Dave’s RV-7A Building Log

With the head of the prop governor correctly positioned, I went ahead and secured the screws and safety wired them. This is the first safety wire I’ve done. The first one I did over, but the rest turned out pretty good.

I also wored a little bit on the fuel line doubler for the firewall. I’d like to put the doubler behind the firewall like the other doublers. However, I’d also like to tie it in with one of the stiffeners. I think I have a plan.

I removed the engine mount from the fuselage in preparation for drilling the fuel line and control cable firewall holes. I did a bunch of measuring and examining and thinking. I’m almost ready to drill the holes.

Sub-50 degrees is just too cold to work out in the shop. I could crank up the heater, but it seems a waste for the 10 or 15 minutes at a time that I’m actually out there. Instead, I brought the parts for the mixture linkage into the house. It’s kind of a complicated gizmo that changes the direction of the mixture actuation and reaches around the sump.

It all went together fine except for some washers. I’m not sure what exactly to use for the large washer that keeps the bearing end on the control arm in case the bearing gives out completely. The plans call for a washer that’s not included in the kit. The kit includes some tinnerman washers, but it doesn’t look like those will work very well. I’ll just order more of the washers called out in the plans. It’s a little frustrating that it takes only 10 minutes to put together the assembly and then I spend another 10 minutes trying to figure out something stupid like washers.

With the studs installed yesterday, it was time to install the governor and cable bracket. Some builders wait until the engine is mounted to deal with the prop governor. It seems much easier to me to work on the stuff on the rear of the engine before it’s installed, as long as it won’t interfere with the engine install itself.

I used a nut, star washer, and plain washer for each stud and torqued them to 140 in-lb per the MT prop install instructions. At first I was worried that I installed the bracket at the wrong angle. The “up” arrow on the drawing from Van’s is not really up.

Both the Vans and MT instructions mention that the prop governor head might need to be rotated. Mine certainly needed it. The control arm was on the bottom. I took these pictures mainly to document how the safety wire was originally.

I decided to go ahead and temporarily mount the control cable on the bracket and governor to find the ideal position of the control head. The cable operates very smoothly. I even found myself making vroom-vroom noises. And then I realized something weird about one of the stops. If you look closely in the picture at the stop on the left, you’ll see that the screw is backwards. The control arm hits the head of the screw rather than the end. I’m not sure if that is intentional or not. I’ll check with Vans.

Reply from Gus:

I think it probably should be the other way around, but it won’t matter.
You will not go to the low rpm stop very often, if ever, and with the cable travel available, there is a good chance that the cable will limit the travel before the arm hits the stop anyway.

The interesting part is that I am getting full travel from the prop governor with plenty to spare. I’m wondering if the stops on the governor are just completely wrong. The only way I know to check them is to run the engine and exercise the governor. I guess we’ll wait and see, because that is a long ways down the road still.

Other than that little issue, the rest of it works well. I was able to set it up to get full stop-to-stop movement of the control arm.

The word from Mahlon is that the prop governor studs should be installed so that the end of the stud that is hard to thread goes into the engine. I tried locking two nuts together on the stud and used that to get the stud installed. It wouldn’t go any further than about 1/4″. I’ll try a cap nut next. Also, I’m not sure if should use the black gasket that came with the governor, the green gaskets that came with the engine, or both.

I moved on to something else. I installed the oil pressure fitting and one of the oil cooler fittings. With the oil filter adapter in the way, I need to use 45 degree fittings for the inlet and outlet. Van’s supplies a 45 and straight fitting in the firewall forward kit. They also supply only one 90 degree fitting for the oil cooler, although the plans clearly call out two fittings. Strange.

I also received my order from SteinAir. It was delivered across the street by UPS. Those idiots have about a 95% success rate. Not good enough. The order was also missing an item I ordered and paid for. I wish I could say that hasn’t happened before. I think it’s time to find a new source for electrical stuff. The order included some more D-sub pins and connectors, some large lug terminals (that were supposed to be in the master kit), a couple smaller fuse blocks, and one red LED swivel cockpit light (there were supposed to be two). At least the light looks pretty cool.

The engine arrived!! I was expecting all sort of wresting with a heavy crate, but it was a non-event. The driver just wheeled the crate into my garage with a pallet jack. It arrived without so much as a scratch. There was some water inside the plastic covering the engine. It’s a good thing they use it. The engine appeared dry.

A small tip for others getting a Mattituck engine: The top of the crate can be removed by unscrewing two bolts. I ended up tearing it apart piece by piece before I discovered that.

Several views of the engine.

There was also a small box of goodies, including a Lycoming engine manual. They provided the fuel line from the pump to the fuel servo, which was also in the Van’s firewall forward kit.

I spent quite a bit of time looking around the engine, indentifying ports, checking out the fuel servo, etc. I was surprised to see the alternator. I wasn’t aware that the engine came with one. It’s a Mitsubishi, but looks much larger than the Nippon Denso alternator I have from Vans. I’m wondering if it would fit inside the cowl. (Edit 12/1/05: Mahlon confirmed that the alternator was a mistake. He said if I can use it, to keep it with their compliments. Nice.)

Another thing I noticed is that with the oil filter adapter that Mattituck uses, one of the ports for the oil cooler is behind the oil filter. It looks like I’ll have to remove the oil filter and use a 45 degree fitting. Not a big deal.

There’s a port on the side of the fuel distribution spider that I’m not sure about. I didn’t think there would be a purge line, but I’m not sure what else it could be. (Edit 12/1/05: Mahlon said the port is for metered pressure, something I most likely will not need. I just need to plug it.)

I wish the P-mags had shown up in time for Mattituck to install them. It’s going to take me a while to figure out installing, wiring, and timing them. Plus I would feel much better knowing that the engine was run successfully with them installed.

