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

Folklore.

Aggressively lean for all ground ops (such that any attempt to apply more than a little power will result in stumbling rather than increased power). Shut it down by pulling the mixture at idle, as soon as you no longer need the fan running.

(For entertainment purposes, can you post the explanation, by the brainstrust that came up with that 'technique', as to the technical underpinnings for it?)

Thanks a lot for that!

That's just the thing about it, it didn't come with any explanation which is why I wanted to ask!

That's unsurprising.

I'm not aware of even a folklore-strewn POH that has that 'technique' in it.

Millions of hours of operation of a simple machine designed in the 1940s and still the fertile soil of folklore sprouts new stuff.

Best thing you can do M1M: Fly aircraft with an all-cylinder engine monitor and do some research to understand the implications of the information it's presenting to you.

Cheers Lead Balloon! Might give that a go in the near future!

Idle at 1,135RPM for 12 seconds plus 1.5s for every 1,000’ of density altitude over standard. If the engine is aligned within 20 degrees of magnetic north, you can reduce that by three seconds, but only on Tuesdays and Fridays.

Run at 1,750RPM for four seconds while going rich/lean/rich as fast as you can, followed by another five seconds on the left magneto only at 900RPM. Sing the last two lines of “The Star-Spangled Banner” while slowly moving to cutoff, which completes the procedure. If in the Southern Hemisphere, it goes without saying that you should use the right magneto instead.

FullWings ,absolutely brilliant spat my coffee out. LMAO

That's the juice, FullWings.

Of course, that's just for the injected 360. In the case of the carby version, you add 3.72% to all those numbers and the singing is instead of the last three lines of "Does Your Chewing Gum Lose Its Flavour On The Bedpost Overnight?"

(Mach1Muppet: If someone advises you to carry a metric shifter and a left handed screw driver in your flight bag, be dubious.)

No need, magnetos sold in the southern hemisphere have had their labeling swapped around so L = R anyway. CASA mandated that all Ls are Rs so that trans hemispherical alignment of cross pollinated rules infusion could occur. This is to avoid confusion when preforming shut downs and mid flight toilet breaks. The only issue is when you cross the Andes backwards flying the pacific route to Australia in a Canadian modified rig then you have to consider what you said carefully.

Don't forget to modify the inverse landing distance by 3 as per CASA holiday choir rules chapter 12.3. I had heard the designer of the O-360 was Sino-Austrian-Cherokee of decent, so singing "Botswanan Lullabies" might be more appropriate.

I was similarly skeptical when I heard of this procedure.

Actually, it's good advice. The lead scavenging agents in 100ll do not work at the combustion temperatures at idle. Leaning on the ground will reduce the quantity of lead built up, but will not remove the lead build up. The 20 second run at 1800 RPM gives a high enough temperature to activate the scavenging agents and remove lead build up. Basically you're doing a lead cleaning procedure at the end of your flight.

Solid gold, ahramin. Solid gold!

So does that mean we do this procedure for all AVGAS piston engines, that is, because its a fuel problem evidently?

O-360 ÈÍ Series Operator’s Manual Lycoming Part Number: 60297-25 ©2007 by Lycoming. All rights reserved.

10. ENGINE SHUT-DOWN. a. Set propeller at minimum blade angle (where applicable). b. Idle until there is a decided decrease in cylinder head temperatures. c. Move mixture control to the idle cut-off position. d. When engine stops, turn ignition switch to off position.

O, HO, IO, AIO, HIO, TIO-360 Series Operator’s Manual Lycoming Part Number: 60297-12 ©2005 by Lycoming
9. SHUT DOWN PROCEDURE. a. Fixed Wing. (1) Set propeller governor control for minimum blade angle when applicable. (2) Idle until there is a decided drop in cylinder head temperature. (3) Move mixture control to Idle Cut-Off. (4) When engine stops, turn off switches. b. Helicopters. (1) Idle as directed in the airframe manufacturer’s handbook, until there is a decided drop in cylinder head temperature. (2) Move mixture control to Idle Cut-Off. (3) When engine stops, turn off switches.

