August Airplane Work

Despite a trip to AirVenture immediately followed by a trip to New Jersey and my need to actually work for a living, I got a good chunk of stuff done on my Bede BD-4C airplane over the last month. I am making progress toward having a flying airplane.

EAA Technical Counselor Inspection

Gale, my EAA technical counselor, came by the hangar to give the airplane a third inspection. Though the FAA only requires a single airworthiness inspection before flight, I am voluntarily participating in the EAA Technical Counselor Program. During each inspection, Gale has had good advice for me on things that I can do to make my airplane safer and more reliable. This program, among many other sources of feedback, is huge in boosting my confidence in my workmanship.

When the FAA’s designated airworthiness representative (DAR) does his inspection, I will show him the forms that the EAA technical counselor filled out. The DAR, in turn, will have more confidence that the parts of the airplane which are difficult for him to inspect have already been looked at by a competent person and the observations recorded.

As with any large project, it is always helpful to have another set of eyes on my airplane. This last time around, Gale spotted several problems, all of which I have corrected, including:

• One of the bolts on the alternator bracket had not been safety wired.
• The nuts holding three of the eight spark plug wires in place had not been tightened.
• The overflow tube from the engine-driven fuel pump was loose.
• The bolt through the rod end on the mixture control lacked a fender washer.

I’ve said it before and I’ll say it again: Thank you, Gale!

Horizontal Trim

I have written extensively about the horizontal trim on the airplane. Briefly, when you fly an airplane, you want it to go along straight and level, even if you take your hand off the control stick. You don’t want the nose to drop or pitch up. The horizontal trim allows you to make small adjustments to the horizontal part of the tail (call the horizontal stabilator on a Bede BD-4C airplane) so that the plane stays level.

In my plane, the pilot operates the trim by moving a lever forward and backward. The lever operates a cable that runs the length of the airplane. The cable, in case you are curious, is a motor boat throttle cable. The cable operates a triangular shaped bellcrank at the back of the fuselage.

After taking these photos, I added a large fender washer underneath the nut at the top of the bellcrank. In the unlikely event that the rod end comes apart, the fender washer will keep the rod end from sliding off, over the nut.

The hole at the back of the bellcrank is attached to a push-pull rod which operates the trim tab. I made a video of the whole thing all working together. You can see that video here: Bede BD-4C Trim Operation.

Tailcone

The trim bellcrank and the bottom of the rudder and the huge gap in the middle of the horizontal stabilator all get covered up (and filled in) by the tailcone. Of all the subassemblies of the BD-4C, the tailcone is one of the biggest PITA.* I made my tailcone in three pieces. The largest is the left side + the bottom + the back, all riveted together. The other two pieces, the right side and the top, screw on.

Here is the big piece (left side + bottom + back) on the airplane. You can also see the push-pull rod running from the trim bellcrank back to the trim tab and the fender washer than I mentioned above.

Adding the top and right side of the tailcone makes the back of the airplane look much more finished.

The bottom, back end of the fuselage has a loop of steel tubing, which functions both as a tie-down (when parking the airplane) and as a tail skid (to protect the plane from bad landings). The bottom of the tailcone includes half of the ventral fin which covers up the tail skid.

Bizarre Tailcone Story

The left side of the BD-4C tailcone has a hole in it.

There is a story about that hole which I feel compelled to share. Jim Bede Sr. added this hole because his son, Jim Bede Jr., was having trouble telling the left side of the tailcone from the right side. “Hole” and “left” both have four letters, and both have the letter L, so it helped Junior keep things straight. To this day, every BD-4 has a hole in the left side of the tailcone.**

Glare Shield

I had been putting off making the glare shield because I feared it would be another PITA. I thought that it would require four bends and several non-right-angle cuts. It turned out to be trivial, just a large rectangle with two bends. I did cut a circular hole for the GPS antenna to stick up through. I also lopped off the corners.

I decided on a pretty large overhang, four inches. I can trim it smaller if I decide that this is too much.

Fresh Air Vents

I purchased NACA scoops from BedeCorp for my fresh air vents. I will bond them to the fuselage skins, right near the pilot’s and copilot’s shins. I found a couple of eyeball vents and will fasten them directly to the scoops. Nice and simple.

Here is the skin for the pilot’s side of the plane. The small hole is for a static port.

Here is a close-up of the scoop and the eyeball vent.

Cowling DZUS Fasteners

The cowling on my airplane is held on with DZUS fasteners.

I spent an evening carefully adjusting the DZUS springs and assuring that every hole is large enough. I also splurged $10 and bought a special DZUS tool; unlike a screwdriver, it has a rounded end which fits into the curved slot on the DZUS studs. Now I can easily install and remove the cowling.

Flap End Covers

I finished fabricating and installing new flap end covers. The covers are held on by truss screws (wood screws with blunt points). A couple of the holes had gotten oversized a bit. I added some wood glue to be sure that the screws do not loosen up and fall out. Here is a photo of the end of the left flap, shot from above.

Other Stuff

I took care of several other small tasks, too.

• Replaced the cover on one of the switches on the instrument panel, changing it from PANEL (for panel lights) to FUEL PUMP for the auxiliary fuel pump. I turn this on for starting the engine, landing, and in case the mechanically driven pump fails.
• I measured for, and ordered, the parts for a cabin heater.
• I checked on the dents in the leading edge of the left wing and was absolutely delighted to find that they had popped out and vanished, all by themselves.
• I filed down an edge of the fiberglass cover for the rudder counterweight. It was scraping slightly against the top of the vertical fin.

Next up… finishing the plenum and air baffling over the engine.

Footnotes

* PITA = Pain In The Ass

** In truth, that story is complete untrue; I just made it up. 🙂

The hole is there because the bellcrank which operates the rudder sticks out a fraction of an inch. I will laugh, though, the first time Jim Jr. calls me up and asks, “Do you know what someone just asked me?!?!”