Bell 206: JetRanger and LongRanger
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I seem to remember there being an instruction from Allison at one point forbidding the use of the starter on shutdown as people were doing it on a regular basis and cracking turbine blades. It was many moons ago, but occasional inadvertent uses should not do any harm.
Phil
Phil
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See the following statement from Rolls Royce CSL 1178
"It has come to Rolls-Royce’s recent attention that a number of Model 250 operators have adopted another engine manufacturer’s cool down procedure intended to reduce coke/carbon formation in the turbine area.
We understand that this procedure calls for the hot engine to be motored with the starter immediately following shut down to provide additional oil flow for cooling the turbine bearing/shafting area.
Operators must understand that this procedure is not recommended by Rolls-Royce and can accelerate rim cracks of the first and second stage turbine wheels due to the thermal shock of introducing a flow of cool air over the turbine wheels."
"It has come to Rolls-Royce’s recent attention that a number of Model 250 operators have adopted another engine manufacturer’s cool down procedure intended to reduce coke/carbon formation in the turbine area.
We understand that this procedure calls for the hot engine to be motored with the starter immediately following shut down to provide additional oil flow for cooling the turbine bearing/shafting area.
Operators must understand that this procedure is not recommended by Rolls-Royce and can accelerate rim cracks of the first and second stage turbine wheels due to the thermal shock of introducing a flow of cool air over the turbine wheels."
...introducing a flow of cool air over the turbine wheels
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Looking for some input on xmsn oil psi on a 206. Xmsn oil psi on ground at 100% was 45 psi. In flight it rose to 50 psi and after one hour began to steadily drop to low 30's. Not enough to illuminate caution light. Replaced psi regulator, bled line to indicator set to 45 psi at 100% flew for 1 hour and stayed rock steady at 45 psi. During delivery today one hour into flight began to steadily decrease. Pilot returned to station and on final dropped to 30 with indication. As hovered to park rose to 40's. Regulator replaced, lines blown out and checked for obstructions, filter removed and inspected. Are we missing something?? Thanks
Following day, replaced pump, same results. Pulled both jets inspected replaced packings, run up, same results. Hung new indicator with same results. All on ground runs starts at 45 and steadily drops to just above 30
Following day, replaced pump, same results. Pulled both jets inspected replaced packings, run up, same results. Hung new indicator with same results. All on ground runs starts at 45 and steadily drops to just above 30
ajwasco,
What is the oil temp doing?
Too much oil will make the MGB run hot and foamy.
Check the correct level. It is not a bubble at the top of the sightglass.
Full is halfway up.
Oil can migrate from the engine over time if freewheel seals are U/S.
What is the oil temp doing?
Too much oil will make the MGB run hot and foamy.
Check the correct level. It is not a bubble at the top of the sightglass.
Full is halfway up.
Oil can migrate from the engine over time if freewheel seals are U/S.
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Oil temp is normal, after about 15-20 min temp is @ 80 and PSI is dropping to about 32 PSI. It's in the green however my concern is why it's dropping from 45-48 to 32 in such a short time. Caution light will illum below 30. Oil level is good and checked again after run during run up oil level center of sight glass, no foaming, no loss of xmsn fluid or increase in engine oil. Not xferring oil. Bout to T in a psi guage to line coming of xmsn and run again to verify what psi is on GB. Thanks for the reply.
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Hello everybody!
Looking for information regarding starting procedure of 206BIII/250C20B/BENDIX.
There was a problem during starting of one particular machine.
Starter was engaged, throtle was cranked at 13% to just past the idle stop, starter released on 58% N1. When it reached 60% N1, it flamed out. To roll off the throttle, it was needed to push the idle stop release button.
Now comes the confusing part (besides why it flamed out).
There are two idle stops. Two clicks, close to one another.
After discussing with different pilots, they all have different starting techniques.
Some say they are gradually feeding the throttle during acceleration, watching TOT and end up just past first click,
some are cranking it open just past the first and are holding it next to it,
some are doing this also but after it peaks they roll it just past the second stop,
and some are cranking it just past the second idle stop and are holding it next to it.
The questions:
Which is the proper procedure? RFM addresses only idle stop (not first, not second).
Are there exact self-sustaining N1 rpm's for this engine?
Does these rpm's depend or have enything to do with position of the throttle during acceleration to idle (if it's left next to the first idle stop from closed side, or between the first and second idle stop, or just past the second idle stop).
Does the flame out described above has anything to do with throttle position during start? (or should the battery condition, ignition exciter, etc... be looked )
I know it's a scarce info, but any thoughts?