I've always found that the circa 700 degrees C EGTs and 200 degrees C CHTs on the next take off and climb are good indications of temperatures that are preventing 'lead build up'. That and proper leaning. Boroscope and spark plug inspections confirm it.

Problem is, Vag, that for most fixed wing aircraft the coolest the CHTs will be is on the flare for landing. All taxiing and idling after that will often result in steadily increasing CHTs.

Engine monitors don't lie.

LB's advice about "Aggresively lean on taxi is good" .When others (usually a cross-hire or flying school) used the aircraft, I had mag drop issues which were usually cleared by high RPM runups, leaned for max RPM and left for 45-60 second until reducing revs for second mag check. I attributed this to poor leaning in taxi.

I had a fouled plug on an O-360 at about 400 ft after takeoff - still climbed ok, but really rough running. Underpants were in danger territority. Quick PAN call and early turn to downwind with a very tight base leg for an uneventful landing. $150 coffee at Rottnest canned and I replaced the plug.

Wait just so I get this completely, should I replace star-stangled banner with Waltzing Matilda when operating in Australia?, also does anything to the procedure change when it is a leap year?

What a ripper of a comment this is! Jokes aside thanks all for clearing this up!

For the sceptics, the following is an extract from the Lycoming Flyer Key Reprints, page 66 under the heading of Spark Plug Fouling;

“Prior to engine shut-down the engine speed should be maintained between 1000 and 1200 RPM until the operating temperatures have stabilized. At this time the engine speed should be increased to approximately 1800 RPM for 15 to 20 seconds, then reduced to 1000 to 1200 RPM and shutdown immediately using the mixture control."

This is an engine manufacturers recommendation, which hasn’t been adopted by aircraft manufacturers.

Interstingly, the above procedure is identical to the published shutdown procedure for a number of radial powered Yak aeroplanes.

The brainstrust being Lycoming. This procedure is recommended by Lycoming, it can be found on page 66 of the Lycoming Flyer Key Reprints. This is a document containing maintenance and operating tips produced by Lycoming.

the procedure is also mentioned in the following Lycoming Service Letter:

https://www.lycoming.com/sites/defau...%20Fouling.pdf

Here’s a current service letter recommending this procedure. However, you need to read the entire document and may find it doesn’t apply to the engine / spark plug combination you’re operating.
https://www.lycoming.com/sites/defau...%20Fouling.pdf

And, For ALL of 'That'.....NOBODY YET has mentioned the 'Thronomister' Pressure Equaliser Requirement.....


COME ON..!!!

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

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.

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.

THIS ^^^
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.

The manufacturers design and build and warranty the engines and have liability issues for what they make and say.

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.

I am not sure that is quite accurate. I am not an engineer and may be wrong however I understood that the idle mixture setting is set on the carb (for FI on the throttle body or fuel control unit) independently (to a large extent) from the manual (cockpit) mixture control. I think mixture can vary with RPM (at least between idle and non idle). Over rich at idle does not imply over rich at 1800RPM. Similarly I think the rev recommendation and mixture adjustment more about controlling temperatures in the combustion chamber and how temperature impacts lead deposition. Again I am not an engineer though.

I was going to say how my memory is heading the same way too as I age but didn't want to take too cheap a shot - FWIW I can't remember exactly how many plug fouling incidents I have had over a similar time period so my memory is probably way worse than yours :)

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****.

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.

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.

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’.

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.

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.

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.

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...

Well Griffo, I'm mentioning it but only because I've heard so many different versions of it that I wouldn't have a bloody clue!!:confused::E

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!:=

Maybe your 360 gets hot due to your aggressive leaning practices..

Must be different fuel in Oz. Certainly my experience of engines in the 152 size needed plugs pulling before 50hrs. We have been operating a PA38 it lasts 50 hrs, even with leaning, quite a bit of lead in plugs.