Lycoming O-360 Shut-down techniques
G'day all,
Been reading about O-360 shut down tips especially:
1. Lean, operate at 1200 rpm for 1-minute. (While taxiing?)
2. Operate at 1800 rpm for 20-seconds
3. Reduce to 1200 rpm and kill with mixture.
How true is the above? Has anyone seen the major issues surrounding improper shutdown?
Cheers,
Mach1
Been reading about O-360 shut down tips especially:
1. Lean, operate at 1200 rpm for 1-minute. (While taxiing?)
2. Operate at 1800 rpm for 20-seconds
3. Reduce to 1200 rpm and kill with mixture.
How true is the above? Has anyone seen the major issues surrounding improper shutdown?
Cheers,
Mach1
https://www.lycoming.com/sites/defau...%20Fouling.pdf
This is all very interesting to me. With the ever increasing price of AVGAS, I, too, have been considering to shut down my engine at night
I'm afraid some here may have thought that my comments were sarcastic. The guidance is also found in Shell documentation:
Lead Fouling | Preventing Lead Fouling in Aircraft | Shell Global
Lead Fouling | Preventing Lead Fouling in Aircraft | Shell Global
Last edited by ahramin; 3rd Dec 2021 at 17:16.
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Yup run up to clear the plugs before shut down, remember you could have done a longish taxy back at low RPM before shut down, so clearing the plugs is always a good thing.
It’s all folklore.
Plenty of folklore has been produced by piston aero engine manufacturers and others.
There are ways to find out if there’s ‘lead build up’ and fouled plugs due to the method of operation.
Fouling due to long taxi at idle is due to an overly-rich mixture. If it’s overly-rich at 1,000 RPM, it’s still overly-rich at 1,800 RPM. That is, unless you lean the mixture…
Aggressive leaning during ground ops and stop the fan as soon as you no longer need it. I remember one fouled plug in 35 years of flying pistons.
Plenty of folklore has been produced by piston aero engine manufacturers and others.
There are ways to find out if there’s ‘lead build up’ and fouled plugs due to the method of operation.
Fouling due to long taxi at idle is due to an overly-rich mixture. If it’s overly-rich at 1,000 RPM, it’s still overly-rich at 1,800 RPM. That is, unless you lean the mixture…
Aggressive leaning during ground ops and stop the fan as soon as you no longer need it. I remember one fouled plug in 35 years of flying pistons.
Last edited by Lead Balloon; 3rd Dec 2021 at 20:53.
1800 rpm is not a mild power setting so depending on where you park, thrashing the engine just before shutting it down may get an less than amused response from the other owners who just got their planes sand blasted or rock pelted. Let alone you try that on a busy apron. Makes total sense until reality kicks in.
As with LB above never had issues with fouled plugs with healthy engines even without significant leaning on the ground. When a particular aircraft started to foul then we tried plug changes and leaning, have to also consider oil fouling as the engine condition deteriorates. If its fouling seriously in short periods theres other things at play.
As with LB above never had issues with fouled plugs with healthy engines even without significant leaning on the ground. When a particular aircraft started to foul then we tried plug changes and leaning, have to also consider oil fouling as the engine condition deteriorates. If its fouling seriously in short periods theres other things at play.
It’s all folklore.
Plenty of folklore has been produced by piston aero engine manufacturers and others.
There are ways to find out if there’s ‘lead build up’ and fouled plugs due to the method of operation.
Fouling due to long taxi at idle is due to an overly-rich mixture. If it’s overly-rich at 1,000 RPM, it’s still overly-rich at 1,800 RPM. That is, unless you lean the mixture…
Aggressive leaning during ground ops and stop the fan as soon as you no longer need it. I remember one fouled plug in 35 years of flying pistons.
Plenty of folklore has been produced by piston aero engine manufacturers and others.
There are ways to find out if there’s ‘lead build up’ and fouled plugs due to the method of operation.
Fouling due to long taxi at idle is due to an overly-rich mixture. If it’s overly-rich at 1,000 RPM, it’s still overly-rich at 1,800 RPM. That is, unless you lean the mixture…
Aggressive leaning during ground ops and stop the fan as soon as you no longer need it. I remember one fouled plug in 35 years of flying pistons.
