Bell 206: JetRanger and LongRanger
RFM all the way..................nothing else!!!
There is no mention of any 2 clicks in the RFM - that's the beginning & end of the story 
don't presume slop in the linkage system equates to 2 clicks 
if all else fails refer the RFM it is Your Bible or Bhagavat Gita 
don't presume slop in the linkage system equates to 2 clicks if all else fails refer the RFM it is Your Bible or Bhagavat Gita
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slop in the linkage system
Yes, the RFM mentions only one click, I was having trouble identifying which one of theese two is THE ONE.
Saint Jack said that second 'click' is the one referenced in the RFM.
Problem solved.
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Let's try to put all of this information regarding 2-clicks into perspective now that we've received so many wide-ranging replies.
1. 'FH1100 Pilot' in his Post #1217 says there is only one click. This is essentially correct but the design of the twist grip and detent button mechanism results in 2-clicks when rolled slowly to detent, this is NOT the result of 'sloppy linkage' nor is there any difference on an Agusta-Bell machine. This is the way the helicopter was designed, built and certified.
2. The 2-click confusion arises when pilots new to the 206 roll the throttle slowly towards detent (light-off) being wary of the scenario 'Hughes500' in his Post #1215 aptly describes ".....he doesn't want the infamous hot start !!!" (and the associated cost).
3. So what happens when a new pilot becomes confused and a definitive explanation is not readily available? Responsible persons like '311kph' in his Post #1208 ask around to find an answer (incidentally, 'Hughes500' in his Post #1215 hits the nail on the head with his statement "...'he is not being positive enough with the throttle....").
4. 'FH1100 Pilot' (for whom I have a lot of respect after reading some his previous postings on other topics) in his Post #1217 states "....I like to mess with other 206B pilots, especially those who don't know the 206 very well....". This of course, represents the other end of the spectrum i.e. "I know it, so why don't you know it". Messing with a pilot who doesn't know the 206 very well and may be doing his first start/s on a Model 250 engine can have significant financial and professional repercussions.
5. Then we have 'Vertical Freedom' in his Posts #1212 and #1220 who appears to have his head in the sand (or snow or ice or whatever they have in Nepal) "....There is no mention of any 2 clicks in the RFM - that's the beginning & end of the story..." oh really! No signs here of any willingness to learn.
6. So where are we, there ARE two clicks if you roll the twist-grip slowly BUT, rolling this slowly is NOT the correct technique for a start. Rather, the twist-grip should be rolled positively to the 'idle' position and, for new pilots to this engine, keep a close eye on the rapidly increasing TOT indicator (remember, there are two temperature 'peaks' during the start).
1. 'FH1100 Pilot' in his Post #1217 says there is only one click. This is essentially correct but the design of the twist grip and detent button mechanism results in 2-clicks when rolled slowly to detent, this is NOT the result of 'sloppy linkage' nor is there any difference on an Agusta-Bell machine. This is the way the helicopter was designed, built and certified.
2. The 2-click confusion arises when pilots new to the 206 roll the throttle slowly towards detent (light-off) being wary of the scenario 'Hughes500' in his Post #1215 aptly describes ".....he doesn't want the infamous hot start !!!" (and the associated cost).
3. So what happens when a new pilot becomes confused and a definitive explanation is not readily available? Responsible persons like '311kph' in his Post #1208 ask around to find an answer (incidentally, 'Hughes500' in his Post #1215 hits the nail on the head with his statement "...'he is not being positive enough with the throttle....").
4. 'FH1100 Pilot' (for whom I have a lot of respect after reading some his previous postings on other topics) in his Post #1217 states "....I like to mess with other 206B pilots, especially those who don't know the 206 very well....". This of course, represents the other end of the spectrum i.e. "I know it, so why don't you know it". Messing with a pilot who doesn't know the 206 very well and may be doing his first start/s on a Model 250 engine can have significant financial and professional repercussions.
5. Then we have 'Vertical Freedom' in his Posts #1212 and #1220 who appears to have his head in the sand (or snow or ice or whatever they have in Nepal) "....There is no mention of any 2 clicks in the RFM - that's the beginning & end of the story..." oh really! No signs here of any willingness to learn.
