Lets talk fuel management

[Timbeck2]

I've been thinking a lot lately about how I don't like the present system of fuel management in my Cherokee. I know how much fuel I have when I stick the tanks during pre-flight. I also know approximately how much I burn per hour at cruise. The fuel gauges are required to be accurate only some of the time as per the regulations. I'm going to install a Garmin G-5 to replace my wonky attitude indicator in addition to my turn and bank. In it's place I had originally planned to install an engine monitor that included fuel flow, EGT, oil pressure, temp, etc, but with the G5 at around $2100 and the engine monitor approaching $3,500 and the fact that all I really wanted to fuel flow, I've decided to go with this:

Someone talk me out of it, alternatives to it, or if you have it, tell me your experience.

 

[bnt83]

I've got an FP-5L hooked to a GTN, sure I could blow a pile of money and consolidate the FP-5L & SR-8A into one engine monitor but it ain't happening.

Works great and easy to read. I'm happy with it.

 

[Chip Sylverne]

You'll get far more value out of an engine monitor. Fuel management is a matter of a known quantity (topped up or to the tabs) and the panel clock. Save the money and put it toward the monitor when you can, or even get a used JPI. 700.

 

[GRG55]

With the exception of the Six, the Cherokee fuel system is generally pretty straight forward, compared to some other planes. No quirks like return fuel only going to one side, that sort of thing.

If you are flying the plane consistently (leaning technique, RPM) the fuel burn flight after flight should be very consistent too. My Cherokee 160 (early model without wheel pants) burned 8.8 gph with miniscule variation. I filled the tanks before and after on numerous cross country flights to check that figure and it hardly varied, so that is what I used along with a personal VFR one hour reserve limit.

I agree with the post above, you will get more value from an EGT/CHT monitor on all cylinders than fuel flow.

 

[Skip Miller]

The fuel gauges are required to be accurate only some of the time as per the regulations

Tim, that Is not true. The fuel gauges are required to be accurate all the time.

The problem is that "accurate" is not defined. Same difference! OK, I'll go back to the Nitpickers' Bench, sit down and be quiet!

 

[AKBill]

I agree with the post above, you will get more value from an EGT/CHT monitor on all cylinders than fuel flow.

I second the vote for EGT/CHT over fuel flow. You will be able to better manage the engine vs watching the fuel flow that will not change much. My 0-320 burns about 8.5gph, I use 10gph as a number for calculating fuel for a needed flight. I installed a CHT kit and now want to see EGT. I should have gone with CHT/EGT to begin with.. I did get the CHT kit for under $200 and installed it myself so not a big loss if I change it out.

 

[bnt83]

I really only use the EGT/CHT when I'm having fouling issues and to monitor cylinder head temps hot days. I really don't see much value in add-on oil temp/pressure and all the other optional things and engine monitor can do on an o-320. I guess that's what really made the used SR8A and FP5L combination work for me.

 

[AKBill]

I really only use the EGT/CHT when I'm having fouling issues and to monitor cylinder head temps hot days. I really don't see much value in add-on oil temp/pressure and all the other optional things and engine monitor can do on an o-320. I guess that's what really made the used SR8A and FP5L combination work for me.

I agree with you on engine monitor issue for the 0-320. I did determine I was having an issue with the #1 cylinder using CHT and did a compression check on #1, it was 56/80. I figure adding EGT would give me a better indication of engine performance.

 

[coloradobluesky]

I have a single EGT/CHT gauge on my carbed Lycoming 0-360 and the only use is to monitor CHT. I can monitor EGT but so what? There is a limit of 500 degrees on my CHT (I dont let it get above 460) and that is what I leave it on all the time.

With carburetion there isnt much you can do about leaning or lean of peak with EGTs. What happens is I lean and the cylinder the EGT is on gets hotter but then one of the other cylinders gets way lean of peak and starts missing. So I cant use the single EGT to lean. I could put EGTs on all the cylinders, and it would tell me which cylinder was leanest, but I couldnt do anything about evening them out with a carbureted engine. So I end up just leaning to an rpm drop and richening a bit. All you can do no matter how much EGT/CHT you have. On a carbed engine, all you can really use is the CHT gauge. And one on the hottest cylinder (the one in back) is all you really NEED (all 4 would be nice though).

Knowing your amount of fuel is CRITICAL. I have sight gauges so I know. But I know pilots that swear their fuel flow gauge tells them to within a gallon how much fuel they have and they trust it more than their fuel gauge. But then again, do you really trust it?

Best thing is to have accurate fuel gauges and a fuel flow monitor. Tanks can leak and that wouldnt show up on the fuel flow would it? Any chance of getting your fuel gauges fixed?

