Mixture rich for taxi?
Silly Old Git
I were bangin me head 
in agreement with Creampuff Chuck
Lots of good oil here , stuff that would take years of bull****ting in an Aero club bar to accumulate all here for free on Proon
in agreement with Creampuff ChuckLots of good oil here , stuff that would take years of bull****ting in an Aero club bar to accumulate all here for free on Proon
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The problem is the lack of aircraft instrumentation, lack of balanced fuel flows in stock engines, lack of pilot knowledge, and lack of competent engine management.[/QUOTE]
Cream,..dont have a problem with your comment at all....dont mind admitting Ive made a few cockups on the engine managment side,and after reading this thread have learned a few things for sure........BUT NOT ALL A/C HAVE TO BE MICRO -MANAGED........
Ive owned this C-185 for 8 yrs,never had a problem,all weve done is add a turbo-charger and beefed up the gear for poaching operations.....and flown it like the manual says to fly it....at 15 gallons/hr not bad and doeant break the bank.....talked to other owners of the same A/C....its all good......the A/c flies better in Alaska than Arizona....but like shelias,they are all different.....
CC ...called a couple of outfits and priced your suggestions.....mate it looks as if the misses is going to have to work the streets for sure....its not cheap.will have to do a gross margin job on this one...........
but the bottom line for me is ........these engines are designed to take a beating ,I say that from the stand point of commercial ops and fun flying,I done both with these engines and aircraft.......
Whilst I find CC,,s info great reading and very informative I also find that you dont have to make it rocket science either.....no disrespect CC,...but the KISS rule prevails for me.........PB
Cream,..dont have a problem with your comment at all....dont mind admitting Ive made a few cockups on the engine managment side,and after reading this thread have learned a few things for sure........BUT NOT ALL A/C HAVE TO BE MICRO -MANAGED........
Ive owned this C-185 for 8 yrs,never had a problem,all weve done is add a turbo-charger and beefed up the gear for poaching operations.....and flown it like the manual says to fly it....at 15 gallons/hr not bad and doeant break the bank.....talked to other owners of the same A/C....its all good......the A/c flies better in Alaska than Arizona....but like shelias,they are all different.....
CC ...called a couple of outfits and priced your suggestions.....mate it looks as if the misses is going to have to work the streets for sure....its not cheap.will have to do a gross margin job on this one...........
but the bottom line for me is ........these engines are designed to take a beating ,I say that from the stand point of commercial ops and fun flying,I done both with these engines and aircraft.......
Whilst I find CC,,s info great reading and very informative I also find that you dont have to make it rocket science either.....no disrespect CC,...but the KISS rule prevails for me.........PB
PB – If I had a buck for every time I’ve stuffed up while aviating…..
The only points I’d make in response to your eminently sensible post are that:
1. leaning to LOP is just as simple or complicated as leaning to anywhere else (twist the knob and watch a gauge);
2. you need to factor fuel costs and savings into the cost/benefit analysis of fitting the gizmos that will:
a. ensure each cylinder reaches peak EGT at approximately the same fuel flow;
b. show you that it’s happening; and
c. help you spot problems before they get dangerous and save on time diagnosing faults; and
3. if your engine can indeed take a beating and you don't want to fit the gizmos, you might as well give it the demonstrably cheaper and least damaging beating: somewhere approximating LOP
The only points I’d make in response to your eminently sensible post are that:
1. leaning to LOP is just as simple or complicated as leaning to anywhere else (twist the knob and watch a gauge);
2. you need to factor fuel costs and savings into the cost/benefit analysis of fitting the gizmos that will:
a. ensure each cylinder reaches peak EGT at approximately the same fuel flow;
b. show you that it’s happening; and
c. help you spot problems before they get dangerous and save on time diagnosing faults; and
3. if your engine can indeed take a beating and you don't want to fit the gizmos, you might as well give it the demonstrably cheaper and least damaging beating: somewhere approximating LOP
G'day Chuck, Radar, et al...
Thanks for the responses.
