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Density Altitude Procedures

ethand

Well Known Member
Hello All

As the weather heats up the density altitude increases and the need to make a few changes both on approach and departure become critical.

While I am located in San Diego, my in-laws are in Prescott, AZ (field altitude 5,045') where DA routinely reaches 7-8k.

I have watched some videos on the leaning before takeoff but I am curious of your best DA procedure. Full run-up while leaning to Peak EGT then richen mixture or ?

Airplane is an RV-10 in my case but open to other discussions for sure.

Thank you
E
 
If runway length is critical, and density altitude is above 6000?, then I do what you suggest: lean to peak, then enrichen 150 F on egt. But with no cowl flaps, and low airspeed, my CHTs will go past 420 F (where my alarm level is set). I also have a pretty good idea of where fuel flow should be, so, for example, if DA limits me to 75% power, I?ll check for 15 g/hr or more FF. But for most runways, the 10 still has plenty of power even full rich. So in practice I only lean enough to insure smooth operation and reasonable power. Once up to speed I?ll lean a bit more if CHTs allow it. For landings, I?ll set best power mixture once at pattern altitude.
 
I have limited experience at high airports but I am getting more since my 6A is based at 8300' and DA is usually well over 10,000.

When I was first flying up here I would lean just like the books tell you to do but my CHTs would get to 425 easy and I had to throttle back and climb slower to keep them from going higher. Talked to my A&P who is also an RV pilot and he said to lean while on the ground but go full rich for takeoff. That has helped my CHTs and I have noticed no roughness from the engine. Also the runway here is 7,000' so no issue with runway length.
 
I?ll have to try that. Mine is a carbureted O-540 at Pagosa Springs elevation 7660. DA usually in 9K range. I?ve been leaning before takeoff and fight to keep my hottest cylinder below 410 on climb out. I too reduce power and accept a reduced rate of climb. Will try the full mixture approach on takeoff next week.
 
Forgot to say what engine I have. I have an O-360 FP.

Doesn't climb as well as I would like but I have never had my plane anywhere near sea level. I would expect it to climb much better down there.
 
I fly my O-360-A1A powered RV6 with CS prop out of Sedona, field elevation 4800'. Flew it this morning, density altitude at take off was 7500'. Off the ground in about 1000' with slow roll to start the takeoff run, so probably really only used about 800' of runway.

Prescott runways are 4800' and 7600' long. You are not going to have a performance problem taking off out of Prescott.

As previous posts have said, I'd be more concerned with managing my CHT's than leaning for max power on takeoff.

I take off with mixture full rich. I've never done a full power runup and leaned for best power before takeoff at Prescott or Sedona. At 1000' AGL I pull the prop back to 2500 rpm and leave it full throttle, established in the climb at 120, monitor CHT's and when ok, then start to lean.

Different airport, shorter runway, higher DA, then you might adjust accordingly. But at Prescott, no problem.

In my opinion, the bigger problem at Prescott is the Embry Riddle traffic. That place is crazy.
 
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