Extended elevator stop

April 14th, 2007

I wrote to Van's to ask their opinion of my elevator travel situation, and their reply was:

Matt,

You can either make a new elevator up stop or add a piece to the existing stop. The horns hitting the aft bulkhead is not a bad thing, but that will not happen when you fix the up stop.

Bruce Reynolds

Okay, I can do that. Since the existing elevator stop is already drilled for the bolts that attach the vertical stabilizer, I decided to leave it alone to avoid causing further problems. Instead, I created this little elevator stop extension out of some 1/8" angle:

It's riveted to the underside of the existing stop, using the existing three rivet holes through the stop and aft deck. It effectively moves the face of the stop forward about 3/32".

I also added three flush rivets to attach the other leg of the stop extension to the aft bulkhead. Probably overkill, but it makes me feel good.

Now to test the new elevator travel. Here's neutral:

Here's the new up position:

I now have 29.4 degrees of up elevator travel, which puts me in the allowable range of 25-30 degrees. I probably could have made my stop extension even a little bit longer, but as long as the elevator travel is within the okay zone I'm happy.

Posted in Elevators, Empennage, Fuselage

Pushroddery

April 8th, 2007

Somehow I managed to get not much done despite having a three day weekend. Hmm.

I decided to install the electric aileron trim kit, but first I needed to get the control sticks and associated pushrods installed. I spent a bunch of time filing and grinding the inside of the passenger stick weldment, which had a big ugly weld bead clogging up the bore. Eventually I got it reamed out and smooth enough that the passenger stick could slip in and out.

I drilled a 3/16" hole through the passenger stick and weldment. There is a service bulletin that advises you to put a bolt through here, making the passenger stick non-removable. Since that would defeat the whole purpose of making the passenger stick in two pieces in the first place, I think I will use some kind of quick-release pin instead. After I drilled and deburred the hole, I greased up the brass bushings and bolted both sticks in place.

I then spent a bunch of time getting the transverse pushrod that goes between the sticks set to the right length. Here's my shade tree method for making sure the sticks were upright.

This photo is to confirm that I did torque the jam nuts on the F-665 pushrod.

Then I put in and adjusted the forward elevator pushrod. It worked out okay, but I would have liked to have had another quarter inch or so of pushrod length to work with – that would have given me more options for moving the neutral stick position around without worrying about keeping proper thread engagement on the rod ends. The duct tape is to protect the finish on the control column in case it bangs into the seat ribs while the elevator pushrod isn't hooked up.

I attached both elevator pushrods at the bellcrank, including all the little washers that go in there. That took a lot of time too. Thank goodness for washer wrenches, or else I'd still be trying to get those washers installed. I haven't tightened any of these nuts yet.

With the elevator pushrods in place I was able to verify that the elevators hit both pitch stops without anything binding (check) and measure the travel. Here's the neutral position:

Maximum down elevator travel is 20.5 degrees. The plans call for a minimum of 20 degrees and a maximum of 25, so I am inside the OK range here.

Maximum up elevator travel is 32.2 degrees. The plans give an allowable range of 25-30 degrees, so I have too much travel here. The elevator horns also contact the aft bulkhead at the same time they hit the up elevator stop. I don't know exactly what that means or whether I should worry about it. Need to call Van's I guess.

There are two mild steel washers that are used on the bolt that goes through the center elevator bearing. I scrubbed all the rust off them, primed them, and painted them with enamel. Then I tie wrapped them to one of the elevators so I won't spend an hour looking for them when I go to install the elevators for good.

After all that I finally was able to start in on the aileron trim. First you have to modify this plastic pivot block by drilling some holes, cutting a notch, and rounding off one edge. No big deal.

Then you cut the mounting plate to length and drill some holes. But – argh! Not a lot of edge distance there if you follow the plans and then get carelss when drilling. Great. Now I have to re-order this part before I can make further progress.