The engine didn’t have dessicant plugs in it. I’m not sure if they’re needed. (Edit 12/1/05: Mahlon said these really aren’t needed for my engine. The cylinders won’t rust.)

These are all questions that I’ll ask Mahlon about.

I spent a little bit of time finishing up the battery box. I had forgotten to put on two nut plates. The engine mount was in the way of installing them. Instead of removing the engine mount (which is still just temporarily mounted anyway), I removed the battery box, installed the nut plates, and installing the box.

I wasn’t feeling so hot last night and today. I took the day off work and crashed on the couch with the dog. But then the FedEx Freight truck pulled up to the door. I ordered the firewall forward kit exactly a week ago.

Of course I had to open the box and start tinkering with the parts. This is definitely the coolest kit so far, exhaust pipes, prop governor, alternator, control cables, fuel and oil hoses. Very cool stuff.

I figured I might as well inventory the kit since I was examining everything anyway. I also studied the plans a bit. There are drawings for the firewall pentrations, cabin heat routing, fuel and oil hoses, and more. It looks fairly detailed.

I ordered the firewall forward kit from Vans. I deleted the cabin heat selector (bought a stainless steel one from EPM-AV) and the wiring harness (bought the wiring kit from SteinAir). I debated for a while about using a B&C alternator instead of the one Vans supplies, but I wasn’t convinced that it was worth the extra $$. I also thought about using a throttle quadrant instead of the push/pull knobs. However, it would have taken some extra time to mount it and I wasn’t sure how much space it would take up in the cabin. In the end, I decided to go for the stock set up, which is almost always less time and less money.

I guess this is a Mattituck thing, but they send you two cases of oil well in advance of the engine delivery. Kinda cool.

I called Aerosance today and got more information about the FADEC system. Some of this was new information and some just confirmed info that Mahlon at Mattituck already gave me.

There are two “cabin options” with the FADEC system. Cabin option 1 is meant for an aircraft with one alternator and one battery. This option includes a backup battery with monitoring system. The backup battery is completely isolated from the rest of the aircraft and is meant only to run the FADEC system. Aerosance officially says the backup battery will last one hour, but in testing they have had it last much longer.

The second cabin option is meant for an aircraft with two alternators and two batteries. It includes a more simple annunciator for the panel (just two lights) and no separate battery. This option is $500 cheaper than option 1.

The other critical bit of information is that the FADEC system draws on average 5.5 amps at 12 volts. The current draw is actually very peaky as the spark plugs fire and the coils re-charge, so that’s why they spec a 10 amp fuse in their electrical drawings.

Currently, I’m thinking I can get a B&C back-up alternator and regulator for the vacuum pad for $430 and have a few spare amps to run other things in the aircraft if for some reason the main alternator goes out.

The other option I’ll need for the FADEC is a serial bus controller. Since the FADEC system is already has sensors for CHT, EHT, manifold pressure, and other info, it can pass it on to an engine monitor display. The controller is pretty pricey at $500, but it’s cheaper than buying two sets of sensors. The FADEC does not monitor oil pressure, oil temperature, or fuel flow. I can read and pass on info about oil pressure & temperature to the engine monitor, or those can be hooked up directly to the engine monitor. I’ll have to check with the engine monitor manufacturer on that.

My current preference for engine monitor is the AF-2500 (formerly known as ACS-2002). I exchanged emails with Rob Hickman earlier in the week, and he said they are working on the interface for FADEC and should have it done by the end of the year.

Overall the folks at Aerosance were very nice and helpful on the phone.

The engine is now officially ordered. I emailed Mahlon last week asking a few questions. He informed me that Mattituck was going to be raising prices soon. I decided it was time to place the order to lock in the lower prices. I’ve been putting off ordering the engine for two reasons. First, it’s an expensive investment in this project. The second thing I’ve been waiting for is the timing. I don’t want to get the engine sooner than I need it. I ideally want it to arrive within 6 months of completion, because that’s how long the engine preservative lasts and when the warranty clock start ticking. According to Mahlon, the 1 year parts and accessories and 2 year cylinder warranty starts 6 months from shipping or when the engine is first started, whichever comes first.

I ordered Mattituck’s TMX-360 engine equipped for a constant-speed propeller with fuel injection, forward facing horizontal induction and FADEC. This engine is a clone of Lycoming’s IO-360 engine, built using new parts that are the same as Lycoming’s or have been improved slightly. I added fuel injection for better performance and to avoid the hassles of carburetor heating/icing. I added the forward facing horizontal sump for better performance and so the cowl doesn’t need the lower scoop. I added FADEC (full authority digital engine control) for better fuel economy and so I won’t have to deal with constantly adjusting the mixture. In most airplanes with an internal combustion engine (i.e. not a jet turbine), there is a knob for adjusting the fuel/air mixture. The pilot must adjust this knob to account for altitude, air temperature, engine heat, etc. I’d rather let the FADEC computer handle that for me.

On the FADEC system, I’m probably going to use the dedicated battery back-up. It’s an expensive option, but provides for continued operation in the event that the airplane electrical system quits. I also added the serial bus interface so the engine monitor can get data directly from the FADEC system rather than having to duplicate many of the probes and sensors.

I chose to use a clone engine over a Lycoming, because they have many minor refinements and are also less expensive. I had narrowed the engine manufacturer down to AeroSport Power and Mattituck based largely on their reputations in the RV community. Of the two, only Mattituck was able to pre-install the FADEC system. Plus, Mahlon at Mattituck has been very helpful in helping me understand these confusing engines.

Mahlon estimated an engine build date of October 6. I might delay that a bit.