Like many, I have been operating ROP by the '50deg method' EGT (only 1 EGT gauge) and checking against CHT / Oil for many years in many types...the precise economics of fuel / power was not of prime concern then - only the 'supposed' long term effect on the donk.
In my former 'full time' flying days I had no perceived probs with engines going full term between overhauls, and no 'specific probs' were brought to my attention.
However, I will always stand to be further educated, and will digest the many articles recommended and 'hone up' my techniques.
An excellent post!
Thanks again.
Thanks for the responses.
Like many, I have been operating ROP by the '50deg method' EGT (only 1 EGT gauge) and checking against CHT / Oil for many years in many types...the precise economics of fuel / power was not of prime concern then - only the 'supposed' long term effect on the donk.
In my former 'full time' flying days I had no perceived probs with engines going full term between overhauls, and no 'specific probs' were brought to my attention.
However, I will always stand to be further educated, and will digest the many articles recommended and 'hone up' my techniques.
An excellent post!
Thanks again.
PB
I lean on the ground and almost every other flight regime.
As others have said about the Lyco 540, the Conty 520 also is much sweeter at idle, with the mixture leaned.
In cruise the 185 runs at around 340-365 deg F Cyl and 1520 (peak around 1600deg F)deg F EGT at 24" and 2300 rpm. Fuel burn is about 53 lph. Lean of peak ops would see burns down to 44 lph and still smooth at the times i have accidently found myself there.
I haven't got GAMI's as yet, but am due to fit the new Conty Matched Injectors soon.
Leaning is also carried out Low level airwork operations, but I would shy away from LOP ops in case any coarse applications of power are required.
I have never had any plug problems between 100 hourly in years.
I have an EI Cyltemp/EGT gauge. Their paperwork suggests keeping combined EGT/Cyl Temps below the 1830 deg F mark, for best Cylinder life. High EGT with low cyl temps or low EGT with higher Cyl temps, within reason.
185.
and if you have info pertaining to the C-185 and its ops,Skywagon,IO 520D Continental .....would be interested to hear......great posts and well worth the read...PB
As others have said about the Lyco 540, the Conty 520 also is much sweeter at idle, with the mixture leaned.
In cruise the 185 runs at around 340-365 deg F Cyl and 1520 (peak around 1600deg F)deg F EGT at 24" and 2300 rpm. Fuel burn is about 53 lph. Lean of peak ops would see burns down to 44 lph and still smooth at the times i have accidently found myself there.
I haven't got GAMI's as yet, but am due to fit the new Conty Matched Injectors soon.
Leaning is also carried out Low level airwork operations, but I would shy away from LOP ops in case any coarse applications of power are required.
I have never had any plug problems between 100 hourly in years.
I have an EI Cyltemp/EGT gauge. Their paperwork suggests keeping combined EGT/Cyl Temps below the 1830 deg F mark, for best Cylinder life. High EGT with low cyl temps or low EGT with higher Cyl temps, within reason.
185.
Grandpa Aerotart
Cost?
What was the quote...$3k?
What did the turbo cost...$35K?
Whilst I agree the underlaying theory can seem daunting...especially when you get into flame fronts, peak power pulses etc the practical side of LOP operations is pure simplicity.
Taxi leaned brutally.
Takeoff full rich, lean enough on climb to keep the hottest CHT under the 380F limit. In cruise pull the mixture back to a specific fuel flow (50 odd Lt/hr in my Bo) watch the hottest CHT...if it is gently climbing, small twist leaner and visa versa. RPM where ever you like...wanna go fast leave it at 2500, wanna go far set it at 2200.
On descent reduce MP as discussed previously..taxi in leaned as you were in cruise/descent...pull to idle cutoff when parked.
Finished.
The biggest plus is that having the technology installed alone teaches you more about your engines inner workings.
The dollars and cents plusses are many too.
* 10-15 liters per hour fuel saving. $15-20/hr?
* The strong likelyhood that if your cyclinders aren't already damaged they never will be leading to the strong likelyhood that a 1700 hr TBO will be more like 2000 hrs ++ in private ops. $2-3/hr?
