Leaning Procedures Step by Step

[Max Clark]

Hi all,

This isn't a ROP vs LOP thread - so hoping not to start that battle. This is a "I've decided I want to run LOP what should my leaning procedures be from startup to shutdown?" question.

As background this started from reading articles by John Deakin (Numbers 8, 15, 16, 18, 19, 43, 63-66, 77 & 78 deal with engine management and running LOP), and Mike Busch (YouTube: Leaning Basics, Obsessed with EGT, Leaning The Advanced Class). Mike has a line, "I operate my engines brutally lean during ground ops and lean-of-peak exhaust gas temperatures during all phases of flight other than takeoff and initial climb" where the "brutally lean" stood out and stuck with me. What's interesting is how silent the POH is on leaning - with the exception of leaning to 1400-1450 EGT on takeoff for maximum performance.

I was taught to lean on ground, go full rich for run up and takeoff, keep full rich during climb until cruise altitude, set power & stabilize then lean, if climbing again full rich first then repeat leaning, and if decent gradually enrich on the way down. There's so much missing from this. Specifically:

1. After startup and during taxi what does "brutally lean" actually mean - just lean until engine roughness and then enrich until smooth?
2. Should run up be lean, or rich?
3. Or should run be full rich, and then during lean to best power (RPM rise) during?
4. Why not always lean to 1400-1450 on every single takeoff and climb?
5. When/how do you set mixture for the blue arc?
6. If climbing after cruise is set, full rich or keep leaned in the blue band?
7. Do something other than keep leaned durning descent until the GUMPS check?
8. After landing "brutally lean" again for taxi

I've tried to document various phases of flight to foster a discussion and procedures so they're captured on this thread. Looking forward to reading your thoughts.

-Max

As an interesting aside - I've stopped using lean finder on my EIS and am now using the big pull technique(still getting more comfortable with that). When I do I end up with EGT in the 1430-1460 range. It's almost like that number range is important or something ;).

[KSMooniac]

If you want to thoroughly understand everything that is happening with the red knob of death, you should strongly consider the www.advancedpilot.com seminar, which I believe online-only now.  You'll learn what happens and how to decide what to do in all phases, plus emergencies or trouble-shooting, far better than discussion forum debate.  And yes, it will turn into a debate before the 2nd page of the thread.    

I'm a LOP guy as well, and use the Target EGT method and Vz climb profile generally speaking, which includes leaning in the climb using the Target EGT.  I stay LOP until shut-down or go-around.

[Paul Thomas]

18 minutes ago, Max Clark said:

Hi all,

This isn't a ROP vs LOP thread - so hoping not to start that battle. This is a "I've decided I want to run LOP what should my leaning procedures be from startup to shutdown?" question.

As background this started from reading articles by John Deakin (Numbers 8, 15, 16, 18, 19, 43, 63-66, 77 & 78 deal with engine management and running LOP), and Mike Busch (YouTube: Leaning Basics, Obsessed with EGT, Leaning The Advanced Class). Mike has a line, "I operate my engines brutally lean during ground ops and lean-of-peak exhaust gas temperatures during all phases of flight other than takeoff and initial climb" where the "brutally lean" stood out and stuck with me. What's interesting is how silent the POH is on leaning - with the exception of leaning to 1400-1450 EGT on takeoff for maximum performance.

I was taught to lean on ground, go full rich for run up and takeoff, keep full rich during climb until cruise altitude, set power & stabilize then lean, if climbing again full rich first then repeat leaning, and if decent gradually enrich on the way down. There's so much missing from this. Specifically:

1. After startup and during taxi what does "brutally lean" actually mean - just lean until engine roughness and then enrich until smooth?
2. Should run up be lean, or rich?
3. Or should run be full rich, and then during lean to best power (RPM rise) during?
4. Why not always lean to 1400-1450 on every single takeoff and climb?
5. When/how do you set mixture for the blue arc?
6. If climbing after cruise is set, full rich or keep leaned in the blue band?
7. Do something other than keep leaned durning descent until the GUMPS check?
8. After landing "brutally lean" again for taxi

I've tried to document various phases of flight to foster a discussion and procedures so they're captured on this thread. Looking forward to reading your thoughts.

-Max

As an interesting aside - I've stopped using lean finder on my EIS and am now using the big pull technique(still getting more comfortable with that). When I do I end up with EGT in the 1430-1460 range. It's almost like that number range is important or something ;).

 

1. So lean that if I advance power past 1,000 RPM, the engine stumbles
2. Full rich because I'm typically at sea level.
3. I don't change mixture during the runup.
4. I lean to target EGT and stay there... the number in large part is immaterial as it could change from airplane to airplane. What I'm looking for is to keep a constant EGT during the climb.
5. I take it the blue arc is LOP? Once I'm cruise altitude and cruising speed, I then set power/mixture to cruise setting. That is not always LOP but I have a pretty good feel for it from muscle memory, sounds, and the fuel flow gauge is always helpful. I then use the JPI for fine tuning, but I don't use the lean find function, I find it easier to look at the raw data. For LOP/Peak, I come at it from the lean side, for ROP from the rich side.
6. I'll go back to full power at target EGT.
7. The only change I make for descent is to lower the RPM. GUMP is not part of my descent; it's part of my approach to landing/landing sequence.
8. Same as #1.

