Fuel Pumps Finished

Time: 2.5 hrs

Well finally I got the fuel pumps installed. There was a lot of trial and error to get everything worked out. Fortunately the pumps all fit in the Rotax box and the placement of the mounting screws worked out as well.I also have all the fuel and oil lines in (just need to torque the fittings).

I decided to change the way I had mounted the pumps to the mounting bracket. I was using the two adel clamp that came with the pumps, but I change to using for stainless steel zip ties instead to make the pumps a bit more secure and save some room. I just needed to drill a few holes in the mounting bracket so that the ties could loop around to secure the pumps. I purpose some ratcheting ties which worked great. it was much easier to get a nice tight pull on the ties.

I like the zip ties better better than the adel clamps and then don’t take up as much space either.

It’s mounted and wired up. I also put in the Capacitors using some crimp on ring connectors. Negative is a M5 screw and positive is M4.

A few photos of the fuel lines (all stainless steel). Everything is roughed in. I just need to make sure all is good and the I can torque the fittings and secure any wiring like for the fuel flow sensor.


Fuel Pump Assembly and Pressure Test

Time: 1.0 hrs

The fuel pumps went together quickly. I purchased some Oetiker ear type clamps from Belmetric. I purchased 14.5mm and 19.8mm size clamps which seemed to fit well. The 14.5 were a tad tight over the fittings, but I was able to get them to work. After I had the pumps assembled I used a differential pressure tester that I purchased from Sky Geeks as well as some extra fittings and a hose that has quick change connectors on the ends (the hose that comes with it one has quick change on one end). This pressure tester can also be used to test the pressure drop on the 914 cylinders using a 12mm adapter to connect to the spark plug hole which may be handy in the future when I do my annuals.

I tested the fuel pumps for leaks up to 30 psi. I found that the Rotax docs for the rubber rebuild on the IS (fuel injected) type engines tests the pumps up to 87psi, but the carburated engines don’t run at as high a pressure, the normal fuel pressure is around 2-5psi over the airbox pressure (which is max around 18psi). I didn’t want to damage anything so I figured 30 psi would be reasonable. The only leak I had was on one of the adapters I used to get the tester connected to the -6AN fitting on the pump. I’m happy that the 5/16″ hose barb to -6AN converts I found don’t leak. Now I have AN fittings on the pumps and don’t need to use rubber to run out of the pumps to connect to the stainless steel hoses.

Just a quick check I ran the tester up to 10psi and set the slow fill back to off. I noticed the pressure dropped off on the second gauge after a few minutes so I knew there was a leak. It turns out the leak was between the M14 adapter and the M14 to -6AN fitting. I was able to tighten that up again and ran the test up to 20, then 30 psi. I left it for about 5 minutes with no noticeable pressure drop and a check with some soapy water on all the fittings just to make sure.

Fuel pumps all assembled and fit into the Rotax fuel pump box. I’m going to check with TAF to see if they have a been made bottom plumbing manifold. I noticed from Craig’s build log that his has a better, tighter bend to it that would fit much better in the Rotax box than the one I have. Also I may work on a better way to attach the pumps to the mounting plate. I’m currently using the clamps that came with the pumps, but I don’t like that I had to mount them towards the ends of the pumps to avoid the screw from hitting the check valves. It’s such a tight fit to get all this stuff into the box. I would prefer more centered so the pumps are more secure or using 2 clamps per pump.

A photo of the differential pressure tester (model E-2A) I got. Aircraft Tool Supply has them as well, but they were out of stock and it wouldn’t have been available for 3-4 weeks. This is the 0.040 orifice one with no master orifice. The hose is the ATS extension hose which has quick disconnects on both ends so I was able to purchase a 12mm (for the cylinder compression checks) and a 14mm (to make the conjoin to the fuel pumps) with quick disconnects that can be swapped out easily. I chose a 14mm adapter just because I was able to find an M14 female to -6AN male fitting.

Fuel Selector and Exhaust

Time: 4 hrs

My fuel selector that I ordered from Andair in the UK came a few days ago so I figured I’d get that installed. I also finished up the mounting of the exhaust and exhaust shroud.