* Savings on labour rates for engineers when you are able to tell them exactly what is wrong, a fecked spark plug or sticking valve for instance, as opposed to "it's running rough" and he spends 5 or 6 hrs working out why...at $60/hr
* Increased range/endurance from knowing exact fuel state and the real useable remaining as opposed to the published useable...my useable fuel went up from 280 liters to 310 liters (I call it 300 though) that I KNOW are useable even in light turbulence...coupled with using less fuel/hr means I am less likely to have to tech stop on longer trips...that could easy save 1 hr plus on a long trip each way...turbonormalising wouldn't have the same effect (via increased TAS) and that costs 10+ times what the EDM/Gamis cost to buy and lots more again in increased maintenance.
I reckon the technology saves me $30/hr over the long run..that is the price recovered in a 18 odd mths...even in pvt ops. Commercial ops would get the money back a lot quicker...imagine the savings on a Baron, C310 or Chieftain
For a TSIO520D (did you turbocharge or turbonormalise?) the savings will be greater because TSIO520s historically operated are lucky to see 75% of TBO and that after a top overhaul along the way.
I know I sound like a zealot...that is because I am. I believe this technology, and it's associated education, should be mandated by CASA in any commercially operated big bore flat 6...especially turbos carrying passengers
Would Whyalla have happened had the aeroplane and the young fella flying it been equiped with this technology and knowledge? I guess we'll never know for sure but I believe it would not have.
How many fuel starvation events would not have occurred in the last 7-10 years?
How much money could have been saved across the industry in fuel, maintenance, insurance etc?
Interesting innit?
What was the quote...$3k?
What did the turbo cost...$35K?
Whilst I agree the underlaying theory can seem daunting...especially when you get into flame fronts, peak power pulses etc the practical side of LOP operations is pure simplicity.
Taxi leaned brutally.
Takeoff full rich, lean enough on climb to keep the hottest CHT under the 380F limit. In cruise pull the mixture back to a specific fuel flow (50 odd Lt/hr in my Bo) watch the hottest CHT...if it is gently climbing, small twist leaner and visa versa. RPM where ever you like...wanna go fast leave it at 2500, wanna go far set it at 2200.
On descent reduce MP as discussed previously..taxi in leaned as you were in cruise/descent...pull to idle cutoff when parked.
Finished.
The biggest plus is that having the technology installed alone teaches you more about your engines inner workings.
The dollars and cents plusses are many too.
* 10-15 liters per hour fuel saving. $15-20/hr?
* The strong likelyhood that if your cyclinders aren't already damaged they never will be leading to the strong likelyhood that a 1700 hr TBO will be more like 2000 hrs ++ in private ops. $2-3/hr?
* Savings on labour rates for engineers when you are able to tell them exactly what is wrong, a fecked spark plug or sticking valve for instance, as opposed to "it's running rough" and he spends 5 or 6 hrs working out why...at $60/hr
* Increased range/endurance from knowing exact fuel state and the real useable remaining as opposed to the published useable...my useable fuel went up from 280 liters to 310 liters (I call it 300 though) that I KNOW are useable even in light turbulence...coupled with using less fuel/hr means I am less likely to have to tech stop on longer trips...that could easy save 1 hr plus on a long trip each way...turbonormalising wouldn't have the same effect (via increased TAS) and that costs 10+ times what the EDM/Gamis cost to buy and lots more again in increased maintenance.
I reckon the technology saves me $30/hr over the long run..that is the price recovered in a 18 odd mths...even in pvt ops. Commercial ops would get the money back a lot quicker...imagine the savings on a Baron, C310 or Chieftain
For a TSIO520D (did you turbocharge or turbonormalise?) the savings will be greater because TSIO520s historically operated are lucky to see 75% of TBO and that after a top overhaul along the way.
I know I sound like a zealot...that is because I am. I believe this technology, and it's associated education, should be mandated by CASA in any commercially operated big bore flat 6...especially turbos carrying passengers
Would Whyalla have happened had the aeroplane and the young fella flying it been equiped with this technology and knowledge? I guess we'll never know for sure but I believe it would not have.