Since fuel is so critical, most of us just fly it down to a 1/4 tank minimum and refuel. Best to not run out of fuel, thats for sure!

And BTW, some pilots are leaning to fuel flow. They actually use fuel flow to tell them how far to lean!

 

[steingar]

I've determined the fuel burn for all the aircraft I've owned. It really isn't at all difficult. Fuel management becomes a watch and just a wee bit of math. I never fly without at least an hour's worth of fuel in the tanks. I've never seen the need for all the instrumentation, and really don't feel I myself need it.

All that said I've never flown behind fuel injection, so I can't run LOP. But I honestly don't think that'd change anything. Fly with the LOP power setting and figure your fuel burn. Back to the watch and math.

 

[Tantalum]

if you have it, tell me your experience

The plane I fly at the club has this exact fuel flow and a JPI engine monitor

I personally love this gauge in the 172, it is very easy to setup and has a couple different modes on it you can flip through.

The JPI is also handy, I use that mainly to manage cylinder head temps during the climb and help with leaning, but for most actual fuel management I use that little fuel flow gauge you posted a picture of. If I had a plane with neither I would feel that my money is better spent on the fuel flow indicator than the JPI, personally speaking for something like the Skyhawk, Archer, Cherokee, etc

 

[NealRomeoGolf]

I love having fuel flow on my Archer. I can set my power settings to it and it has been super accurate down to a tenth of a gallon on fill ups. I can also tell when I forget to turn off my fuel pump (yeah, I know....checklist).

 

[kyleb]

<snip> I've never seen the need for all the instrumentation, and really don't feel I myself need it.

<Snip>

Back to the watch and math.

I use the watch and math method myself, but have accurate fuel gauges and a heck of an engine monitor to spit out numbers to entertain me. I like having both.

 

[jordane93]

I'm curious how this guy made this flight non stop? Assuming ferry tanks? ~8 hours in a GA plane would be death for me

http://flightaware.com/live/flight/N916BL

 

[bnt83]

I agree with you on engine monitor issue for the 0-320. I did determine I was having an issue with the #1 cylinder using CHT and did a compression check on #1, it was 56/80. I figure adding EGT would give me a better indication of engine performance.

I have an old O-320E2D and put a reman carburetor on using a part number out of a Lycoming service instruction on it a few years ago which reduced fuel consumption. The FP-5L helps reaffirm that it really doesn't burn that much fuel. I'm averaging about 7.5 gallons an hour for flights between 1.5 and 2 hours. I once flew a 5 hour leg at 7,500 feet and landed to verify the FP-5L was indeed right (it was) and I still had 11 gallons (1.46 hours) of fuel on board!

My fuel gauges work and all but seriously, they still suck.
#1 They have tiny scales and difficult to see where Cessna put them, especially at night.

#2 They are subject to turbulence --pretty self-explanatory

#3 They are subject to aircraft loading & power settings -- Anything that affects what pitch it flies at in level flight. So going balls to the wall with one person aboard will read differently than a cabin full of crap and putting around at 2100 RPM.

#4 I think even bus voltage changes how they read. They are really current meters right? So they will read differently with alternator online vs battery voltage.

The FP-5L uses and optical sensor an counts how many times the notches on a wheel go by it inside the flow sensor. It is essentially immune to everything that makes the old fuel gauges inaccurate.

 

[Caramon13]

I've been thinking a lot lately about how I don't like the present system of fuel management in my Cherokee. I know how much fuel I have when I stick the tanks during pre-flight. I also know approximately how much I burn per hour at cruise. The fuel gauges are required to be accurate only some of the time as per the regulations. I'm going to install a Garmin G-5 to replace my wonky attitude indicator in addition to my turn and bank. In it's place I had originally planned to install an engine monitor that included fuel flow, EGT, oil pressure, temp, etc, but with the G5 at around $2100 and the engine monitor approaching $3,500 and the fact that all I really wanted to fuel flow, I've decided to go with this:

Someone talk me out of it, alternatives to it, or if you have it, tell me your experience.

I went with the JPI FS 450:



Worked really well for me and the gauge is like $500, install probably right around that as well.

The nice thing is if you forget to put in the amount of gas you topped off with someplace along your way to the next destination you can "update" it and it will retroactively "update". Some gauges won't let you do that.

 

[bnt83]

I think the Electronics International version blends in better with the rest of my instrument panel & equipment and the fuel flow sensors are a tad cheaper if you ever need a replacement. EI flow sensors look like aircraft parts JPI look more like boat parts.

 

[Caramon13]

I think the Electronics International version blends in better with the rest of my instrument panel & equipment and the fuel flow sensors are a tad cheaper if you ever need a replacement. EI flow sensors look like aircraft parts JPI look more like boat parts.