6. So where are we, there ARE two clicks if you roll the twist-grip slowly BUT, rolling this slowly is NOT the correct technique for a start. Rather, the twist-grip should be rolled positively to the 'idle' position and, for new pilots to this engine, keep a close eye on the rapidly increasing TOT indicator (remember, there are two temperature 'peaks' during the start).
After 7000+ hrs on a 206, mostly Bendix but some Chandler-Evans CECO, I have never seen 2 clicks. Probably because I have never been a pussycat with rolling the throttle on.
Start: N1 accelerating through 13% and likely to pass 15%, snap to past idle so button pops up, gently roll back against the stop. Be aware that holding against the stop will make it difficult to shut it off in a hot start situation. You can in fact have the throttle fully OPEN at this stage without anything untoward happening.
This is because the N1 FCU has only 3 tasks:
1. start the engine, and bring it to idle
2. Control the fuel acceleration schedule when the throttle is advanced/ retarded
3. limit N1 to 105%.
So, once you crack it to idle, it doesn't care where the throttle setting is until it reaches 58%, and then it looks around and says "Where is the throttle?"
If it sees it still fully open, then it will pour fuel in to make it accelerate and burn its @ss off. If it is at idle, it calmly sits at 62% or thereabouts, and waits for the throttle to move.
Once at idle: let it sit for a minute to calm down, then up to some setting past 70% to allow the Gen to be turned on without dragging the N1 back down below self-sustaining RPM.
Roll on the throttle gently, and the FCU controls the schedule nicely - the TOT will jump each time you open the throttle, let the N1 accelerate, then drop back to its normal setting.
On shutdown, make sure you close the throttle fully - I once had a sticky throttle cable, and after doing what I thought was a normal shutdown, I unstrapped, took off my helmet, and wondered why the blades weren't almost stopped, and what that strange noise was - the engine was still trundling along at 18% N1. Surprised the heck out of me.
Start: N1 accelerating through 13% and likely to pass 15%, snap to past idle so button pops up, gently roll back against the stop. Be aware that holding against the stop will make it difficult to shut it off in a hot start situation. You can in fact have the throttle fully OPEN at this stage without anything untoward happening.
This is because the N1 FCU has only 3 tasks:
1. start the engine, and bring it to idle
2. Control the fuel acceleration schedule when the throttle is advanced/ retarded
3. limit N1 to 105%.
So, once you crack it to idle, it doesn't care where the throttle setting is until it reaches 58%, and then it looks around and says "Where is the throttle?"
If it sees it still fully open, then it will pour fuel in to make it accelerate and burn its @ss off. If it is at idle, it calmly sits at 62% or thereabouts, and waits for the throttle to move.
Once at idle: let it sit for a minute to calm down, then up to some setting past 70% to allow the Gen to be turned on without dragging the N1 back down below self-sustaining RPM.
Roll on the throttle gently, and the FCU controls the schedule nicely - the TOT will jump each time you open the throttle, let the N1 accelerate, then drop back to its normal setting.
On shutdown, make sure you close the throttle fully - I once had a sticky throttle cable, and after doing what I thought was a normal shutdown, I unstrapped, took off my helmet, and wondered why the blades weren't almost stopped, and what that strange noise was - the engine was still trundling along at 18% N1. Surprised the heck out of me.
RFM all the way..................nothing else!!!
Saint Jack......who are You to tell me, or anyone of unwillingness to learn? that is the height of obnoxious arrogance 
After 24years in this game I'm still learning!!! 
(every day up here working these extreme altitudes) 
Following your statement I went out & double checked the throttle on our B206BIII - 9N-AII & there is NO 2 clicks......did You hear? No 2 clicks
it's likely some slop in the linkages but it was never designed with 2 clicks 
So please before You miss-lead or miss guide lower timers; follow the Rotorcraft Flight Manual procedures
Thank You & Happy Landings always
VF
After 24years in this game I'm still learning!!! (every day up here working these extreme altitudes) Following your statement I went out & double checked the throttle on our B206BIII - 9N-AII & there is NO 2 clicks......did You hear? No 2 clicks
it's likely some slop in the linkages but it was never designed with 2 clicks So please before You miss-lead or miss guide lower timers; follow the Rotorcraft Flight Manual procedures
Thank You & Happy Landings always
VF
Last edited by Vertical Freedom; 21st Jan 2014 at 13:19.