How many fuel starvation events would not have occurred in the last 7-10 years?
How much money could have been saved across the industry in fuel, maintenance, insurance etc?
Interesting innit?
Last edited by Chimbu chuckles; 2nd Nov 2006 at 02:55.
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Great thread, really enjoying the informed discussion (makes a change on Pprune, eh!).
Not withstanding the professionalism and economy derived from correctly handling engines, Pakeha-Boy makes some valid comments re: the robust nature of modern engines and KISS.
In my line of work I ran into two mutually exclusive aims when instructing on the IO-540. One aim was to have students operate the aeroplane in the absolutely correct manner, the other was the wider aim of preparing them for a profession which would most likely see them never flying another piston engined aircraft.
With that in mind there were inevitably compromises. I didn't want to churn out students who had an intimate understanding of flame-front propagation and detonation at the expense of more applicable lessons (airmanship, rules, blah blah). Those compromises relied on trusting that broad-brush engine handling rules of thumb were 'good enough for government work', and the engines were robust enough to cope with some non-optimal mixture/rpm/throttle management.
It wasn't until some time after I had started teaching on the IO-540 that it became apparent there was 'a better way', and I tried to learn and implement as much as I could. However, I would never have my students learn that stuff - (in my opinion) in the short time they spend at the ab-initio level, there are more important lessons.
Not withstanding the professionalism and economy derived from correctly handling engines, Pakeha-Boy makes some valid comments re: the robust nature of modern engines and KISS.
In my line of work I ran into two mutually exclusive aims when instructing on the IO-540. One aim was to have students operate the aeroplane in the absolutely correct manner, the other was the wider aim of preparing them for a profession which would most likely see them never flying another piston engined aircraft.
With that in mind there were inevitably compromises. I didn't want to churn out students who had an intimate understanding of flame-front propagation and detonation at the expense of more applicable lessons (airmanship, rules, blah blah). Those compromises relied on trusting that broad-brush engine handling rules of thumb were 'good enough for government work', and the engines were robust enough to cope with some non-optimal mixture/rpm/throttle management.
It wasn't until some time after I had started teaching on the IO-540 that it became apparent there was 'a better way', and I tried to learn and implement as much as I could. However, I would never have my students learn that stuff - (in my opinion) in the short time they spend at the ab-initio level, there are more important lessons.
Last edited by Capt W E Johns; 2nd Nov 2006 at 03:02. Reason: Spelling
Grandpa Aerotart
For fully funded airline cadets I agree the MCPL is the way to go...for everyone else...give me 1/2 a day and I could teach them the nuts and bolts...30 minutes in a suitably equiped aeroplane and the mystery of the red knob dissappears.
KISS? You'll go a long way to find someone who believes in it more than I do in a practical sense. You'll also go a similar distance to find someone more burdened with a mind that needs to know why?
It has been known to get me in trouble from time to time
KISS? You'll go a long way to find someone who believes in it more than I do in a practical sense. You'll also go a similar distance to find someone more burdened with a mind that needs to know why?
It has been known to get me in trouble from time to time
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CC....mate,she,s a full turbo mate....18k.....it helps when the "other owner" ia an LAME/A&P.........the Gamis are not that expensive really ,less than $3k....and after showing this stuff to me mate ,we have decided to probably go with it,as we dont forsee the sale of this stratocrusier.......so youve cost me bloody money mate!!!!..............more poaching for sure!!!!!
185skywagon....yeah mate,your #,s and operation are similar..... love the bloody thing,........
and CC ...nice to hear youve gotton your carcass in trouble a few times.....NOW THAT,....MAKES MY DAY!!!....
PB
185skywagon....yeah mate,your #,s and operation are similar..... love the bloody thing,........
and CC ...nice to hear youve gotton your carcass in trouble a few times.....NOW THAT,....MAKES MY DAY!!!....