The quoted publication starts by saying that plug fouling is caused by low temperatures and rich mixtures.
Lean the mixture till anything over 1200-1300 rpm causes a stumble.
Thats properly leaning for taxiing.
If they recommend you sing the star spangled banner on shutdown, I personally would think it is at least worth learning the first line or two or maybe knowing how to hum the tune.
There are ways to find out if there’s ‘lead build up’ and fouled plugs due to the method of operation.
Fouling due to long taxi at idle is due to an overly-rich mixture. If it’s overly-rich at 1,000 RPM, it’s still overly-rich at 1,800 RPM. That is, unless you lean the mixture…
Fouling due to long taxi at idle is due to an overly-rich mixture. If it’s overly-rich at 1,000 RPM, it’s still overly-rich at 1,800 RPM. That is, unless you lean the mixture…
I have no doubt that you have only had one plug fouling incident in 35 years and that your technique works. In fact leaning on taxi is actually what Lycoming recommend so no argument from me.
I guess where we differ is when the manufacturer recommends a shutdown technique on a particular engine, I don't readily dismiss it. Lycoming have bulletins and service instructions for their engines (as @roundsounds posted). I would not be quick to think they should be ignored.
my 2c
The effectiveness of all these procedures can and has been proven or disproven. Comparisons can and have been made between the condition of engines run in accordance with them and engines not run in accordance with them. Plugs can and have been removed and inspected. CHTs can and have been monitored. Boroscope inspections can and have been carried out. Comparisons, inspections and monitoring now done over millions of hours and many, many engine monitors.
What you have to realise is that the engine manufacturers base their recommendations on test stand operations. That’s where the recommendation came from about running at idle until the CHTs start dropping. That’s because on the test stand running at ‘high power’ makes the CHTs ‘hot’ then running the engine at idle reduces CHT. But in the real world the coolest CHTs usually are is on the flare and roll after landing. All operations after that – even at idle – usually result in an increase in CHT. The numbers on the engine monitor don’t lie.
You don’t have to be an engineer to work out whether mixture set to full rich is or is not ‘over rich’ at 1,800 RPM compared with 1,000. You can measure fuel flow at each, you can read the engine monitor and you can pull the plugs and inspect them after the differing procedures. A properly set up engine is still ‘quite rich’ at FULL throttle and full rich. You can prove it by leaning the mixture with the throttle set to full: Lo and behold, the engine produces more power! (But don’t do that for long…)
A while ago I was asked to do a 50 hourly oil change and plug inspection a bog standard C172. It spent most of its life taxiing before take off for a few circuits then taxiing after circuits. The red knob was usually touched only twice during each of these flights: full rich before start and idle cut off to shut down.
The plugs were pitch black. I wouldn’t have put them in my lawn mower. Full power during take off and ‘medium’ power – in excess of 1,800 rpm – during downwind before pulling it back for base and final was never enough to ‘overcome’ the consequences of the almost-continuously over rich mixture. 1,800 RPM might make the engine hotter, but it’s still running too rich if the mixture is set to full rich – even more so if you are above MSL ISA.
You can take whatever cheap shots you like. I should have said I also remember numerous failed plugs over 35 years. That’s not the same as fouled plugs. The percentage of plugs that are bad, new out of the box is quite surprising.
Ah, warranty claims. You’re absolutely right. An engine manufacturer would refuse a warranty claim if an operator had failed to comply with the manufacturer’s recommendation to sing the star spangled banner on each shut down. It’s what engine manufacturers do. But that shouldn’t stop us calling out bull**** when it’s bull****.
What you have to realise is that the engine manufacturers base their recommendations on test stand operations. That’s where the recommendation came from about running at idle until the CHTs start dropping. That’s because on the test stand running at ‘high power’ makes the CHTs ‘hot’ then running the engine at idle reduces CHT. But in the real world the coolest CHTs usually are is on the flare and roll after landing. All operations after that – even at idle – usually result in an increase in CHT. The numbers on the engine monitor don’t lie.