To me the EI instruments look overly basic and cheap, but you gotta like your panel though, so that matters. Also the EI instruments don't have a lot of the features of the JPI ones..so you lose a bit.

 

[tawood]

I went with the JPI FS 450:

View attachment 53718

Worked really well for me and the gauge is like $500, install probably right around that as well.

The nice thing is if you forget to put in the amount of gas you topped off with someplace along your way to the next destination you can "update" it and it will retroactively "update". Some gauges won't let you do that.

This is what I have on my Cherokee, and I love it.
I almost never fly with 50 gallons, and fly almost exclusively with 36 or less (at or below the tabs). Most of my flights are either less than two hours, or flights done in two hour hops for pee breaks, etc., so anything over 36 gallons is a waste of payload (and you know how important payload is in the Cherokee). I love this gauge, and I find it incredibly accurate...typically when going from 36 gallons to 10 gallons it is within .2 gallons correct, and quite frankly, that could be due to my error in filling, or the gas pump readings, not the JPI. I can just hit a button, and see exactly how much I have left. Also, I use it for management between the tanks, switching every 5 gallons (That may seem too frequent for some, but remember, this is a fuel sipping PA28 140. Every 5 gallons is like every 40 minutes). @Timbeck2 I'd say go for it.

 

[James331]

A engine analyzer is required in my book if flying IMC, night or over inhospitable terrain.

I'd go as far as to say you'd be better off not buying insurance for a year in favor of a analyzer.

 

[Timbeck2]

Caramon13 you've convinced me to switch to the JPI. After watching the videos, I see that it has more features than the EI one I posted above for about $50 price difference.

 

[Timbeck2]

This is what I have on my Cherokee, and I love it.
I almost never fly with 50 gallons, and fly almost exclusively with 36 or less (at or below the tabs). Most of my flights are either less than two hours, or flights done in two hour hops for pee breaks, etc., so anything over 36 gallons is a waste of payload (and you know how important payload is in the Cherokee). I love this gauge, and I find it incredibly accurate...typically when going from 36 gallons to 10 gallons it is within .2 gallons correct, and quite frankly, that could be due to my error in filling, or the gas pump readings, not the JPI. I can just hit a button, and see exactly how much I have left. Also, I use it for management between the tanks, switching every 5 gallons (That may seem too frequent for some, but remember, this is a fuel sipping PA28 140. Every 5 gallons is like every 40 minutes). @Timbeck2 I'd say go for it.

Okay...I'm convinced now. Although an engine analyzer would be the best way to go, with a fixed pitch prop I'm not as concerned with the other parameters than I would with a constant speed prop. So I think the JPI is still a better way to go when compared on a good, better, and best scale.

 

[bnt83]

To me the EI instruments look overly basic and cheap, but you gotta like your panel though, so that matters. Also the EI instruments don't have a lot of the features of the JPI ones..so you lose a bit.

I don't really like the red display. I do like the connector and compactness better. The photocell dimmer can simplify installation a bit. Those photo cells seem to fail a lot on king stuff so I tend to wire the dimmer circuits even if they have a photo cell.

Fuel flow is the bomb no matter what you get.

I like the Aerospace Logic fuel quantity indicators too but not enough to put one in my airplane which already has a FF.

 

[Caramon13]

Okay...I'm convinced now. Although an engine analyzer would be the best way to go, with a fixed pitch prop I'm not as concerned with the other parameters than I would with a constant speed prop. So I think the JPI is still a better way to go when compared on a good, better, and best scale.

Tim, my Cherokee had an Insight G1 w/ Carb heat option on it for engine monitoring. Believe me, I spent a VERY long time justifying the cost to move to a complete solution, either JPI or EI. A lot of them gave me oil temp, pressure, RPM, etc, but at the end of the day, I had all I needed with two instruments. The FS 450 and the G1 insight. The other stuff I used analog gauges which worked very well.

The Insight is this one, was already installed in the plane when I bought it, but it's like $1500.

 

[arkvet]

You'll want the full monitor. FF is only a small part of what you'll love with a JPI or equivalent monitor. Wouldn't fly my PA32 without it.

 

[Timbeck2]

I already have a carb temp/OAT gauge and any added oil temp/pressure and RPM will be redundant even IF I installed an engine analyzer. For my little Cherokee, its all I need. My main concern was fuel flow. I been on a few trips where the fuel gauges read below 10 but I'd like to know exactly how much below 10 they really held. It could be the difference in landing now or being confident I have the fuel, plus reserve to make it to the next fuel stop.