PB
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Hey, I thought that big red knob is used to cut the engine? No way I'm touching that in flight! 
Ok, I'm joking ... but that's the attitude of a lot of low timers I guess. The more experience we get, the more confident we get, and the better we'll be at engine management.
Ok, I'm joking ... but that's the attitude of a lot of low timers I guess. The more experience we get, the more confident we get, and the better we'll be at engine management.
So whats the advice for flying an aircraft with no operating EGT gauge let alone a JPI 700? Lean till rough and then richen a little in the air? Lean till rough on ground?
BTW I've seen LOP operation with a JPI on Doug Spriggs Cessna at Arkaroola.
BTW I've seen LOP operation with a JPI on Doug Spriggs Cessna at Arkaroola.
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LOP
Chimbu C
I have read just about everything I can find on this subject, including what you have written here and in previous posts.
So tell me, given that I only have an EGT and CHT in the Bo but generally fly at 2300/full throttle at A080 to A100 (maybe 65% power at best from the IO520), why would I not just lean until it runs rough then richen (?) it just enough for smooth running?
Cheers
R
I have read just about everything I can find on this subject, including what you have written here and in previous posts.
So tell me, given that I only have an EGT and CHT in the Bo but generally fly at 2300/full throttle at A080 to A100 (maybe 65% power at best from the IO520), why would I not just lean until it runs rough then richen (?) it just enough for smooth running?
Cheers
R
Grandpa Aerotart
At 65% and below there is absolutely no reason why you couldn't.
Sunfish what sort of aeroplane doesn't have an EGT?
Just got back from an all nighter in the mighty Boeing...but it was made more pleasant by my latest American Bonanza Society Mthly mag being in my pidgeon hole last night.
Very interesting story about a chap enroute to Oshkosh in his F33A in formation with a bunch of other Bonanzas as part of the huge formation thing they do each year. As he tools along FD&H he suddenly gets a CHT high temp alarm from his all cylinder monitor...looks down and sees one CHT at 410F and heading north at a rate of knots.
He pulls power and enrichens mixture in an attempt to remedy the situation...nothing works so hits NRST APT on his GPS and diverts immediately to an airfield 12nm away and lands safely. Engineers trouble shoot and find a MONUMENTAL crack in the offending cylinder which starts at one spark plug hole and travels through both the inlet and exhaust valve holes all the way to the other spark plug hole and a bit beyond.
He was just minutes away from having that entire cylinder head depart through the cowl followed by a catastrophic engine failure and forced landing. Instead they change the cylinder and a day or so later he is on his way to Oshkosh. At Oshkosh the all cylinder monitor manufacturer downloads and plots the engine data recorded throughout the event and they are able to see it all happening via data points recorded every 6 seconds.
Had he not had a good quality engine monitor he would have never known a thing until it was too late..with possible/probable dire consequences.
How much money did his all cylinder monitor save him?
What does it cost to fix an aeroplane even after a REALLY well executed wheels up forced landing into a paddock...50, 60, 70k?
Instead it cost him labour + parts to change a cylinder and piston.
Even if LOP aint your thing there is plenty of compelling reasons to replace the antiquated junk that passes for engine instrumentation in 95% of the fleet with the latest technology...and it aint even expensive.
Sunfish what sort of aeroplane doesn't have an EGT?
Just got back from an all nighter in the mighty Boeing...but it was made more pleasant by my latest American Bonanza Society Mthly mag being in my pidgeon hole last night.
Very interesting story about a chap enroute to Oshkosh in his F33A in formation with a bunch of other Bonanzas as part of the huge formation thing they do each year. As he tools along FD&H he suddenly gets a CHT high temp alarm from his all cylinder monitor...looks down and sees one CHT at 410F and heading north at a rate of knots.
He pulls power and enrichens mixture in an attempt to remedy the situation...nothing works so hits NRST APT on his GPS and diverts immediately to an airfield 12nm away and lands safely. Engineers trouble shoot and find a MONUMENTAL crack in the offending cylinder which starts at one spark plug hole and travels through both the inlet and exhaust valve holes all the way to the other spark plug hole and a bit beyond.
