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Lycoming O-360 Shut-down techniques

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Lycoming O-360 Shut-down techniques

Old 3rd Dec 2021, 03:22
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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
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Old 3rd Dec 2021, 03:28
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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?)
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Old 3rd Dec 2021, 03:33
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Originally Posted by Lead Balloon View Post
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!
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Old 3rd Dec 2021, 03:42
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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.
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Old 3rd Dec 2021, 03:51
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Originally Posted by Lead Balloon View Post
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!
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Old 3rd Dec 2021, 05:05
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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.
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Old 3rd Dec 2021, 05:33
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FullWings ,absolutely brilliant spat my coffee out. LMAO
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Old 3rd Dec 2021, 05:36
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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.)
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Old 3rd Dec 2021, 05:45
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If in the Southern Hemisphere, it goes without saying that you should use the right magneto instead.
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.

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?"
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.
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Old 3rd Dec 2021, 05:48
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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.
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Old 3rd Dec 2021, 05:54
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Solid gold, ahramin. Solid gold!
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Old 3rd Dec 2021, 05:58
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So does that mean we do this procedure for all AVGAS piston engines, that is, because its a fuel problem evidently?
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Old 3rd Dec 2021, 06:15
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O-360 ČÍ 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.
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Old 3rd Dec 2021, 06:17
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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.
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Old 3rd Dec 2021, 06:18
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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.
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Old 3rd Dec 2021, 06:22
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Originally Posted by Vag277 View Post
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.
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.
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Old 3rd Dec 2021, 08:03
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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.
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Old 3rd Dec 2021, 08:33
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Originally Posted by FullWings View Post
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.
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!
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Old 3rd Dec 2021, 11:31
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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.
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Old 3rd Dec 2021, 11:36
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Originally Posted by Lead Balloon View Post
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?)
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

Last edited by roundsounds; 3rd Dec 2021 at 11:47.
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