Category: Engine and Accessories

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Improving the Fuel Pressure Regulator

The airplane has the EFII System 32 electronic ignition and electronic fuel injection. There are several positives of using a system like this and one serious negative. The system makes for easier starting and better fuel economy. The downside is that the system is electrically dependent, which means the electrical system has to be very robust, and redundant (compared to a traditional system with a mechanical fuel pump and magnetos).

Anyway, I recently had an issue with the engine surging at high idle speeds. With help from the manufacturer, I was able to find the issue (an unreliable throttle position sensor). During the course of my investigation, I began a discussion with two other pilots that have the EFII system (Sam R and Dwight M). They both are excellent resources.

They looked at my engine data and noted that my fuel pressure tended to drop off a bit at high manifold pressures. We discussed the issue and decided that the fuel pressure regulator was the likely cause. Sam suggested that I replace the FPR from EFII with a better one made by Borla. The cost was about $250, but his own testing suggested that the Borla did a much better job of maintaining fuel pressure.

The hardest part of the job was manufacturing the bracket to mount the Borla FPR on the firewall since its layout was different from the original Aeromotive regulator. With some help from Tom at TSFlightlines I got that part figured out and installed the new FPR. It worked perfectly and the log data showed a very clear improvement over the older regulator.

The blue line is the fuel pressure during a flight with the new Borla fuel pressure regulator
The red lines are flights with the older Aeromotive fuel pressure regulator that I replaced.
This is the older Aeromotive fuel pressure regulator that I replaced.
This is the new pressure regulator. Note that I added a 45 degree adaptor to take some of the tension off the host between the regulator and the #5 injector.

I disassembled the old regulator to check for damage. As we suspected, the reason it was not maintaining pressure well is because the steel ball in the regulator had spalled the edge of the aluminum seat.

The edge of the aluminum seat is clearly worn. The manufacturer says this should never happen and if it does, the fuel pressure regulator should be replaced.
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Cylinder Compression Check

This is a typical check that you accomplish at each annual condition inspection.

You remove one sparkplug from each cylinder and then use a compression checking tool to check each cylinder to ensure there are no leaks past the valves or the piston rings. Paul Dye has a pretty good video on Youtube of how to use the tool:

KITPLANES Firewall Forward: Compression Testing

I find top dead center (TDC) on each cylinder and then charge each cylinder in turn to 80psi of air and observe if the cylinder is “holding” the air. Any value above about 60 psi indicates the cylinder is OK. Of course, it makes sense to look at the valves as well using a borescope if you suspect any other issues.

This test puts a lot of pressure on the propeller which can cause it to turn. If your head happens to be in the way, you can get whacked hard by the propeller (ask me how I know). The key is that the piston must be all the way up and both valves closed (this is top dead center on the compression stroke). If the piston is not at TDC when you bring the air pressure up the propeller will want to spin backward if you are before TDC and forward if you are beyond TDC.

I had the help of Dave F. and Enzo C. which makes doing the test easier and safer though I know most aviation mechanics do this test solo.

Today the test went well on five of the cylinders. I need an adaptor to get to the sixth one. I will do that last one when I get back out to the airport to continue the inspection.

Update: I was able to remove the EGT sensor on cylinder #6 which then gave me access to the lower sparkplug hole.

Here are the numbers:

#1 77/80

#2 72/80

#3 78/80

#4 72/80

#5 78/80

#6 78/80

After doing this test I decided to change the spark plugs. This engine configuration uses automotive sparkplugs which are much less expensive than aviation ones. They cost about 1/4 the price of aviation ones so changing them more often isn’t a big deal.

In this engine I use NGK BR8EIX short reach plugs gapped to .032. They require an adapter to fit the 18mm holes in the cylinders because they are only 14mm in diameter.

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Oil Change

The annual condition inspection is due this month. I can do the inspection and sign it off under the new FAA MOSAIC rules because I took the 16 hour course that they mandate and because my updated airworthiness certificate allows it.

The first task (of many) is to change the oil.

I got to work on it yesterday. It will likely take two to three full days to complete.

I started on the firewall forward.

I warmed up the engine by flying a couple of patterns with my friend Enzo. Then we uncowled the airplane. The first task was to change the oil.

