This part in the checklist makes no sense to me

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JanF
Airman First Class
Posts: 83
Joined: 19 Oct 2018, 14:10

This part in the checklist makes no sense to me

Post by JanF »

The checklist says
Takeoff
6 Open throttles slowly to full throttle (with runaway turbo, THROTTLE BACK FIRST then move manifold pressure selector
to “0”).
Should I first apply full throttle and then move them back and also set the manifold selector to zero ?
That would cut the power to the engines right ?! So I we could not take off ?!

Gypsy Baron
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Joined: 02 Aug 2008, 17:04
Location: San Francisco

Re: This part in the checklist makes no sense to me

Post by Gypsy Baron »

That portion of the post refers to a runaway turbo situation, not a normal takeoff. Note the parenthesis.

Paul

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JanF
Airman First Class
Posts: 83
Joined: 19 Oct 2018, 14:10

Re: This part in the checklist makes no sense to me

Post by JanF »

Gypsy Baron wrote: 27 May 2021, 18:03 That portion of the post refers to a runaway turbo situation, not a normal takeoff. Note the parenthesis.

Paul

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So that is an aborted take off.
What is a runaway turbo situation ?

Gypsy Baron
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Posts: 3396
Joined: 02 Aug 2008, 17:04
Location: San Francisco

Re: This part in the checklist makes no sense to me

Post by Gypsy Baron »

Yes, the runaway turbo would be cause for an aborted takeoff. Or in flight, the shut down and feathering of the engine experiencing the runaway turbo.

I don't recall exactly what the indications were the last time I experienced a runaway turbo. Either the MP or RPM for that engine went to maximum, or a very high reading, and was uncontrollable.

Paul

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Masterius
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Re: This part in the checklist makes no sense to me

Post by Masterius »

JanF wrote: 28 May 2021, 06:17 What is a runaway turbo situation ?
When it happened to me, the manifold pressure went over 50 (maybe even up to 60; I just remember it being wayyyy too high), and adjusting the manifold pressure selector down to zero did little to nothing to lower the manifold pressure. I had to throttle back almost to zero to get the manifold pressure down. If I remember correctly, the waste gate had failed and needed replacing, so throttling back and adjusting the manifold pressure dial to zero did not reset the runaway turbo.
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alan CXA651
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Joined: 15 Mar 2016, 08:23

Re: This part in the checklist makes no sense to me

Post by alan CXA651 »

Hi .
I can confirm the MP is the gauge that goes to max , shutting down and feathering of prop is the course of action on the effected engine .
If I get a message of runaway turbo , I will throttle all engines back momentarily , to see which one does not respond , so I don’t shut down the wrong engine by mistake .
Regards Alan. 8)
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