[79FT]: Building Things
...or was it pickles?
|On:||May 17, 2019|
|In:||[Chickenhouse Charger] 2019 Annual|
|Tags:||6781G, MA5 Charger, Annual, engine, Rotec TBI, prop|
So after having discovered the electrical mess, I realized that she's gonna be sitting for a while.
Pickle time! Damn, this pickling thing is becoming a thing, excuse my tautologies...
I had to put her together enough to be able to run the engine to circulate and warm up pickling oil.
And she was apart. With intakes off, TBI almost off, no oil, and such.
So first, it was to be intakes.
RTV where there should be none
Somebody put RTV to "seal" the intake gasket. Oh well.
Did you know that those 1 1/2 inch rubber hoses that go on intake tubes are much easier with very thin coat of oil?
Oiling the hoses
And then, it was the TBI.
Recall that when I was putting her apart, I found pipe dope on the TBI inlet port?
Let me explain.
Fuel goes into gascolator. Then it branches: one branch goes to the engine driven pump, the other goes to the electric pump. Then, they go to the regulator on the TBI. Then, a couple of 90 degree fittings feed it into the TBI's inlet port, which has the "last chance" screen in it.
That's the port here, right above the airflow straightener:
TBI from the down low
See that white gunk? That's Teflon dope. "Aircraft grade"; whatever.
Here's the problem.
TBI inlet hole
Fuel has to go there, into that inlet hole. That's what the screen fitting screws into. Right past that, inside the TBI itself, there's a turn, another turn, and a spray bar that sprays gas into the intake, injection-style, thru a tube with a bunch of tiny holes. That's why there are screens in the fuel system: to prevent gunk from clogging up those tiny holes.
So now, what happens when you take a male fitting out of a female threaded hole, and the fitting was doped? Some of that stuff ends up on the female portion. Next time the fitting is put in, dope remnants will be pushed in past the engaged threads, and possibly clog up the works.
Not. Good. At. All.
That's why there is the copper crush gasket behind that screen fitting - to seal it to the TBI body w/o requiring anything extra. You can kinda see that gasket all smudged around with that dope on the first picture.
So I had to deal with it.. Clean it out somehow.
It was crumbly, but sticky enough to not want to come out.
I tried every solvent on hand. Nope.
I tried carefully scraping it out with a dental probe. Yeah, kinda worked, but I wasn't satisfied.
I tried every solvent in my buddy Dick's hangar. Nope.
In desperation, I drove to the local Home.. strike that, Aerospace, Depot, thinking about picking up every kind of solvent they had and I didn't.
And then, I remembered this:
I don't know what kind of concoction that is; but it worked! The hole was clean. Next time was a couple days after, and when I got back to the hangar, I discovered that it has turned into a lake :(
Lake in my hangar
Grading's all screwed up around our hangars, and when we get lots and lots of rain, they flood. Not too much though, luckily. This was the second time in the past few weeks - first time, I had my tools scattered around the floor. This time, I was smarter...
Anyway, back to the TBI. The rest of it went together quite nicely. I discovered that there was TorqueSeal put on the idle mixture screw.
Why? No idea. That screw is spring loaded. Should stay put.
Torque Seal where there should be none
I wanted to flush the lines and then the TBI to make absolutely sure none of that dope went it. The best way to do that would be with the electrical pump; but I'm a one man show.... and the switch for it is 5 feet away from the firewall.
So, I had to rig me up a little doodad.
The simple click switch
.. with ring terminals
The ring terminals were hooked up to the Master Solenoid in such a way that when the button was clicked on, the Solenoid would close.
The pump was turned on.
This way, I could click my button, Master Solenoid would close, and the pump would start running. Neat-o! I'll need it later, too.
Flushing - braided hose provides nice bond to the airframe
I borescoped the engine (looked alright - I'll post a report about this later, maybe...); and it was time to fill'er up with oil.
Pickling oil was mixed up next, and into the engine it went.
A pitcher of pickling oil
A recipe for a mess...
