Cessna 182 fuel burn

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Pdw431

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Paul
I just purchased a 1966 Cessna 182 the engine is a 0-470. I normally fly it at 22 squared and the book says I should about 11.5 gph. I am seeing about 16-17 gph. I am leaning the engine and and a little dumb founded why the fuel burn is so off. I usually fly 5500ft and I fly 50 degrees rop. Any suggestions? Thanks
 
Yeah, that's a bunch of gas.

Do you have a fuel flow meter or are you basing it off of or a fuel dipstick before and after flight?
 
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Well I have a engine monitor but it is telling me that my fuel flow is right but when I fill he plane up I am shocked! Something is not right just trying to get a few ideas where to start. I am new to this plan and engine.
 
How many fill ups have you done? I wouldn't jump to a conclusion after only one. Keep a cumulative count over a few fill ups
 
If you are doing the computation manually, the 470 is chugging down 21 gph in the climb.
 
I had 1 bad fuel cap but that is fixed. This has been 3-4 fill ups. I am keeping a log of everything and monitoring it. I just wanted to know if anyone else had this issue.
 
I recall a model (can't remember which, in CAP) that required leaning to get max power on takeoff, depending on temps - you leaning by the book?
 
Do you notice a different drain rate if you flip the selector to the right tank vs. the left tank?
 
I was actually going suggest that you make sure you have the right dipstick. I accidentally bought the wrong fuelhawk once, and it caused my fuel calculations to be way off. Kind of an elementary thing, but can cause you to think you have more or less fuel onboard than you think you do.

For what it's worth, I have a '62 C-182E and typically cruise at 21/2300 and on a long trip, I average 11.5-12 gph, which is close to book numbers. If it's a short trip with a shorter cruise period, I'll average 13+ gph because of the higher fuel flow in the climb and less time at the lower cruise fuel burn. I don't have a fuel flow meter, so it's just based on dipping the tanks before and after.
 
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Well it might be I have just talken 2 hour trips and shorter I have not had a long trip yet. Okieflyer that is what I was expecting about a 12-14 burn I will do a little more research and see what I find. Yes I do have the right dip stick.
 
No one suggested the obvious

Are you sure you're flying the right plane and didn't "accidently" take your neighbors 206????


In all seriousness though hope you figure it out soon!! I would use an app like foreflight that takes into account the climb and descent burns and climb rates etc see what it says you should burn for a flight and cross check it with that

For me the overall flight comes to within half a gallon of what's planned. That way it takes into account the burn and climb rates and winds in the clim etc
 
If that setting is 65% power or lower, lean it more. Lean it all the way to rpm drop and richen a bit.
 
Here's one for you: check your tach...shortly after I bought my '75 182P I discovered my tach was off by about 200 rpm when I hooked up a digital tach. I was wondering why my numbers didn't seem to work out right.

Also, are you topping off the tanks and measuring? Make sure you're level, and all that. It seems even when level that I can squeeze a few more gallons when I thought I was filled up.
 
I will try leaning more aggressively the engine monitor was upgraded before I bought the airplane. And yes the airplane is in the same position every time I fill it. No I have an 0-470.
 
I fly a 66 182J as well with 0-470R. Home field is 5500' and I usually fly between 9500' -11500'. I plan for 13 gal/hr and that is pretty close to what I get.....maybe a little less. Leaning technique is lean till rpm drop and enrich 2 - 2/12 full turns both at runup and after reaching cruise altitude. Your numbers seem high. I suggest try leaning more aggressively using above technique.
 
MtnMarcus said:
I fly a 66 182J as well with 0-470R. Home field is 5500' and I usually fly between 9500' -11500'. I plan for 13 gal/hr and that is pretty close to what I get.....maybe a little less. Leaning technique is lean till rpm drop and enrich 2 - 2/12 full turns both at runup and after reaching cruise altitude. Your numbers seem high. I suggest try leaning more aggressively using above technique.
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I agree with this. That's how I do it too. I generally peak down at the EGT to make sure it's in the ballpark.

Honestly though, I can't see a little more aggressive leaning making 3-4 gph difference at a given power setting. Maybe if the OP had been running full rich, but surely he's not all that far off on the mixture, if at all. I could be wrong. Good place to start though. Good luck.
 
Random thoughts:

Never seen ours go much above 15 GPH in cruise ever, even hammering along above 65% power at 3000' MSL. We typically see 11.5 cruising WOT and prop back slightly at 8500-9500' MSL very consistently. The O-470 WILL suck a lot of gas at takeoff Lowe at sea level, but sounds like that's not your scenario.

Bad bladder wrinkle in a tank or both, making the tank hold a lot less fuel than you think it is? Rare but... mentioning it, since it's not too hard to check and could be dangerous.

Same vein: Someone else said wrong dipstick or not calibrated correctly.

Are you sure about how much the tanks hold?

What's the tailpipe look like? Properly leaned on 100LL the tailpipe will look like it has a light colored grey ash ring around it. If it's covered around the end with black soot and the belly is black behind the tailpipe, something is wrong.

