Bell 206: JetRanger and LongRanger
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over 95% of all LTE mishaps involve bell 206's because the tail rotor is much more marginal on a 206 than most helicopters.
The term LTE is a misnomer, as I have posted an pprune many times. Most single rotor helicopters have never experienced an "LTE" mishap.
Short of left pedal is far different than approching to a hover and spinning until you crash. If the 206 had a large enough (satisfactory) tail rotor, it would not experience LTE any more often than other types. I will post a study I did a few years back that shows its propensity.
The term LTE is a misnomer, as I have posted an pprune many times. Most single rotor helicopters have never experienced an "LTE" mishap.
Short of left pedal is far different than approching to a hover and spinning until you crash. If the 206 had a large enough (satisfactory) tail rotor, it would not experience LTE any more often than other types. I will post a study I did a few years back that shows its propensity.
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NR and N2 in Autorotation
I have been working on B206 for about 10 years, the governing range does not start till 70% and has absolutly no effect below that. You will not get a noticeable split in the needles in autorotation because the 'free turbine' is no longer loaded and the idle gas flow will keep the N2 at roughly the same sped as NR. The gas turbine engine is a very simple beast so never compare it with how a piston engine and clutch works. Piston engines mechanically drive the gearbox through the clutch. Turbine engines pass air over the free turbine which then drives the gearbox through the freewheel unit. In theory you could hold the blades of a free turbine while the engine is running, impossible on a piston engine. In practice anything above ground idle and the torque is too high and something would break.
Of course the terms ' ground idle' and 'flight idle' confuse lots of people depending on your country of origin. 'Ground idle' is when the engine is running at around 62% or so, 'flight idle' is when the engine is running at max goverened rpm, it means you can commit avaition, notice I sayed 'GOVERNED' rpm. The governor is there to control engine rpm as compared to rotor rpm, so if you pull collective lever the rotor rpm drops and the governor tells the fuel control to chuck in more fuel to maintain rotor rpm.
I am not trying to teach pilots or others how to suck eggs, but some people are not taught correctly or get on the wrong track at an early stage! I am not criticising any of the previous posts but there does seem to be some bad feeling about a subject that could potentially kill people, we are all professionals be we engineers or pilots and can all take advice and accept it without abuse. Wether you are right or wrong we are here to learn and no-one is ever too old to learn, if so, it is time to retire from the industry. Happy flying one of the safest and most reliable helicopters in the WORLD!!
Of course the terms ' ground idle' and 'flight idle' confuse lots of people depending on your country of origin. 'Ground idle' is when the engine is running at around 62% or so, 'flight idle' is when the engine is running at max goverened rpm, it means you can commit avaition, notice I sayed 'GOVERNED' rpm. The governor is there to control engine rpm as compared to rotor rpm, so if you pull collective lever the rotor rpm drops and the governor tells the fuel control to chuck in more fuel to maintain rotor rpm.
I am not trying to teach pilots or others how to suck eggs, but some people are not taught correctly or get on the wrong track at an early stage! I am not criticising any of the previous posts but there does seem to be some bad feeling about a subject that could potentially kill people, we are all professionals be we engineers or pilots and can all take advice and accept it without abuse. Wether you are right or wrong we are here to learn and no-one is ever too old to learn, if so, it is time to retire from the industry. Happy flying one of the safest and most reliable helicopters in the WORLD!!
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Talk about ask a simple question!
As I seem to have started a slanging match, here are a few more details.
Yes I'm inexperienced on the 206, maybe 180 hours or so and 2 sessions of Bell school under my belt.
I have maybe flown 8 or so 206's and every single one, including those at Bell, during an autorotation showed a definite needle split.
So here I am flying an aircraft that has just been rebuilt, yes I'm being cautious.
I do an auto and something that I personally haven't seen before happens: the needles don't split. So we decided to call it a day because we had has some other teething problems and make some calls. Simple safety in my book.
The next day we were out again after our more experienced brethren assured us that all was well.
The reason for posting it here: I know that some very experienced people frequent this board. Judging some of the answers to my query I'm glad I did.
Quite why it degraded into the thread that it did I don't know, but now I'm the wiser: Sometimes they split and sometimes they don't!