After filling the sump up, it was time to check for oil pressure. Lycoming tells you in SB1241C to pre-oil your engine by cranking with the starter in 10-30 second bursts until oil pressure comes up to 20 PSI.
Well, oil pressure gauge on the Charger is finicky, so I wanted it to at least move.
Oh wait. She has an ignition/start switch. No way I can use that to crank and not have a hot mag w/o messing with P-Leads.
Also, I might want to crank from around the firewall (the prop was still off).
But I had my pushbutton doodad!
So I rigged it up to the starter solenoid this time.
Of course I misunderstood the way the starter solenoid was wired.
It had two terminals.
I thought one of them was ground; with the wire going to the firewall. The other then was supposed to be positive.
That didn't work.
I measured it - between those terminals - nothing. "Dead starter solenoid", I though. Crap! It was 8pm. Auto parts stores were closing soon.
I rushed to a nearby O'Reilly. Picked up a starter solenoid. Went back.
Measured it too. NOTHING? How come? Something was amiss.
Only then I started suspecting that something was off. That other terminal on the original starter solenoid I was hooking my positive wire to was all corroded and looked like it never had a nut.
OH! The way it's supposed to be wired is that positive goes to the same terminal where that wire I thought to have been ground was. It wasn't a ground wire - it was a diode. And the ground was off of the case of the solenoid.
So, we're cranking now.
30 seconds. No pressure. 30 more. No pressure. Crap!
I unhooked the oil pressure sending hose (the one that hooks up to the line that goes to the gauge).
Crank. No oil. A couple bubbles is all I got.
The oil pump de-primed itself?
Kinda makes sense I guess? The plane was sitting for way too long :(
So, I took off the oil cooler return line. Dumped another quart of oil in there.
I had this hose fitting that goes on top of an oil bottle that was very neatly set up to mate with the engine oil hose's flare: so I could squeeze the bottle and push the oil in.
After the whole quart, I re-hooked the line back onto the oil cooler, and tried again.
Success! Now, I saw oil coming out of the oil pressure sending hose.
Hooked it up to the gauge line, and saw the gauge move, finally. Good.
Damn, with all that cranking I ran out my old battery I had put in there.
Now, have to flip the battery (to put in the good one - the flying one - I always use my old battery from the Cheetah when I mess with electrical, not to abuse the actual "production" battery).
Now, the top spark plugs go back in, the ignition wires get hooked up.
Bolt one - start it in. Bolt two. Bolt three.
Bolt 4. Doesn't go in? Not even a chance? What the hell?
I pulled the prop back off and laid it down. Put the front crush plate on top (that one positions the bolts).
No matter what I did, there'd be at least 3 out of 6 bolts that won't go in. This time, it was a few dry days, and I guess the prop moved enough to have the "top" and "bottom" holes (if looking at the prop horizontally) move closer together. It was off by almost a 1/16th.
So here I was. With an engine that was cranked for a total of a few minutes, and probably had scraped a lot of oil off of cam lobes and lifters.
With a prop.
I couldn't put on.
Which I needed.
To fire the damn thing up.
It was late. I tidied up, and went home.
I wrote a note to Frank Johnson who made the prop that same night, and called him the next day.
He wasn't surprised. "Redrill" is a simple fix.
But I was a bit apprehensive, and this was a nice excuse to meet him. He's 2 hours away from me. We agreed to meet in a few days, at the first time he was available.
So, the engine with oil scraped off the lobes had to sit for another couple days.
Nothing I could do in that short a time...
The weekend hit us; and it is a weekend in May, in Texas. Which means...
The annual fit inspection
Into the trailer the prop went, and to Frank's we drove.
All tucked in
Of course, it took us 15 minutes out of 3 hours I spent there to fix it. The rest of it? Well, what can two guys who're crazy about airplanes do at one of those guys' shop and hangar? Hmm... What could we do? :)
The weather was swell, and I was in a good mood - and airport was on the way back from Frank's.
So, I went straight to the airport.
