i've always been wondering and no one ever told me...

rotateandfly · Post by **rotateandfly** » Mon Mar 20, 2006 10:13 am

Ive always been meaning to ask these two questions:

1.) How do you decode UPPR WINDS (FDs)??

Its easy to figure out what numbers to use according to a specific time frame, but then what wind direction and speed is "3624-17"??
Is it Winds from between 240 degrees true and 360 degrees true at 17 knots?

2.) I keep on reading crap about "lean of peak" in Flying magazine. What does it mean? When I fly and lets say my power setting is 2400 RPM i start leaning gently until the RPM peaks and then I keep on leaning until im back at my original power setting. Am I doing anything wrong?? Cuz in my POH it says "lean to peak RPM", thats now what ive been taught however..

Any clarification on these two questions will have me sleep again tonight

Raven20000 · Post by **Raven20000** » Mon Mar 20, 2006 10:35 am

"3624-17"?? means wind are 360 degrees true at 24 knots, and the temperature is -17 degrees.

For the second question you are right, your leaning for best economy or lean of peak.

bater · Post by **bater** » Mon Mar 20, 2006 11:27 am

If you're "leaning to peak" or running "lean of peak" in a carburated, or NON-GAMI(brand name fuel injectors) engine, it's going to be extremely hard on your engine. In a carburated engine, you should be running slightly "rich of peak"... This ensures that no one cylinder will be too lean, as there are always slight differences in the mixture between cylinders. Unless, as I mentioned previously, you have GAMI injectors and a good engine analyzer, do not run "lean OF peak" or "leaned TO peak".

This is just a broad view of things.. If you want to read more great, indepth articles, go to GAMI.com and poke around. You'll learn alot!
cheers

rotateandfly · Post by **rotateandfly** » Mon Mar 20, 2006 11:36 am

wow ok Ill check out the website. Now how do i lean rich of peak?

rotateandfly · Post by **rotateandfly** » Mon Mar 20, 2006 11:38 am

and more importantly how do I go about leaning rich of peak/lean of peak using EGT?

bater · Post by **bater** » Mon Mar 20, 2006 11:45 am

well, the theory of it is this; once you're "lean of peak" your power is controlled with the mixture, not the throttle. as you lean even further, power drops off, as well as temperature, since there is more air going through the engine. They say running like this keeps the engine extremely clean and does no damage at all, since temps are lower than they would be at "peak" It's not something you want to try if you don't know what you're doing, or don't have the right equipment.

On a side note:
I knew a guy who ran his TSIO-520 like this, and when it came time to have it checked out by the Continental people, they said it was immaculate for the amount of hours on it.

zaac · Post by **zaac** » Mon Mar 20, 2006 12:01 pm

If you keep the power at 65% or less you can lean as much as you want without any damage.

might be · Post by **might be** » Mon Mar 20, 2006 1:16 pm

nice trolling !!

trey kule · Post by **trey kule** » Mon Mar 20, 2006 1:25 pm

Zaac wrote:

If you keep the power at 65% or less you can lean as much as you want without any damage.

.....ah sure....and if you lean enough you probably will save alot on fuel as well as not having that noisy old engine to worry about.

To the serious one however, GEM monitors users book is really quite good as it shows the proper curves, explains the whole thing, and, if you own one, how to use it properly.

5x5 · Post by **5x5** » Mon Mar 20, 2006 6:52 pm

To lean rich of peak, get established in level flight (trimmed and desired rpm). Slowly lean the mixture until you get a slight drop in rpm. You don't have to watch the tach (you should be looking outside), you can hear the change. Then begin to enrich the mixture until you get maximum rpm (peak). Then enrich another 1/8 to 1/4 inch. Or what ever the owner of your plane has in their SOPs.

The whole debate over mixture settings has gone on for decades and there is no right answer. Proponents of both lean or rich abound and each has their own reasons. You as the pilot - do as the owner asks.

As a relatively inexperienced pilot be careful leaning the mixture - if you do it too rapidly the engine can slow down considerably (even stop if done too rapidly and taken too lean) which can be disconcerting to you and especially your passengers. It will typically restart as soon as the mixture is pushed in again, but it tends to make your heart beat a little faster.

BTD · Post by **BTD** » Tue Mar 21, 2006 1:25 pm

To lean Rich of peak: Simply lean out the mixture. As the EGT rises continue leaning until it stops rising and starts to fall. You have now reached the maximum EGT.

From this point you can either enrichen the mixture to get the temp to drop, or lean the mixture to get the temp to drop. Leaning rich of peak (eg 50 degrees rich) means that you enrichen the mixture until it is 50 lower than it peaked at. The opposite works for leaning on the lean side of peak.

Your peak EGT will usually not be exactly the same each day. It changes with the outside temperature etc. So each time is like leaning for the first time. You have to watch where it peaks.

Hope that helps.

Kilo-Kilo · Post by **Kilo-Kilo** » Tue Mar 21, 2006 1:39 pm

In addition, the EGT is only on one cylinder, so the others may be running hotter when using it to adjust the mixture if this is not the optimum cylinder. This is where it is nice to have a GEM.

rotateandfly · Post by **rotateandfly** » Tue Mar 21, 2006 2:05 pm

BTD, that answered my question!

FlyYukon · Post by **FlyYukon** » Fri Mar 24, 2006 12:34 am

How I do it:

Lean until the rpm drops, then: (If twist type: 2 or 3 twists to the Rich side) or about 1/4 to 1/2 inch on the non-twist type.
Better to run slightly rich than too lean.

FY

FlyYukon · Post by **FlyYukon** » Fri Mar 24, 2006 12:44 am

In relation to the Upper winds.. D = direction S= Speed, T=Temnperature.

Upper wind temperatures are not forcast for the 3000' levels, so that would be DDSS: 2115 210T 15 kts.

For above 3000' levels:
DDSSTT: 3320-5 330T 20kts -5C. Theres a forcast level ( i forget which) where the negative on the temperature is dropped.. lets say..
3000 9000..... 12000..... 15000 (dots for spacing)
9900 3320-19 3523-27 023233 <- 020T 32kts -33C

Note that 9900 means the winds are (exam answer) Light and Variable NOT calm.

One other note:

At high altitudes winds can exceed 100kts.. in that case..

18000
540342

On initial look that is winds from 540 at 3kts -42C .. odd..

take 50 from the coded direction, and add 100 to the windspeed, which makes:

54 - 50 = 04 03 + 100= 103 therefore, the winds are forcast at

040 @ 103kts -42C

Hope I didnt confuse ya, but ask you/an instructor for clarification if I did, or even if I didnt

FY

rotateandfly · Post by **rotateandfly** » Fri Mar 24, 2006 7:00 am

FlyYukon,

thanks for your replies! Actually, i read the same information about FDs in this book i bought called "The Complete Advanced Pilot" and I guess I asked here because i didnt really understand. However, having read your explanation it did become clear to me!

-Dave

P.s. Watch Top Gun! (you were the one who hadnt seen it right?

)

FlyYukon · Post by **FlyYukon** » Fri Mar 24, 2006 9:04 am

Ok.. ok.. I'll give it a watch.. when I finally get back home..

FY

rotateandfly · Post by **rotateandfly** » Fri Mar 24, 2006 11:50 am

at a boy