starter/gen in alison c20 engines
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starter/gen in alison c20 engines
I looked in my bell training book and couldnt find it. I would swear that I had been told that the Starter/gen on the 250 series eng wont start (iginte) when in the gen position? Is this ture.
The exapmle given was if you had a simple eng failure (assume no re-ignite), and had ample time, you could flip the gen swith off and it the starter button.
How about other starter/gen like the one on the astar?
Anyone
thanks
RB
The exapmle given was if you had a simple eng failure (assume no re-ignite), and had ample time, you could flip the gen swith off and it the starter button.
How about other starter/gen like the one on the astar?
Anyone
thanks
RB
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Well definatly the EC120 and from memory the as350 standard starting procedure is to start with the gene in the on position. never did fly a 206.
they dont have allisons though
they dont have allisons though
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I would swear that I had been told that the Starter/gen on the 250 series eng wont start (iginte) when in the gen position? Is this ture.
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The engine will start with the Starter / Generator switch selected to GEN.
The problem with this is that as soon as you release the starter button at 58% , the generator will come on line, with the possibility that it will drag the engine below idle!!!
Thats why we normally wait the minute, then up to 70% , then GEN on !!
Well thats my understanding of it!!!!
The problem with this is that as soon as you release the starter button at 58% , the generator will come on line, with the possibility that it will drag the engine below idle!!!
Thats why we normally wait the minute, then up to 70% , then GEN on !!
Well thats my understanding of it!!!!
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In which aircraft is this C-20 engine installed? I would agree with Shawn's reply. Unless there is an aircraft specific electrical configuration notwithstanding, when the pilot engages the starter circuit, the generator switch position (on or off) should not prohibit the starter from functioning. In some aircraft the engine may start slower with the generator switch in the on position.
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Courtesy of Integrated Publishing
Igniter Circuit
Starter Circuit
Generator and DC Bus
OK it's for an AH-1 but it will show you the workings. A 206 obviously has a lot less parts. If you dredge around you will see in this case the ignition is completely seperate.
Interesting web site.
Igniter Circuit
Starter Circuit
Generator and DC Bus
OK it's for an AH-1 but it will show you the workings. A 206 obviously has a lot less parts. If you dredge around you will see in this case the ignition is completely seperate.
Interesting web site.
There are a lot of things about the "standard-issue" 206 that people don't completely understand. Having the throttle open will not prevent a start attempt (heh, but you better be quick to react !). They will start quite happily with the boost pumps off. Similarly, they'll start right up with the de-ice/anti-ice valve on. They'll start (sort of) with the fuel valve "Off." Heck, they'll even start with the rotor brake on (or alternatively, the main rotor blade securely tied down).
The reality is, as others have pointed out, that the Allison 250-series will absolutely start with the Generator switch in the "ON" position. Yes, as soon as you release the starter button, the generator will start generating. No, it won't effect a thing...in most cases.
Excuse me while I slip into my "grizzled old-timer" mode:
Back in the bad old days...when our 206A's had weak-ass C-18 engines with weak-ass NiCad batteries, the generator load could possibly drag the N1 down below 58% if you turned it on prematurely - like right after start. So we let the starter cool for a minute, then goosed the N1 up to 70% before making it switch over to be a generator. However, with modern batteries and stronger engines, this is simply not a problem.
If you watch most 206 pilots, few release the starter right exactly at 58% anyway. Some keep it depressed right to 62% and nothing bad happens. It's hard to hit that 58% mark, especially if the engine is accellerating rapidly. If that is the case, once it gets over 50% I release the button. Usually it'll be right at 58% or so when the button unclicks. But who cares, it's not *that* important.
Leave the generator switch in the "ON" position all the time and it won't hurt a thing. At least you'll never forget to turn it on. And in a 206B there is no caution light to remind you that you didn't (oops! - raise your hand if you've never done this). However, leaving the generator on all the time is counter to the published checklist, and of course the Decel Check (in the C-20 series) is predicated with the generator off.
In multi-engine aircraft that use the Allison 250 engine, as soon as you start the second engine you can switch it immediately to "Generate" with no delay, no one-minute wait, and not even having to increase the N1 to 70%. This should tell us something.
The reality is, as others have pointed out, that the Allison 250-series will absolutely start with the Generator switch in the "ON" position. Yes, as soon as you release the starter button, the generator will start generating. No, it won't effect a thing...in most cases.
Excuse me while I slip into my "grizzled old-timer" mode:
Back in the bad old days...when our 206A's had weak-ass C-18 engines with weak-ass NiCad batteries, the generator load could possibly drag the N1 down below 58% if you turned it on prematurely - like right after start. So we let the starter cool for a minute, then goosed the N1 up to 70% before making it switch over to be a generator. However, with modern batteries and stronger engines, this is simply not a problem.