The prop went on beautifully.
It was nice, sitting in a running, shivering airplane, to watch the sunset. If you looked up, it almost felt like flying. With the buzz, the shake, the smell and the noise.
A couple days later, I went back to the hangar, sprayed the engine top and replaced spark plugs with desiccant.
Now, I can focus on the electrical mess...
The Muffler plug
There are three simple rules for making a smooth landing. Unfortunately, no one knows what they are.
...Comanche, no Comanche?
|On:||May 15, 2019|
|In:||[Chickenhouse Charger] 2019 Annual|
|Tags:||6781G, MA5 Charger, Annual, baffles|
Baffle seals on this plane are original reinforced neoprene rubber, and they were in pretty beat up shape. There is a lot of gaps, they sag in places, making the seal really not that good.
So one of the things I decided to do is to redo them.
Pardon the cruddy pictures; but those ones are the only ones I have :(
One of the things I noticed immediately is that baffle seals were turned the wrong way in the nosebowl area; where the front "air ramp" joins the bottom of the nosebowl.
Here's the nosebowl and the front ramp:
Notice the circled area? Here it is, from the back:
That marked rubber seal is in the circled area. Notice it's turned the wrong way; "into" the cowling, rather than away from it? Ram air hitting that front "ramp" will "bend it in", and leak into the underside of the engine compartment - precisely where it's not supposed to go.
Naive me thought that it was just wrongly installed - the rubber needed to have been folded up and out, "into" the lip of the nosebowl.
Correct and current seal orientation
Ha! Well, Remo (the guy who built the Charger) thought different.
There's just not enough room there. Everything is super tight. The seal just won't go there and stay there. There's just no room.
Look at the above two pictures - inside and outside - again. You'll understand why. Use pop rivet line as your reference.
Here's where the problem gets worse. Ramp is really thin - so with just a mild pressure, I can make that gap between the ramp and the bowl 1/4 - 3/8 inches. Guess what happens when ram air hits it... :)
What ram air does...
Okay, so then I went digging.
I thought this was a standard bowl. I was right!
It's an old Comanche single style bowl (I think).
Looks similar? I researched further.
Here's a guy making replacement ramps for Comanches, with some good pictures.
Front ramp on a Comanche
Okay; see the difference? Comanche ramps are curved the other way.
Changer vs. the Comanche
This is cross section. Mine's on the left, Comanche's on the right. Red is nosebowl; blue is this ramp, and black is my baffle seal.
Mine is "concave". Comanche is "convex". So if I got my thinking right, this makes the Comanche version more rigid facing the wind.
Drawing from the Comanche's parts' manual confirms this proper curve.
Comanche parts manual on baffles
The parts I'm talking about are numbers 11 and 12, bottom right corner.
But how the heck do they seal them? Notice that the material on the drawing above seemingly has some "dots" on it (as opposed to the rubber material on the side baffles).
Well, back to our "remade Comanche front baffles" guy.
Forward baffles from Comanche Gear guy
Well, I guess that makes sense. Felt wrapped around the front ramp.
Felt is thick and, contacting the nosebowl, I guess, will create a good enough seal if the ramp is rigid enough. I am guessing that Comanche's ramps are way more rigid than mine due to that opposed curve.
So where are we at with all this?
Remo probably built this noseramp himself. It looks very custom. It's too thin and doesn't have rigidity - ram air will flex bend it "into" the cowling. It's not sealed properly practically along all of that bottom edge between the bowl and the ramp.
The only hope for it is that it's aerodynamic-ish and looks like a "dozer blade" - curved up. Maybe the nosebowl lip deflects the air enough for it not to go under too much:
Can I replace the current rubber seal with felt?
Maybe. The front of the engine moves. The ramp's aluminum is very light - I am afraid that if I were to add any reasonable quantity of felt to it to hold the seal tight it will warp the aluminum via relative motion of that ramp (hooked up to the engine) rubbing on the bottom of the nosebowl. Or worse yet, make a hole in the bowl.