Tach: Poor man's way to check the tach... taxi to where a sodium vapor light is behind you on the ramp at night and run the engine up to a multiple of 60. (1200 works well.) The strobe effect of the sodium vapor light at 60 Hz should "stop the prop" right at 1200. If it's off by much you'll be able to tell. Just move smoothly from about 1000 through 1200 and see where it does it. (Or faster if the tach is slow.). Of course you can fancy and use a visual tach and a mark/sticker on the prop like a shop does, but sodium vapor lights are free. :)

Do you have an EGT gauge or are you leaning by some other method?

You mentioned you have an engine monitor. We don't, but we do have an EGT gauge. We lean to roughness then back about half a turn rich on the mixture or a smidge more. The EGT gauge is slowish to respond and this can actually make the EGT *look* like its rising after enrichening. If you wait until it settles and the lean it a bit though, it'll go higher, proving you really are rich of peak. We don't like to keep it at the rough point long enough to get the highest temp out of it. Not happy when it's running rough. So to get quickly into the ballpark we just do it by roughness. Usually even with factory CHT gauge on any sort of warm day, our limit in the climb is that CHT rising, even with decent baffling and the cowl flaps wide open.

We also lean on the ground because of our DA here and take off at less than full rich, but not recommended below 3000' DA. We're full rich down there. We have to lean for takeoff for best power up here. It ends up significantly rich of where it eventually gets leaned to, but it's not full forward for takeoff.
 
My 182P, with an O-470, I've flown for a little over 3 years and 325 hours consistently burns 12-13gph
 
When I'm that low my fuel burn is very similar in my 182r.
 
What Denver said.

Cruise in my stock O-470s @ 2200RPM/22" MP = 11 - 12GPH depending on altitude and temp. This earns me around 130-135KTAS
 
Forget your EGT gauge. EGTs are a garbage in garbage out instrument. If it's not set right for your cruise altitude, it's useless.

Lean it to rough and one turn in. If that's not getting you 12GPH then something is wrong.
 
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denverpilot said:
Random thoughts:

Never seen ours go much above 15 GPH in cruise ever, even hammering along above 65% power at 3000' MSL. We typically see 11.5 cruising WOT and prop back slightly at 8500-9500' MSL very consistently. The O-470 WILL suck a lot of gas at takeoff Lowe at sea level, but sounds like that's not your scenario.

Bad bladder wrinkle in a tank or both, making the tank hold a lot less fuel than you think it is? Rare but... mentioning it, since it's not too hard to check and could be dangerous.

Same vein: Someone else said wrong dipstick or not calibrated correctly.

Are you sure about how much the tanks hold?

What's the tailpipe look like? Properly leaned on 100LL the tailpipe will look like it has a light colored grey ash ring around it. If it's covered around the end with black soot and the belly is black behind the tailpipe, something is wrong.

Tach: Poor man's way to check the tach... taxi to where a sodium vapor light is behind you on the ramp at night and run the engine up to a multiple of 60. (1200 works well.) The strobe effect of the sodium vapor light at 60 Hz should "stop the prop" right at 1200. If it's off by much you'll be able to tell. Just move smoothly from about 1000 through 1200 and see where it does it. (Or faster if the tach is slow.). Of course you can fancy and use a visual tach and a mark/sticker on the prop like a shop does, but sodium vapor lights are free. :)

Do you have an EGT gauge or are you leaning by some other method?

You mentioned you have an engine monitor. We don't, but we do have an EGT gauge. We lean to roughness then back about half a turn rich on the mixture or a smidge more. The EGT gauge is slowish to respond and this can actually make the EGT *look* like its rising after enrichening. If you wait until it settles and the lean it a bit though, it'll go higher, proving you really are rich of peak. We don't like to keep it at the rough point long enough to get the highest temp out of it. Not happy when it's running rough. So to get quickly into the ballpark we just do it by roughness. Usually even with factory CHT gauge on any sort of warm day, our limit in the climb is that CHT rising, even with decent baffling and the cowl flaps wide open.

We also lean on the ground because of our DA here and take off at less than full rich, but not recommended below 3000' DA. We're full rich down there. We have to lean for takeoff for best power up here. It ends up significantly rich of where it eventually gets leaned to, but it's not full forward for takeoff.
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Just marking this so I can find it again
 
Flew a ton of flights in similiar 182.....short and medium trips usually less than an hour each way......always got 10gph....
 
Are you leaning for best power as you climb to cruising altitude, or just leaving it full rich?
 
We log everything :) When we picked up our 182P (0-470) we had to finish a top end break-in so both mechanics (theirs and ours) recommended cross country it a 75% power for the last 8hrs or so (previous owner did the first 12hrs). I think we were at 23" and 2400rpm and did a several 1hr flights. The worst was during a really humid, 90+ degree day at 2800msl and was 15.8gph. The rest of these flights were under 14gph.

Now, all of this is with one of those fuel hawk sticks. We made sure we had the right one. However.....it is still a very crude measurement!!

