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Engine mixture setting on landing


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Good morning, I have been reading Mooney space for months and find the information very helpful.  My son and I just purchased a 1966 M20E last month with my wife's blessing.  He is IFR rated pilot with 200 hours and I am an A&P but not a Mooney A&P.  (Big Difference).  The reason for buying is to get my son through his commercial training. After that I would like to get current again and use it for trips with my wife.

He has 23 hours since we purchased so I had him bring it from PHX Deer Valley airport about 1200 ft to Show Low AZ 6500 ft for an oil change and to let me look everything over.  This is where the story gets long but bear with me I want to make sure you have all of the information.  When he was flying up yesterday SOW airport had a NOTAM that the runways where closed for maintenance and they would open again at 7pm.  I had him land at Snowflake airport 10 miles away so we could bring the aircraft to SOW when it reopened at 7.  The flight from PHX to Snowflake was good with no problems.  However when we went to get the aircraft at 6:30 last night to ferry to SOW, about a 6 min flight, upon landing the engine died when we exited the run way. We tried a hot start procedure and it did not start so we did a flooded start and it fired back up but was running a little rough for a few seconds but then seemed to clean itself out and run smooth.

The aircraft does not have any engine monitoring system just the standard gauges.  Per the POH/Owner Manual the landing procedure is Mixture full rich and boost pump on, we left the aircraft in this configuration until we exited runway.  This is where I need your opinions, at 6500 ft is there another setting for fuel mixture?  I think the engine was flooded but not sure if it is something we did wrong or a problem with engine?  We are going in today to run it up and change oil but wanted any opinion on what else we might look for.

Thanks

 

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Not sure if this will pertain to your situation or not, but we used the “fat finger rule” when I was completing my PPL. Airport was at 3000 ASL, and the flight school rule was to lean it just a touch to prevent fouling. 

6500’ would lead me to believe you’re VERY rich on the mixture. 

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With an actual altitude or density altitude that high you do not want to go full rich. Remember carb heat also enritchens the mixture too. I've had mine sputter and pop on final because of it.

I have a digital egt and aim for 1250C. Or about an inch out on our mixture control.

You'll want to research high altitude operations. For example how to lean for takeoff. If you knew that setting, that's what you would want to use in the pattern for landing.

I'd also look to see the last time your carb was OH. A lot of people ignore it....don't!



Sent from my SM-G960U using Tapatalk

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Definitely too rich.  Do you at least have an EGT gauge?  For now I'll assume not.  However, I would encourage you to make a good engine monitor one of your first upgrades.  Here is what I would do without an engine monitor but be sure to get other opinions.

1.  Ground ops.  After start, lean to peak RPM or better yet, lean until the engine starts to stumble and then enrichen just enough to make it run smoothly.  You'll have to enrichen quite a bit in order to do the engine/mag check.  If you plan to sit on the ground more than a couple minutes after the engine check then lean back for ground ops.

2.  For takeoffs below about 2000' I'd use full rich.  Above that, assuming you have a vernier mixture, I probably lean by a twist or so for each additional 1000'.  For takeoffs up around 5000' or higher, I might do what John Deakin (Pelican's Perch) suggests.  Early in the takeoff roll, grab the mixture and move it fairly quickly back and forth and feel the power.  Let it settle where you feel the best power or a bit rich of that point.  If I you have an EGT gauge.  See what it says for takeoffs at SL (or 1200' if that is as low as you can get) and shoot for the same EGT on all takeoffs regardless of altitude.

3.  In cruise, you can use the old lean until you feel a loss of power/speed or engine roughness whichever comes first.  Then enrichen just enough to restore engine power/smoothness.

4.  Once I lean for cruise, I don't touch the mixture again until I am either performing a go-around or shutting down at the parking spot.  I also don't turn on the boost pump for landing but I don't think that will affect the mixture (but I could be wrong).  I think the boost pump on is more as a backup for your mechanical pump should it decide to fail in that one minute before landing while at low altitude after having worked just fine for a couple hours of cruising.  If I have to go around, I've trained myself to always go cowl flaps open, then mixture rich, then prop full forward, then throttle full forward.

Just my $.02 worth.

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33 minutes ago, Boilermonkey said:

With an actual altitude or density altitude that high you do not want to go full rich. Remember carb heat also enritchens the mixture too. I've had mine sputter and pop on final because of it.

I have a digital egt and aim for 1250C. Or about an inch out on our mixture control.

You'll want to research high altitude operations. For example how to lean for takeoff. If you knew that setting, that's what you would want to use in the pattern for landing.

I'd also look to see the last time your carb was OH. A lot of people ignore it....don't!