 

[simtech]

I Installed an Fs-450 in my Cherokee early on. I love it and have it to where I'm always within a tenth or so when I fill up. I still stick my tanks and cross check sticks, fs-450, and gauges and have found the piper gauges pretty darn accurate. I also have it tied to my gx-60 and it gives me required and fuel remaining at way points. It's really handy and easy to use. And for the price can't beat the info it gives.

 

[Timbeck2]

You'll want the full monitor. FF is only a small part of what you'll love with a JPI or equivalent monitor. Wouldn't fly my PA32 without it.

I hear ya but at this point at least for me, it all falls within the wants vs needs realm.

 

[murphey]

I have a single EGT/CHT gauge on my carbed Lycoming 0-360 and the only use is to monitor CHT. I can monitor EGT but so what? There is a limit of 500 degrees on my CHT (I dont let it get above 460) and that is what I leave it on all the time.

Do you have the Lycoming docs about the O-360? 500 is catastrophic device failure. Anything over 450 is very bad. I try to keep the CHTs below 400, which is difficult in the southwest in the summer.

Quote from Lycoming Flyer Key Operations publication (will happily post on my website if anyone wants a copy):

8. For maximum service life, maintain the following recommended limits for continuous cruise operation:
a. Engine power setting — 65% of rated or less.
b. Cylinder head temperatures — 400˚ F. or below.
c. Oil temperature — 165˚ F. — 220˚ F.

From the Lycoming 360 Operators Manual, 2000 ed, section 3-1:

With carburetion there isnt much you can do about leaning or lean of peak with EGTs. What happens is I lean and the cylinder the EGT is on gets hotter but then one of the other cylinders gets way lean of peak and starts missing. So I cant use the single EGT to lean. I could put EGTs on all the cylinders, and it would tell me which cylinder was leanest, but I couldnt do anything about evening them out with a carbureted engine. So I end up just leaning to an rpm drop and richening a bit. All you can do no matter how much EGT/CHT you have. On a carbed engine, all you can really use is the CHT gauge. And one on the hottest cylinder (the one in back) is all you really NEED (all 4 would be nice though).

Yup....On the cherokees (all variant IIRC) #3 is directly in front of the oil cooler hole, and always runs hot.

My personal fuel management device is my watch and my rear end. 2.5 hours on both. 3.5 in an emergency. But I flight plan for 10 gph know it's always less. I'm jealous of those who can fly more than 4 hours at a time and need really accurate fuel management. But my body just won't cooperate.

Knowing your amount of fuel is CRITICAL. I have sight gauges so I know. But I know pilots that swear their fuel flow gauge tells them to within a gallon how much fuel they have and they trust it more than their fuel gauge. But then again, do you really trust it?

Best thing is to have accurate fuel gauges and a fuel flow monitor. Tanks can leak and that wouldnt show up on the fuel flow would it? Any chance of getting your fuel gauges fixed?

Since fuel is so critical, most of us just fly it down to a 1/4 tank minimum and refuel. Best to not run out of fuel, thats for sure!

And BTW, some pilots are leaning to fuel flow. They actually use fuel flow to tell them how far to lean!

 

[James331]

Think the main part of a analyzer is the CHT/EGT for each jug, also per leaning, ya want to lean and cowl flap for target CHTs.

Fuel flow should just be math, properly leaned; RPM/MP at altitude = fuel flow.

Fuel flow into what your tanks showed when you stuck them before departing = endurance.

 

[TommyG]

Okay...I'm convinced now. Although an engine analyzer would be the best way to go, with a fixed pitch prop I'm not as concerned with the other parameters than I would with a constant speed prop. So I think the JPI is still a better way to go when compared on a good, better, and best scale.

They were having sales, might still be on chief aircraft and a spruce on monitors. Just bought a JPI 830 with a $600 discount. That was about a month ago. Still waiting for a window of time to install it. Luckily my comowner is an a&up and we know plenty of people to help us. I think the average shop price to install is around 2k and up.

 

[bnt83]

Do you have the Lycoming docs about the O-360? 500 is catastrophic device failure. Anything over 450 is very bad. I try to keep the CHTs below 400, which is difficult in the southwest in the summer.

My dad chews me out for anything over whatever Mike Busch said was his rule. I laughed my ass off because manufacturers are all over the map on where redline is. Continentals are generally lower than Lycoming but the A65 Continental was the highest I found that day with a redline being a searing 550 degrees F. http://rgl.faa.gov/Regulatory_and_G...d2128e86257950006e9e94/$FILE/E-205 rev 17.pdf

Typically I can climb from 1,300MSL to about 4,000MSL at full power cruise climb at which point CHTs start decreasing as I continue up.