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Author Topic: Power lever position on engines start  (Read 363 times)

Roberto Serrano

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Power lever position on engines start
« on: December 17, 2022, 01:16:06 pm »
Why in some Commanders model you start the engines with the power lever just a little aft of flight idle. With Commanders with Bendix FCU start the power lever flight idle and the Woodward FCU just a little aft of flight idle. What is the technical o mechanical reason for that ?
Roberto Serrano

donv

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Re: Power lever position on engines start
« Reply #1 on: December 17, 2022, 03:21:06 pm »
I'm not sure I can give a full technical explanation (need Barry Lane to do that), but the critical thing in starting a 331 engine is that the props not slip off the start locks. So, if you were to have the power lever too far back, as oil pressure starts to come up, it is possible to cause that to happen.

Starting at flight idle is always safe from that perspective, with either Bendix or Woodward.

However, the difference between Bendix and Woodward is that at flight idle on the ground, with the condition levers in LOW RPM, the Bendix will be at about 65% and the Woodward will be at about 90%. So if you start a Woodward at flight idle (which is perfectly fine), you have to remember to pull it back as it goes through 65-70%, or it will go up to 90% and make a bunch of noise.

Does that answer your question?

Roberto Serrano

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Re: Power lever position on engines start
« Reply #2 on: December 18, 2022, 11:54:45 pm »
ThanksÖ
Roberto Serrano

donv

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Re: Power lever position on engines start
« Reply #3 on: December 19, 2022, 12:07:06 am »
Glad you are here! Please ask any other questions you think of.

Roberto Serrano

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Re: Power lever position on engines start
« Reply #4 on: December 19, 2022, 07:21:11 pm »
If I have other question Iíll do.
Roberto Serrano

Bruce Byerly

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Re: Power lever position on engines start
« Reply #5 on: December 20, 2022, 11:08:38 pm »
I'm not sure I can give a full technical explanation (need Barry Lane to do that), but the critical thing in starting a 331 engine is that the props not slip off the start locks. So, if you were to have the power lever too far back, as oil pressure starts to come up, it is possible to cause that to happen.

Starting at flight idle is always safe from that perspective, with either Bendix or Woodward.

However, the difference between Bendix and Woodward is that at flight idle on the ground, with the condition levers in LOW RPM, the Bendix will be at about 65% and the Woodward will be at about 90%. So if you start a Woodward at flight idle (which is perfectly fine), you have to remember to pull it back as it goes through 65-70%, or it will go up to 90% and make a bunch of noise.

Does that answer your question?

I believe Bendix should idle at 70%. I agree with the rest but havenít had a prop slip off the locks myself, just know that it will get hot if itís left in reverse calling for negative blade angle.  That seems the most common mistake. Seems intuitive.  For Woodward, starting where the NTS test light barely comes on should gone about right to idle close to 65-70% right?

Adam Frisch

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Re: Power lever position on engines start
« Reply #6 on: December 24, 2022, 07:32:29 am »
You guys with the luxury of NTS lights... ;)
Slumming it in the turboprop world - so you don't have to.

donv

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Re: Power lever position on engines start
« Reply #7 on: December 24, 2022, 07:24:53 pm »
Does the 680V not have NTS lights?

I know on the Cheyenne 400, they did away with them also... so if not, you are in good company!

Adam Frisch

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Re: Power lever position on engines start
« Reply #8 on: December 26, 2022, 05:03:51 am »
Nope, no NTS lights and no way to check on startup. Can't do a serial start either - it's always in parallel.
Slumming it in the turboprop world - so you don't have to.

donv

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Re: Power lever position on engines start
« Reply #9 on: December 26, 2022, 12:38:27 pm »
No series start is a bummer. I did a series start a couple of days go, because it was below freezing. I know you use GPUs a fair amount, and that is a decent substitute. In my case, I don't have anyone who could pull the GPU plug.

Bruce Byerly

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Re: Power lever position on engines start
« Reply #10 on: December 26, 2022, 10:03:32 pm »
Nope, no NTS lights and no way to check on startup. Can't do a serial start either - it's always in parallel.

The truth is the whole NTS test is a waste of time, money, resources and downtime since about 1976.  Iíve never seen an honest NTS system failure. Only that of the NTS test system.  But donít quote me on that!

Series starts are also mostly useless for most operators. But there again, itís essential to have the option. In my case, I donít want to be flying at the north or South Pole.  Anything from around 0C does fine on parallel with normal batteries and likely down to 0F.

donv

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Re: Power lever position on engines start
« Reply #11 on: December 26, 2022, 11:24:58 pm »
Bruce, what you are saying about the NTS system is exactly what I have heard from others as well! I was told that is why the Cheyenne 400 eliminated it. I suspect the 1200 would also not have had it.