I ordered my fuel selector with AN fittings instead of the NPT fittings that the TAF one comes with. It turns out there isn’t a whole lot of room in the dash where the fuel selector mounts (what else is new). I ended up having to swap the -4AN with the -6AN fittings around on the fuel selector (Left/Right tank connections) and then I had to use my heat gun to heat up the fiberglass on the dash so I could bend out the flanges a bit to make room for the 90º AN fittings. I got all the fuel lines cut and the AN hose ends put on. I still need to install the M4 rivnuts in the fuel selector and torque down the hose fittings.

The exhaust went quick. There’s really no photos in the manual on how to mount the shock mount and adel clamp so it took some experimentation to make sure the exhaust didn’t hit the engine mount or anything else. For the exhaust shroud I used some large hose clamps to hold the shroud closed tight so I could drill the holes for the rivets. I also put an adel clamp on the heater hose that runs up to the heater box to secure the hose.

My Andair FS2020 fuel selector valve. I ordered it with -6AN fittings on the top for the fuel feed and return and -4AN (return), -6AN (feed) for the connections to the fuel tanks. This photos was taken before I swapped the -6AN and -4AN fittings around (on the sides). I did this because the -4AN fittings are smaller so they fit better closer to the dash.  I also got the clear anodized faceplate so that it matches my vents and other hardware… hey it’s got to match.

Exhaust shroud installed. I used a few large hose clamps to get it all held closed tight so that I could drill the holes for the remaining rivets. This uses the stainless steel/steel mandrel rivets.

This is what I came up with for mounting the exhaust. I couldn’t find any photos of mention of it in the manual, but this seems to work. The clamps holding the exhaust to the engine and other clamp are the Rotax exhaust clamps (Rotax #951 550) which I ordered from Lockwood Aviation Supply.

Well it all fit. I couldn’t run the hoses directly down, they run up a little and then down. I also couldn’t use my 60º fittings on the return and feed (on the top) because the one closest to the dash hit the dash, but the 90º fitting fit OK.

The fuel selector basically installed.

My faux dash in place… working on some ideas for where everything will go. I need to start thing about who will cut the panel. If I can get a hold of some CAD software I can get most of it designed and so it should make the cutting a bit cheaper.

My upholstery should be here any day now so hopefully that came out OK. I also purchased the wings so I’ll have to go pick that up and start working on those soon.



Fuel Pump Connection

Time: 0.25hrs

I purchased a few of these adapters that convert a hose barb into an AN fitting. The only ones I could find came from a company in Australia called Aeroflow. The seem to fit well so  I have high expectations that they’ll work. I just order a differential pressure tester so that I can check the fuel pump assembly (and these fittings) for leaks. I’m also thinking of switching to the Oetiker type clamps instead of the fuel hose clamps I’m using mainly to save some space so that things fit a little better and so I can more easily get the nuts onto the posts to secure the pumps.

The fitting has an O ring that helps the fitting tighten on the hose barb. I guess I’ll have to replace them when I replace the other fuel pump hoses every five years.

I hope these work. It’ll be nice to just attach the braided hoses directly to the pumps rather than having to use intermediate rubber hose in between. I also need to see if I can better place the clamp for the left pump. It’s a bit high, but any other place the mounting bolt hits the check valve.


Time: 3.0hrs

Over the past few days I did a few miscellaneous items on the plane. I’m waiting on a few small parts so that I can make better progress, but there’s still lots to be done even without the needed parts.

Things done today:

  • Mounted GEA24 and TCW battery backup
  • Finished up carpet on copilot and pilot areas
  • Torqued bottom oil pump bolt
  • Torqued a few of the oil line fittings
  • Installed safety wire on fuel pump bolt
  • Cleaned up some wiring
  • Made up a small circuit board to hold the components needed for the RPM and Oil Pressure sensors
  • Cut and clecoed the heater shroud input tube onto the heater shroud.

I mounted the battery backup under the shelf so that it’s a little easier to get to. The batteries will need to be changed sometime plus there is a fuse that may need to get replaced if is every blows.