[Ragsf15e]

23 minutes ago, Paul Thomas said:

 

1. So lean that if I advance power past 1,000 RPM, the engine stumbles
2. Full rich because I'm typically at sea level.
3. I don't change mixture during the runup.
4. I lean to target EGT and stay there... the number in large part is immaterial as it could change from airplane to airplane. What I'm looking for is to keep a constant EGT during the climb.
5. I take it the blue arc is LOP? Once I'm cruise altitude and cruising speed, I then set power/mixture to cruise setting. That is not always LOP but I have a pretty good feel for it from muscle memory, sounds, and the fuel flow gauge is always helpful. I then use the JPI for fine tuning, but I don't use the lean find function, I find it easier to look at the raw data. For LOP/Peak, I come at it from the lean side, for ROP from the rich side.
6. I'll go back to full power at target EGT.
7. The only change I make for descent is to lower the RPM. GUMP is not part of my descent; it's part of my approach to landing/landing sequence.
8. Same as #1.

I agree with all of these, but 1 & 3 don’t work together.  You have to richen somewhat to do the runup, but it can still be very lean.  
The bottom line is that for low power settings (like 65% and less), you can’t hurt the engine no matter where you put the mixture as long as you maintain CHTs in proper temp with airspeed (cooling airflow).  Doing a lean runup is very low power.  It stress tests the ignition better than a full rich runup.

Target egt in climb is great.

I just descend at cruise power when it’s smooth and enjoy the speed!

[Alan Maurer]

Mooney People, I like ROP. Since  we fly Mooney Airplanes....these were meant to go FAST. I did try the LOP once and was cruising about 12 knots slower. And my plane is (or was) a TWO DX so I bought the STC to up the HP to 310 HP. Does it cruise faster....NO....but the take off roll is shorter

and the climb  out is better. This is Florida so air is hot and thin. I lean for taxiing before and after landing. I understand that low power setting and lean setting will not cause any problem. RPM on take off is 2700 RPM and at 1000 AGL I dial back to 2500 FPM. Usually manage TAS of 185 KTS

Blue Skies,                      (We love to fly...fast)

Alan

[Paul Thomas]

39 minutes ago, Ragsf15e said:

I agree with all of these, but 1 & 3 don’t work together.  You have to richen somewhat to do the runup, but it can still be very lean.  
The bottom line is that for low power settings (like 65% and less), you can’t hurt the engine no matter where you put the mixture as long as you maintain CHTs in proper temp with airspeed (cooling airflow).  Doing a lean runup is very low power.  It stress tests the ignition better than a full rich runup.

Target egt in climb is great.

I just descend at cruise power when it’s smooth and enjoy the speed!

I'm full rich during the runup (see #2); if I didn't change it from 1, the engine should have died. Sorry if it wasn't clear.

[Max Clark]

1 hour ago, KSMooniac said:

If you want to thoroughly understand everything that is happening with the red knob of death, you should strongly consider the www.advancedpilot.com seminar, which I believe online-only now.  You'll learn what happens and how to decide what to do in all phases, plus emergencies or trouble-shooting, far better than discussion forum debate.  And yes, it will turn into a debate before the 2nd page of the thread.    

I'm a LOP guy as well, and use the Target EGT method and Vz climb profile generally speaking, which includes leaning in the climb using the Target EGT.  I stay LOP until shut-down or go-around.

Thanks Scott I'll look this up.

[Max Clark]

26 minutes ago, Alan Maurer said:

Mooney People, I like ROP. Since  we fly Mooney Airplanes....these were meant to go FAST. I did try the LOP once and was cruising about 12 knots slower. And my plane is (or was) a TWO DX so I bought the STC to up the HP to 310 HP. Does it cruise faster....NO....but the take off roll is shorter

and the climb  out is better. This is Florida so air is hot and thin. I lean for taxiing before and after landing. I understand that low power setting and lean setting will not cause any problem. RPM on take off is 2700 RPM and at 1000 AGL I dial back to 2500 FPM. Usually manage TAS of 185 KTS

Blue Skies,                      (We love to fly...fast)

Alan

Also Ovation 2 IO-550-G and just did the HP STC. I try to fly 10k MSL WOT 2500 RPM LOP and get 165 TAS with about 10.7 GPH.

Curious what your FF is ROP - 20 KTS is a lot!

[Jackk]

Just remember the POH/AFM supersedes LOP ops

 

takeoff should always be max available power

 

as other said lean the snot out of it for taxi, it’s also a safety check, if you try to take off with that setting the engine should just quit 

[Max Clark]

12 minutes ago, Jackk said:

takeoff should always be max available power

FWIW my POH has "Check and Set to top of BLUE ARC on EGT" for Takeoff, and "FULL RICH or BLUE ARC on EGT" for Cruise Climb and Vy, and "FULL RICH" for Vx.