Thanks
Looking for information regarding starting procedure of 206BIII/250C20B/BENDIX.
There was a problem during starting of one particular machine.
Starter was engaged, throtle was cranked at 13% to just past the idle stop, starter released on 58% N1. When it reached 60% N1, it flamed out. To roll off the throttle, it was needed to push the idle stop release button.
Now comes the confusing part (besides why it flamed out).
There are two idle stops. Two clicks, close to one another.
After discussing with different pilots, they all have different starting techniques.
Some say they are gradually feeding the throttle during acceleration, watching TOT and end up just past first click,
some are cranking it open just past the first and are holding it next to it,
some are doing this also but after it peaks they roll it just past the second stop,
and some are cranking it just past the second idle stop and are holding it next to it.
The questions:
Which is the proper procedure? RFM addresses only idle stop (not first, not second).
Are there exact self-sustaining N1 rpm's for this engine?
Does these rpm's depend or have enything to do with position of the throttle during acceleration to idle (if it's left next to the first idle stop from closed side, or between the first and second idle stop, or just past the second idle stop).
Does the flame out described above has anything to do with throttle position during start? (or should the battery condition, ignition exciter, etc... be looked )
I know it's a scarce info, but any thoughts?
Thanks
Long time since I owned a 206 but there sounds like you didn't open the throttle for the idle stop to engage. See it on 500's when throttle isn't opened enough for idle stop to engage. Engine will accelerate past 58% then flames out as there isn't enough fuel . Would suggest either an issue with your idle stop or your starting sequence. I always open throttle until you feel idle stop engage then wind back to it that way you know you have opened it far enough
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I've never heard of two idle stops, and find it difficult to imagine how that would be possible. It might feel like there is another stop below the actual stop, but that's just a feel, and there is no stop. You can roll the throttle to just below the idle stop and feel a slight click, but when you're actually past the stop, the idle release button will pop up.
With a Bendix, the procedure is to open the throttle to the idle stop, just a bit more, and wait, while holding the idle stop button down so the throttle can be closed if necessary. If you roll the throttle back against the stop before pressing the detent, you run the risk of not being able to close the throttle even with the detent pressed. You do not want to try to start a BIII while modulating the throttle. If you can do that, then the fuel rigging is wrong, and that may be why the engine flamed out.
With a Bendix, the procedure is to open the throttle to the idle stop, just a bit more, and wait, while holding the idle stop button down so the throttle can be closed if necessary. If you roll the throttle back against the stop before pressing the detent, you run the risk of not being able to close the throttle even with the detent pressed. You do not want to try to start a BIII while modulating the throttle. If you can do that, then the fuel rigging is wrong, and that may be why the engine flamed out.
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Hi 311kph. From an old 206 hand, here are my answers to your queries:
1. Which is the proper procedure? RFM addresses only idle stop (not first, not second). The 2-click idle stop has been a characteristic of the 206 Series from Day 1. The second 'click' (going from shut-off to idle) is the one referenced in the RFM.
2. Are there exact self-sustaining N1 rpm's for this engine? Probably. It must be remembered that 'idle' is more accurately termed 'flight-idle' and is a higher setting than 'ground-idle' to ensure that the rotor blades rotate at a speed that ensures the pilot retains aerodynamic control of them otherwise wind gusts etc. while sitting on the ground may result in a blade strike (on tailboom), mast bumping or spike knock. Perhaps someone with knowledge of the turboprop installation can add to this.
3. Does these rpm's depend or have enything to do with position of the throttle during acceleration to idle (if it's left next to the first idle stop from closed side, or between the first and second idle stop, or just past the second idle stop).No, the engine RPM acceleration after light-off is a function of, first, the start-derich system and then the acceleration control setting on the FCU (note that different P/N's of FCU have different adjustment controls to fine-tune the start). Of course, a good battery/GPU will give better starts. Remember that this engine requires a hot and fast start - not a slow and cool one, there is an DDA/Allison/RR document on this topic but sorry, I can't remember the details.
4. Does the flame out described above has anything to do with throttle position during start? (or should the battery condition, ignition exciter, etc... be looked ) Most probably, with the twist-grip at the 'idle' position (second 'click' going from shut-off to idle) check the pointer on the FCU. It should be at or slightly below the 30 degree mark, if it requires adjustment it is vital to ensure afterwards that the lever firmly contacts shut-off stop and max-power stop - failure to ensure this will lead to other problems. You said the engine flamed out when it reached 60% N1, this rules out the battery condition and the exciter as source of the problem.