I have changed the oil once before on this engine. I forgot that the manufacturer installed a quick drain on the bottom left side of the oil sump. I took the other drain plug out which is more difficult and results in more spilled oil. Lesson learned for the next time.

I took a sample of the used oil to send to AVLABs for analysis. My airplanes have always had relatively new engines so I have never had a report come back with any issues, but I still prefer to send the sample off.

Changing the oil is a mundane and a bit frustrating task for one reason: The oil filter is difficult to get to and hard to take off and re-install. It almost always ends up creating a bit of a mess because there is really no way of taking off the filter without spilling some oil on the engine components below it.

I used a big 1″ box end wrench to take the filter off, but in retrospect it might be easier if I had a shorter wrench. There is no way to get a torque wrench on the filter so I have to reinstall it to my best estimate on torque.

I use a boatload of paper towels to catch the oil that inevitably spills when I take the filter off. I have heard that some guys use disposable baby diapers for this. I might give that a try.

After reinstalling the drain plug (and safety wiring it) and the oil filter (and safety wiring it too), it was time to put oil back in the engine. I used 8 quarts of Phillips X/C multi-weight (20w-50). This is a bit more than necessary, but it accounts for the oil that is in the filter. I also have a bunch of Phillips Victory 20w-50 on hand. The only difference between the two is that the Victory has anti-scuff guard. Lycoming does not say this is needed for my engine, it is more needed for turbocharged engines and some older, smaller engines. On the other hand, Lycoming says it is ok to use the Victory oil so I will likely use that at the next oil change.

145 hours on the engine.

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More Engine Work including the Half Raven

We worked on more of the firewall forward tasks today. We had intended to fit the lower canopy around the exhaust but got side-tracked by the Half Raven kit. It doesn’t look too hard but it took the better part of a day to complete it.

The hoses from AS Flight Lines were perfect (again). Steve also helped me to figure out how to install the entire setup despite being on a camping trip.

The white canister is the Half Raven. It has an internal ball that covers and uncovers two ports inside the unit. Oil that would leak out of the breather tube on top of the engine (especially if you do inverted manuevers) now is mostly recycled and returned to the engine. The big orange hose goes to the oil sump .

We installed the Sniffle Valve. It took way longer to figure out where it goes then it does to install it.

The sniffle valve looks like something you would buy at Lowes for about $8. Nope, $120.

We installed the oil dip stick. Short, easy job.

We gapped and installed all the sparkplugs (after I searched high and low for the 18mm to 14 mm adapters. I finally found them upstairs by my desk. Glad I did, replacing them would be $100.

Tomorrow is moving day. We will be going to get the wings which have been in storage in Williamsburg and bring them to my hanger. I will also bring the tail too. If I get really ambitious I will bring the whole project to the hanger (30% likelihood).

16 hours (2 people x 8 hours).

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Cowl Done, Exhaust System Nearly Done, Misc.

After a one week holiday at the lake, I am back to work on the airplane project.

The cowling is done with the exception of the fasteners across the bottom of the firewall. I will also have to make additional trim cuts on the bottom cowling to accommodate the Vetterman exhaust system.

I have spent more time on the exhaust then I thought I would. The Vetterman exhaust is very well designed and fits the engine very well. It’s all the little stuff that takes a significant amount of time. Fabricating the hangers, doing the heat muffs and scat tubing, installing and wiring the EGT probes, installing the heat shields to protect hoses and the FT-60 etc. With the exception of connecting the wires, that is all done now.

My Dad and I knocked out the oil door on the top cowling today.

As of now the “to do list” stands at about 50 items.

Here is the final paint scheme design:

24 hours (2 people x 12 hours)

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Engine, Cowling and Miscellaneous

Jim Van Laak stopped by to assist on the engine work. We did the final fit and attachment of the snorkel, attached the mixture and throttle cables, safety wired the propeller and the primary alternator and began working on the cowling.

