LANCECASPER

Fuel Flow on Take-off

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54 minutes ago, chadsuv said:

I see 25gal/hr on take-off. 

That seems low but I am not a Bravo driver.  Savvy recommends 26.2 - 26.7gph FF for full power takeoff in my TSIO-360 (252 Encore) to keep everything cool on the way up.

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10 hours ago, LANCECASPER said:

Question for all Bravo owners:How many gph is your full power fuel flow on take-off?

Now, I'm curious @LANCECASPER.  What are you experiencing and are you concerned for some reason?  Also, did you recently install a new monitor?  I did and I have been trying to tweak the K factor setting to get the fuel flow just right....

 

 

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Just checked a bunch of flights in Savvy... 30.5.. going down to 30 at 1000' where you pull back to 34/2400. 

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Where do you see the gph at?  I have Fuel Pressure on my Moritz gauge.  I can pull up gph on my JPI700 but never pay attention to the gph on take-off.

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On 6/10/2019 at 7:30 AM, alextstone said:

Now, I'm curious @LANCECASPER.  What are you experiencing and are you concerned for some reason?  Also, did you recently install a new monitor?  I did and I have been trying to tweak the K factor setting to get the fuel flow just right....

 

 

Mine is too low so we are checking a few things.

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Between 28.6 and 30.2 for me (easily extracted from EzTrends "Data Trends" with option "Report Data Type" = Max. If you have an IAT probe then this is also an easy way to check the max MP setting as required by Lycoming curve 13495-A)

Engine POH curve 13491 specifies mixture strength 0.60lbs/BHP-Hr which would be ~27GPH - personally I would be happy with that to +10% which is just about where I'm at

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I'm at 27.8 on Take-Off but but I get a hight TIT warning on the JPI (1600 F) at full power climbs. If I dial it back to a cruise climb the TIT comes down of course. Any Bravo owners or gurus have any ideas?

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17 hours ago, LANCECASPER said:

I'm at 27.8 on Take-Off but but I get a hight TIT warning on the JPI (1600 F) at full power climbs. If I dial it back to a cruise climb the TIT comes down of course. Any Brao owners or gurus have any ideas?

Sounds like the warning threshold is set too low on the JPI.  I fly mine at 1580 to 1600 TIT.  1650 is the upper limit and I think that's where my JPI warning is set. My TIT is pretty high if I do a full power climb.  I almost always do a climb at 2500/32" and the flow rate is about 24gph.

Edited by nfonville

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1750 tit max on the M model but I have a personal max of 1600 in cruise but fly peak on decent 29” 2000 which often yields 1650 or better.

i agree warning on Jpi is set too high.

Climb out for me is 35 2500 full rich gives me about 1550 tit and 24-25 gph.

cruise at 31 2400 or 31 2200 wind dependent 100 rop usually yields around 1600 tit. And 18 gph.

On 6/20/2019 at 10:48 AM, aviatoreb said:

If you had a sudden drop in pressure like that in flight - that might be grounds to divert immediately and get on the ground asap, and be possibly ready to declare an emergency.  Take it from a guy who had an exciting flight almost a year and a half ago.  Ending with a dead stick landing on a runway.  If you are flying and a major system like your power plant is showing signs of failure, don't just plow on and don't wait for complete failure before getting yourself on the ground.

Thankfully all is well.  And I don't mean to be knocking you.  Just talking out loud for the community.

 

50 minutes ago, nfonville said:

Sounds like the warning threshold is set too low on the JPI.  I fly mine at 1580 to 1600 TIT.  1650 is the upper limit and I think that's where my JPI warning is set. My TIT is pretty high if I do a full power climb.  I almost always do a climb at 2500/32" and the flow rate is about 24gph.

 

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When you say "Full Power climbs" are these with all three controls fully in?

For me that is only something I do for take off or obstacle clearance, but if memory serves, get a TIT of 1300-1400 and certainly no alarms (I have my JPI set to alarm at 1700 for TIT) After gear and flap retraction, I come back to 34"/2400 and ~22-24GPH for a 1450 TIT and hold that until top of climb

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4 hours ago, Awful_Charlie said:

When you say "Full Power climbs" are these with all three controls fully in?

For me that is only something I do for take off or obstacle clearance, but if memory serves, get a TIT of 1300-1400 and certainly no alarms (I have my JPI set to alarm at 1700 for TIT) After gear and flap retraction, I come back to 34"/2400 and ~22-24GPH for a 1450 TIT and hold that until top of climb

Yes, all three controls fully in, and that's also where my TIT used to be, 1300-1400 range. How do i get my fuel flow back close to 29 or 30 instead of 27.8 where it is?

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@M20Doc Bravo Fuel flow setting question... how to adjust FF for T/O power...

My answer was quite simple... take plane to favorite mechanic and ask...   :)

Best regards,

-a-

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18 hours ago, LANCECASPER said:

Yes, all three controls fully in, and that's also where my TIT used to be, 1300-1400 range. How do i get my fuel flow back close to 29 or 30 instead of 27.8 where it is?

I guess there's a few things you can check before getting into an overhaul of the injection unit, and I suspect someone more experienced than me can give you a more comprehensive list, but if it were me I'd start with:

  • All fuel strainers, screens and filters
  • Fuel pump pressures
  • Flexible and solid lines for kinks, bends, dents etc

Before getting into serious work, I think I'd also get the TIT probe and gauge checked to be sure I was looking at a real problem rather than an indication error!

If everything so far checked out, my next step would be to the distribution spider and the fuel metering unit. Other than the idle settings I don't know what other adjustments are possible on the aircraft, the RSA "Operation and Service Manual" 15-338e suggests those are the only ones, but then it also states that lengthening the mixture screw enrichens the mixture, and certainly on mine it leans it. The fault finding section has the rather vague "Replace Injector" and "Clean flow divider valves" for the "Low take off fuel flow" problem

FWIW, I've just checked a few recent flights and I'm getting (an indicated/logged) max of 28.9 GPH on take off, so you're not that down on fuel flow. My k-factor for the fuel flow has been adjusted to make the overall accuracy good, but I don't know the linearity of the error in the flow meter

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On my last few flights, I’ve also been seeing 28.7-28.9 GPH on take off. 

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Does the M20M have an aneriod adjustment like the TCM engines for full power fuel flow?  Mine was a little low, according to Savvy, and got with my MSC and we got it adjusted in just about the time it took to take the cowl off.

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