moparrob66
Pre-takeoff checklist
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- Mar 31, 2024
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Moparrob
Beautiful! Where'd you get that so quickly?
Off the front of my airplaneBeautiful! Where'd you get that so quickly?
Well there’s less chance of getting oil on your windshield now.
FIFYBogus. I was hoping that was it was a Lycoming rear engine pickup
On the dual-mag issue I've looked at it too. I think just about everyone looks at the design and says WTF were they thinking. OTOH do the actual stats support the idea that there's a notably higher failure rate with these mags? I haven't seen any good evidence to support that- obviously at one time Lycoming thought it would be just fine. Is this a case of it just not looking good but not actually being a problem in practice?
Odd... The only mags I've had fail were from the gears, and I was told it's quite common here in the colder regions. In the winter especially, the nylon gears get heated way up every flight and then get really cold again, and it makes them brittle, and teeth and whole gears fail.Many years ago, I was told it was simply based on failure modes. Mechanical drive gear failures were basically nonexistent and if there was a drive failure it usually took out other drive gears that didn't require any redundancy. The electrical side was another matter.
Not yet. I'm this far:Jim - do you have a picture of the end of the camshaft?
Send the current oil off to Blackstone for oil analysis and see what comes up. I'm wondering if because your engine has had unit averages for Iron near 46-48 at points in the past, it doesn't raise alarms despite being above universal averages. Also not sure if their universal averages are specific to your engine model or all piston-GA models. It would be interesting to know what data set it uses to show the universal averages.
Iirc on once of my early reports, the analyst mentioned my lead being higher due to the averages being based on a 40hr run. The 25 hour people are bringing the average down. Iron might be the same issue.Lead is also over - so I question looking only at iron in hindsight wondering if the number is related to things thing that occured, while ignoring all the other variances in the sample. This is kind of classic confirmation bias.
The gears I'm referring to are the drive gears in the accessory case, not the internal distributor/spur gears. The issue some brought up was the single drive gear side. However, usually if there is an accessory gear failure it tends to take out the other systems drive gears. So the idea was given the low drive gear fail rate, only the electrical side needed to have redundancy which was where the majority of mag failures are to include those nylon distributor gear failures. Regardless, I believe Lycoming discontinued the use of single drive, dual-mags only because their supplier quite producing them and not due to overall failure rates. If you took care of them they were a solid mag.Does the dual mag use metal gears or something, or would it be susceptible to this sort of failure as well?
It's still beautiful... Are you going full overhaul?Off the front of my airplane
I think we need a work party at Jim’s place. But, no beer until the engine is back together! If each of us takes a cylinder, we’ll have her apart and back together in no time!I actually looked up how far away you were. I am *REALLY* good at tearing things apart.
Fortunately you've got a book to tell you how to put it back together
TBD. I'm leaning towards doing it. I need to get a handle on how much time and cost that's going to add, as well as what shape the engine is in now.It's still beautiful... Are you going full overhaul?
Not yet. I'm this far:
View attachment 134576
Spent a couple hours building a wooden workbench to hold it. Something I could walk around and is a little more of a comfortable working height. Got my bags and my note cards and my micrometers and my dial indicators and bore gauges. Armed with an updated Lycoming direct drive overhaul manual. Just need to work up the nerve to turn that first screw...
It's been pretty good. I have a little green and a little red. If you look close at the filthy mirror, you can see that i also have the correct color combineThe tractor is the correct color
Due to my previous job, I’ll have to disagree. Jim knows who I used to fly for.The tractor is the correct color.
Looks like you worked up the nerve.It's been pretty good. I have a little green and a little red. If you look close at the filthy mirror, you can see that i also have the correct color combine
Made some progress this evening. Bad news is that I don't have a 5-6" micrometer, and my 1-2" only reads thousandths whereas the piston pin specs are in the ten thousandths. Going to have to buy or borrow a couple micrometers. It's been a while since I've done anything to this level of precision.
Using crude, half ass measures like dial calipers (don't judge me... I'll do it right later...) and guestimating between hash marks on the mic, everything Ive measured so far has been within factory limits.
View attachment 134580
I intend to write down every measurement i take whether I make it an overhaul or not. If not, it will show what kind of shape the engine is in, and if we do the full overhaul, having the measurements will add legitimacy to a field overhaul signed off by a random mechanic.If you are going through all this trouble, make sure your micros are calibrated and/or have gage blocks on hand.
I also write the measurements down for future reference though that does not seem to be all that common.
I got fancy on my trials motorcycle and 3d printed block off plates and plugs for the various orifices during a rebuild.Tape over or plug those holes with rags to keep insects and other undesirables out. Even wind blown dirt.
I never use rags or towels around engine builds. Especially red shop rags that you see in many garages including mine….
When I built my RV-6, I used red shop towels to clean the tanks, my hands, etc. during the assembly/sealing process. After the first few hours on the airplane, I was shocked at how much red lint was in the gascolator screen. Based on that, I'm not using 'em anywhere near an engine or fuel system in the future...Most folks would be surprised where red rags show up after work’s been done. Strangest place I saw was in the centerline fuel transfer valve of an E-3. Discovered about 3 sorties/20 hours after coming out of a phase inspection.
Judging by the timestamps, your "moving slow" looks to be about 4x my normal speed.Moving slow trying not to damage anything.
Shop lent me theirs, which itself is a homemade version. Also one side is made for a 4 cylinder, and the other side a six, but there's only 8 bolts. Did I mention they don't do engine work? It was a bit fiddly moving bolts and plates around to move it evenly, but i got it done. I'm thinking I might make my own based on their design. I think all their engine tools date from when the U of I closed their A&P program 15(?) years ago. Since then, some of them have walked off or been repurposed.Did you use Lycoming's case splitting tool (or a homemade version)? If not, how'd you split it?
Don’t you have a different case on the way? Curious what the plan is.…I spent a lot of time checking dimensions in the accessory case this afternoon. Pretty much everything measured on the tight side of new spec.
New crank cases. Will reuse the old accessory case & gears, so I was measuring all that stuff up. Of course, later I realized that all the gear backlash measurements i took will have to be redone, as the gear shafts mount on the back of the crankcase.Don’t you have a different case on the way? Curious what the plan is.
Been thinking a lot about that. I decided a couple years ago not to bother because 4800 hours seems like such an impossible goal. This project will be a couple hundred on its own though by the time I count research. I think I'm going to start tracking, as well as go back through my logbook and add up oil changes and whatnot.I hope you're logging all this in case you want your a&p
I hope you're logging all this in case you want your a&p.
Also... I think you found your new hobby
Good & hardgiving us the POA special!