You don’t have to be an engineer to work out whether mixture set to full rich is or is not ‘over rich’ at 1,800 RPM compared with 1,000. You can measure fuel flow at each, you can read the engine monitor and you can pull the plugs and inspect them after the differing procedures. A properly set up engine is still ‘quite rich’ at FULL throttle and full rich. You can prove it by leaning the mixture with the throttle set to full: Lo and behold, the engine produces more power! (But don’t do that for long…)
A while ago I was asked to do a 50 hourly oil change and plug inspection a bog standard C172. It spent most of its life taxiing before take off for a few circuits then taxiing after circuits. The red knob was usually touched only twice during each of these flights: full rich before start and idle cut off to shut down.
The plugs were pitch black. I wouldn’t have put them in my lawn mower. Full power during take off and ‘medium’ power – in excess of 1,800 rpm – during downwind before pulling it back for base and final was never enough to ‘overcome’ the consequences of the almost-continuously over rich mixture. 1,800 RPM might make the engine hotter, but it’s still running too rich if the mixture is set to full rich – even more so if you are above MSL ISA.
You can take whatever cheap shots you like. I should have said I also remember numerous failed plugs over 35 years. That’s not the same as fouled plugs. The percentage of plugs that are bad, new out of the box is quite surprising.
Ah, warranty claims. You’re absolutely right. An engine manufacturer would refuse a warranty claim if an operator had failed to comply with the manufacturer’s recommendation to sing the star spangled banner on each shut down. It’s what engine manufacturers do. But that shouldn’t stop us calling out bull**** when it’s bull****.
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Another factor: fine wire vs massive electrode spark plugs. O-360 is permitted to have either.
Experience showed that fine wire had less prevalence of fouling issues (but 4 times as expensive) - longer lasting too which is clearly good, but plugs should have been inspected/cleaned/rotated at 100hrly anyway.
Experience showed that fine wire had less prevalence of fouling issues (but 4 times as expensive) - longer lasting too which is clearly good, but plugs should have been inspected/cleaned/rotated at 100hrly anyway.
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So at taxi speed is the carb. only feeding fuel through the slow run idle jets. Seems if carbs. aren't set right there seems a stutter at 1200-1300 rpm. Is this the change over point.
So what's the point leaning carb. engines when taxying.
Never had any problems properly set up carb. ign. and plugs.
But do believe plugs should be pulled at 25, not pushed to 50 hour check as we do.
So what's the point leaning carb. engines when taxying.
Never had any problems properly set up carb. ign. and plugs.
But do believe plugs should be pulled at 25, not pushed to 50 hour check as we do.
What is the basis of your belief that plugs should be pulled at 25 hours rather than 50? Have you observed any difference between a plug pulled at 25 versus 50? If yes, what was the difference? If they’re getting dirty or full of lead gubers in 25 hours, the engine’s being run too rich for too long.
The point of leaning an engine during ground operations is to reduce the risk of plug fouling due to an overly-rich mixture. It can be tricky getting it right on some carb’d engines because the setting is sometimes close to ICO, but with practise it’s easy. The point of “aggressively” leaning is to avoid the possibility of the engine being able to produce much more than idle / taxi RPM. Full throttle/RPM with the engine ‘slightly’ leaned can be ‘bad’.
The point of leaning an engine during ground operations is to reduce the risk of plug fouling due to an overly-rich mixture. It can be tricky getting it right on some carb’d engines because the setting is sometimes close to ICO, but with practise it’s easy. The point of “aggressively” leaning is to avoid the possibility of the engine being able to produce much more than idle / taxi RPM. Full throttle/RPM with the engine ‘slightly’ leaned can be ‘bad’.
Leaning on taxi out would only be advised as far as the run-up bay, once you have completed your pre take-off checks the settings should remain that way until after take-off to avoid things like out of trim or take-off with the mixture leaned. If the aircraft is significantly fouling in the taxi between the run-up bay/area and take-off then you really should get it worked on to alleviate whats causing it.
