« Archives in February, 2014

It’s go time.

7 hours.

313TD is now ready to fly.   It is legal, insured, fueled and ready.  If I didn’t have a mountain of work to do at work, I could go up there, push the airplane out into the open, fire it up, and take off.

It’s not finished.  Don’t get confused on that: Wheel pants and gear leg fairings still have to be done, and I’m still working out the engineering particulars on that one, because I have to suspend the aircraft in such a way that the weight is off the wheels to align the fairings.   Otherwise they act like little rudders, pointing the plane in an off-track direction.   This means you have to fight it with rudder input, and that means you lose efficiency because your airplane is essentially trying to fly sideways.

Efficiency is important.   Yesterday, I bought 22 gallons of aviation gasoline at $6.06 a gallon.  Ouch.   The reason for buying this gasoline is in preparation for the first flight, and also to calibrate the fuel level sensors in the wing tanks.   Each tank holds 21 gallons for a total of 42, so the plan was to do one tank at a time.

Our local Oxnard EAA chapter, which consists of the 8 guys who can reliably show up on the last saturday of every month and take care of business, has access to the really cool hand cranked fuel cart, which pumps both forwards and backwards and measures the amount of fuel pumped in either direction.

I called the Jet Center and had them put 22 gallons in the cart,  Which I could then use to increase the level in each tank according to the calibration “marks” on the EFIS.  If I recall correctly, these are 0.1, 4.6, 8.3, 12.5, 16.7, and 21.0 gallons.    The sensor is attached to a float inside the tank connected to a rheostat, and the numbers it puts out are simple resistance values read by the EFIS.   So with each amount pumped in, the settings menu gets the resistance value entered at that amount.   Simple.   I’m not sure how dead-on-balls accurate it is, but my initial test with the pump put 5 gallons into a 5 gallon gas can, so that was probably good enough.   I’m also not sure how much fuel it took to prime the pump and fill the filter chamber, but I’d put it at roughly half a gallon.   That’s OK, I drained about 2 and a half gallons from the aircraft tanks into a 5 gallon can before I started.

Also, this process needs to be done with the airplane in level attitude, because that’s when your fuel level actually matters.  Once again, Ron’s old lift was the solution for lifting the tailwheel.   The process was to pump 21 gallons into one of the tanks, set the levels, then pump it back into the fuel cart to verify the settings.    This also involved draining the current tank after the pump had sucked all the fuel out of the section where the fuel cap is, because even after pumping out all the fuel, there’s still 4 gallons left in the tank.   Also, when the pump runs dry, it still moves the counter.   Did I mention this thing is hand cranked? Yeah.  I’m sore.  Anyway, I repeated this process twice on each tank and the numbers were within .2 gallons each time, so the pump and the sensors appear to be doing the right thing.

So that’s done.   I’m ready to scramble.   All I need now is a day with good weather and relatively little outside stress, and we’re going up.

All Together Now

7 hours.

With the airworthiness inspection in the rear-view mirror, the next phase of this little adventure starts in earnest.   Of course, “airworthy” is kind of a misnomer.   It’s not airworthy until all the parts I took off for the inspection are back on.   That’s all the inspection panels, wing root fairings, floor panels, and interior.

When Dave and i measured the down angle of the flaps, we got one at 47 degrees and one at 49.   They’re supposed to be at 45, so that was first on my list to fix, but I measured them from the bottom side instead of the top and they both dialed out at 45.   Go figure.   After that, it was on to the interor panels.   I put the baggage bulkhead back in, flap actuator covers, then baggage carpet, bulkhead cover, and side panels.

After that it was the floor panels, with their multitudes of velcro discs designed to hold the carpet steady.   Then the front spar covers, and the tunnel cover.   This got interesting, because there are two holes in the firewall with platenuts that have nothing in them.   I can’t get the AN4 bolt in one of them and the other has a slightly off-center hole, so the bolt won’t seat in the threads of the platenut.   Bah.  Argh.   So I made the decision to put them in from the firewall side, which I’ll do later.

Then the fuel pump cover, with the newly attached fire extinguisher went in.   After that, I put in the carpeting, side panels, and stick boot covers.   It now looks like a proper airplane, and I could fly it, except for one thing:   The roll trim is wired backwards.

Yeah, I know, aren’t you supposed to be “ready for flight” when you call for the inspection?   Well, he didn’t make me fire up anything electrical, so I wouldn’t have caught this, because when I checked the trim motor, I saw the little arm on the trim servo move to the right when I toggled the right side of the 4-way on the stick.   Toggle the left side, the arm goes toward the left.   My brain failed to register that the arm is connected to wires attached to the bottom of the sticks, on the other end of the pivot point, so the arm is actually the reverse of the direction the sticks are moved in flight.

As soon as I realized this, all I could hear was Gunnery Sergeant Hartman in Full Metal Jacket:   “What side was that, Private Pyle?”

This, of course, is after I’d screwed down the fifty or so floor panel screws and installed the carpets and seating.   I figured it might be fun to sit in the airplane and get comfortable with the final UI of my airplane and practice things like getting the fire extinguisher out of its bracket, reaching fuses, finding the most comfortable rest spots for my elbow, that sort of thing.  So imagine my disappointment when I realized I’d have to pull the seat cushions, carpeting, and floor panels to switch the trim wires.

That’s a project for this weekend.   I also need to finish the cowl hinge pins, plug the aforementioned firewall holes, blob a little more RTV into the seams between the baffles and the engine, and do some taxi tests.   I know it taxis, I just want to see if I can get the under-cowl temps down a little more.