Saint Jack, point taken on the "I know it so why don't you?" attitude. But I *try* not to demonstrate the starting technique in a demeaning or condescending way - I just try to show 206B pilots what happens during the start sequence. And I do stress that you *cannot* try such shenanagins in anything but an aircraft equipped with the 250-C20 engine. But again, point taken.
During the start, some 206 pilots...especially low-time instructor pilots...open the 206 throttle with extreme caution. It's like they're scared of it. They just squeak it open very timidly to lightoff, sooooo sloooooowly as if going past lightoff might cause it to overtemp. Perhaps they believe that they can "modulate" the throttle (and therefore the TOT) or perhaps they believe that it's possible to "give it too much fuel" if you open too far. Both are incorrect.
About the clicks. I've been flying 206's since 1982. And you know what, I've never noticed two *clicks*. That's probably because some B-models I've flown didn't do that. Plus, they're irrelevant. What really matters in the start is that you open the throttle to lightoff and make sure it doesn't a) flame out, or b) overtemp. The *clicks* or the button have nothing to do with that. Fuel control linkage position (i.e. "throttle") is all that matters. Experienced 206 pilots know this.
Some pilots hold the both the starter button *and* the idle-release down during the start so they can roll it off easily if needed. Which is fine...as long as...you don't inadvertently let the throttle slip back a bit and flame out...and as long as...you remember to get the throttle *above* the detent at some point. Pilots who hold the idle-release button down during the start will NEVER hear any *clicks*.
We might note (and remember) that a few different aircraft use the C-20B engine. The idle-release mechanism in the H-500 and FH1100 are very different from the setup Bell uses. (I have no idea what they use in the Enstrom 480 or Soloy 47.)
A word about TOT peaks. Yes, there typically are two. But! I've seen some fuel controls that are set up with very high lightoff temps and rather cool derich (or acceleration) temps. This causes a start where there are no definable "peaks" in the TOT, just one "spike" toward the redline and a gradual decrease of TOT as the N1 comes up. Point being: They all start a little differently; each 250-series has its own "personality" if you will. Different does not mean better or worse. DO NOT write it up if you don't see two distinct TOT peaks. DO write it up if the TOT has a tendency to frequently go over the redline into the transient on most starts, both hot and cold.
People hyperventilate over starting a turbine. Yes, the financial risk is high if you screw up, but the procedure is neither difficult nor complicated. Best thing to do is RELAX. Here's what I do - here is your pre-start and start checklist - all you need to get a 206B running:
1) MAKE SURE the battery is on, the blade tiedown is off, the throttle is closed, the fuel valve is on. MAKE DOUBLY-SURE. Triply sure. The position of *any* other switch or circuit breaker does not matter at this point. "Battery, tiedown, throttle, fuel valve" is all you need. All that other stuff was put there by the lawyers and the FAA. Hydraulics off? Who cares. Generator on? Big deal. Worry about all that other crap *after* you get it going. This ain't the space shuttle.
2) Hit the starter button. There are three things you're going to look for in quick succession. As the N1 comes alive, WATCH THE TOT that it's not increasing. If it's not, good! Now check for the oil pressure to start coming up, and check that the main rotor blade is turning. This is why I leave the blade right out front. You'll see it start to turn before you introduce fuel and won't have to worry about it at the 25% N1 point (which, if it's *not* turning then you have to abort the start because you probably left the blade tiedown on LIKE I TOLD YOU TO CHECK). And why would you want to take your eyes off the TOT during a critical point in the start?! Get this checklist item out of the way early, BEFORE you light it off.
Okay, recap: Hit the starter button with your eye on the TOT, quick glance at the oil pressure gauge and then another quick glance up at the rotor blade. Easy-peasy. Now, back to the N1.