He was just minutes away from having that entire cylinder head depart through the cowl followed by a catastrophic engine failure and forced landing. Instead they change the cylinder and a day or so later he is on his way to Oshkosh. At Oshkosh the all cylinder monitor manufacturer downloads and plots the engine data recorded throughout the event and they are able to see it all happening via data points recorded every 6 seconds.
Had he not had a good quality engine monitor he would have never known a thing until it was too late..with possible/probable dire consequences.
How much money did his all cylinder monitor save him?
What does it cost to fix an aeroplane even after a REALLY well executed wheels up forced landing into a paddock...50, 60, 70k?
Instead it cost him labour + parts to change a cylinder and piston.
Even if LOP aint your thing there is plenty of compelling reasons to replace the antiquated junk that passes for engine instrumentation in 95% of the fleet with the latest technology...and it aint even expensive.
Interesting read fellas....
Quick quesiton.. I noticed in Deakins engine temp/EGT/FF graphy there was no indication of richening the mixture for the engine run. Many manuals advocate the mixture full rich for engine runs.
My question is is the leaned engine run good or bad practise?
Quick quesiton.. I noticed in Deakins engine temp/EGT/FF graphy there was no indication of richening the mixture for the engine run. Many manuals advocate the mixture full rich for engine runs.
My question is is the leaned engine run good or bad practise?
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Lads and Lasses,
John Deakin has a 56 page PDF download available at http://www.advancedpilot.com/downloads/prep.pdf and a good Power Point show at http://www.advancedpilot.com/downloads/targetegt.pps
Cheers,
Brian
John Deakin has a 56 page PDF download available at http://www.advancedpilot.com/downloads/prep.pdf and a good Power Point show at http://www.advancedpilot.com/downloads/targetegt.pps
Cheers,
Brian
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The runup to lean or not to lean?
G'day Bula,
Not to appear sarcastic but you now have all the info in this thread to answer that one yourself.
The answer is both yes and no, it all depends on circumstances.
The points you need to balance up to decide include some of and possibly more of the following:
A good starting point is how hot is your engine right now if you've been taxiing all over the field and it's hot day and your in a tightly cowled aircraft, well you can work out the answer from there.
If your oil temp or cht is above normal again probably not.
Are you in a hurry, if so then probably don't gin about and get going with a conventional runup.
Things are cool and you are in an aircraft with proper engine instruments then you have a lot to gain from a lean runup as a diagnostic tool, particularly diagnostic for the ignition system.
If you have the privelige of always flying one aircraft with proper instrumentation (proper being cht/egt for every jug + fuel flow) then try and lean to the same values each time. This then becomes a bit of a preflight trend monitor. When at significantly different elevations you'll lose the bench mark but still a good educational tool.
For a good diagnostic on the ignition you want try and induce one of the plugs to fail, whether it be the plug that actually fails or the harness or the mag doesn't matter for the initial test. The idea is to create a high combustion pressure so as to increase the sparking resistance and this happens about 40' ROP. Also going to full power would achieve the same, however unless you are over freshly swept concrete this is a bit insulting to your prop and will heat up you engine quite a bit.
I understand that the cht gained during the take off roll is always much the same so if you start with a hot engine it will be even hotter than normal as you cross the upwind end.
The other trick, again only if you have proper instruments other wise it becomes a bit meaningless and confusing is to go so lean that each jug is about to snuff then run a mag check and look at the egt reactions.
Prop cycling should be done full rich if you intend to do it at higher RPM's ie above say 1500 RPM you won't hurt it as rule if you don't but it is easier and quicker to do it rich. Your engine don't much care for being run hard on the ground so anything that reduces the time spent at high power on the ground is a good thing.
It's all a matter of circumstance's
Hope that helps a bit
M
Not to appear sarcastic but you now have all the info in this thread to answer that one yourself.
The answer is both yes and no, it all depends on circumstances.