I am using the Skybolt fastener system for the top cowling and using the Van’s hinge system on the firewall side of the lower cowling. I have to say the Skybolt hardware is very nice — their documentation not so much. I am pretty sure I would never have figured it out without Chris Moon and Jim’s assistance. My father and I have nearly completed all the Skybolt fasteners on the aft edge of the top cowling. Still need to adjust each fastener so they lock down flush (easy adjustment).

A few key things I have learned:

  • you can’t preinstall the Skybolt receivers into the flanges because you need the hole open to scribe the line up on the inside of the cowling.
  • the receivers have a small pin that you remove after you make final adjustments. This pin needs to face away from the firewall for easy access.

My niece, Sarah, graciously helped by climbing into the airplane and installing a couple washers and nuts that I couldn’t get to (my hands are too big).

I am hoping to finish most of the cowling work this week. Then the exhaust system will be the last big thing to work on. Maybe even move the airplane to the hanger on Saturday.

20 hours.

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Snorkel Continued and Miscellaneous

My Dad and I worked on the snorkel some more. We used flox to secure the snorkel to the filter flange. We built the alternate air door and floxxed and riveted it in place. We also decided to build up the bottom edge of the face of the snorkel that attaches to the fuel servo. The snorkel is essentially done now.

Fiberglass work is a bit like arts and crafts day at the cub scouts. It ain’t beautiful, but I think it came out pretty good. You can see the alternate air door here.

We re-torqued the propeller bolts to 65 ft-lbs using the $70 wrench from Anti-splat.

My $70 wrench. Banana for scale.

We adjusted the prop governor. We had to move the bolts attaching the control head over one hole to be able to add the prop governor bracket for the control cable. We also had to re-clock the actuator arm about 180 degrees so it is on the bottom rather than on the top. That was where the fun began. The Van’s plans call for using an AN3-10A bolt and a particular washer stack. We did that and found that it was impossible to tighten the nut tight enough to align the cotter key hole in the bolt with the castle nut. If you wrench on the nut, the bolt will sheer off right at the cotter key hole (ask me how I know). We then tried an AN3-11A bolt and found that it was too long if installed as called for by the plans and hits the body of the governor. Finally ended up using the longer bolt and putting it in from the outside which gives much better clearance (this will be the first of two times that I had to go off the plans to make something work today).

The plans call for the bolt to come from the inside to the outside. Due to the thicker arm on the governor arm it was necessary to use a longer bolt (which doesn’t fit going left to right). I checked the motion and all looks good.

Next up, the spinner back plate. The Whirlwind uses a different style two piece back plate compared to the one in the Van’s plans. You don’t have to build it (nice!). The manufacturer’s plans say to put the bolts in from the back and put the nut on the front side of the back plate. There is simply no way to do this, so I put the bolts through from the front side and put the nuts on the back side. This should be safe and secure.

We began fitting the top cowl onto the airplane. We immediately realized that the spinner backplate on the Whirlwind is significantly different than the one Van’s calls out. This mean trimming a lot more off the cowling near the spinner. We have it close now. There is definitely more trimming and sanding in our near future though.

14 hours (2 people x 7 hours)

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Baffles and the Snorkel

We have been working on the baffles for a few days now. There are a lot of connection points for the baffles. Some are easy to install and some are a real bear. On each “corner” of the engine there is a floating connector that a bolt threads into. They are in a difficult spot to get to and you have to get them lined up properly to get the bolt in. A bit of grease helps to keep them in place while you tighten the bolt.

The next un-fun step is to fabricate the rods that connect the bottom of the baffles together. I needed to borrow a 6-32 die to thread the rods – which is actually hard work.

The good news is that the baffles are 98% done (one bolt is giving me a hard time).

We also began working on the snorkel. As several people have pointed out you will likely spend 20 hours thinking about a task that takes 3 hours. We have it mostly cut to the correct size now. I need to glass up the corners of the snorkel where it goes into the filter holder. Then I need to cut the hole for the alternate air source.

The key here is to make four vertical cuts (one at each corner) on the snorkel. Each cut should be about 3 inches long. This will allow the snorkel to slide up into the filter frame. After I attach the snorkel to the frame, I will “repair” the corners.

I may modify the fuel servo end of the snorkel to make the hole size more closely match the FM 150 inlet. I know people that have done this and others that have left it as is.