3) Okay, if the N1 is accelerating smartly, start opening the throttle around 13% so we get a lightoff at 15%. If you're already at 15% NO BIG DEAL. Light it off. Go right to the detent as previously described. Once it lights off, KEEP HOLDING THE STARTER BUTTON DOWN. You'd be surprised at how many piston pilots release the button at lightoff. Oops!
4) Once it lights off, simply monitor the TOT and be prepared to cut it off if it exceeds the redline for more than ten seconds or if it looks like it'll go past the dot or triangle. If it does go over the redline, start counting "one-thousand one, one-thousand two..."
5) If the engine is accelerating nicely, you can release the starter button at any time above 50%. I've seen some pilots who are fanatical and neurotic about holding that damn button down until 58% EXACTLY! It. Doesn't. Matter. Or, hold the button down longer if you want to! If the engine *isn't* accelerating nicely at this point, there's probably something wrong. Either it's very, very cold out or you probably should've used an APU or battery cart.
6) Once you've released the starter, goose the N1 up a bit so you're sure you're above the idle-release, and then come back down to idle and verify the N1 is 60-62%. Congratulations, you're done.
Back in the bad old days of 206A with 250 C-18 engines, if you turned the generator on right after the start, the load of the generator could drag the weak-a** compressor down below 58%, triggering the Engine-Out warning system. So Allison and Bell wisely insisted that you don't turn the generator on below 70% N1. This "problem" has been solved with the mighty C-20 series. Turning the generator on at 58% (usually) has no discernable effect on the N1. Trouble is, Bell never modified the start checklist, which still calls for you to sit at idle for one minute (if the engine is cold) before going to 70% to turn the generator on. Hey, better safe than sorry, I suppose.
Me? Once it's in a stable idle at 62%, I turn the generator on. Yes, yes, I watch the N1 and the loadmeter. If nothing bad happens, then I turn on all my other electrical consumers while I'm waiting for the one-minute warmup (and I do my anti-ice and idle hydraulic check too). This way, when the one-minute is up I'm ready to roll to 100%, do a quick hydraulic check and go. You can spend ten minutes getting a 206B ready for takeoff. You don't have to. (Again, it's not a 747.) There are a lot of things you can do while you're sitting there twiddling your thumbs for that minute.
Remember, the checklist is not a "do-list." Just get all of the items accomplished before you takeoff; it really doesn't matter in what order you do them, as long as they're done.
Starting a turbine might seem complicated, or "tricky" to the uninitiated. But it's a piece of cake, really. I didn't realize how good I had it until I started flying these old helicopters with a radial piston engine. You actually do need three hands to start a Sikorsky S-55. I'm going to suggest that we put the starter button on the floor...like where some modern ships have the remote copilot intercom button (or where the high-beam button used to be on old cars for you guys out there who are as old as me).
During the start, some 206 pilots...especially low-time instructor pilots...open the 206 throttle with extreme caution. It's like they're scared of it. They just squeak it open very timidly to lightoff, sooooo sloooooowly as if going past lightoff might cause it to overtemp. Perhaps they believe that they can "modulate" the throttle (and therefore the TOT) or perhaps they believe that it's possible to "give it too much fuel" if you open too far. Both are incorrect.
About the clicks. I've been flying 206's since 1982. And you know what, I've never noticed two *clicks*. That's probably because some B-models I've flown didn't do that. Plus, they're irrelevant. What really matters in the start is that you open the throttle to lightoff and make sure it doesn't a) flame out, or b) overtemp. The *clicks* or the button have nothing to do with that. Fuel control linkage position (i.e. "throttle") is all that matters. Experienced 206 pilots know this.
Some pilots hold the both the starter button *and* the idle-release down during the start so they can roll it off easily if needed. Which is fine...as long as...you don't inadvertently let the throttle slip back a bit and flame out...and as long as...you remember to get the throttle *above* the detent at some point. Pilots who hold the idle-release button down during the start will NEVER hear any *clicks*.