The points you need to balance up to decide include some of and possibly more of the following:
A good starting point is how hot is your engine right now if you've been taxiing all over the field and it's hot day and your in a tightly cowled aircraft, well you can work out the answer from there.
If your oil temp or cht is above normal again probably not.
Are you in a hurry, if so then probably don't gin about and get going with a conventional runup.
Things are cool and you are in an aircraft with proper engine instruments then you have a lot to gain from a lean runup as a diagnostic tool, particularly diagnostic for the ignition system.
If you have the privelige of always flying one aircraft with proper instrumentation (proper being cht/egt for every jug + fuel flow) then try and lean to the same values each time. This then becomes a bit of a preflight trend monitor. When at significantly different elevations you'll lose the bench mark but still a good educational tool.
For a good diagnostic on the ignition you want try and induce one of the plugs to fail, whether it be the plug that actually fails or the harness or the mag doesn't matter for the initial test. The idea is to create a high combustion pressure so as to increase the sparking resistance and this happens about 40' ROP. Also going to full power would achieve the same, however unless you are over freshly swept concrete this is a bit insulting to your prop and will heat up you engine quite a bit.
I understand that the cht gained during the take off roll is always much the same so if you start with a hot engine it will be even hotter than normal as you cross the upwind end.
The other trick, again only if you have proper instruments other wise it becomes a bit meaningless and confusing is to go so lean that each jug is about to snuff then run a mag check and look at the egt reactions.
Prop cycling should be done full rich if you intend to do it at higher RPM's ie above say 1500 RPM you won't hurt it as rule if you don't but it is easier and quicker to do it rich. Your engine don't much care for being run hard on the ground so anything that reduces the time spent at high power on the ground is a good thing.
It's all a matter of circumstance's
Hope that helps a bit
M
Thanks mate. Good juices there. The company I work for operate a mixed fleet of aircraft from 20 000kg turbines to smaller BN2b. Coming into the wet we experience alot of excesive mag drops due to the mixture being overly rich. The company SOP is not to lean during taxi and to run the engine up with the mixture full rich.
Their general jist seems to be avoiding the masking of an FCU problem. All in all it seems to cost the company a lot of money to replace the FCU on a perfectly good aircraft by flying engineers around the place, aswell as aircraft ground time. I'd love to get this changed but I need some good old grease for the wheel. Them be good oil to look at the IO-540 service manual and go from there.
Any further input would be appreciated
Their general jist seems to be avoiding the masking of an FCU problem. All in all it seems to cost the company a lot of money to replace the FCU on a perfectly good aircraft by flying engineers around the place, aswell as aircraft ground time. I'd love to get this changed but I need some good old grease for the wheel. Them be good oil to look at the IO-540 service manual and go from there.
Any further input would be appreciated
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G'day Bula,
Glad to help where I can,
If you are experiencing an increasing mag drop due to increasing richness then I imagine that you must have a very very rich mixture. The simple test is at shut down just pull to idle cut off very slowly whilst watching the tach. Just prior to the engine finally quiting you should see about 25 to 50 RPM increase as the mixture reaches a best power mixture ratio. If you have a greater increase then you are to rich, less and to lean, so just ask engineering to tweak it it's a simple adjustment.
If you have a fuel flow meter a 290hp I0-540 should be indicating a fuel flow of 2.8 to 3.2 GPH at 1000 RPM, (roughly) 4 GPH is to high.
As for lean taxi/runup masking a FCU issue, can't quite fathom that, might need someone else to way in on that one.
A simple FCU check is to see consistantly correct values of fuel flow matching with left and right engine plus or minus a little and a value of at least 140 lb/hr a side at take off and into the intial climb that is for I0-540 E2B5 290hp.
Best place for your numbers is the Engine set up manual. As just because the hp figure might be similar to your engine other issue's are at play like compression ratio and the need for greater richness for detonation suppression for those with higher ratio's.
Anyone thinking of quoting those numbers please check validity first, I'm going off memory here, so just use them for a starting point for curiousity.
If your SOP's say full rich then unfortunatly full rich it is being a maverick in the field isn't prudent.