Hope this helps.
1. Which is the proper procedure? RFM addresses only idle stop (not first, not second). The 2-click idle stop has been a characteristic of the 206 Series from Day 1. The second 'click' (going from shut-off to idle) is the one referenced in the RFM.
2. Are there exact self-sustaining N1 rpm's for this engine? Probably. It must be remembered that 'idle' is more accurately termed 'flight-idle' and is a higher setting than 'ground-idle' to ensure that the rotor blades rotate at a speed that ensures the pilot retains aerodynamic control of them otherwise wind gusts etc. while sitting on the ground may result in a blade strike (on tailboom), mast bumping or spike knock. Perhaps someone with knowledge of the turboprop installation can add to this.
3. Does these rpm's depend or have enything to do with position of the throttle during acceleration to idle (if it's left next to the first idle stop from closed side, or between the first and second idle stop, or just past the second idle stop).No, the engine RPM acceleration after light-off is a function of, first, the start-derich system and then the acceleration control setting on the FCU (note that different P/N's of FCU have different adjustment controls to fine-tune the start). Of course, a good battery/GPU will give better starts. Remember that this engine requires a hot and fast start - not a slow and cool one, there is an DDA/Allison/RR document on this topic but sorry, I can't remember the details.
4. Does the flame out described above has anything to do with throttle position during start? (or should the battery condition, ignition exciter, etc... be looked ) Most probably, with the twist-grip at the 'idle' position (second 'click' going from shut-off to idle) check the pointer on the FCU. It should be at or slightly below the 30 degree mark, if it requires adjustment it is vital to ensure afterwards that the lever firmly contacts shut-off stop and max-power stop - failure to ensure this will lead to other problems. You said the engine flamed out when it reached 60% N1, this rules out the battery condition and the exciter as source of the problem.
Hope this helps.
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Vertical Freedom: I've been involved with 'jetties' (A, B and L) for over 40 years and all of them had two clicks, all of them. The next time you sit in your 'JetBox', close the doors and ensure the cockpit is quiet. Put the twist-grip to 'shut-off' and then slowly roll it towards 'idle' - this must be done slowly - and as the twist-grip gets to the detent position listen for a soft 'click', at the same time look at the idle release button and you'll see slight movement (usually from side-to-side) - this is the first of two 'clicks'. Keep rolling and almost immediately you'll hear another louder 'click' and see the button pop out - this is the second 'click' and is the correct 'idle' position of the twist-grip. I'm surprised you haven't heard about this previously as the 'two-click' topic has been discussed over and over again in the past, I believe it was also featured in an earlier edition Rotorbreeze.
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Thanks guys, much appreciated!
@Saint Jack Great info, great help
Just been trough every machine here, everyone has two idle stops. In quiet hangar you can hear (and feel) them both snap.
So, we'll use second one as the one referenced in the RFM, no gradual feed, no first click,...
@Hughes500 Thanks. Could be that he didn't open the throttle enough for the idle stop to engage. He said that after the flame out he pushed the button and rolled it off, but couldn't said with certainty that it was actually locked and needed pushing release button.
With all the noise and vibrations going one, you can't rely much on hearing. You can feel clicks on your finger, but I guess the only thing certain is to just pass stops, roll it back and ensure it won't go back to cut-off.
Thank you guys
@Saint Jack Great info, great help
Just been trough every machine here, everyone has two idle stops. In quiet hangar you can hear (and feel) them both snap.
So, we'll use second one as the one referenced in the RFM, no gradual feed, no first click,...
@Hughes500 Thanks. Could be that he didn't open the throttle enough for the idle stop to engage. He said that after the flame out he pushed the button and rolled it off, but couldn't said with certainty that it was actually locked and needed pushing release button.
With all the noise and vibrations going one, you can't rely much on hearing. You can feel clicks on your finger, but I guess the only thing certain is to just pass stops, roll it back and ensure it won't go back to cut-off.
Thank you guys
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Relatively new, yes. There is also a story here about a guy who's been flying mostly 212. One day he sat in JetDanger, starter, 15%, whacking the throttle all the way (full open), then back to idle stop, watch TOT - game over.
So yes, being a relatively new with Allison along with hearing the above story, it could be that he was a bit shy with throttle.
Anyways, easy fix, no harm done.
So yes, being a relatively new with Allison along with hearing the above story, it could be that he was a bit shy with throttle.
Anyways, easy fix, no harm done.
So many misconceptions, so little time...