As for 25 hour checks, god are you trying to nail the final nails in GAs coffin for no reason. Our fleet of Warriors ran 100 hours between checks in ham fisted training with no engine monitoring, simple egt and very mild leaning and the engines exceded TBO except for a few rare cases where a warranty item had to be called on (non operational caused issue). Until AD-ENG-4 this all worked fine and never had any issues related to operating. The carby O-320-D3G was relatively bullet proof, as with the O-235s on 152s. If told we had to pull the plugs every 25 hours you'd get a stern look from the owner. The O-360 series much the same unless its put in a Seminole and then that's more a cam issue and not leaning related, although thrashing it at 1800 rpm just prior to shut down would not help it. I reckon half modern engine issues are to do with them being pulled apart way more often than they need, rather than only when required. Non invasive condition monitoring is the way to go, let it run until it shows signs its not happy, then play with it. Alter operating patterns and process to make it operate longer and happier between techs pulling things apart and changing things.
As for 25 hour checks, god are you trying to nail the final nails in GAs coffin for no reason. Our fleet of Warriors ran 100 hours between checks in ham fisted training with no engine monitoring, simple egt and very mild leaning and the engines exceded TBO except for a few rare cases where a warranty item had to be called on (non operational caused issue). Until AD-ENG-4 this all worked fine and never had any issues related to operating. The carby O-320-D3G was relatively bullet proof, as with the O-235s on 152s. If told we had to pull the plugs every 25 hours you'd get a stern look from the owner. The O-360 series much the same unless its put in a Seminole and then that's more a cam issue and not leaning related, although thrashing it at 1800 rpm just prior to shut down would not help it. I reckon half modern engine issues are to do with them being pulled apart way more often than they need, rather than only when required. Non invasive condition monitoring is the way to go, let it run until it shows signs its not happy, then play with it. Alter operating patterns and process to make it operate longer and happier between techs pulling things apart and changing things.
Last edited by 43Inches; 5th Dec 2021 at 23:23.
It's not just plugs that get lead fouled. Valve problems from lead fouling are much more expensive and time consuming to deal with. Plus plugs get cleaned regularly anyway.
As for not leaning after the run-up is done, what if you don't do a run-up that flight? Personally, I put the mixture rich entering the runway.
As for not leaning after the run-up is done, what if you don't do a run-up that flight? Personally, I put the mixture rich entering the runway.
Again pre take-off checks are just that, to set the aircraft up for take-off. You change any of the critical settings after you have run those checks/checklist you set yourself up for a distraction based ATSB appearance. Unless you are doing multiple pre-take off checks before you depart, which just over complicates things. Doing critical actions while entering a runway for departure is not great airmanship as you set yourself up for either missing that action or missing your lookout in a busy environment. Much better pilots than me have succumbed to this so I avoid doing anything but concentrate on lookout and the take-off anywhere near a runway, not worrying if something I should have done stationary well away from there has been done. And not confusing this with a quick scan that everything is where it should be prior to rolling, but that is just conformation, not actions that could be missed in a rush.
Reminds me of Navajos and taking off on Auxillaries, because the operator had some weird method of taxiiing on auxes and if you missed the pre take-off checklist item to change tanks to mains you ended up star centerfold in the crash mags. This happened more than once, I wonder if operators still do this sort of nonsense.
A lot of this is airmanship as well, blasting the parking area at 1800 rpm just prior to shut down makes no sense, and if you are doing this arbitrarily without thinking even worse.
Reminds me of Navajos and taking off on Auxillaries, because the operator had some weird method of taxiiing on auxes and if you missed the pre take-off checklist item to change tanks to mains you ended up star centerfold in the crash mags. This happened more than once, I wonder if operators still do this sort of nonsense.
A lot of this is airmanship as well, blasting the parking area at 1800 rpm just prior to shut down makes no sense, and if you are doing this arbitrarily without thinking even worse.
Now it's valves as well? Once more: boroscope inspections...
I see that Shell's into it as well, here, e.g.:
I thought it was 1800 rpm. Anyway...
The 'remedy' quoted is based on intuition rather than real world data.
When I start my 360, if I sit at idle the engine gets warmer. Then it gets warmer. Then it gets hotter. Then it gets really hot. And, if I'm stupid enough to sit there idling or taxiing around without taking off, it will get even hotter and finally reach 'red line'. And, after I land and pull off the runway, the engine gets slowly hotter and hotter and hotter and...
