Changed the oil in my Hatz tonight and checked the engine compression. Oil change was routine and messy, but the compression is worrisome... two cylinders at 40/80, the others are 60 and 70. Seems to be leaking mainly past the exhaust valves, gotta consider what to do next. O-290 parts ain't cheap these days, anybody got a mid time narrow deck O-320 laying around?
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Is this new? Fly it hard and try again. Did you stake the valves? Worth a shot. Might need nothing more than a valve guide ream and a quick lapping of the valve/seat.
I wouldn't do anything based on one compression test. That's like sneezing once and declaring you have a cold.
What have compression tests been like in the past, has it been getting worse? And more importantly, how's it run? Does it seem to be making good power?
TFF
Well-Known Member
Special case but a friends 235 ran with four cylinders below 60 for a long time. You did a valve lap job before. That’s where I would start. I have lapped valves with cylinders on but it is easier off. I would go ahead and do this.
First off, safety is number one, but you are able to do more with your homebuilt because you can decide where you personally stand.
The stinker is really rings for the 290. They are expensive. There are auto sources. Rings are rings if they are the right size and for the right cylinder wall. Most 290s running today probably have 320 valves and guides. Yes the perfect valve seat seal is wanted but even good compression cylinders have pits in the valves and seats in them if they have time on them. My friends 235 had a lot of guide wear. That’s where I ended up telling him to call it and really fix it. I was worried a valve was going to break off pushed too long. His were really excessive, like rattle not just loose.
They are tough engines.
First off, safety is number one, but you are able to do more with your homebuilt because you can decide where you personally stand.
The stinker is really rings for the 290. They are expensive. There are auto sources. Rings are rings if they are the right size and for the right cylinder wall. Most 290s running today probably have 320 valves and guides. Yes the perfect valve seat seal is wanted but even good compression cylinders have pits in the valves and seats in them if they have time on them. My friends 235 had a lot of guide wear. That’s where I ended up telling him to call it and really fix it. I was worried a valve was going to break off pushed too long. His were really excessive, like rattle not just loose.
They are tough engines.
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Stake the valves and have a second person hang on the prop so you can smack 'em good. I was doing this once or twice and found the second person is good for advice "Good enough!" LOL
The compression was bad about 20 hours ago, so that's what I've been doing, flying it and hoping it would improve.
Can somebody elaborate on staking the valves? I get the general idea but I'm hazy on the details or how hard to hit it. The engine is running fine and making good power. It looks like the cylinders were replaced (.020 oversize) about 225 hours and 12 years ago.
Can somebody elaborate on staking the valves? I get the general idea but I'm hazy on the details or how hard to hit it. The engine is running fine and making good power. It looks like the cylinders were replaced (.020 oversize) about 225 hours and 12 years ago.
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Take a dead blow plastic mallet, pull off the correct LOL valve cover, run the compression test pressure up to 40 or 50 and beat the exhaust valve stem. The collective fantasy is there is carbon on the valve that just needs to be dislodged. When I used to do them sometimes the pressure would go up and start to come down. If you get up to a number you like then stop.
Got the vertical stab drilled onto fuselage. Before I committed to drilling the front spar, I clamped everything up, verified the key dimensions called out in the plans, and even attached the rudder to check for binding.
Happy to say I got edge distance on the lower row of rivets on the VS forward spar to mounting plate.
Also, did some goofing around with instrument panel ideas...
[
Happy to say I got edge distance on the lower row of rivets on the VS forward spar to mounting plate.
Also, did some goofing around with instrument panel ideas...
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Nice progress. I need to get my panel and start doing that.
AncientAviation
Well-Known Member
slowly, slowly coming along....
Mitchell wing b10 ribs....
This is the largest 1/4" rib - #2 - and weighs in at 184g with just under 5m of wood used....
Started off on the small stuff but now onto the biggest ribs as finding decent wood (# grains and grain slope) is more and more challenging... fear I will have a fair amount of wood left over for making kiddie swords or stakes for the garden peas!
Mitchell wing b10 ribs....
This is the largest 1/4" rib - #2 - and weighs in at 184g with just under 5m of wood used....
Started off on the small stuff but now onto the biggest ribs as finding decent wood (# grains and grain slope) is more and more challenging... fear I will have a fair amount of wood left over for making kiddie swords or stakes for the garden peas!