Posted in Ailerons, Fuselage

Anniversary present

April 6th, 2007

I have the best spouse ever:

Posted in Misc

Finished ELT door

April 4th, 2007

Okay, new plan. I could have made the Hartwell latches work and look okayish, but then I found these Camloc pushbutton latches. They are the same ones that are used to hold shut the oil filler door on a lot of certified aircraft, which normally makes them expensive – I think they are something like $36 apiece from ACS. Thank goodness, though, for the local aircraft surplus place, where they can be had for five bucks each. At that price I couldn't resist, so I picked up a handful to use for little projects like this. It's way easier to make a round hole for one of these guys than to file out the odd-shaped square hole for a Hartwell latch.

I had to build a new door to fit the new latches, but that was no big deal. I had plenty of extra scrap 0.032" from Airparts laying around anyway. This new door actually fits a lot better along the hinge area, which is a bonus.

I don't really know why I primed all these pieces. Superstition, probably.

Here's the finished product after riveting. I used some scrap 0.063" angle to make stiffeners at the fore and aft ends. The hinge pin has a bend in the end, and is inserted in such a way that it's prevented from backing out by the F-727L baggage floor rib. Simple as can be.

And here it is with the baggage floor screwed in place in the fuselage. It seems plenty strong enough with the stiffeners in there. It's also pretty easy to get the ELT in and out.

I couldn't tell how much "grab" the latches had until everything was installed for good, because it was too floppy to tell when it was just clecoed together on the bench. It turned out that the door had a little bit of rattle to it, so I riveted in some 0.032" striker plate thingies to give the latches something extra to hang on to. Now the door clicks shut and doesn't move.

This is what it looks like all buttoned up. With the carpet on top you won't even know it's there, but it's nice to know that I'll be able to get to the ELT in a hurry if I need it, and without needing any tools.

What a mess. Time to clean the workshop.

Posted in Fuselage

ELT access door

April 1st, 2007

After not getting very much done yesterday, I wanted to pick a simple project and blast through it today. I chose the access door for the ELT, and I got it mostly done after several hours of work. The goal was to create a door in the baggage floor that covers the ELT and fastens with latches that can be opened without any tools – I figure that might make a difference after an accident. The latches also have to be flush when the door is closed – this area will be covered with carpet, so protruding fasteners like these won't work. The last goal was to avoid sacrificing any of the strength of the baggage floor, despite cutting a big hole in it.

I started by cutting a blank out of 0.032" alclad and match drilling it to some of the screw holes in the left side baggage floor. This piece was the start of a doubler for the big hole I later cut in the floor.

I fashioned it into a doubler ring, using a unibit, snips, and files. Before it's installed permanently, I'll bevel the edges so the material of the baggage floor will lay over it properly.

Then I cut the hole in the floor, using the same method. The doubler has a 3/8" lip on three sides, and no lip on the side where the hinge goes. The hole looks overly large here, but you actually need this much area in order to get the ELT in and out and to give the latches a place to fasten. And yes, at this stage I did make doubly sure that I could finagle the ELT in and out through the hole.

I made a simple door out of more 0.032" and fit it for a hinge. I also fashioned some scrap angle into stiffeners that run along the front and back.

Test fitting the door. Notice that I doubled up on the screw holes around the door to reduce the amount of flex.

More test fitting of the door. The way the door matches the cutout in the area of the hinge leaves a little to be desired, but I'm not too worried since this will all be hidden under the carpet when people are looking at my airplane.

To keep the door closed, I'm using a pair of Hartwell latches. (Compare ACS's new price to their surplus price – ouch! Luckily I can get surplus ones locally even cheaper.) I only had time to rough out the hole for one latch, but it turned out okay. A little more filing and deburring and it will be done, then I'll do the other one to match. I wish Avery sold a drill bit that would make a square hole.

Here's a view of the back side of the latch. These are designed for thicker material, so I'm probably going to have to make some shims to make them flush with the top of the door – otherwise I suspect I would have latches opening inadvertantly when I put luggage back there.

My other project today was removing the blade from my mower and taking it to the hardware store to be sharpened. It won't be done till Friday, so that means I get to avoid mowing the hateful lawn, which is already getting pretty long, for yet another week. I can't imagine ever regretting that decision!

Posted in Firewall Forward

« Older Entries
Newer Entries »