[Mooney in Oz]

2 hours ago, Alan Maurer said:

I lean for taxiing before and after landing.

Hi Alan,

Do you mean you lean before taxiing and after landing?

Sorry if I misunderstood.

[Jackk]

59 minutes ago, Max Clark said:

FWIW my POH has "Check and Set to top of BLUE ARC on EGT" for Takeoff, and "FULL RICH or BLUE ARC on EGT" for Cruise Climb and Vy, and "FULL RICH" for Vx.

Would the blue not be max power?

 

*I have no blue arch

[Tommooney]

5 hours ago, Max Clark said:

Also Ovation 2 IO-550-G and just did the HP STC. I try to fly 10k MSL WOT 2500 RPM LOP and get 165 TAS with about 10.7 GPH.

Curious what your FF is ROP - 20 KTS is a lot!

I burn 16 gph. I try to go as fast as possible.

[McMooney]

man way too much thought, hehe.  

lean on ground to keep engine from fouling and why burn extra fuel

full rich and run up per the poh, 

full rich take off,  lean slightly till altitude ( per poh )  just enough to get needle off the lower stop while watching temps.

 

lean once i get settled at altitude, 

if i'm going distance and i'm in no rush, at below like 65%, i now just follow the old school method of leaning till stumble, enrich till just smoother.

generally get way less fuel burn for maybe 10 or 15 kts.

 

I know we are supposed to go fast but  5 to 15 mins just doesn't register for me

[Shadrach]

@Max Clark, mixture setting should be driven by your operational goals, it should not be a goal in and of itsself.  LOP ops are very useful, especially down low staying out of headwinds.  There is little reason to run LOP at high cruise altitude. Peak EGT will yield similar brake fuel consumption without much speed penalty. My general SOP is as follows:

LOP when cruising at DAs between SL and 5,000.

Peak when cruising at DAs between 5,000 and 9,000

100ROP when cruising above 9,000

I modify as needed depending on conditions and mission goals.

Generally speaking, I like to go as fast as I can for the quantity of fuel being burned.

I play the winds as much as possible. This time of year it's not hard to find 40kt winds at altitude. Yes you typically have to fight them on one leg, but that's an ideal time to cruise at low altitude LOP.  I did a 400nm round trip today. Outbound leg tailwind at 9,500@185-190kts GS (100ROP) and returned with a headwind at 4,500@ 135-145kts GS at peak EGT.

[DC_Brasil]

16 hours ago, Max Clark said:

 

1. After startup and during taxi what does "brutally lean" actually mean - just lean until engine roughness and then enrich until smooth?
2. Should run up be lean, or rich?
3. Or should run be full rich, and then during lean to best power (RPM rise) during?
4. Why not always lean to 1400-1450 on every single takeoff and climb?
5. When/how do you set mixture for the blue arc?
6. If climbing after cruise is set, full rich or keep leaned in the blue band?
7. Do something other than keep leaned durning descent until the GUMPS check?
8. After landing "brutally lean" again for taxi

Hello

1 - lean so much as the engine will not develop meaningful RPM if you try to apply takeoff power. This will have two effects: lean operation at low power and protects you from inadvertently trying to takeoff forgetting to enrichen the mixture.

2 and 3 - Follow the most recent manufacturers' recommendations. For most of the Lycoming direct drive engines it will be Service Instruction SI-1132B. It says to do the run-up at 50-65% power and Best Power mixture. For most engines it will be higher than the POHs 2000 RPM.

4 - Takeoff is when we get as close to maximum rated power as possible. Aviation engines have large compression rates and will need excess fuel to allow for thermal protection against detonation. So it is NOT a good idea to takeoff very lean. Aspirated engines should be running at full rich unless density altitude is playing a role (about > than 3000ft you should find best power).  Turbocharged engines will always "think" they're at sea level so you always takeoff with mixture full rich, unless your POH tells you otherwise. 

5 - If you are looking for operating LOP the best technique is Mike Busch's big mixture pull until noticing a drop in power output. Then enrichen slowly to peak EGT, and then stablish the regimen you wish (LOP or at peak). After you do it a few times and establish your LOP operation you will start to notice the LOP fuel flow for different altitudes, as EGT will vary depending on atmospheric conditions and RPM settings, and relate it to a TAS. After a while you'll be able to do the big mixture pull, feel the engine loose a little power and then enrichen to a known fuel flow while crosschecking with airspeed. I my plane (IO-360-A3B6D) that equates to about 8.8 to 9.2gph up until 5500 feet and 7.7 to 8.2 gph at 11,000. For me it leads to a 139kts TAS.

6 - It really depends on your operation and how fast you wish to climb. You CAN climb LOP. However it will require monitoring temps more closely as your mixture will become richer as atmosphere becomes thinner. ROP climb will yield more power and a quicker climb.

7 - It varies. How high and how lean were you in cruise? If you were very high and running LOP your engine will show signs of over lean mixture as you descent. 

8 - I have it in my After landing checklist: mixture ...... LEAN. Same as after start.