Lycoming O360 A3A odd sound

Firefighter_324 said:
Ok thanks.. I will try the hard and lean.. I always run Lean of peak and 75% power maybe I'm still a touch to rich.. I use the CHT gage and not the stumble then back off method


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Stumble and enrich to the right sound and smooth condition is the way to best do it given stock instrumentation. CHT only allows you to monitor the results and trends, you can't really set mixture from the raw numbers. As long as you aren't seeing CHTs above 380 and climbing, or below 220, the numbers themselves are meaningless.
 
thanks for the info.. I thought I was doing a good job at leaning but I now know I need to be much more aggressive!


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Firefighter_324 said:
thanks for the info.. I thought I was doing a good job at leaning but I now know I need to be much more aggressive!


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Most people do. When I worked as an aircraft mechanic, it was obvious who leaned aggressively and who didn't just by how often the planes were in the shop with exhaust valve problems. Those same carbon deposits when formed on the valve seats are what cause burned valves, and when it and the lead cake onto the valve stem, that is the primary source of guide wear/valve wobble and 'morning sickness' stuck valves.

Running leaded gas rich is about the most horrible way to feed an engine.
 
Why do we still have it? The market is slow to respond to such a low volume commodity that has high liability attached. Sunoco has been making an unleaded high octane racing fuel for years that would be perfect. I was talking to one of their guys about submitting it for the UL AvGas replacement, "we don't want anything to do with that market." Shell and GAMI both have a fuel in the works, I thought they had approvals a while back, but I haven't seen any big batch refined and marketed.
 
Henning said:
Why do we still have it? The market is slow to respond to such a low volume commodity that has high liability attached. Sunoco has been making an unleaded high octane racing fuel for years that would be perfect. I was talking to one of their guys about submitting it for the UL AvGas replacement, "we don't want anything to do with that market." Shell and GAMI both have a fuel in the works, I thought they had approvals a while back, but I haven't seen any big batch refined and marketed.
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Supplying all of the world's Avgas is low volume?:confused:
 
Jaybird180 said:
Supplying all of the world's Avgas is low volume?:confused:
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Yes, very low, much of the world takes no delivery. It is still a batch refining process rather than a continuous one as other fuels are. Plus there are higher liabilities to producing a bad batch. You might have to replace everybody's engine. Look what happened to Mobil 1 oil and Contintal 520s.
 
Yup, listen to your wrench turner. Glad it is not turning out to be a broken engine.

On noise cancelling headsets. I bought into them early. One morning we were on the hunt for an overpriced hamburger with my buddy Ed in my Super VIking. I kept hearing this sound come and go, like a buzz. Could not figure out what it was. Took my head set off - nada, no buzz. Put it back on and at about 30 second intervals there would be this short buzz come and go.
Back on the ground in 20 degree weather we are getting our jackets on (mine was in the back seat) and found my pager was set to vibrate. That was what I was hearing. The pager inside of a leather jacket, on the back seat, was audible over an IO540 engine at cruise power. Made me a believer in noise cancelling.
 
Dr. O said:
Yup, listen to your wrench turner. Glad it is not turning out to be a broken engine.

On noise cancelling headsets. I bought into them early. One morning we were on the hunt for an overpriced hamburger with my buddy Ed in my Super VIking. I kept hearing this sound come and go, like a buzz. Could not figure out what it was. Took my head set off - nada, no buzz. Put it back on and at about 30 second intervals there would be this short buzz come and go.
Back on the ground in 20 degree weather we are getting our jackets on (mine was in the back seat) and found my pager was set to vibrate. That was what I was hearing. The pager inside of a leather jacket, on the back seat, was audible over an IO540 engine at cruise power. Made me a believer in noise cancelling.
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It really is some nicely tuned technology, I have to say. I noticed a marked increase in the ability to hear anomalous things as well.
 
Henning said:
Yes, very low, much of the world takes no delivery. It is still a batch refining process rather than a continuous one as other fuels are. Plus there are higher liabilities to producing a bad batch. You might have to replace everybody's engine. Look what happened to Mobil 1 oil and Contintal 520s.
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Yup, I live in oil country, and many of my hangar neighbors work in the industry. All of them tell me they could whip up a batch of perfectly acceptable unleaded avgas TOMORROW -- except for the government regulations and liability exposure.
 
Henning said:
Why do we still have it
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very simple, the equipment we are required to use will not preform well on a lesser fuel.

When the FAA gets off its A$$ and allows the after market ignition systems and the fuel systems that can use it we will see hell freeze over.
 