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Finished the condition inspection. No surprises as cylinder compressions were all in the mid to high 70's over 80. Oil filter looked great inside and lab sent the oil analysis back as normal with numbers that closely matched that last ones I got. New plugs, cap, & rotor and it runs very sweet. Hot idle oil pressure still sits at 26 PSI. Fuel flow test was excellent, all lights working, cables inspected & lubricated, etc.
I did a bit of cleaning, greasing, and tightening up on the tail wheel and pulled the wheel pants off to do a bit of glass repair on them along with a new coat of spray bomb white while inspecting landing gear, tires, brakes, wheel bearings, etc. Seems with the small tires the grass runways tend to beat the wheel pants up a little.
Nothing of note to be concerned with but in truth I didn't get a lot of flying done over the last year. Hopefully that changes!
I did a bit of cleaning, greasing, and tightening up on the tail wheel and pulled the wheel pants off to do a bit of glass repair on them along with a new coat of spray bomb white while inspecting landing gear, tires, brakes, wheel bearings, etc. Seems with the small tires the grass runways tend to beat the wheel pants up a little.
Nothing of note to be concerned with but in truth I didn't get a lot of flying done over the last year. Hopefully that changes!
AncientAviation
Well-Known Member
Finished the second #2 rib and it only weights 152g... the one made a few nights ago was c. 184g.
Not much in absolute terms but 20% for what should be identical! I blame the glue (although I only mixed 25g of glue in total for the rib and had surplus in both cases so I'm just guessing!)
For fun, most of the metal work for the B10 wing is done... needs some bending, drilling and reaming to happen....
Not much in absolute terms but 20% for what should be identical! I blame the glue (although I only mixed 25g of glue in total for the rib and had surplus in both cases so I'm just guessing!)
For fun, most of the metal work for the B10 wing is done... needs some bending, drilling and reaming to happen....
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Installed the remote control on my hangar door. The key fobs work, but the new app doesn't (shocker!). Have to do more troubleshooting tomorrow, but it doesn't bother me much since I wasn't really expecting to use an app anyway. On the plus side, the key fobs work from outside the metal hangar without mounting an external antenna. My contractor has worked on other hangars with door remotes and they always had to install an external antenna.
And I discovered the grading we did on the yard causes water to seep under one of the hangar walls when we get heavy rain, so we have to fix that. If it's not one thing, it's another.
And I discovered the grading we did on the yard causes water to seep under one of the hangar walls when we get heavy rain, so we have to fix that. If it's not one thing, it's another.
"Seek and ye shall find."
The seating position in my Hatz isn't the greatest; in particular, my left knee starts hurting whenever I make a long flight. Part of the issue, I think, is the way I have to hold my leg to avoid hitting the pitch trim lever... what it needs is a pad to rest my knee against.
No big deal to make, but I wanted something quick and dirty to test it first, like a piece of pool noodle or thick pipe insulation snapped over a fuselage tube. I didn't have anything like that laying around, and since it's not urgent I figured I'd wait until I found something or was in a store that sold such things.
Last night, I went flying, and laying on the grass between the runway and taxiway was... two short pieces of pool noodle taped together. No idea where they came from, but it was real windy the day before from the remnants of Ida, so it could have blown in from anywhere. How convenient was that?
After landing, I went over and picked it up, cut it to length, and put it on, we'll see how it works the next time I fly.
If it works out a more elegant pad is in order, of course.
The seating position in my Hatz isn't the greatest; in particular, my left knee starts hurting whenever I make a long flight. Part of the issue, I think, is the way I have to hold my leg to avoid hitting the pitch trim lever... what it needs is a pad to rest my knee against.
No big deal to make, but I wanted something quick and dirty to test it first, like a piece of pool noodle or thick pipe insulation snapped over a fuselage tube. I didn't have anything like that laying around, and since it's not urgent I figured I'd wait until I found something or was in a store that sold such things.
Last night, I went flying, and laying on the grass between the runway and taxiway was... two short pieces of pool noodle taped together. No idea where they came from, but it was real windy the day before from the remnants of Ida, so it could have blown in from anywhere. How convenient was that?
After landing, I went over and picked it up, cut it to length, and put it on, we'll see how it works the next time I fly.