1) The Bell 206 has ONE idle stop. Not two. There *may* be two *clicks* heard as you oh-so-slowly increase the twist-grip up from cutoff. The first *click* may have something to do with slop in the design of the plunger/lock/release mechanism on the 206 twist-grip. The first *click* means nothing. You rotate the "throttle" positively to the IDLE-DETENT. *That* is the proper position for introducing fuel in a C-20 equipped with a Bendix fuel control.
2) With a Bendix fuel control, at light-off (15%) you get EXACTLY the same amount of fuel at the idle-detent as you do at "full-throttle." Hear me now: You CANNOT get "extra" fuel from a Bendix if you go above idle during the start (like, below 40-45% N1 or so). What you get at the detent is ALL you're going to get.
I like to mess with other 206B pilots, especially those who don't know the 206 very well, and especially in a particular ship that I do know well. While demonstrating a start, I'll get to 15% N1 and then rotate the throttle to FULL. Sometimes I'll even "pump" the throttle like I'm priming a Bell 47. The ship starts absolutely normally. It freaks people out. All the way out. People do not believe this. Supposedly knowledgeable people will tell you different - that the more you go past the idle-stop the more fuel you'll get. WRONG! Doesn't work that way. Isn't designed that way. (It should not be necessary to point out - although somebody surely will - that you cannot do this in an 206L-1, L-3 or L-4.)
311kph, I do not know why your 212 pilot torched the 206B if he did what you described. That should not have been a problem. Perhaps there was some other issue with the engine (or maybe it was an L-model and not a B-model?). I'm always very cautious when starting a ship I'm unfamiliar with.
So. Do not be afraid to go right to the idle-detent stop (or slightly above, as Gomer Pylot suggests) when starting a 206B. If the "throttle" is open far enough to get fuel into the burner can, that's all the fuel you're going to get. Period.
3) The RR 250-series engine is fairly self-sustaining at about 45%. We keep the button down to 58% (and set the idle just above that) to keep the main rotor turning, as has already been suggested. You can release the starter button "early" (like below 58% and the engine will run just fine - as long as the throttle is above the detent and the TOT is under control).
4) Another misconception with the RR-250 is about opening the "throttle" with the engine shut down but the fuel valve on and the electric fuel boost pumps operating. OPENING THE THROTTLE DOES NOTHING. It does *not* allow fuel to be pumped into the burner can. This has to do with the design of the engine-driven fuel pump...which is what we call a "positive-displacement" pump. If it is not turning, then the boost pumps CANNOT push fuel past it. All the boost pumps do is supply fuel under pressure to the engine-driven pump. If the engine-driven fuel pump quits on you in flight, your engine WILL quit, whether your boost pumps are on or not. Thankfully, the engine-driven fuel pump is a pretty reliable device.
So before you hit the starter button, ALWAYS ALWAYS ALWAYS do one final throttle check: Idle-to-full-back-to-detent-then-cutoff. Then you KNOW thy throttle is fully closed.
Having said that, I once heard that if the engine-driven fuel pump is turning as little as 2% it can supply "normal" pressure to the fuel control. Just keep that in mind, for it may be true.
I've had various fuel control problems over the years, mostly associated with rigging. So preflight the linkage well. With the engine cowling open, manipulate the fuel control linkage to fully open and check the pointer. Then pull it back down to idle and check the pointer again. DO NOT FORGET TO CLOSE THE THROTTLE in the cockpit before you initiate the start sequence or you'll be in for a nasty surprise.
To recap: If you're getting two *clicks* as you open the "throttle" while starting a Bell 206B then you're doing it wrong. Go right to the idle-cutoff detent. Make sure the button pops all the way out. Once you release the starter button at 58% and the N1 rpm is up, then increase the throttle slightly and come back down to the idle-stop for your one-minute warmup. If the engine flames out you know you didn't go far enough. Practice makes perfect.
4) The 206B-III checklist calls for a "decel-check" at the end of the day. If I'm going to be doing training in a 206B, I like to do a decel-check before take-off, so that I know it's not going to flame out if we roll the thing to idle in flight to practice an auto or something.
1) The Bell 206 has ONE idle stop. Not two. There *may* be two *clicks* heard as you oh-so-slowly increase the twist-grip up from cutoff. The first *click* may have something to do with slop in the design of the plunger/lock/release mechanism on the 206 twist-grip. The first *click* means nothing. You rotate the "throttle" positively to the IDLE-DETENT. *That* is the proper position for introducing fuel in a C-20 equipped with a Bendix fuel control.
