Takeoff RPM Overpower

[Carbon8]

Hey guys,

Just curious I have noticed lately on takeoff my RPM will go into the redzone, I have a CGR-30P engine monitor for RPM and on takeoff once airspeed gains the RPM will go to 2740RPM. I just twist the prop back a bit to get it back to 2700RPM. 

Just wondering if this is a concern? Could it be due to cold weather flying making more power than standard? 

Thoughts? 

 

Thanks

 

 

[carusoam]

C8,

You might want to have your prop control/governor looked at... and adjusted...

The 2700 rpm redline has some serious guidelines about what overspeed is and what needs to be done after you have experienced it...

You have enough going on at T/O to manually adjust the controls each time...

As far as being temperature related...it shouldn’t be... typically rpm gets checked once a year at annual and should stay on target the whole year...

Yes, the plane makes more power when it is cold... but, the gov’s job is to maintain a set rpm....

Often Some blips occur on high tech engine monitors during the T/O run...  the mechanical governor has some lead/lag issues related to being a mechanical device during acceleration...   so the alarm goes off but the rpm still settles in at 2700rpm...

So... If more than a blip, and you control it by adjusting the knob.... show your mechanic exactly how much you adjust the knob to get 2700rpm... this will minimize the research work and test flying he may need to make...

PP thoughts only, not a mechanic...

Best regards,

-a-

[Yetti]

First thing is to verify.  The phone apps are pretty good at verifying.

[Carbon8]

Verify what Yetti?

[ArtVandelay]

Verify what Yetti?

RPM gauge is accurate I think.


Tom

[Carbon8]

How would a phone app verify RPM? 

Other question is would this even be noticeable on an analog gauge, I only notice it because its digital and flashes red, but on an analog is 40RPM even a noticeable mark

[orionflt]

check your prop governor by going to full rpm while in cruise and start a decent, see if your rpm increases above 2700, if it doesn't then the governor is set correctly.

40 RPM on take off is not a concern, your low pitch stop may need to be tweaked.

Brian

[Davidv]

4 minutes ago, Carbon8 said:

How would a phone app verify RPM? 

Other question is would this even be noticeable on an analog gauge, I only notice it because its digital and flashes red, but on an analog is 40RPM even a noticeable mark

Maybe there’s something wrong with my plane but it always goes above the red line on takeoff until I dial it back once over 500 ft.  Since my gauge is analog and everything else acts/sounds normal, I chalked it up to an imprecise indicator or the redline on the gauge not perfectly calibrated...

Let me know if anyone thinks this is more serious than I’ve assumed

[Carbon8]

55 minutes ago, orionflt said:

check your prop governor by going to full rpm while in cruise and start a decent, see if your rpm increases above 2700, if it doesn't then the governor is set correctly.

40 RPM on take off is not a concern, your low pitch stop may need to be tweaked.

Brian

Brian,

Will try this, I normal use 2600RPM for all other stages of flight and it never moves regardless of climb, cruise, or decent. Will set it to 2700 and check but so far I have only ever had it happen on takeoff. 

 

[Shadrach]

2 hours ago, Carbon8 said:

How would a phone app verify RPM? 

Other question is would this even be noticeable on an analog gauge, I only notice it because its digital and flashes red, but on an analog is 40RPM even a noticeable mark

 

These work beautifully from the cockpit of a Mooney. While not certified, they are as accurate as anything on the market 

https://www.amazon.com/Hangar-Micro-Digital-Tachometer-HAN156/dp/B0006N72U2/ref=asc_df_B0006N72U2/?tag=hyprod-20&linkCode=df0&hvadid=312697294768&hvpos=1o1&hvnetw=g&hvrand=11392890202001130439&hvpone=&hvptwo=&hvqmt=&hvdev=t&hvdvcmdl=&hvlocint=&hvlocphy=9008037&hvtargid=pla-568348828936&psc=1

[jetdriven]

First flight of the day, a few RPM overspeed seems to be normal. In the maintenance manual it says to fly for five minutes with the prop control full forward and at cruise speed. Then note the RPM and adjust it. Hartzell governors are about 25 to 30 RPM for 1 turn of the adjustment screw, fyi for your Mechanic. 

Edited March 7, 2019 by jetdriven

[Yetti]

13 hours ago, Carbon8 said:

How would a phone app verify RPM? 

Other question is would this even be noticeable on an analog gauge, I only notice it because its digital and flashes red, but on an analog is 40RPM even a noticeable mark

By sound.  Pop pop Pop divide by the number of cylinders.  The RC optical ones are pretty accurate also.  They use the propeller spinning by and divide by 2 or  how ever many blades.

[jaylw314]

13 minutes ago, Yetti said:

By sound.  Pop pop Pop divide by the number of cylinders.  The RC optical ones are pretty accurate also.  They use the propeller spinning by and divide by 2 or  how ever many blades.

Do the RC optical ones work while sitting in the cockpit?  I have one, I hadn't thought about using it.  

[Culver LFA]

The rc prop tach works great from the cockpit, I have the same one in my Mooney toolbox.  I think it is one of my most loaned out tools to the neighborhood 

[0TreeLemur]

14 hours ago, Davidv said:

Maybe there’s something wrong with my plane but it always goes above the red line on takeoff until I dial it back once over 500 ft.  Since my gauge is analog and everything else acts/sounds normal, I chalked it up to an imprecise indicator or the redline on the gauge not perfectly calibrated...

Let me know if anyone thinks this is more serious than I’ve assumed

Mechanical tachs tend to run slow as they age.  It is unusual for one to read erroneously high.  I like the suggestion by @Yetti that you verify using another means.

[Yetti]

3 hours ago, jaylw314 said:

Do the RC optical ones work while sitting in the cockpit?  I have one, I hadn't thought about using it.  

Worked sitting in the right seat

[jaylw314]

1 minute ago, Yetti said:

Worked sitting in the right seat

Hah!  I looked at the amazon link you sent, and it looks very similar to my RC optical tach.  I'll give it a try, thanks!

[Guest]

Here is what a Lycoming says about overspeed.

Clarence

https://www.lycoming.com/sites/default/files/SB369R Engine Inspection after Overspeed.pdf

[MikeOH]

Hmm, per that SB one is suppose to record ANY overspeed, even less than 5%???

I wonder how many 2740 rpm overspeeds (2700 rpm redline) get recorded in the engine log?

[jaylw314]

41 minutes ago, MikeOH said:

Hmm, per that SB one is suppose to record ANY overspeed, even less than 5%???

I wonder how many 2740 rpm overspeeds (2700 rpm redline) get recorded in the engine log?

I read it as IF the definition of momentary overspeed (>10% OR > 3 sec) is exceeded, then any overspeed (even if less than 5%) needs to be recorded.

[Bryan]

wrong thread - deleted

[PR474]

First flight of the day, a few RPM overspeed seems to be normal. In the maintenance manual it says to fly for five minutes with the prop control full forward and at cruise speed. Then note the RPM and adjust it. Hartzell governors are about 25 to 30 RPM for 1 turn of the adjustment screw, fyi for your Mechanic. 

How about for MaCauley prop? Also which way do you turn the screw to increase rpm?

Thanks, Paul


Sent from my iPad using Tapatalk

[Hank]

Turn clockwise to move forward. Moving forward increases RPM.

It's even easier in my C:  push the lever forward to increase RPM. Nothing turns except the altimeter and artifical horizon setting knobs and, of course, the yokes.