We might note (and remember) that a few different aircraft use the C-20B engine. The idle-release mechanism in the H-500 and FH1100 are very different from the setup Bell uses. (I have no idea what they use in the Enstrom 480 or Soloy 47.)
A word about TOT peaks. Yes, there typically are two. But! I've seen some fuel controls that are set up with very high lightoff temps and rather cool derich (or acceleration) temps. This causes a start where there are no definable "peaks" in the TOT, just one "spike" toward the redline and a gradual decrease of TOT as the N1 comes up. Point being: They all start a little differently; each 250-series has its own "personality" if you will. Different does not mean better or worse. DO NOT write it up if you don't see two distinct TOT peaks. DO write it up if the TOT has a tendency to frequently go over the redline into the transient on most starts, both hot and cold.
People hyperventilate over starting a turbine. Yes, the financial risk is high if you screw up, but the procedure is neither difficult nor complicated. Best thing to do is RELAX. Here's what I do - here is your pre-start and start checklist - all you need to get a 206B running:
1) MAKE SURE the battery is on, the blade tiedown is off, the throttle is closed, the fuel valve is on. MAKE DOUBLY-SURE. Triply sure. The position of *any* other switch or circuit breaker does not matter at this point. "Battery, tiedown, throttle, fuel valve" is all you need. All that other stuff was put there by the lawyers and the FAA. Hydraulics off? Who cares. Generator on? Big deal. Worry about all that other crap *after* you get it going. This ain't the space shuttle.
2) Hit the starter button. There are three things you're going to look for in quick succession. As the N1 comes alive, WATCH THE TOT that it's not increasing. If it's not, good! Now check for the oil pressure to start coming up, and check that the main rotor blade is turning. This is why I leave the blade right out front. You'll see it start to turn before you introduce fuel and won't have to worry about it at the 25% N1 point (which, if it's *not* turning then you have to abort the start because you probably left the blade tiedown on LIKE I TOLD YOU TO CHECK). And why would you want to take your eyes off the TOT during a critical point in the start?! Get this checklist item out of the way early, BEFORE you light it off.
Okay, recap: Hit the starter button with your eye on the TOT, quick glance at the oil pressure gauge and then another quick glance up at the rotor blade. Easy-peasy. Now, back to the N1.
3) Okay, if the N1 is accelerating smartly, start opening the throttle around 13% so we get a lightoff at 15%. If you're already at 15% NO BIG DEAL. Light it off. Go right to the detent as previously described. Once it lights off, KEEP HOLDING THE STARTER BUTTON DOWN. You'd be surprised at how many piston pilots release the button at lightoff. Oops!
4) Once it lights off, simply monitor the TOT and be prepared to cut it off if it exceeds the redline for more than ten seconds or if it looks like it'll go past the dot or triangle. If it does go over the redline, start counting "one-thousand one, one-thousand two..."
5) If the engine is accelerating nicely, you can release the starter button at any time above 50%. I've seen some pilots who are fanatical and neurotic about holding that damn button down until 58% EXACTLY! It. Doesn't. Matter. Or, hold the button down longer if you want to! If the engine *isn't* accelerating nicely at this point, there's probably something wrong. Either it's very, very cold out or you probably should've used an APU or battery cart.
6) Once you've released the starter, goose the N1 up a bit so you're sure you're above the idle-release, and then come back down to idle and verify the N1 is 60-62%. Congratulations, you're done.
Back in the bad old days of 206A with 250 C-18 engines, if you turned the generator on right after the start, the load of the generator could drag the weak-a** compressor down below 58%, triggering the Engine-Out warning system. So Allison and Bell wisely insisted that you don't turn the generator on below 70% N1. This "problem" has been solved with the mighty C-20 series. Turning the generator on at 58% (usually) has no discernable effect on the N1. Trouble is, Bell never modified the start checklist, which still calls for you to sit at idle for one minute (if the engine is cold) before going to 70% to turn the generator on. Hey, better safe than sorry, I suppose.