Can I replace the ramp? Well, everything's possible; but that's a massive undertaking. That ramp / nose baffle, Comanche-style, has that compound curve, and I don't have time or skill to do it fast. 2 months? Maybe, if I get lucky. BTW this is probably why Remo did it this way - because his is just an aluminum sheet, wrapped around the front of the engine, "neck cone" style, and cut to fit.
So, what do I do?
After discussing this at length with my good friend Ben, we settled on testing this out first to see how bad the air flow going "under" will be. I can mark the bottom of the nosebowl with some tinted oil, and go fly. Oil streaks will tell me if the air is flowing under a lot, or not so much.
I'll also replace all the other baffle seals, which will improve cooling. There's a lot of gaps to RTV, too.
I don't want to replace the bottom nosebowl ones, because actually there the rigidity of old neoprene rubber seals should help...
The nicer an airplane looks, the better it flies.
...and 1/2 of May
|On:||May 14, 2019|
|In:||[Chickenhouse Charger] 2019 Annual|
|Tags:||6781G, MA5 Charger, Annual, Rotec TBI, baffles, prop, fabric|
Well, as usual, I got too focused on the plane and the mess I got myself into; and didn't log things as they went...
I will split the notes in multiple posts; by theme / subject. Just general notes here.
We got together with John, my IA, and continued working on the plane early April.
We pulled the prop, so that I will have access to baffles (I wanted to redo them).
John re-riveted the air takeoff flange back to the front ramp.
Meanwhile, I started disassembling the fuel system to get to the screens, including the oil sump screen, and clean them.
TBI intake airflow straightener
Okay, stop right there. See that fuel inlet, right above the air intake? See the little smudge of dope around the inlet fitting? Yep. Teflon dope. Rotec explicitly tells you not to put ANYTHING on there - there's a copper crush gasket behind that fitting.
TBI crush gasket
See all that dope above? Okay, that thread on the TBI is a female thread. Dope will be all in it, and guess what will happen when I screw the fitting back in? Yep. It'll go into the TBI fuel galleys. Right to where that spray bar is with tiny little holes in it. Not Good (c).
TBI holes plugged
I noticed evidence of possible intake leaks, so without "burping" the engine, decided to pull the intakes and replace the gaskets. This is my karma. I did that on the Cheetah just a year ago, and scraping remnants of one of those gaskets and re-chasing the threads took me about 10 hours; maybe more.
Also: interesting note: she has intake tube clamps on studs and not bolts like every other Lycoming I've seen. Old, narrow-deck cylinders :).
When we pulled it, bolts were in the thru holes on the wooden prop really tight.
Pulling the prop
She has the prop made by Frank Johnson of Performance Propellers fame, and after contacting him, he just suggested to re-drill the holes and re-coat them inside with something.
Well, I got me a 29/64 (1/64 oversize) reamer, and went to town.
But first, I needed a rack.
My prop rack
Built with a 1/2" pipe, some foam, pipe brackets, screws, 2x6s screwed to the table, and my 3/8" drive extension rod. You get the idea :). Redneck engineering galore.
Prop on the rack
This whole thing was happening over a few days by the way; and when I finally got my reamer and had time to deal with it, the holes.. extended. Wood moves!
Hey, we had much rain then, and prop "swelled" a bit methinks.
But I still decided to fill the holes as much as I could.
Even got me some nice scales for mixing System Three ClearCoat.
A filled hole
Fabric on this plane is old. Flyable from what I am being told by experts, but old. Cracking, peeling paint.
Original logs say that she was covered in Polyfiber. But the current finish looks more like Imron and the company - "flexible" automotive poly. It's cracking and peeling around areas of high wear (prop wash, etc).
Sad, sad fabric
John (my IA) wanted to take a Maule fabric tester to it; but I didn't want holes in my wings.
I discussed this with a few guys that worked with fabric their whole lives, and we came to a consensus that for now this is fine. Will just fill with silver, and keep on flying. Incidentally, that's what Glenn has been doing, too.