As I seem to have started a slanging match, here are a few more details.
Yes I'm inexperienced on the 206, maybe 180 hours or so and 2 sessions of Bell school under my belt.
I have maybe flown 8 or so 206's and every single one, including those at Bell, during an autorotation showed a definite needle split.
So here I am flying an aircraft that has just been rebuilt, yes I'm being cautious.
I do an auto and something that I personally haven't seen before happens: the needles don't split. So we decided to call it a day because we had has some other teething problems and make some calls. Simple safety in my book.
The next day we were out again after our more experienced brethren assured us that all was well.
The reason for posting it here: I know that some very experienced people frequent this board. Judging some of the answers to my query I'm glad I did.
Quite why it degraded into the thread that it did I don't know, but now I'm the wiser: Sometimes they split and sometimes they don't!
All helicopter types have their little idiosyncrasis that the pilot has to be aware of!
The AS-350 has the Jackstall
The R-22 has the low-G mast bumping thingy
& The JetRanger has the LTE risk.
It´s no problem, the pilot just has to be aware of it and it´s not going to happen to you!
The AS-350 has the Jackstall
The R-22 has the low-G mast bumping thingy
& The JetRanger has the LTE risk.
It´s no problem, the pilot just has to be aware of it and it´s not going to happen to you!
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Yeeeup ... they all have their little peculiarities ...
The Hu 500A&C models as well as the Bo105 and the Bk117 will run out of left pedal on takeoff at high weights and DAs, albeit in a very benign fashion.
The AS350 will run out of Ng and right pedal at altitude.
The BH412 will let you know it doesn't appreciate slow flight with a right crosswind and can be very naughty to you if you try a high gross wt takeoff from a turbulent deck!!!
And the PUMA will put your passengers to sleep if you fly at 14000' (just be careful you don't go to sleep as well!!!!).
The Hu 500A&C models as well as the Bo105 and the Bk117 will run out of left pedal on takeoff at high weights and DAs, albeit in a very benign fashion.
The AS350 will run out of Ng and right pedal at altitude.
The BH412 will let you know it doesn't appreciate slow flight with a right crosswind and can be very naughty to you if you try a high gross wt takeoff from a turbulent deck!!!
And the PUMA will put your passengers to sleep if you fly at 14000' (just be careful you don't go to sleep as well!!!!).
Not Bach Yet
pprune fan #1 said:
but that's got to say something.
Yes, a three day ban from the moderator. Defy further, you are history. This will be a civil web site, Mr. Fan.
PedalStop
Rotorheads Moderator
but that's got to say something.
Yes, a three day ban from the moderator. Defy further, you are history. This will be a civil web site, Mr. Fan.
PedalStop
Rotorheads Moderator
Last edited by PedalStop; 17th Jul 2005 at 16:44.
I know where you are going Nick and I agree that designers of new helicopters should make them better than the old one´s!
But the JetRanger is hardly a "flawed" design for a well trained pilot to fly.
There have been manufactured 7300 JetRangers that have flown 38 million hours (and still counting). The JetRanger’s history of reliability and flexibility, combined with the best safety record among all single-engine aircraft make it everything but a "sub-standard aircraft"!
There may be newer better aircraft made but they are perhaps not economically profitable for all operators.
And operators are using these machines to make money and not just to drill expensive holes in the skies.
So for us "Brave" pilots that dare to fly the JetRanger we will just have to keep on and hope the best
But the JetRanger is hardly a "flawed" design for a well trained pilot to fly.
There have been manufactured 7300 JetRangers that have flown 38 million hours (and still counting). The JetRanger’s history of reliability and flexibility, combined with the best safety record among all single-engine aircraft make it everything but a "sub-standard aircraft"!
There may be newer better aircraft made but they are perhaps not economically profitable for all operators.
And operators are using these machines to make money and not just to drill expensive holes in the skies.
So for us "Brave" pilots that dare to fly the JetRanger we will just have to keep on and hope the best
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Nick,
I think you are wise to suggest that we insist on a better standard with each generation of aircraft, however, what makes the big picture quite different from cars is the level of training and awareness that any pilot should have before going off in a different aircraft type.
LTE does not just happen, it is well documented and a known phenomenon that can occur when the conditions are right.