The GEA24 is mounted and I also finished up all the wiring to it (not shown in the photo). I made up a small circuit board that has the diodes and resistors that’s needed for the RPM and oil pressure sensor to interface to the GEA24.

This is a very simple pre-done board that I bought from Sparkfun. The board internally has every set of 3 holes connected so you can lay things out to connect to each other without having to run wires. I used the captive screw terminals so I can connect the RPM wires from the TCU on the one set and the signal wire from the oil pressure sensor on the other set (only one of the two is used). To install it I connected the wires to the captive screws and then just wrapped it with some silicone tape and the tie wrapped it to the J243 connector of the GEA24.

Firewall Forward Work Continued

TIme: 3hrs

I had a productive day today getting a few things done on the engine. I worked on putting together the exhaust shroud for the heater and also finished up the radiator/oil cooler bracket. The exhaust shroud needed all the holes drilled in the large clamps that hold the shroud cover onto the exhaust. There’s quite a few holes that need to be drilled, but once you get set up it goes along quickly. I used RTV to seal up the mating surfaces and also filled the area where the inlet and outlet tubes attach to the shroud. I’m waiting on the bolts and a longer tube for the front (the one I had was too short to reach past the cowling.

On the radiator/oil cooler mount I just needed to install the cam locks. I’ve been getting the hardware from Skybolt. I purchased a simple non adjustable, non floating receptacle and had a few of the -6 length studs already. I just need to put some kind of rubber on the part that presses against the oil cooler so it doesn’t wear and scratch the cooler.

Oh yeah and also my Andair fuel check valves came in so I test fit them into the fuel pump assembly. It’s tight but they fit. I had to order these from Andair in the UK since they seem to be the only ones that have the check valves with the 5/16″ hose barb.

All the holes drilled in the exhaust shroud. The last row of holes needs to be after it’s fitted onto the exhaust when the clamps have been tightened. TAF supplies stainless steel rivets with a steel mandrel to use on the shroud.

A few photos of the shroud installed on the exhaust. I order some 1.5″ (0.065 wall) anodized aluminum tube for the front inlet. I needed a bit longer tube so that it will stick out from the cowling (will need to cut a hole in the cowling for that) Also to get the shroud on I had to remove the bracket that attaches to the exhaust. You just need to remove one of the engine mount bolts and an M10 Allen screw to get the bracket off.

Radiator and oil cooler brackets are done. I had to modify the camloc receptacle a little so that it would fit flat on the bracket. I just had to file one edge a bit.

Well it all fits. The sides of the box bow out slightly, but should be fine. And yes I know I have the fuel pumps reversed (I think I have the check valves in the right direction, but I’ll check it out before I install them). It seems like they fit better in the box this way and the box is labelled “in” and “out” so I wanted to make it so the labels are accurate. It shouldn’t really affect the hose braided lines.

Oil Cooler and Radiator Mount Bracket

Time: 2.5 hrs

Since I now have almost all the FF parts from TAF I was able to put together the mounting bracket for the oil cooler and radiator. This is the newer way the coolers are mounted to the lower cowling. The old way was a plate and cams type of mount.

After cleaning and demurring I alodined the parts so they hold up a little better. It would have been much easier to put this together except TAF didn’t drill the rivet holds for the radiator bracket to main mount bracket. I don’t know if they did this on purpose thinking that every install might be a little different or if it just slipped by QC. In any case not too had to get the parts in place and drill out the holes.

Everything laid out. I need to add in some padding to the ends of the swivel part that hold the oil cooler down so that it doesn’t get scratched up. I also need to get some camloc receptacles to attach the brackets top the cowling.

Also note I have the UNF fittings on the oil cooler since I’ll be using AN hoses and fittings for the oil lines. I installed these as well and used some Loctite 648 as specified in the Rotax manual.

I had previously cut down some M6 bolts to use as pins for the bottom of the radiator. Today I  ground them down a bit to make them smooth so it’s easier to slide them out when removing the lower cowling.