limited or temp limited you can pretty closely estimate how much of the limiting power factor you’ll have left (plus any surplus power check temp on the engine limited scenarios).
Add in some general experience about how much power in addition to hover power you need to climb vertically, depart normally, etc and you can pretty accurately predict what your gauges are going to say and what margins you need off of the performance charts.
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From: White Waltham, Prestwick & Calgary
If it helps, these numbers served me well in Canada:
For a quick and dirty power check in the Bell 206, if you approach at 60 kts and 250 fpm ROD, the torque reading will approximate what will be needed in the hover. This is because 250 fpm reduces the thrust required to transition into the hover by about 15%, which is much the same as for ground effect and there should be minimal collective movement at the end as the machine will stop by itself anyway if you have ground effect.
More formally, you need to find the distance between the bucket speed at the bottom of the power curve and the power available. At a safe height near the landing site, fly straight and level into wind at the best rate of climb speed. Note the power used.
Then apply maximum power to see what is available. Subtract 10% and remain within the resulting value.
Here are the figures for a Bell 206:
Departure. Note the N1 in a 2-foot hover and increase the power until a 5-minute takeoff power limit is reached (Torque, N1 or TOT). The difference is your power margin.
N1 Margin (%) Takeoff
1 Cushion Creep*
2 Shallow Climb
3 Steep Climb
4 Towering
5 Vertical
*Not allowed under EASA Operations rules.
N1 is used because it provides a steadier reading.
With a 206, 10% is more than enough to clear a confined area.
Arrival. From straight & level at 200 feet above the site at 40 kts, note the N1 and increase the power until a 5-minute takeoff power limit is reached. The difference is the margin.
N1 Margin (%) Approach/Landing
4-5 Running Landing
6 Zero Speed
7 Normal to low hover
8 Normal to high hover
9 Steep to high hover
10 Vertical Approach
For a quick and dirty power check in the Bell 206, if you approach at 60 kts and 250 fpm ROD, the torque reading will approximate what will be needed in the hover. This is because 250 fpm reduces the thrust required to transition into the hover by about 15%, which is much the same as for ground effect and there should be minimal collective movement at the end as the machine will stop by itself anyway if you have ground effect.
More formally, you need to find the distance between the bucket speed at the bottom of the power curve and the power available. At a safe height near the landing site, fly straight and level into wind at the best rate of climb speed. Note the power used.
Then apply maximum power to see what is available. Subtract 10% and remain within the resulting value.
Here are the figures for a Bell 206:
Departure. Note the N1 in a 2-foot hover and increase the power until a 5-minute takeoff power limit is reached (Torque, N1 or TOT). The difference is your power margin.
N1 Margin (%) Takeoff
1 Cushion Creep*
2 Shallow Climb
3 Steep Climb
4 Towering
5 Vertical
*Not allowed under EASA Operations rules.
N1 is used because it provides a steadier reading.
With a 206, 10% is more than enough to clear a confined area.
Arrival. From straight & level at 200 feet above the site at 40 kts, note the N1 and increase the power until a 5-minute takeoff power limit is reached. The difference is the margin.
N1 Margin (%) Approach/Landing
4-5 Running Landing
6 Zero Speed
7 Normal to low hover
8 Normal to high hover
9 Steep to high hover
10 Vertical Approach
Thread Starter
Joined: Jun 2025
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From: Pune
Originally Posted by [email protected]
If you calculate your max HOGE GWT for the conditions, subtract 5% from that to give a lower GWT and use that as a maximum, you are assuring yourself of a 5% Thrust Margin which gives you the ability to cope with light turbulence and a small vertical climb capability.
Great idea. Thanks
Thank you TwinHueyMan and paco . your explanations have helped clear lot of my doubts and have given more insight in the 206