Me? Once it's in a stable idle at 62%, I turn the generator on. Yes, yes, I watch the N1 and the loadmeter. If nothing bad happens, then I turn on all my other electrical consumers while I'm waiting for the one-minute warmup (and I do my anti-ice and idle hydraulic check too). This way, when the one-minute is up I'm ready to roll to 100%, do a quick hydraulic check and go. You can spend ten minutes getting a 206B ready for takeoff. You don't have to. (Again, it's not a 747.) There are a lot of things you can do while you're sitting there twiddling your thumbs for that minute.
Remember, the checklist is not a "do-list." Just get all of the items accomplished before you takeoff; it really doesn't matter in what order you do them, as long as they're done.
Starting a turbine might seem complicated, or "tricky" to the uninitiated. But it's a piece of cake, really. I didn't realize how good I had it until I started flying these old helicopters with a radial piston engine. You actually do need three hands to start a Sikorsky S-55. I'm going to suggest that we put the starter button on the floor...like where some modern ships have the remote copilot intercom button (or where the high-beam button used to be on old cars for you guys out there who are as old as me).
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I was hoping to post this yesterday but Mrs. Saint Jack insisted that I take her shopping for the up-coming Chinese New Year festivities.
'FH1100'. I fully agree with 'Ready2Fly' - a great input and a good refresher for those who do not fly a 206 every day. I'm also happy to see that we're essentially on the same page. We're good.
'Vertical Freedom'. The information given in the RFM is sufficient to ensure safe operation of the helicopter - we all know this. In addition to knowing the contents of the RFM, pilots learn a vast amount of detail regarding the background of individual requirements - the 'how', 'why' and 'where for' - of their helicopter during the conversion training, from a training captains, from refresher training and from interacting with other pilots etc.
However there's always room for improvement and from time-to-time the information in the RFM will be complemented by additional detail as it becomes necessary - but not always in the form of an RFM revision. Often, such complementary information may appear as an Operational Safety Notice, an Information Letter or even an article in Rotorbreeze (although such an article generally seeks to add depth and clarity to a topic rather than announce specific requirement/s).
Nor does this complementary information solely originate from Bell, DDA/Allison/RR also publish information that goes to the heart of safe flight operations, for example Commercial Service Letter (CSL) No. 1176, 'Optimized Start Technique for Allison 250-C20 Series and C20R Series Engines' ought to be a must-read document for everyone associated with 206 Series helicopters. There's a lot of highly relevant information here that is not in the RFM.
Strict adherence to the RFM is quite right and proper - but not to the exclusion of supplementary information, wherever it may come from, that is aimed solely at broadening the knowledge of the pilot in order to ensure safer operation of the helicopter.
I'm now drawing a line under this topic, fly safe.
'FH1100'. I fully agree with 'Ready2Fly' - a great input and a good refresher for those who do not fly a 206 every day. I'm also happy to see that we're essentially on the same page. We're good.
'Vertical Freedom'. The information given in the RFM is sufficient to ensure safe operation of the helicopter - we all know this. In addition to knowing the contents of the RFM, pilots learn a vast amount of detail regarding the background of individual requirements - the 'how', 'why' and 'where for' - of their helicopter during the conversion training, from a training captains, from refresher training and from interacting with other pilots etc.
However there's always room for improvement and from time-to-time the information in the RFM will be complemented by additional detail as it becomes necessary - but not always in the form of an RFM revision. Often, such complementary information may appear as an Operational Safety Notice, an Information Letter or even an article in Rotorbreeze (although such an article generally seeks to add depth and clarity to a topic rather than announce specific requirement/s).
Nor does this complementary information solely originate from Bell, DDA/Allison/RR also publish information that goes to the heart of safe flight operations, for example Commercial Service Letter (CSL) No. 1176, 'Optimized Start Technique for Allison 250-C20 Series and C20R Series Engines' ought to be a must-read document for everyone associated with 206 Series helicopters. There's a lot of highly relevant information here that is not in the RFM.
Strict adherence to the RFM is quite right and proper - but not to the exclusion of supplementary information, wherever it may come from, that is aimed solely at broadening the knowledge of the pilot in order to ensure safer operation of the helicopter.
I'm now drawing a line under this topic, fly safe.