2) With a Bendix fuel control, at light-off (15%) you get EXACTLY the same amount of fuel at the idle-detent as you do at "full-throttle." Hear me now: You CANNOT get "extra" fuel from a Bendix if you go above idle during the start (like, below 40-45% N1 or so). What you get at the detent is ALL you're going to get.
I like to mess with other 206B pilots, especially those who don't know the 206 very well, and especially in a particular ship that I do know well. While demonstrating a start, I'll get to 15% N1 and then rotate the throttle to FULL. Sometimes I'll even "pump" the throttle like I'm priming a Bell 47. The ship starts absolutely normally. It freaks people out. All the way out. People do not believe this. Supposedly knowledgeable people will tell you different - that the more you go past the idle-stop the more fuel you'll get. WRONG! Doesn't work that way. Isn't designed that way. (It should not be necessary to point out - although somebody surely will - that you cannot do this in an 206L-1, L-3 or L-4.)
311kph, I do not know why your 212 pilot torched the 206B if he did what you described. That should not have been a problem. Perhaps there was some other issue with the engine (or maybe it was an L-model and not a B-model?). I'm always very cautious when starting a ship I'm unfamiliar with.
So. Do not be afraid to go right to the idle-detent stop (or slightly above, as Gomer Pylot suggests) when starting a 206B. If the "throttle" is open far enough to get fuel into the burner can, that's all the fuel you're going to get. Period.
3) The RR 250-series engine is fairly self-sustaining at about 45%. We keep the button down to 58% (and set the idle just above that) to keep the main rotor turning, as has already been suggested. You can release the starter button "early" (like below 58% and the engine will run just fine - as long as the throttle is above the detent and the TOT is under control).
4) Another misconception with the RR-250 is about opening the "throttle" with the engine shut down but the fuel valve on and the electric fuel boost pumps operating. OPENING THE THROTTLE DOES NOTHING. It does *not* allow fuel to be pumped into the burner can. This has to do with the design of the engine-driven fuel pump...which is what we call a "positive-displacement" pump. If it is not turning, then the boost pumps CANNOT push fuel past it. All the boost pumps do is supply fuel under pressure to the engine-driven pump. If the engine-driven fuel pump quits on you in flight, your engine WILL quit, whether your boost pumps are on or not. Thankfully, the engine-driven fuel pump is a pretty reliable device.
So before you hit the starter button, ALWAYS ALWAYS ALWAYS do one final throttle check: Idle-to-full-back-to-detent-then-cutoff. Then you KNOW thy throttle is fully closed.
Having said that, I once heard that if the engine-driven fuel pump is turning as little as 2% it can supply "normal" pressure to the fuel control. Just keep that in mind, for it may be true.
I've had various fuel control problems over the years, mostly associated with rigging. So preflight the linkage well. With the engine cowling open, manipulate the fuel control linkage to fully open and check the pointer. Then pull it back down to idle and check the pointer again. DO NOT FORGET TO CLOSE THE THROTTLE in the cockpit before you initiate the start sequence or you'll be in for a nasty surprise.
To recap: If you're getting two *clicks* as you open the "throttle" while starting a Bell 206B then you're doing it wrong. Go right to the idle-cutoff detent. Make sure the button pops all the way out. Once you release the starter button at 58% and the N1 rpm is up, then increase the throttle slightly and come back down to the idle-stop for your one-minute warmup. If the engine flames out you know you didn't go far enough. Practice makes perfect.
4) The 206B-III checklist calls for a "decel-check" at the end of the day. If I'm going to be doing training in a 206B, I like to do a decel-check before take-off, so that I know it's not going to flame out if we roll the thing to idle in flight to practice an auto or something.
Last edited by FH1100 Pilot; 19th Jan 2014 at 06:51.
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A250 Fuel system
Engineering here (!) - confirm point (4), the fuel nozzle has a spring loaded metering valve within it. Fuel will not flow to the primary nozzle until pressure exceeds 30psi (and to the secondary nozzle as well at pressures over 150psi). Boost pump pressure is nominally what, 4-10psi? Either way, not enough to open the primary nozzle flow.
Simples
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Simples
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@FH1100 Pilot : Thank you for extensive reply. The 212 pilot that torched the 206, long time ago, some say it was B, some say it was L, so no luck there...
Here:
I don't suppose it makes any difference this being Agusta-Bell? Guess not.
Well then,
'' Dear Mr. Bell...''
Here:
I don't suppose it makes any difference this being Agusta-Bell? Guess not.
Well then,
'' Dear Mr. Bell...''