But that doesn't mean you can't try and educate the policy makers or put your thoughts forward for the merits of change. At least it shouldn't.
Regards
M
Glad to help where I can,
If you are experiencing an increasing mag drop due to increasing richness then I imagine that you must have a very very rich mixture. The simple test is at shut down just pull to idle cut off very slowly whilst watching the tach. Just prior to the engine finally quiting you should see about 25 to 50 RPM increase as the mixture reaches a best power mixture ratio. If you have a greater increase then you are to rich, less and to lean, so just ask engineering to tweak it it's a simple adjustment.
If you have a fuel flow meter a 290hp I0-540 should be indicating a fuel flow of 2.8 to 3.2 GPH at 1000 RPM, (roughly) 4 GPH is to high.
As for lean taxi/runup masking a FCU issue, can't quite fathom that, might need someone else to way in on that one.
A simple FCU check is to see consistantly correct values of fuel flow matching with left and right engine plus or minus a little and a value of at least 140 lb/hr a side at take off and into the intial climb that is for I0-540 E2B5 290hp.
Best place for your numbers is the Engine set up manual. As just because the hp figure might be similar to your engine other issue's are at play like compression ratio and the need for greater richness for detonation suppression for those with higher ratio's.
Anyone thinking of quoting those numbers please check validity first, I'm going off memory here, so just use them for a starting point for curiousity.
If your SOP's say full rich then unfortunatly full rich it is being a maverick in the field isn't prudent.
But that doesn't mean you can't try and educate the policy makers or put your thoughts forward for the merits of change. At least it shouldn't.
Regards
M
As many have already said, very good discussion...
What started as a basic "should I lean on taxi?" question has become an in-depth discussion on ROP v's LOP which has been around for years.
Many of the posts here (mainly Chuck's stuff - thanks for taking the time) seem to be written from an owners point of view. Not surprising if they're written by owners!
I have long been interested in the concept of LOP in properly instrumented aircraft. Rat****'s last post asked the very question I was thinking (try finding a piston ship in Australia's GA fleet with 6 point engine instrumentation - they do exist, but very rare). The answer seems to be "yeah, you can do it".
Now when I go flying, I get paid to do it by the bloke that owns the engines, and he has decided how he wants me to handle 'em (via SOPs). He's not going to think I'm doing him a favour. Without wanting to sound dramatic, if I do it differently, and things get funky (for whatever related or unrelated reason) - I am possibly left to explain why, but almost certainly off to look for another job. If there's injury involved I may never be employed again.
If only I worked for Chuck et al.
That's without the additional (perhaps small) complication of doing it one way in the check ride - their way, and another on my own - the right(?) way. If they don't want to equip the machines properly, why should I stick my neck out by choosing to "know better".
To summarise the above - 
I cannot risk
Now it's late
CR
(Love those things!)
What started as a basic "should I lean on taxi?" question has become an in-depth discussion on ROP v's LOP which has been around for years.
Many of the posts here (mainly Chuck's stuff - thanks for taking the time) seem to be written from an owners point of view. Not surprising if they're written by owners!
I have long been interested in the concept of LOP in properly instrumented aircraft. Rat****'s last post asked the very question I was thinking (try finding a piston ship in Australia's GA fleet with 6 point engine instrumentation - they do exist, but very rare). The answer seems to be "yeah, you can do it".
Now when I go flying, I get paid to do it by the bloke that owns the engines, and he has decided how he wants me to handle 'em (via SOPs). He's not going to think I'm doing him a favour. Without wanting to sound dramatic, if I do it differently, and things get funky (for whatever related or unrelated reason) - I am possibly left to explain why, but almost certainly off to look for another job. If there's injury involved I may never be employed again.
If only I worked for Chuck et al.
That's without the additional (perhaps small) complication of doing it one way in the check ride - their way, and another on my own - the right(?) way. If they don't want to equip the machines properly, why should I stick my neck out by choosing to "know better".
To summarise the above -
I cannot risk
Now it's late
CR
(Love those things!)