Throttle setting for gear warning

[Dream to fly]

My throttle cable is coming loose and is causing the gear warning to come on at 20inhg.  Is there a factory setting parameter?   The set screw has been tightened all over the place and I am tempted to replace the whole dam thing but I'd like to have a set point that is correct and not guessing like it appears has been done in the past.  

[carusoam]

J,

there is a really good thread that includes pics around here somewhere…

the micro switch is right on the throttle under the panel…

It is essentially a position warning that equates to an MP…

The maintenance manual probably has the MP range that is recommended… 

Should be easy to adjust unless something is worn or fallen apart…

Search user supplied parts for best way to replace the throttle control… (done often around here)

PP thoughts only, not a mechanic…

Best regards,

-a-

[EricJ]

Your POH or SM should have the adjustment spec, but it's typically a Manifold Pressure setting.   I had to replace my switch and just guessed initially based on throttle position and then adjusted it a little bit from there after flying it a few times.   It is not a precision adjustment.

 

[Jim Peace]

Throttle cable loose?

[TheAv8r]

I recently had a new throttle cable installed in my E and had the A&P set the gear warning to 10" MP. It's on page 38 of the E POH "The gear warning horn may be checked in flight by retarding the throttle with the gear up. The horn should sound at about 10 inches Hg manifold pressure."

[RobertGary1]

7 hours ago, jacenbourne said:

I recently had a new throttle cable installed in my E and had the A&P set the gear warning to 10" MP. It's on page 38 of the E POH "The gear warning horn may be checked in flight by retarding the throttle with the gear up. The horn should sound at about 10 inches Hg manifold pressure."

I thought it was 12”

[Hank]

41 minutes ago, RobertGary1 said:

I thought it was 12”

It is on my C.

[Dream to fly]

Thanks for the numbers. I didn't find it in the POH but after spending some time drinking with the cable and the switch I have gotten it to settle in at 14 in. I think a new cable will be needed to get it to stay because where the set screws rest is completely messed up. The last owner was just a hack. But I did accomplish getting my overhead lights to illuminate the instrument panel

Sent from my E6910 using Tapatalk

[47U]

6 hours ago, Dream to fly said:

I have gotten it to settle in at 14 in.

There was a SB to replace the engine controls, SB M20-174, which says 11 to 13 inches manifold pressure.  I’ve seen reference in a different SB to adjust it at 3/8” from idle cutoff.  If you like it at 14” no one will be the wiser.  Fly on!

[Hank]

7 hours ago, Dream to fly said:

. . . .after spending some time drinking with the cable and the switch . . . .

Sounds like a fun troubleshooting experience! 

[TheAv8r]

11 hours ago, RobertGary1 said:

I thought it was 12”

Maybe it's different from the E to the C? Doesn't make much sense to me, but here's from the POH. The SB quoted in this thread is likely the more accurate source.

[Hank]

9 minutes ago, jacenbourne said:

Maybe it's different from the E to the C? 

Probably related to the different engines, 200hp E vs. 180hp C. They're probably similar ppwer outputs.

[philiplane]

setting to the higher end of the range is better. There are days when you might be carrying 11-12 inches on short final, and there would be no warning horn if you left the gear retracted. 12 inches is about the lowest you want to set the switch. 

[AIREMATT]

1 hour ago, 47U said:

There was a SB to replace the engine controls, SB M20-174, which says 11 to 13 inches manifold pressure.  I’ve seen reference in a different SB to adjust it at 3/8” from idle cutoff.  If you like it at 14” no one will be the wiser.  Fly on!

This is for 1966-1968 F model if that matches your F.

[Skates97]

An easy way to set it where you want is go up and fly, pull the throttle back to 11-13", wherever you want it set, and make a little mark on it with a sharpie. Once back on the ground simply pull the throttle out to where your mark is and adjust the switch so that is where it comes on. Along with some of the comments above about setting it higher than lower I have mine set at 13".

[RobertGary1]

1 hour ago, Skates97 said:

An easy way to set it where you want is go up and fly, pull the throttle back to 11-13", wherever you want it set, and make a little mark on it with a sharpie. Once back on the ground simply pull the throttle out to where your mark is and adjust the switch so that is where it comes on. Along with some of the comments above about setting it higher than lower I have mine set at 13".

On the quadrant there is a hole for a screwdriver. I find its not too hard to adjust it in flight at altitude.

[AIREMATT]

10 hours ago, Skates97 said:

An easy way to set it where you want is go up and fly, pull the throttle back to 11-13", wherever you want it set, and make a little mark on it with a sharpie. Once back on the ground simply pull the throttle out to where your mark is and adjust the switch so that is where it comes on. Along with some of the comments above about setting it higher than lower I have mine set at 13".

That’s exactly how we did my C a few years back after some work on it. Simple to do and no chance of bungling something while flying at the same time.

Dan

[Don Gates]

Mine is set at 13” .  It was a bit of trial and error but not too hard….

[R-Banger]

On 12/17/2021 at 9:13 AM, Skates97 said:

An easy way to set it where you want is go up and fly, pull the throttle back to 11-13", wherever you want it set, and make a little mark on it with a sharpie. Once back on the ground simply pull the throttle out to where your mark is and adjust the switch so that is where it comes on. Along with some of the comments above about setting it higher than lower I have mine set at 13".

This is exactly how I went about it. Mine goes on at 12" now and it is perfect.

[M20F-1968]

While you are considering the 50 year old factory gear warning system, consider installing the P2 gear warning system (and likely the Laser Landing Height System seen on this forum by MicroKit).  They are both worth the time and expense and they will add valuable info.

John Breda

[Fly Boomer]

https://www.p2inc.com/

[Fly Boomer]

https://www.p2inc.com/wp-content/graphics/matrix-aas/6601_usersguide%200507.pdf

[MBDiagMan]

On 12/16/2021 at 12:37 PM, carusoam said:

J,

there is a really good thread that includes pics around here somewhere…

the micro switch is right on the throttle under the panel…

It is essentially a position warning that equates to an MP…

The maintenance manual probably has the MP range that is recommended… 

Should be easy to adjust unless something is worn or fallen apart…

Search user supplied parts for best way to replace the throttle control… (done often around here)

PP thoughts only, not a mechanic…

Best regards,

-a-

Yes, there is a good thread with pictures.  I took and posted most of those pictures.  If you search under my moniker in a date range of late 2018 I think you will find it.  I finally figured out what was wrong that was keeping my from getting it right, but I can’t remember the solution. I’m pretty sure I posted the solution on that thread.

As far as the MP setting, I think mine goes off at about 12.5” as seen on the JPI.

Hope this helps.

[MBDiagMan]

Here’s the thread.  My problem was incorrect cable connection under the engine.

Hope this helps.

[Bob R]

On 12/16/2021 at 9:50 AM, Dream to fly said:

My throttle cable is coming loose and is causing the gear warning to come on at 20inhg.  Is there a factory setting parameter?   The set screw has been tightened all over the place and I am tempted to replace the whole dam thing but I'd like to have a set point that is correct and not guessing like it appears has been done in the past.  

I’d have to look to be sure, but should come on at 12 or 14”.