Meanwhile, we have some final electrical connections to make, and will need to start on the exhaust soon.

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Propeller and Miscellaneous Stuff

My father, Drew and I installed the propeller onto the engine this morning. It is a Whirlwind 74HRT fiberglass propeller. It is a very nice looking propeller and I am excited to try it out (hopefully soon). It is not especially heavy, but it is important to install it straight and pull up the six bolts evenly.

The first task before installing the propeller is to remove the metal plug in the end of the crankshaft. It is there if you are using a fixed pitch propeller. I used a screwdriver and a hammer. You basically punch the center of the plug until it deforms and then the plug falls out. I know some people drill a hole in it to get it out, but that risks getting some contamination into your crankcase.

The three of us lifted the propeller on and hand tightened the bolts. I’d like to say it went on very smoothly with little effort. The truth is that the first time we did it, we didn’t get it on straight and I decided to take it back off and try again. When we took it off, I noticed that one of the threaded bushings had been pushed back on the crankshaft flange. The Lycoming tech support guy had a great suggestion on how to reseat this bushing without damaging it. You take a big socket and put an installation bolt through it and insert the bolt into the front side of the bushing. As you tighten the bolt it will pull the bushing forward. Much better (and easier) then hitting it with a mallet.

You can see the bushing pushed backward here. A socket and bolt on the other side works great to pull it back into place.

The installation manual calls for the bolts to be torqued to 65 ft-lbs. Even with a crows foot, I was only able to get my torque wrench on to two of the six bolts. A $70 wrench for this task is available from Anti-Splat Aero. I hated parting with $70, but I love Anti-Splat and was only momentarily sad.

Meanwhile we put the RTV onto the baffles. You install a relatively thin coat in several places on each baffle. It takes 24 hours to dry so they are sitting off to one size until tomorrow morning. Before doing the RTV, I test fitted the two back baffles – they fit tight but they do fit. Tight is much better than loose.

Two of the four baffles with the RTV on them.

We continued to sand and fit the cowling halves down in the basement (it’s cooler down there). I made the decision to use SkyBolt fasteners for most of the cowling instead of piano hinge. $400 with a discount from SkyBolt.

Next up, install the baffles, more wiring and fitting the cowling. The Vetterman exhaust will be soon after that. Then lots of clean up tasks like wire management, intersection fairings, timing the mags etc.

Nine hours (3 people x 3 hours)

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Firewall Forward Continued

My Dad and I continue to grind through the various electrical and plumbing tasks forward of the firewall. We also began working on the cowling which is lots of messy grinding and sanding.

You have to cut/grind both halves of the cowling to the scribe lines. One problem we ran into is that the scribe lines are very difficult to see.

We installed the oil cooler and the hoses to it.

Things are starting to get crowded back here.

We did the initial wiring to the right P-Mag. So far I decided to leave the other P-Mag off to give more access to the fuel pump until I finish the hose connections there.

We worked on running some of the ignition wires and putting the adel clamps where they need to be. Two big learnings here:

  • The safety wire trick for closing adel clamps while you are trying to get the bolt through them is GOLD. Simply put a loop of safety wire around the clamp(s) and use your safety wire pliers to close them up. So much easier than trying to squeeze them with your fingers or a pair of traditional pliers.
  • In the case where you need to enlarge the holes in the adel clamp for a bigger bolt, it is super easy to do with a uni-bit and painfully difficult with a traditional drill bit. In defense of Van’s they tell you this in the instructions.

I did some of the butt splices for things like the fuel and oil pressure sensors. I didn’t like the way some of them came out so I will likely redo at least some of them. I ordered longer pieces of heat shrink to slide over the splice to give them a cleaner look.

I broke down and ordered a Bogert tow bar from Spruce (significantly cheaper than ordering directly from the manufacturer). I had one for my RV-10 and they are good quality, but I think $200 is sort of highway robbery for one of these things. Just my opinion.

I realized that the trailer I had planned to use to transport the airplane to the airport isn’t wide enough to accommodate the landing gear. I have a couple of alternate plans and I don’t have to address this issue for a couple more weeks (my engine work is taking longer than I anticipated).

20 hours (2 people x 10 hours)