Jay Honeck said:
Yup, I live in oil country, and many of my hangar neighbors work in the industry. All of them tell me they could whip up a batch of perfectly acceptable unleaded avgas TOMORROW -- except for the government regulations and liability exposure.
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And all the aircraft that were certified on 100/130 and rated to run on 100ll will then become trash.
 
Henning said:
Vapor pressure and stability across a greater temperature span.
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Tetraethyl lead is unrelated to vapor pressure or fuel stability.

Avgas's relatively low vapor pressure is achieved by limiting the amount of butane and isoprntane in the blend.

Avgas stability is achieved by avoiding olefins... Only paraffins and aromatics, unlike most mogas.

Paul
 
Henning said:
Sunoco has been making an unleaded high octane racing fuel for years that would be perfect.
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None of Sunoco's unleaded racing fuels appear to meet the 100 motor octane spec of avgas:

http://www.racegas.com/fuel/compare

The leaded ones do, but of course, so does leaded avgas.

Note that most of the unleaded fuels have oxygenates, which pose problems in aviation applications. All their fuels appear to violate the avgas Gravity spec as well...

Paul
 
Henning said:
It is still a batch refining process rather than a continuous one as other fuels are.
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All gasoline is made in batches.

The distinction I think you're going for is blending...

Mogas batches are typically continuously blended of the eight to fifteen Mogas components a given refinery is capable of producing.

Avgas batches are less frequently made... The last refinery I worked in might make one or two batches of Mogas a day, and in summer, one or two batches of avgas a month.

But... There is little incentive to continuous blend avgas... It's simple, only four constituents, not fifteen. And avgas is blended to a fixed recipe, not a dynamically corrected one like Mogas, where variations in component properties are compensated for in real time by tweaking the recipe.

Avgas blend component properties are more stable... No compensation typically required. If any is required, it's handled in the final additization step... The target recipe is typically 1.5 grams/gallon of lead, versus the ~2 gram max in the spec. That gives room for correction.

Paul
 
Jay Honeck said:
Yup, I live in oil country, and many of my hangar neighbors work in the industry. All of them tell me they could whip up a batch of perfectly acceptable unleaded avgas TOMORROW -- except for the government regulations and liability exposure.
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I used to live and work in Port Arthur.

I suspect your neighbors haven't looked at the avgas ASTM spec in a while.

Remember that Texas is one of the few states that doesn't require *any* gasoline to meet ASTM Spec. However, Lycoming and Continental do require fuel used with their engines to meet spec.

Where were these guys while the Exxon, Shell, BP, Texaco, Phillips and Chevron led ASTM committee struggled ineffectively from 1991 until 2010 to come up with a solution? :)

Paul
 
Tom-D said:
very simple, the equipment we are required to use will not preform well on a lesser fuel.

When the FAA gets off its A$$ and allows the after market ignition systems and the fuel systems that can use it we will see hell freeze over.
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How would you accomplish that? Retard timing to allow lower octane fuel to not detonate? How do you communicate to the pilot that he may no longer have the required takeoff performance to clear obstacles?

What changes would you make to the fuel system?

Tom-D said:
And all the aircraft that were certified on 100/130 and rated to run on 100LL will then become trash.
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100LL meets the 100/130 spec. The proposed new fuels appear to exceed the 130 part of the spec, which should improve warbird performance.

Paul
 
Tom-D said:
very simple, the equipment we are required to use will not preform well on a lesser fuel.

When the FAA gets off its A$$ and allows the after market ignition systems and the fuel systems that can use it we will see hell freeze over.
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Well, there are ways to make better fuel, they already are in other markets, and they don't have lead. Continental has a certified FADEC engine replacement for all their engines according to their sales guy at OSH.
 
PaulMillner said:
All gasoline is made in batches.

The distinction I think you're going for is blending...

Mogas batches are typically continuously blended of the eight to fifteen Mogas components a given refinery is capable of producing.

Avgas batches are less frequently made... The last refinery I worked in might make one or two batches of Mogas a day, and in summer, one or two batches of avgas a month.

But... There is little incentive to continuous blend avgas... It's simple, only four constituents, not fifteen. And avgas is blended to a fixed recipe, not a dynamically corrected one like Mogas, where variations in component properties are compensated for in real time by tweaking the recipe.

Avgas blend component properties are more stable... No compensation typically required. If any is required, it's handled in the final additization step... The target recipe is typically 1.5 grams/gallon of lead, versus the ~2 gram max in the spec. That gives room for correction.