If you watch most 206 pilots, few release the starter right exactly at 58% anyway. Some keep it depressed right to 62% and nothing bad happens. It's hard to hit that 58% mark, especially if the engine is accellerating rapidly. If that is the case, once it gets over 50% I release the button. Usually it'll be right at 58% or so when the button unclicks. But who cares, it's not *that* important.
Leave the generator switch in the "ON" position all the time and it won't hurt a thing. At least you'll never forget to turn it on. And in a 206B there is no caution light to remind you that you didn't (oops! - raise your hand if you've never done this). However, leaving the generator on all the time is counter to the published checklist, and of course the Decel Check (in the C-20 series) is predicated with the generator off.
In multi-engine aircraft that use the Allison 250 engine, as soon as you start the second engine you can switch it immediately to "Generate" with no delay, no one-minute wait, and not even having to increase the N1 to 70%. This should tell us something.
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Naive question time...wasn't there a thread on here several months ago on a related topic, which implied that if you left the gen switch on, the starter would turn into a generator the instant you let go of the button? The reversal of the load (from driving the engine to being driven by the engine) could break the quill shaft. Then again, I could be getting forgetful.
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I have had various discusion regarding this after I went for a Job on the 355 at east mids he wanted both engines up and running at flight idle before switching the generators on
my training at PAS was to take the engine to 70% ng on which ever engine you where starting first then generator and invertor on then start the second engine and when at 58% Ng and self sustained generator and invertor on, and as PPrune states above no 1 minute delay
the discusion following meeting Nigel and checking with PAS was that in the early models there was a problem with the quill shaft breaking should the generators be switched on before flight idle but AS modified things and the above procedure was then in order. 70% ng was as discussed above due to pos ng droop.
Th AS flight manual still has take the engines to flight idle before generator on but i have been asured that there is a supliment for cover the reasons explained above
This is my interpriotation of what I was tought.
Regards
Bravo 99 (AJB)
my training at PAS was to take the engine to 70% ng on which ever engine you where starting first then generator and invertor on then start the second engine and when at 58% Ng and self sustained generator and invertor on, and as PPrune states above no 1 minute delay
the discusion following meeting Nigel and checking with PAS was that in the early models there was a problem with the quill shaft breaking should the generators be switched on before flight idle but AS modified things and the above procedure was then in order. 70% ng was as discussed above due to pos ng droop.
Th AS flight manual still has take the engines to flight idle before generator on but i have been asured that there is a supliment for cover the reasons explained above
This is my interpriotation of what I was tought.
Regards
Bravo 99 (AJB)
Last edited by Bravo 99 (AJB); 12th Apr 2004 at 21:57.
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Good post, PPFan 
Bravo 99 - we tried that at Cougar, out of curiosity, and to try and standardise because we had a 206 as well and a junior pilot - the end result of starting as AS 355 the jetranger way was a generator light on almost all the time - it doesn't like it at all. Starting the second engine with gen on is correct.
Phil
Bravo 99 - we tried that at Cougar, out of curiosity, and to try and standardise because we had a 206 as well and a junior pilot - the end result of starting as AS 355 the jetranger way was a generator light on almost all the time - it doesn't like it at all. Starting the second engine with gen on is correct.
Phil
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Hi phil
This is where i got a bit lost really becouse the manual says to startengine no 2. Proceed as for no one engine generator not engaged when engine is running at idle speed engage both generators pre mod 1732 lights out.
Although i have been advised that the sup is in the manual i dont have the sup in the manaul i have would i be correct then in thinking that the procedure is an operator SOP rather that the a full AS mod
obviously when you work for a specific operator you go by his ops manual but my thinking is still not clear as to right our wrong
but as i said you would work to the Operators ops manual but it would be nice to find the correct answer.
Regards
Bravo 99 (AJB)
This is where i got a bit lost really becouse the manual says to startengine no 2. Proceed as for no one engine generator not engaged when engine is running at idle speed engage both generators pre mod 1732 lights out.
Although i have been advised that the sup is in the manual i dont have the sup in the manaul i have would i be correct then in thinking that the procedure is an operator SOP rather that the a full AS mod
obviously when you work for a specific operator you go by his ops manual but my thinking is still not clear as to right our wrong
but as i said you would work to the Operators ops manual but it would be nice to find the correct answer.
Regards
Bravo 99 (AJB)
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If I remember correctly, our book said to turn the first generator on after starting the second engine, but I seem to remember the factory guy having them on, or even switching something off - as you said, it gets a bit confusing! It was a long time ago.....
Phil
Phil
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from what I remember from my type course,is that the gen switch moves the starter to gen mode.Hitting the start button sets the autorelight off.On the 500,there is a situation where the starter hangs at 40%.the starter and gen get hooked together,and slow the process..the minute wait is to allow the voltage in the nicad battery to recover.
Last edited by lamanated; 17th Apr 2004 at 03:13.