I worked on baffles a bit, but then, everything went downhill. We'll talk about baffles in the next post. And the downhill part, afterwards :).
The owner's guide that comes with a $500 refrigerator makes more sense than the one that comes with a $50 million airliner.
...wing root fairings
|On:||Apr 06, 2019|
|In:||[Chickenhouse Charger] 2019 Annual|
|Tags:||6781G, MA5 Charger, Annual|
Only had a few hours today, so decided to concentrate on taking off the wing root fairings. As I mentioned before, the "back-side accessible" screws were set up to have nuts on them rather than nutplates. Well, I don't know about that accessibility....
It ended up being 3 hours for ~30 screws.
Root fairing off
Most of them on the back side of the wing require you reaching with a wrench thru the rear cockpit, and my arm is just barely long enough to do that successfully. Since nuts are nyloc, no way I can hold them with my fingers - they need a socket.
Some of those nuts are in a U-type channel over which the fabric is glued, and some of the holes are off-center: making it impossible to put a socket over them.
I could've ground a socket down; but I don't have a grinder - so especially one of the nuts took a while to get off. And oh, you have to do all that without dropping the nut and the washer onto the floor (and having them go into the tail). So the process looked like this:
Having magnetic sockets helped. They weren't deep enough to grab most of the fully tightened nuts because screws protruded from them. I used them as magnets sometimes, and sometimes used my magnetic "fishing for lost hardware" probe.
Now I'm writing this, I realized what I should've been doing is using a long extension and a 90 degree adapter on my socket. Damn! But this still doesn't solve the problem with some of the nuts that were hidden almost behind things that were in the way (ie, a trim control wheel's attachment structure that's welded into the fuselage).
One of those pesky nuts
I'm considering replacing those nuts with Tinnerman-type and screws with sheet metal screws thru Tinnermans. I'd put some anti-chafe tape inside the U-channel, and then Tinnermans on top of it. Since Tinnermans are long, when undoing (or tightening) the screw, they will turn and touch the side of the U-channel, which will act as a wrench.
Wing attachment - right side
And that's literally all I got done today. Just took those damn screws out.
When you’re sitting in the rubber raft looking up where your airplane used to be, it's too late to check the flight plan
... getting familiar
|On:||Mar 30, 2019|
|In:||[Chickenhouse Charger] 2019 Annual|
|Tags:||6781G, MA5 Charger, Annual|
After getting the Charger, I have decided to fix a few basics.
Getting a bit ahead of myself, a series of coincidences (airport closed, baffles' condition, intake leak, and others) made me decide to go thru the annu... sorry, Condition inspection (damn, will have to get used to new nomenclature :) ).
Cowling came off.
Discovered a few booboos:
Since I will need some helps with skills and tools with riveting, and we'll need to pull the prop to change (and turn the right way) the seals, decided that I will put her thru annual.
Studying the systems (I was mainly concentrated on fuel and other al lines and hoses to see where things go), discovered a few things, too
Crack in inlet ramp: stop drill
Inlet ramp baffle: turned the wrong way
Inlet ramp's take-off flange - un-riveted itself
TBI - Regulator Side
TBI - Throttle linkage
Electrical fuel pump and gascolator
#1 bottom plug - in pretty good shape
Engine compartment right side
Spent the rest of the day taking off fairings and access panels. This is the first thing I thing could've been done better here methinks. Everywhere where it was deemed that the back side would be "accessible", Remo used #6-32 nyloc AN nuts on machine screws instead of nutplates. Well, some of those nuts are not accessible, and I gave up on quite a bit of them around the rear wing root fairings.
Need to standardize on fasteners' length so that I don't juggle 10 different screw sizes.
Gotta love that easy access!
Flying wires' fairing
My laborers for the day working on wheelpants
Fighter pilots make movies, attack pilots make history.
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This website only shows how I did things in my various projects. These pages are for information and personal entertainment only and not to be construed as the only way, or even the perceived correct way of doing things. You are responsible for your own safety and techniques.