Sent from my SM-G960U using Tapatalk
 

E shouldn't have a carb

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28 minutes ago, Boilermonkey said:

Yeah, duh...whoops.    The leaning is still the solution to the OP's issue.

I agree. Most of my flying has been from and to airports at less than 1000' MSL. My wife and I flew to Pueblo, CO (around 4,600 MSL) last fall on a high DA day. We had to wait for TO clearance for about 5 minutes and since I was at my normal to me full rich, I experienced what I suspect was the onset of some plug fouling. Went as lean as I could and by the time I got clearance, it had straightened out. Richened mixture to 1250° EGT for take off and everything went fine.

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Hi JR!

We also recently bought a 66 E and we live in Flagstaff, with an actual elevation of 7000' and summer density altitudes close to 9000'. Although we've only had this plane for a couple of weeks, this is the second aircraft I've owned here with the IO-360. We lean aggressively during grounds ops and never use full rich for take off or landing... it's just too rich up here. I do turn on the boost pump, which shouldn't impact richness (I believe), and I lean out more when off the runway.

Happy AZ flying!

Ross and Kara

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RSA fuel injection systems meter fuel according to the volume of air passing through the venturi. The density of the air is lower at higher altitudes, so fewer molecules of air per given volume as you go up means the mixture gets richer as you climb. This is why we have to lean. When landing at high altitude airports, I leave the mixture at cruise or may enrich it slightly in case of a go around.

Idle mixture may still be too rich with this setting and the engine may still die at a high altitude airport if you close the throttle. The idle mixture is controlled for about the first half inch of throttle travel by the idle mixture valve which is mechanically linked to the throttle. You set the idle mixture by adjusting the length of the connecting linkage. Normally, this will be set for the elevation you normally operate. If that's sea level and you go to a high altitude airport, the idle mixture is going to be too rich and you may have to pull the manual mixture out quite a bit to get the engine to run properly. Also on startup, you don't want to go to full rich, or it will probably die on you.

Skip

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Ok, now that we’ve worked out his mixture issue, let’s focus on the important stuff:  He said he had his WIFE’S BLESSING.   Now he must learn the Principle of Compensatory Gifting.

Powerflo Exhaust?  Cowl mod? Engine monitor?  Heh heh she wants new furniture or other things... make sure you get that first.

Bet you had no idea you’d find that kind of advice here.  

Mooneyspace: strengthening marriages one Mooney at a time...

 

Edited by Aviationinfo
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Thanks for the advise and input everyone. We ran it up today and changed oil no problems, everything worked great.  We were just to rich for alt.

engine monitor is first on my wish list.

 

Russ I think we have twin 1966 M20E here in Arizona.

IMG_0106.PNG

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You’re an AP based at SOW? If so, I’d love to get your info! I fly in frequently (I have a cabin in Pinetop and leave a truck at the field year round).  Would be great to have a resource to reach out to if needed - like the time a magneto ate itself and I had to fly a mechanic up from Tucson!

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14 hours ago, ragedracer1977 said:

You’re an AP based at SOW? If so, I’d love to get your info! I fly in frequently (I have a cabin in Pinetop and leave a truck at the field year round).  Would be great to have a resource to reach out to if needed - like the time a magneto ate itself and I had to fly a mechanic up from Tucson!

Was the FBO not able to help with it?

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20 hours ago, ragedracer1977 said:

You’re an AP based at SOW? If so, I’d love to get your info! I fly in frequently (I have a cabin in Pinetop and leave a truck at the field year round).  Would be great to have a resource to reach out to if needed - like the time a magneto ate itself and I had to fly a mechanic up from Tucson!

i am an A&P but like I said not a Mooney Mechanic.  However, if you ever need help in SOW please look me up, we are in hangar #2 & #3 at the airport. Usually a helicopter sitting in front of the hangar door.  I do know some A&P's in the area who can help if we can not figure it out.

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Welcome aboard JR W.

For additional info regarding mixture setting for Best power...

Some people use what is called the EGT method for setting power... GSXer and a few others gave the basics for it...

It will really help to have an engine monitor for your high DA (density altitude) operations... a single EGT like you should have will work in a pinch....

Another thing that will be important for your health... performance charts and Density Altitude calculations...

Warming weather and airport altitudes of 6k’ are things to be very familiar with... a safety rule that got lost once before...

Best regards,

-a-

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Good evening,

I had the same thing happen to me on landing, 

1) Mixture full rich and electric boost pump on

what we found to be the problem was the electric boost pump was producing 

too much pressure(well above the red) and flooded out the carburetor,

replaced boost pump, problem went away. My engine quit three times

before we figured it out. Just a thought

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