You say the engine monitor is right but the sticked tank level reads more. Here is one thing we noticed early on. We would fill. Then stick the tanks. And we would immediately seem to be missing a couple gallons. These sticks are only so accurate. And just a little wing tilt can throw it off. And that cold gas coming out of the ground. And, I think it immediately starts flowing to the other tank. I think those 3 items make sticking the tank more of a good sanity check than a precise measurement.

We also keep a long running total. To date 532gals filled, 44.9hrs on the tach ==> 11.9gph. That includes lots of 23 squared, training, etc.

A dumb question, when you shutdown do you pull out the mixture? If so does it die within about 1..4 seconds?

Another place you can kill a lot of gas is taxiing. Lean like crazy once its warmed up a bit. On our flight after the one 16gph, we leaned aggressively on the ground and we're sure that was the reason for the outlier.

I could see the tach being off effecting this as well since your saying the fuel stick vs tach is wrong and the engine monitor fuel flow reading is right.

This could be a long shot...what if you were always getting some unwanted carb heat? Would that run it rich and account for missing fuel? But then again your fuel monitor would show that I think.
 
My flying club has a 182P with an O-470 and we have 10 years of data showing a pretty consistent 12.5 to 13 gph. Everyone pays on the tach, so generally they aren't running it too hard. 22 squared is probably typical.
 
I also run 2200 RPM at cruise and WOT, which is about 21-22 inches at altitude. It's the sweet spot for fuel burn and speed at around 7-8k feet.

I only see 1-2 knots difference (if that) between 2200 and 2300 and I'm not going to flog it at 2450 just to squeeze out another 5 knots.
 
Thinking more about this and taking into consideration the crudeness of the fuel stick accuracy:

After a flight, let it sit for 5 minutes by the pump or where the fuel truck will stop by:

1.) Stick the tanks and record the numbers.
2.) Fuel up both tanks (full or near full).
3.) Wait about 10 minutes and stick them again and record and compare.

for our 182 with bladders even with no movement of the aircraft we already see a discrepancy here. We usually fill up to 70 or 75 gallons since topping it off it starts to run out the vent behind the pilot side strut. The discrepancy is often 2...4 gallons vs what was actually pumped in. At first we thought it was our local self serve pump and some computation between $$$ and gallons. However I get the same effect when the LL truck stops by where I am training. In the end I think you just need to use total fuel purchased vs total tach time over about 10 flights and you will probably see a number a bit higher than your cruise numbers from the computer. The number will be skewed a bit higher by the climbs out and if you do not aggressively lean during taxi.

And maybe its more akin to measuring (with a stick) how many gallons are in a water bed. As you fill it more the shape is probably changing and pushing out to its extents and thus the amount added may not seem linear???
 
....should all take place inside the engine.

Often the discrepancy is fuel leakage.
Every Cessna I ever flew leaked fuel out of the low wing while parked.
 
Our club had a 1971 182N with an O-470. Over the course of about 8.5 years and well over 1000 hours with all kinds of different missions and pilots, it averaged within a tenth of 13gph. (Gallons purchased divided by tach hours.) Cruise burn, of course, was somewhat lower and climb was higher.
 
JCranford said:
I was at 10.5 the last x/c I did. Usually at 11.5
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Here's WOT at 10,500 today.

It was hot out. 65F up there today. Got a whopping 17" MP plus a smidge. ;)

a6124a4a7dc0f18a12903cf2d39b6b42.jpg
 
Shepherd said:
....should all take place inside the engine.

Often the discrepancy is fuel leakage.
Every Cessna I ever flew leaked fuel out of the low wing while parked.
Click to expand...

That is what happened to a buddy of mine in his 172.

He was getting too high of a fuel burn as well, the problem was small pin hole leaks in the fuel lines. Very small leaks hard to notice.
 
To the OP, start over. Fill the tanks and go fly. Re-fill and set your K factor on the fuel monitor for fuel used. Repeat three or four times to get your K factor dialed in. Once you have a good reference for fuel burn you can chase fuel loss if you have any. Trying to reconcile burn with a stick in partial tanks doesn't work. Until you have a good K factor you're chasing your tail.
 
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Stewartb said:
To the OP, start over. Fill the tanks and go fly. Re-fill and set your K factor on the fuel monitor for fuel used. Repeat three or four times to get your K factor dialed in. Once you have a good reference for fuel burn you can chase fuel loss if you have any. Trying to reconcile burn with a stick in partial tanks doesn't work. Until you have a good K factor you're chasing your tail.
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Should the tank selector switch be in the off position on 182's for accuracy?
 
455 Bravo Uniform said:
Should the tank selector switch be in the off position on 182's for accuracy?
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Can't see why... from a totalizer's point of view it's all one big tank.

Off doesn't stop fuel from moving side to side since it'll move through the upper vent line between the tanks, at least on the bladder models. Not sure on later wing tank modules.

This is why if you park it with the vent downhill and the vent backflow is weak, fuel will start coming out of the underwing vent line.

Maybe I'm missing something about the question?
 
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