Gentle aircraft handling and an awareness of the immediate environment regarding LTE should stop the problem.
Now, how do you make pilots aware without a demo?? I think it would be a good idea to have an LTE awareness video, something along the lines of the Robinson Safety video. Something that all pilots of 206s should watch every year or so. It may already exist.
I had been flying for 7 years before I heard of LTE. Granted, I was flying Gazelles and LTE was something that only happened in the US....not!
I was a passenger in a Gazelle that did 5 or 6, 360 deg turns, undemanded, caused by a clumsy pilot in a strong wind.....and the yaw stopped only when we crashed. That was my intro to LTE and I am certain that awareness is the key.
I think you are wise to suggest that we insist on a better standard with each generation of aircraft, however, what makes the big picture quite different from cars is the level of training and awareness that any pilot should have before going off in a different aircraft type.
LTE does not just happen, it is well documented and a known phenomenon that can occur when the conditions are right.
Gentle aircraft handling and an awareness of the immediate environment regarding LTE should stop the problem.
Now, how do you make pilots aware without a demo?? I think it would be a good idea to have an LTE awareness video, something along the lines of the Robinson Safety video. Something that all pilots of 206s should watch every year or so. It may already exist.
I had been flying for 7 years before I heard of LTE. Granted, I was flying Gazelles and LTE was something that only happened in the US....not!
I was a passenger in a Gazelle that did 5 or 6, 360 deg turns, undemanded, caused by a clumsy pilot in a strong wind.....and the yaw stopped only when we crashed. That was my intro to LTE and I am certain that awareness is the key.
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l think Nick has a valid point! We should be expecting more from aircraft manufacturers and striving towards safer more user friendly aircraft and not accepting flaws and/or inadequacies as part and parcel to the industry. What happens when a car manufacturer discovers a flaw in their design, they recall 'all' the affected vehicles and make the necessary changes at 'their' expense. Why, because if they don't they know they'll get their arses sued the next time an accident can be attributed to that problem. With aviation, firstly they don't admit any flaw on their part as that would be an admission of guilt, rather they provide an 'optional' alternative at the owners expense!
The reason jetrangers have so impressively sold X amount of units and flown X amount of hours isn't necessarily because they are such a great aircraft it's because they filled a large hole in a market that had very little competition. Why are they still being used in such large numbers, because safety and technology advances come at a cost that most operators aren't prepared to entertain! Thankgod times are a changing and there are a few better options out there today!
Granted, better training and awareness of things like LTE will prevent accidents but maybe we should be looking at the root cause of these kinds of problems and address them before blaming the pilot who may or maynot have known as much as he should have.
The reason jetrangers have so impressively sold X amount of units and flown X amount of hours isn't necessarily because they are such a great aircraft it's because they filled a large hole in a market that had very little competition. Why are they still being used in such large numbers, because safety and technology advances come at a cost that most operators aren't prepared to entertain! Thankgod times are a changing and there are a few better options out there today!
Granted, better training and awareness of things like LTE will prevent accidents but maybe we should be looking at the root cause of these kinds of problems and address them before blaming the pilot who may or maynot have known as much as he should have.
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The normal 206L4 tail rotor is so "underpowered" that at altitude, you can hover 70% Torque with the pedal against the stop, if any light breeze comes from the wrong direction it will just weathervane you into the wind and there will be absolutelly no pedal to stop it from spinning, and no mention of the interesting possiblilites of what could happen when you take off in these conditions.
The 407 on the other hand could probably hover on TR power alone if you could point the thing down!
The 407 on the other hand could probably hover on TR power alone if you could point the thing down!
Last edited by BlenderPilot; 18th Jul 2005 at 04:24.
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A Bell 206B may have less than adequate tail rotor authority, but a 206BIII with the 65" T/R has enough control for most situations. If you hit the stops with a III, then you are definitely doing something out-of-the-ordinary. In my 5,000+ hrs on III's, I can't recall ever hitting the (L) stop.
Blender, Yes, the 407 pedal control is superb
Blender, Yes, the 407 pedal control is superb
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Bell 206 Safety
It is often "quoted" that the Bell 206 helicopter is the safest single engined aircraft in the world. Usually reference to FAA statistics is made to qualify this statement.