If it works out a more elegant pad is in order, of course.
pwood66889
Well-Known Member
Visited it to see how the team is doing.
Seems like I get a day or 2 of progress, then life seems to get in the way.
Finally got back in the shop today and worked out the stack up on the elevator horns and center bearing. And then, I decided to drill the end of the elevator horns for the control tube rod end bearing by taking the whole thing off, assembling upside down and clamping the elevators in trail to match drill. The"BigGator" drill guide was the perfect size to clamp between the elevator horns for match-drilling. It was so easy, I don't know why it isn't written this way in the plans.
Plus, mounting the elevators onto the horizontal stab first and then bolting the whole thing onto the fuselage is much easier that futzing around with elevator hardware with the HS stab already bolted onto the fuselage.
Finally got back in the shop today and worked out the stack up on the elevator horns and center bearing. And then, I decided to drill the end of the elevator horns for the control tube rod end bearing by taking the whole thing off, assembling upside down and clamping the elevators in trail to match drill. The"BigGator" drill guide was the perfect size to clamp between the elevator horns for match-drilling. It was so easy, I don't know why it isn't written this way in the plans.
Plus, mounting the elevators onto the horizontal stab first and then bolting the whole thing onto the fuselage is much easier that futzing around with elevator hardware with the HS stab already bolted onto the fuselage.
AncientAviation
Well-Known Member
Found the nicest bits of wood for the spars and then had to figure out where best to cut it given the imperfections in the wood. A fair bit of maths as I only had a 100cm ruler and the spars are 2.7m and 2.3m and taper.
I have the cheapest most basic entry level band saw which I have hardly used so minimal skill level anyway. Was way too scared to get to close to the pencil line so no doubt a fair bit of planing in my future... all 4 of the 2.7m rough cut... been putting this off for a while as wasn't sure how to go about it but in the end relatively happy with what I have here....
I have the cheapest most basic entry level band saw which I have hardly used so minimal skill level anyway. Was way too scared to get to close to the pencil line so no doubt a fair bit of planing in my future... all 4 of the 2.7m rough cut... been putting this off for a while as wasn't sure how to go about it but in the end relatively happy with what I have here....
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AncientAviation
Well-Known Member
I cannot confirm or deny whether a strategic sick day was employed yesterday. I certainly didn’t turn up to the office 
I did get the main spars planed and then the scarf joints rough cut and cleaned up on the sander. Almost cut one of the spars the wrong way - I would have spent the night crying if I did! Lots of looking at plans, laying things out on the floor, checking and testing before cutting. Glad I got it right!
also got to rough cut then finish the 4 outer spars also. All in all pretty happy with it but guess I need to find a local inspector before making the spars.
cordless ryobi planer has been one awesome tool…
I did get the main spars planed and then the scarf joints rough cut and cleaned up on the sander. Almost cut one of the spars the wrong way - I would have spent the night crying if I did! Lots of looking at plans, laying things out on the floor, checking and testing before cutting. Glad I got it right!
also got to rough cut then finish the 4 outer spars also. All in all pretty happy with it but guess I need to find a local inspector before making the spars.
cordless ryobi planer has been one awesome tool…
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gtae07
Well-Known Member
Still putting off work on my canopy to run wires instead (the latter is much more enjoyable). Wiring in the fuselage is about 33% done now; most of the panel wiring is just running connectors to switches and that can hopefully be done on the bench once I get a wire length set.
Canopy work will resume towards the end of the month; I have a few weekdays off in a row while my son is in school and that'll be the time to glue it on the frame. I know my canopy won't be the prettiest but it won't come off...
After that comes a little work plumbing in pressure sensors, and then it'll be time to hang the engine...
Canopy work will resume towards the end of the month; I have a few weekdays off in a row while my son is in school and that'll be the time to glue it on the frame. I know my canopy won't be the prettiest but it won't come off...
After that comes a little work plumbing in pressure sensors, and then it'll be time to hang the engine...
Had a warm (82°F, I know you southwestern guys will laugh) day today, so it was time to wash the plane after work, maybe the last chance this year to do it comfortably. It needed it, bug splats and some bird crap, but when I flew it afterward to dry it off I was amazed at how much nicer it looked in the sunshine, I guess it was dirty or dusty overall, not just in spots. You don't notice as it creeps up on you.