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On the maintenance side here. I've rebuilt many collective sticks/ throttle assemblies. There is only one stop on that throttle. It's a 'step' that holds the pin down and releases when you rotate.
As far as why the engine flamed out, beyond the rigging check, I noticed there were dual controls installed in the aircraft. Check that the dual collective is engaged correctly into the base slot.
The throttle is connected through the dual collective stick as well, and if the slot doesn't engaged perfectly, it will cause flame out.
As far as why the engine flamed out, beyond the rigging check, I noticed there were dual controls installed in the aircraft. Check that the dual collective is engaged correctly into the base slot.
The throttle is connected through the dual collective stick as well, and if the slot doesn't engaged perfectly, it will cause flame out.
1 lump or 2
Well there Yer go - ONE click.....Yes we must learn the quirks & uniqueness's of each & every machine machine we operate as Saint Jack rightly stated 
I have more than 4000 h 206 and i think i know what´s the meaning off 2 clicks.
If you turn the throttle very smoothly the spring comes for half a millimeter first, after that, the spring jumps in the whole engaged position......
But this fact has no influence in the fuel flow. i always say, the 206 has a digital fadac...there is only 1 or 0
If you turn the throttle very smoothly the spring comes for half a millimeter first, after that, the spring jumps in the whole engaged position......
But this fact has no influence in the fuel flow. i always say, the 206 has a digital fadac...there is only 1 or 0
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TQ gauge fluctuating question
On an L3, if I pull the collective aggressively at takeoff (1 POB or at MAUW) the TQ gauge flicks + and minus 5% as if the power is coming on then off. If I lower the collective to 30% or less for a few seconds then resume the flight, all's OK. Is this the FCU 'lagging' or a fault with the governor? If I take off "gently" then all vital signs are good.
The workshop has been unable to reproduce the problem. I can. Occasionally. Apologies if this question has been discussed before - I couldn't find it.
The workshop has been unable to reproduce the problem. I can. Occasionally. Apologies if this question has been discussed before - I couldn't find it.
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You don't mention any N2/Nr droop? I'd be surprised if it was the FCU since it does what it's told when in the governed range. But also for consideration is the lives of both PTG and FCU, as they mature the scheduling becomes less precise (though within prescribed limits). Poss, though doubtful, could be air in the torque gauge line? Would be very interested in anyone else's hypotheses - VFR
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fokker
it can depend upon what you are comparing it to. Also depends if you have a Bendix or Ceco, the ceco being slower to respond than the bendix i believe.
If you are trying to fly it like a 500, then the response will probably be called slow, however if you fly it like a 47 or 205, then it should respond pretty well. We don't have any problem with RPM droop, however we also fly ours like a big ol 205 without sudden collective changes and it all works out fine.
If you are getting RPM droop from gentle collective changes then go see your engineer.
it can depend upon what you are comparing it to. Also depends if you have a Bendix or Ceco, the ceco being slower to respond than the bendix i believe.
If you are trying to fly it like a 500, then the response will probably be called slow, however if you fly it like a 47 or 205, then it should respond pretty well. We don't have any problem with RPM droop, however we also fly ours like a big ol 205 without sudden collective changes and it all works out fine.
If you are getting RPM droop from gentle collective changes then go see your engineer.
Most of which can be rigged out unless the PTG is a duffer.
You should actually see a slight increase in N2 from flat pitch to hover as normal.
This is "droop compensation". Without it the following applies -
Clear now? 
You should actually see a slight increase in N2 from flat pitch to hover as normal.
This is "droop compensation". Without it the following applies -
Droop has many uses and applications in the control of engines.
Without some form of droop, engine-speed control would be unstable in most cases.
- Droop is defined as a decrease in speed setting at the load increases.
Droop is expressed as a percentage of the original speed setting from no load to full load.
The normal recommended percent of droop is 3% to 5%. A minimum of 2.5% is required to
maintain stability in a speed-droop governor.
If, instead of a decrease in speed setting an increase takes place, the governor is showing
negative droop. Negative droop will cause instability in a governor.
In a system without droop, a load increase will cause the engine to slow down. The governor will
respond by increasing the fuel until the engine has returned to the original speed.
