Fuselage « Matt's RV-7 Project

Archive for the ‘Fuselage’ Category

Access panel seals

Tuesday, February 27th, 2024

To seal the avionics access panels, I borrowed Dan Horton's idea for making rubber gaskets. First I used a sponge to apply a layer of PVA to the inside of the access panels, and let it dry overnight to a smooth film:

I stuffed the area under the access holes with aluminum foil to catch any sealant drips:

Then I applied a generous bead of proseal to the mounting flanges, and screwed the panels in place:

I used acetone to clean up all the squeeze-out, then left everything to cure for a week:

After I was sure the proseal was fully cured, I removed the screws and was able to gently pry off the access panels. The PVA film peeled off the aluminum and stuck to the proseal:

I used an xacto knife to trim off the excess blobs along the inner edge, and dissolved the PVA with a wet paper towel. Result, perfect gaskets that fit my access panels exactly:

If you are reading this and you are planning to install this kind of access panel in the future, I'd recommend adding a thin spacer (say 0.020"-0.032") between the fuselage skin and the mounting ring. That would allow for the rubber seals to be thicker and probably to work better.

Posted in Fuselage |

Repacked wheel bearings

Sunday, February 4th, 2024

Since eventually this thing will need to roll, I removed the wheels, disassembled the bearings, and cleaned off all the old dried-out grease with mineral spirits and brake cleaner. Then I repacked the bearings with Aeroshell 22 – no pictures of that step since my hands were messy.

Wheels back on the plane, nuts tightened, and cotter pins inserted:

Brake caliper back plate bolts torqued and safetied:

Posted in Landing gear |

Cockpit miscellany

Sunday, January 7th, 2024

A variety of cockpit-interior work in this post…

Having read about too many airplanes destroyed by brake fires, I've always made it a point to carry a small fire extinguisher in my airplanes. I have no illusions that I'll be able to put out a fuel or oil fire, but if I can prevent an overheated caliper from torching my airplane or someone else's, it's worth the effort to carry one. So I bought a small 1.25 lb Halon extinguisher (expensive!) and mounted its bracket to the forward tunnel cover, which will position it between the seat cushions:

I bolted the lap belts and crotch straps to their brackets in the floor:

I installed the approximately one million screws for the forward seat pans, and also attached the stick boots with additional screws. I have to say I'm not thrilled with how well my interior paint is holding up – I've tried to be careful with it, but it chips really easily. On the next airplane I'll have to use something different.

I had a local vinyl sign shop make me an "Experimental" placard that meets the requirements of FAR 45.23(b):

Since I already painted the baggage bulkhead with textured paint, I figured the vinyl wouldn't stick very well, so I masked off and sanded down a rectangular area and then painted it flat black:

Looks good and can't be missed:

I bolted the shoulder harnesses to the anchor cables with castle nuts and cotter pins, and then installed the baggage bulkhead with a further half-million screws:

This is all bringing back memories of my previous RV… half the work of doing an annual inspection is just taking out all these screws and putting them back in.

Posted in Fuselage |

Brake fluid

Sunday, December 31st, 2023

Before filling the brake system with fluid, I removed the calipers and took out the pistons so I could install improved o-rings. These are necessary to take full advantage of the higher-temperature brake fluid available these days (MIL-PRF-83282D) and were quite difficult to find in small quantities in the correct temperature rating of -40º to +400ºF. I ended up ordering them from Van's, which took a while due to their current difficulties. I lubed the new o-rings and the caliper bore with silicone before installing.

It's funny that this is all the brakes you get to stop nearly a ton of airplane traveling at highway speeds. Small wonder I chose to use high-temp brake fluid, since these can get really hot under heavy use.

To bleed the brakes, I cobbled together this contraption from a small pump oiler and a special adapter designed to go on the bleeder fittings:

To catch the overflow from the brake reservoir, I plumbed a catch can using a coke bottle and some brass fittings. Additional details of how this works can be seen in the photos below:

Before starting, I put down some old t-shirts under all the potential leak spots, to hopefully keep the floor clean:

I recruited a friend to help pump brake fluid while I crawled inside checking for leaks and tapping on things to clear out air bubbles. Happily we had no leaks and – I think – ended up with a solid result. We went through a lot of paper towels and rubber gloves, and didn't take any pictures during the process, but you may assume it was messy despite our best efforts to be sanitary about it.

Clear tubing at the top of the reservoir allows air bubbles to be pumped out. We kept pumping fluid until the brakes were solid and bubbles stopped appearing in the tube:

The end result was a reservoir totally filled to the top, which is fuller than it needs to be. I used a syringe to siphon out about an inch of fluid before installing the vent cap.

All the accessories are stored inside a messy plastic bag for future brake work. From the quart can of brake fluid I opened, I ended up with about a pint left over, which is stored in a mason jar I stole from my wife's canning supplies.

Posted in Fuselage, Landing gear |

Final flap install

Sunday, August 6th, 2023

I installed the flap channel and backrest brace in the fuselage, and connected and tidied all the wires for the flap motor, positioning system, and cabin speaker:

The travel allowed by flap positioning system is well-matched to the actual stroke of the actuator. After some adjustment, I was able to get essentially the maximum amount of travel the motor can achieve, but now it's under quasi-automatic control.

I hung the flaps on the wings once again:

This time I safetied the hinge pins:

Installed the flap pushrods and torqued/marked all the fasteners. Here you can see the rudder cable guards paying dividends – they allow the bolts to be inserted like they appear in the picture, instead of from the opposite direction which would be a whole new level of difficulty:

I temporarily installed the flap covers to keep stuff from falling down there and disappearing forever:

I will triple-check the rigging in a future work session, but I should now be able to use the flaps as a neutral reference for the ailerons, which will be useful when I go to install the wingtips:

And finally, here's a video showing how the flaps move automatically to the next position with each click of the "down" switch, followed by full retraction when the switch is moved to the "up" position:

Posted in Flaps, Fuselage, Wings |