Can anyone direct me a link etc. where this "quote" comes from.
(If indeed it was ever the case!)
Can anyone direct me a link etc. where this "quote" comes from.
(If indeed it was ever the case!)
"The JetRanger’s history of reliability and flexibility, combined with the best safety record among all single-engine aircraft"
From BHT webpage.
I have heard this and read for many years. I remember reading a booklet from the NTSB about single engine aircraft accident statistics where where it was clear that the B 206 was safer than other single engine aircraft. You could try to search www.ntsb.gov also!
It is amazing if this still holds true with all the single engine turboprops on the market like Cessna Caravan, Malibu Mirage, TBM 700 & PC 12 that a helicopter would be safer considering the much more dangerous nature of work that a helicopter will perform.
I remember though reading somewhere that Cessna claims that the PT6 in their C-208 has the best reliabilty record for an engine.
From BHT webpage.
I have heard this and read for many years. I remember reading a booklet from the NTSB about single engine aircraft accident statistics where where it was clear that the B 206 was safer than other single engine aircraft. You could try to search www.ntsb.gov also!
It is amazing if this still holds true with all the single engine turboprops on the market like Cessna Caravan, Malibu Mirage, TBM 700 & PC 12 that a helicopter would be safer considering the much more dangerous nature of work that a helicopter will perform.
I remember though reading somewhere that Cessna claims that the PT6 in their C-208 has the best reliabilty record for an engine.
I heard this claim, but couched more in terms like these:
"It is the aircraft least likely to have a problem which results in a crash. If it IS involved in a crash, it is the one in which you are most likely to survive." When you consider having to maintain 50 knots in a plank when you dig into the hardwoods, the idea of an auto into a clearing sounds more inviting.
That sort of stuff makes the apprehensive grandma, about to go for her first flight off the ground, more likely to get on board. Could also be Bell Bull5h1t.
"It is the aircraft least likely to have a problem which results in a crash. If it IS involved in a crash, it is the one in which you are most likely to survive." When you consider having to maintain 50 knots in a plank when you dig into the hardwoods, the idea of an auto into a clearing sounds more inviting.
That sort of stuff makes the apprehensive grandma, about to go for her first flight off the ground, more likely to get on board. Could also be Bell Bull5h1t.
It has been a long time since I flew a 206 - but If you are conducting a power assurance check as per the flight manual and you are 18% low you have a major problem.
When was the last time you did a power recovery wash?
Next suspect the bleed valve is not closing.
Next suspect would be the compressor and hot section.
Best of luck!
Remember a power assurance graph is basically a paper engine.
The chart says a spec engine at a given Alt. (29.92inches or 1013) and temp. that a given N1 and ITT should give you a specific torque.
If your real installed engine produces less torque for a given N1 and ITT then it is below spec and if it produces more torque then it is above spec - whch is a good thing!
I only say this because I have seen a few folks who have a hard time fiquring out what the chart is telling them.
When was the last time you did a power recovery wash?
Next suspect the bleed valve is not closing.
Next suspect would be the compressor and hot section.
Best of luck!
Remember a power assurance graph is basically a paper engine.
The chart says a spec engine at a given Alt. (29.92inches or 1013) and temp. that a given N1 and ITT should give you a specific torque.
If your real installed engine produces less torque for a given N1 and ITT then it is below spec and if it produces more torque then it is above spec - whch is a good thing!
I only say this because I have seen a few folks who have a hard time fiquring out what the chart is telling them.
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Mr Shellfish, get that engine to a doctor before it's affliction spreads to the rest of the fleet.
1. Ask yourself, 'when was the compressor last inspected? (case halves)'
2. Has the power deteriorated gradually, or overnight? (bleed valve failure will increase TOT by about 20-25 deg at those settings)
3. N1 seems to be high for the torque (only memory ) and will usually point to a front end problem.
1. Ask yourself, 'when was the compressor last inspected? (case halves)'
2. Has the power deteriorated gradually, or overnight? (bleed valve failure will increase TOT by about 20-25 deg at those settings)
3. N1 seems to be high for the torque (only memory ) and will usually point to a front end problem.