Due to the combined properties of inertia and power lag, the engine speed will continue to increase
beyond the original speed setting, causing an overshoot in speed.
The governor again will respond to decrease speed to correct for the overshoot.
It will over-correct the speed in the other direction causing an undershoot.
This overcorrection of speed in both directions (instability) will amplify until the engine trips out on over-speed.
This instability problem can be eliminated with droop. As the load increases, the speed setting is decreased.
When the governor moves to correct for the speed decrease caused by the increased load,
it will be correcting to a lower speed setting. This lower speed setting prevents the speed from overshooting.
Without some form of droop, engine-speed control would be unstable in most cases.
- Droop is defined as a decrease in speed setting at the load increases.
Droop is expressed as a percentage of the original speed setting from no load to full load.
The normal recommended percent of droop is 3% to 5%. A minimum of 2.5% is required to
maintain stability in a speed-droop governor.
If, instead of a decrease in speed setting an increase takes place, the governor is showing
negative droop. Negative droop will cause instability in a governor.
In a system without droop, a load increase will cause the engine to slow down. The governor will
respond by increasing the fuel until the engine has returned to the original speed.
Due to the combined properties of inertia and power lag, the engine speed will continue to increase
beyond the original speed setting, causing an overshoot in speed.
The governor again will respond to decrease speed to correct for the overshoot.
It will over-correct the speed in the other direction causing an undershoot.
This overcorrection of speed in both directions (instability) will amplify until the engine trips out on over-speed.
This instability problem can be eliminated with droop. As the load increases, the speed setting is decreased.
When the governor moves to correct for the speed decrease caused by the increased load,
it will be correcting to a lower speed setting. This lower speed setting prevents the speed from overshooting.
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Fockerpilot asks can droop be adjusted on bendix system.
There is a precise rigging procedure in the Maintenance Manual. Tell your MRO what the symptoms are, and they should be able to identify whether it is a rigging or PTG problem.
You should be able to fly the JetRanger and LOngRanger without constantly using the "Beep" switch.
Bell have a website where you can ask questions about their product and receive advice to rectify issues. Bell publications and access to web data is free.
What Fockerpilot is referring to in post 1235 is static droop, which is acceptable in the hydromechanical governing system on the Bell 206 series. If it is more that .5 to 1 percent before it resets back to the selected RPM(100%), further investigation would be warranted.
There is a precise rigging procedure in the Maintenance Manual. Tell your MRO what the symptoms are, and they should be able to identify whether it is a rigging or PTG problem.
You should be able to fly the JetRanger and LOngRanger without constantly using the "Beep" switch.
Bell have a website where you can ask questions about their product and receive advice to rectify issues. Bell publications and access to web data is free.
What Fockerpilot is referring to in post 1235 is static droop, which is acceptable in the hydromechanical governing system on the Bell 206 series. If it is more that .5 to 1 percent before it resets back to the selected RPM(100%), further investigation would be warranted.
Last edited by owen meaney; 7th Jan 2015 at 08:10.
The PTG itself cannot be adjusted.
The rig of the droop compensation can and should be checked with the AMM as a few errors can be made although it may not be worth it.
PTG's get worn out, sticky through lube drying out, the jet faces and levers get worn through dirt. There is/was a jet cleaning procedure but ..................
Bendix PTG's commonly don't get to Overhaul period.
I would look at the history of the unit with respect to how much dirt, smoke or other pollutants it has eaten and also the calendar time installed on the aircraft
which would reflect condition of the lubricant.
All of which could point to a bad PTG. They run on air after all.
The rig of the droop compensation can and should be checked with the AMM as a few errors can be made although it may not be worth it.
PTG's get worn out, sticky through lube drying out, the jet faces and levers get worn through dirt. There is/was a jet cleaning procedure but ..................
Bendix PTG's commonly don't get to Overhaul period.
I would look at the history of the unit with respect to how much dirt, smoke or other pollutants it has eaten and also the calendar time installed on the aircraft
which would reflect condition of the lubricant.
All of which could point to a bad PTG. They run on air after all.