I see that Shell's into it as well, here, e.g.:
Engines that have been involved with long, low power descents, or have taxied for some distance, can have quite low cylinder temperatures and this - as we now know - can lead to lead fouling. Again the advice from Textron Lycoming and Teledyne Continental Motors to remedy this is: once on the aircraft is on the stand, the engine speed should be kept between 1000 and 1200 rpm until the engine temperatures have stabilised.
The 'remedy' quoted is based on intuition rather than real world data.
When I start my 360, if I sit at idle the engine gets warmer. Then it gets warmer. Then it gets hotter. Then it gets really hot. And, if I'm stupid enough to sit there idling or taxiing around without taking off, it will get even hotter and finally reach 'red line'. And, after I land and pull off the runway, the engine gets slowly hotter and hotter and hotter and...
Last edited by Lead Balloon; 6th Dec 2021 at 06:19.
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'Thronomister' Pressure Equaliser Requirement.....
And I find it hard to believe that this thread has progressed so far on what is really a simple procedure.
Which consists of following the instructions that which every single Instructor, Check and Training or Chief Pilot I have ever flown under/for has given me. This has mainly consisted of "Read the Flight Manual" and do what it tells you to do!
The 'remedy' quoted is based on intuition rather than real world data.
When I start my 360, if I sit at idle the engine gets warmer. Then it gets warmer. Then it gets hotter. Then it gets really hot. And, if I'm stupid enough to sit there idling or taxiing around without taking off, it will get even hotter and finally reach 'red line'. And, after I land and pull off the runway, the engine gets slowly hotter and hotter and hotter and...
When I start my 360, if I sit at idle the engine gets warmer. Then it gets warmer. Then it gets hotter. Then it gets really hot. And, if I'm stupid enough to sit there idling or taxiing around without taking off, it will get even hotter and finally reach 'red line'. And, after I land and pull off the runway, the engine gets slowly hotter and hotter and hotter and...
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Leaning on taxi out would only be advised as far as the run-up bay, once you have completed your pre take-off checks the settings should remain that way until after take-off to avoid things like out of trim or take-off with the mixture leaned. If the aircraft is significantly fouling in the taxi between the run-up bay/area and take-off then you really should get it worked on to alleviate whats causing it.
As for 25 hour checks, god are you trying to nail the final nails in GAs coffin for no reason. Our fleet of Warriors ran 100 hours between checks in ham fisted training with no engine monitoring, simple egt and very mild leaning and the engines exceded TBO except for a few rare cases where a warranty item had to be called on (non operational caused issue). Until AD-ENG-4 this all worked fine and never had any issues related to operating. The carby O-320-D3G was relatively bullet proof, as with the O-235s on 152s. If told we had to pull the plugs every 25 hours you'd get a stern look from the owner. The O-360 series much the same unless its put in a Seminole and then that's more a cam issue and not leaning related, although thrashing it at 1800 rpm just prior to shut down would not help it. I reckon half modern engine issues are to do with them being pulled apart way more often than they need, rather than only when required. Non invasive condition monitoring is the way to go, let it run until it shows signs its not happy, then play with it. Alter operating patterns and process to make it operate longer and happier between techs pulling things apart and changing things.
As for 25 hour checks, god are you trying to nail the final nails in GAs coffin for no reason. Our fleet of Warriors ran 100 hours between checks in ham fisted training with no engine monitoring, simple egt and very mild leaning and the engines exceded TBO except for a few rare cases where a warranty item had to be called on (non operational caused issue). Until AD-ENG-4 this all worked fine and never had any issues related to operating. The carby O-320-D3G was relatively bullet proof, as with the O-235s on 152s. If told we had to pull the plugs every 25 hours you'd get a stern look from the owner. The O-360 series much the same unless its put in a Seminole and then that's more a cam issue and not leaning related, although thrashing it at 1800 rpm just prior to shut down would not help it. I reckon half modern engine issues are to do with them being pulled apart way more often than they need, rather than only when required. Non invasive condition monitoring is the way to go, let it run until it shows signs its not happy, then play with it. Alter operating patterns and process to make it operate longer and happier between techs pulling things apart and changing things.