Paul
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:confused: Most fuel refining is done in a continuous refining process that only stops for maintenance at the refineries I've been to.
 
Lead in gas reduces pre detonation, boosts octane a little, and is a lubricant for valves. Of course, like most things, too much of a good thing is bad.

When cars went to unleaded (for pollution reasons) they had to harden the valve seats.
 
Update... Man oh man do I feel dumb.. So the "pinging" noise came back again even after I thought I cured it with aggressively leaning even more than usual... I did find it though! It was the oil check door on my cowling. I never noticed because of the "hump" and being in the left seat but sure enough at anything over 5 degrees pitch up and full rich that thing buzzes like you wouldn't believe (I can see it) so I need to fix the latch and or put new rivets in now.. Sounded just like detonation!
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Hehe, well at least you found it!

On a recent avionics upgrade apparently the oil door "came off in flight", according to the people that ferried the plane back and forth from my home field.

Explain to me how that happens? My guess is they didn't latch the dang thing properly. Anyhow..I have a new one now that DOESN'T flap near as much. Lots more bolts in the cowling too then the old one had.

Maybe a new one is a fix?
 
I knew it I knew it!! My own story: I heard this buzzing noise that was new. It sounded like it was from the engine or somewhere in front of me.

One day after complaining, my buddy and I went up and sure enough he heard it too. He said, slow the plane down. Then, pitch up. Now, pitch down...level off, give it gas....each time we did the sound would come and go. Pitch up, we'd hear the buzzing, pitch down...crickets.

Ended up being the windshield sealant on my windscreen. A section had come loose in the middle but both ends were still affixed. At the right AOA, the wind would get up underneath it and start vibrating that flap of sealant. Pitched down, wind held it flat and no noise.

Re-sealed my windshield and the noise has never returned in 3+ years. So congrats, I know the sense of relief well! :yes:
 
They all seem ok but it sure does balloon the door up a lot maybe I'll make sure they are all extra secure and not letting any excess air through.. The rivets seem right and the latch seems decently tight but is somewhat spring loaded.. I can pry the door up slightly with my fingernail when it's latched.. Should I bend it down a little or possibly put some sort of seal around the door? Like a thin rubber seal ?


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Firefighter_324 said:
They all seem ok but it sure does balloon the door up a lot maybe I'll make sure they are all extra secure and not letting any excess air through.. The rivets seem right and the latch seems decently tight but is somewhat spring loaded.. I can pry the door up slightly with my fingernail when it's latched.. Should I bend it down a little or possibly put some sort of seal around the door? Like a thin rubber seal ?


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Call Piper. Cheap call, and you may luck out with a solution.
 
Firefighter_324 said:
They all seem ok but it sure does balloon the door up a lot maybe I'll make sure they are all extra secure and not letting any excess air through.. The rivets seem right and the latch seems decently tight but is somewhat spring loaded.. I can pry the door up slightly with my fingernail when it's latched.. Should I bend it down a little or possibly put some sort of seal around the door? Like a thin rubber seal ?


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Yup....tighten up the door seal and it might stop it from ringing.
 
Was it supposed to have a seal on it to begin with?? it has no seal at all in it.. Maybe that's my problem !


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I was just going make a thin gasket out rtv but that may be better stuff !


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The gasket helped some but it looks like I'm going to have to replace the hinge.. Does anyone know where I can purchase a replacement hinge and the size of rivets to use? Is this an item I'm going to have to get from Piper ?
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Found the part numbers... But no idea where to buy the hinge new and no idea what size of rivets to use..


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Looks like standard MS20001 extruded 2024T3 hinge stock. Look at Aircraft Spruce.

(Later) I now see they reference the MS20001 series but don't list it in their online catalog (?). Don't substitute the formed hinge stock, look for the much stronger extruded stuff.
 
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Thanks for the info. I believe I have located some 3 foot stock of the extruded.. now I need to figure out the rivet size...

Should I be using soft or hard flush rivets? I leaning towards the hard but the fiberglass is making me thing soft ???!!?? AD426 rivet..
 
Firefighter, here's the pic I was talking about..best pic I could get you at the moment. Won't be at the plane until Sunday at the earliest.
 
I have the door off and located the hinge stock.. Now I'm trying to decide if it's worth buying the river squeezer just to do the blind rivets.. I already have rivets and a rivet gun for pop rivets like the above picture though... I also think I should probably replace all the rivets around the entire oil door "lip" that is still on the cowl.. They are obviously loose since the paint has came off of them over time.. Grrrr
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