I'm broke, but plane is OK

tmyers said:
Hmmmm. All I know is that when using LOP on the JPI each cylinder EGT bar flashes when the monitor sees a peak temp followed by a slight drop in temp. When that cylinders starts flashing it is by definition lean of peak. By the time the last cylinder flashes three are more on the lean side of peak and the last cylinder is just lean of peak. When that happens I push the LF button and the display indicates a fuel flow that JPI defines as the GAMI spread.

This is not my interpretation, but is what the JPI manual states. All I am asking is if 1.2 is bad, ok, good, or great.
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1.2 gph isn't very good for a big bore 6 cylinder engine. "Good" is less than 0.5 gph and great is less than 0.2 gph. Another measure of "goodness" is how far LOP you can go on the richest cylinder (the one that peaks last going from rich to lean) before the engine begins to run rough at 6000-8000 DA. This is also a good indicator of the health of your ignition system if the GAMI spread is tight. BTW, AFaIK, JPI's measurement isn't all that accurate so you might want to make the check manually and compare the results.

If someone answered this alreadt, sorry for the length of time, I am not the fastest Typer on an iPad
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I can't type on my iPad anywhere near as fast or accurate as I can on a tactile keyboard either. Could be that due to old habits dying hard.
 
Well I only have 2/3 of a big bore 6. If I had the 540 the nose of my Arrow might separate from the tail.
 
gismo said:
JBTW, installing injectors has to be the easiest upgrade task ever, especially if access to the top of the cylinders is easy (unfortunately not the case with your C177RG). If I were you I'd ask if I could perform the work myself under the supervision of your A&P to keep your total cost down. The only caveat is that you must take care to not overtighten the injectors. Use a low range torque wrench and tighten to the lower specified limit (something like 25 in-lbs IIRC). This is less torque than I can apply with a screwdriver and with a ratchet it's easy to overdo it. The threads on the injectors are tapered and with excessive torque you can generate a lot of radial pressure in the cylinder which is a known cause of cylinder cracking. About the only other issue is to avoid cross threading the fuel line's compression nut onto the top of the injector.
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I watched my mechanic swap my injectors a couple of months ago and it didn't seem difficult to get at them. But I don't think I'd trust myself to do a job like this where a slip could cost big $$$ or even kill me or my passengers. Anyway I'm a theory person not a wrench person. I'd want him to watch me like a hawk, and then it wouldn't save me any money to do the work myself.

BTW John Paul said my flight test data was "typical", with about a 1 gph spread. David, you're lucky if your IO-360 runs smooth LOP with factory injectors. I've heard some people say that most IO-360s can run LOP, but most is not all.
 
Clark1961 said:
I had similar concerns but the reality is pretty simple. You send in your data and money and they send you injectors. The injectors really aren't custom made but they are selected for your engine model. It appears to me that the data really isn't used other than to say yea or nay on their injectors helping.
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John Paul confirmed this by email last night. They do use the data for tweaking if needed to reduce the spread further.

I'm sending in my order today. :)
 
The IO360 in our arrow runs rather well LOP, I once decided to see how far I would have to pull the red lever to make it rough, and it got quiet first.
 
wsuffa said:
Welcome to the club. Mine is in annual right now, needed to open the fuel tanks and discovered that someone in the past used the wrong kind of sealant, which has been impossible to remove, leading to a very expensive labor bill to clean the old crap out of there & rework the nutplates.

Had to replace the ELT this year, too, with a 406 unit.
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Holy Smokes! Your still in Annual? I'm hurting for you!
 
AdamZ said:
Holy Smokes! Your still in Annual? I'm hurting for you!
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Shop was closed for 10 days for summer vacation. Family-run operation. The fuel tank sealant issue turned out to be a major deal - and the correct sealant requires a 24-48 hour cure time. So here we are...

That said, the tanks are sealed & reassembly is ongoing. Hoping for early next week.
 
wsuffa said:
Welcome to the club. Mine is in annual right now, needed to open the fuel tanks and discovered that someone in the past used the wrong kind of sealant, which has been impossible to remove, leading to a very expensive labor bill to clean the old crap out of there & rework the nutplates.

Had to replace the ELT this year, too, with a 406 unit.
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Sorry to hear. My first annual was my most expensive, due to the many hours of labor my A&P racked up trying (and failing) to remove the corrosion from my spar carrythrough. That was the only part of the job not covered by insurance.

But there's no question that planes are at least equal to boats as big holes to shove money into. Hope you're back in the air soon.
 
I know -- it's just an experiment I'd rather perform on the ground instead of in flight. ;)
 
azure said:
I know -- it's just an experiment I'd rather perform on the ground instead of in flight. ;)
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When it gets quiet, push the mixture back in. Problem solved. ;)
 
Skylane81E said:
Yep. I think I've been engine off four times in singles and only once in a multi.
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Happened in the Aztec semi-regularly as I'd sometimes let the outboards drain all the way down depending on the trip. Happened in the Navajo when I was trying to teach the importance of fuel management to the student, and he was ignoring the gauge bouncing off the bottom. He got the point afterwards. :D
 
azure said:
I know -- it's just an experiment I'd rather perform on the ground instead of in flight. ;)
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It's really no different than closing the throttle. Push the control back in and it gets noisy again right away.
 
azure said:
I know that too -- intellectually. I still really, really hate the idea of doing it.
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Closing the throttle removes the air and the fuel, closing the mixture just removes the fuel. Why should that be more worrisome than removing both? Some old rotary engines (the kind where the prop is bolted to the crankcase and the case and cylinders spin while the crankshaft remains fixed to the airplane) didn't have a carburetor. The pilot controlled the engine's speed by turning off the spark to one or more cylinders. On a diesel when you close the "throttle" (actually just a linkage to the fuel pump) the fuel is cut off until the engine slows down. Just goes to show there are multiple ways to manage engine output besides a throttle. In my car when you lift your foot off the "gas pedal" the engine computer shuts the fuel off completely until the RPM drops to idle and if you're coasting downhill it can remain off for a long time but it never fails to "light off" once the delivery of fuel resumes.

I suspect that if you had been taught to control engine power with the mixture with the throttle left wide open (yes that would be difficult to do precisely and without creating undesirable combinations of FF and MAP) you'd fear closing the throttle.
 
azure said:
Sorry to hear. My first annual was my most expensive, due to the many hours of labor my A&P racked up trying (and failing) to remove the corrosion from my spar carrythrough. That was the only part of the job not covered by insurance.

But there's no question that planes are at least equal to boats as big holes to shove money into. Hope you're back in the air soon.
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Yep.

I've had a number of years of decent annuals - there were a couple of minor PM things (replacing the DZUZ fuel cap retainer springs in the fuel flappers, clean the fuel strainers, etc) that required opening the fuel tanks... where we discovered the issue. And it was a human-caused issue from someone using the wrong sealant. The rest is/was pretty much expected & we've got a couple of preventative items that are easily deferred to next year.

As I recall, the first annual was pretty good, but we had to OH the engine early on as the case developed a minor crack & the cost difference to repair the case vs OH was small enough that it made more sense to OH. But that was quite a few years ago.
 
I used to routinely run one tank dry back in the 80's. That's how I was taught.

It doesn't just stop running, you notice a reduction in power and you just switch tanks.
 
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