Posts by Dave Berenholtz

Dave Berenholtz
1308 posts
http://www.alongwayroundtheworld.com

Solving the Ground Cooling Problem 1

Date:  12-02-2024
Number of Hours:  6
Manual Reference:  no ref

Identify Goals
The plane is almost ready for first flight. I have now done 11 taxi tests. It steers well at low speed , and we have ironed out a few small avionics issues. I still have a radio problem to solve. I’m really liking the bigger cockpit than my usual Long-EZ and the improved visibility.

All seemed ready  for a fast taxi text except for one thing. It just gets too hot on the ground. My design brief is at least 30 minutes at idle revs with the engine not too hot for take off. Ideally it would never get too hot just sitting still but I’ll settle for 30 or 40 minutes as realistic behind a few Boeings and Airbus size planes in a queue. It may happen, I don’t need to wait for that scenario to sort out the issue.

If I flew now, and even if it was great cooling in flight, I’d still have the ground problem. I fixed that ground cooling later it might then not be OK in the air. This would make a first flight now, well, not useful. This time we have to go in order, fix the ground cooling issue, then first flights.

Identity the Cause
What is the problem exactly caused by? That’s easy, I have almost no air going through the radiators. Once flying there will be 100-200 knots of air roaring through them, in the taxi almost nothing! The prop on a regular plane pushes air through the cowls and cools the engine, on a pusher it does nothing you can notice.

Isolate the Issue and Collect Data
This was a series of four ground tests in the runup bay each from 30 to 40 minutes duration. I wrote down data at the time and also have real information collected every second by the avionics and recorded on an SD card.

I had install 2 X 5.2″ fans on the back of one radiator and one 5.2″ fan on the other. I had tested and found reverse flow or rather my smart avionics guy noticed it. He may read this so I’d better not take the credit. The fix was some gaffer tape. Now I have three fans flush to the back of the radiators covering  71sq” out of 207sq”. I’d also done one runup to 2300rpm while standing on the brakes. Wow did it get hot fast then! Usually I am sitting at about 860rpm which was the number I used for these four focused data collection tests.

Test 1 Cowls Off
Test 2 Top Cowl OFF Bottom ON
Test 3 Top Cowl ON, Bottom Cowl OFF
Test 4 Both Cowls ON

Simple Data Analysis
I’ll spare you the ton of information and just show this rough chart I drew up. Time is on the bottom 0 to 40 minutes and temperature in F° from 70° to 250°  With a 1.4 bar cap (20psi) and the coolant in a 50:50 mix it will boil at around 250F°

You can see with both cowls, the green triangles, I’m heading straight for this maximum at the 28 minute mark and the oil, the tan dots, is getting close to maximum as well. In reality if I went to take off and raised the rpm from 860 to 2300-2500rpm the coolant would boil, probably before I left the runway.

Coolant pressure got to 19 psi with both cowls on. 20psi will blow the cap and overflow the coolant. Not good. Bottom cowl off and it got to only 10psi for the same time period. A huge difference.

Both cowls off, the dark blue, and life is good. Except I need the cowls on the plane for drag reduction! Top cowl on bottom off and I would be close to maximum temperatures at takeoff but its looking like possible if I could ‘vent’ the lower cowl and then seal it up again. They call these things cowl flaps. BUT wait! There is another issue.

Delta T
 This is the difference between the coolant temperature coming straight out of the engine and the temperature after the pumps, radiators and the heat exchanger just before it returns to the engine. I haven’t shown the collected numbers but overall its around 6F° in flight it should be nearer 14 -16C°!!! So the first thing to address is the fact that the cooling system is not effective with the fans going. It should be better than this.

Possible Solutions
First I need to make the fans more effective and then test again. If cooling is still not good enough then some sort of cowl flap or vent system, probably in the lower cowl based on the testing, will be needed.

I’ll show you what we have been up to in the next post getting the fans to do a better job and how I have begun to set up a way to trial cowl openings without destroying my existing cowls. .

 

 

Thirteenth Year Summary

Date:  12-01-2024
Number of Hours:  0
Manual Reference:  no ref

Build start DEC 1 2011
Today is DEC 1 2024

The workshop build log now shows 16,088 hours of time over the last 13 years. This is nearly 5 hours a day for the last year, no wonder I feel a little worn out. I really pushed as hard as I could everyday to get the just delivered engine installed, the aircraft ready and first flight done before today. No so.

The engine is installed. It was a HUGE job. I ended up ditching the coolant related fittings I’d bought with the engine for better quality Aussie made performance car parts. The radiators were finally finished and mounted as were the coolant pumps and fans. One task seem to lead into the next as I had to find a way to fit all this ‘stuff’ under the cowls.

A lot going on here up top.

A lot going on down the bottom.

There was also a  lot of wiring work under the plane and on the inside. You can see where the two water pumps ended up too. Of course the firewall titanium and fiberfrax installation was all a part of this years jobs before the engine had its ‘final’ install.

The cockpit was ‘finalised’

The panel done with all the sensors now hooked up and quite a list of other things. The last big phase of the wiring marathon. Weight and balance happened along with fuel calibration.

This is one of 5 pieces of paper which declares that I have a real airplane that is legal to be flown.  That was a big day.

The cowls have been painted and other jobs that were all a much bigger job than I thought. This is nothing new. The exhaust pipes had to be repositioned to be central to the cowl openings as well, one of many tasks so near the end of the build.

The engine does run. It probably cost me around 4 months and a lot of grief to get it going after the installation was completed.

First up, the supplied flywheel did not have the magnetic timing triggers in the correct place.  It took us some time and many rabbit holes to find the problem. We eventually confirmed that the magnets were moved to the right place and the sparkplugs firing correctly. The engine still wouldn’t start or run properly.

This was when ring gear teeth and starter motor gear were destroyed during our start attempts. That turned out to be a fuel mixture problem which led to significant backfires and the parts loss.  In the end I replaced the lightweight Skydynamics flywheel with a more standard Superior part with the magnets preinstalled by EFII.  I also replaced the BandC starter with a Skytec.

It wasn’t cranking well either. That needed the 4AWG cable replaced with 2AWG and along with a new starter that one was solved. In fact that was the only fault that was down to me and just a small delay on the journey.

This fuel/timing problem was the fuel ‘map’ that came with the engine. It was just plain wrong. Eventually a race car guy was involved and we tweaked the numbers to get the engine going. I finally obtained the map that the engine was run on in the USA test cell. That didn’t work well at all probably due to the different induction used. The next map was from the same engine as mine with the same induction and this is ‘usable’ but it will need a lot of work to get right in later testing.

I will give a big shout out to ‘Simon’ my avionics guy and friend who has been fantastic on this journey. He is well experienced in cars and airplanes and stuff with engines in general. I probably still couldn’t fix a lawn mower on my own. That said, I know more than I used to.

Here is the first taxi a month ago, Nov1st 2024, with the plane moving under its own power for the first time. Certainly a milestone, second only to first flight.

What now?  I thought I’d be doing first flight before now but the engine does not cool well on the ground. This must be solved. The standard I want to achieve is 30 minutes at idle without the engine being too hot for take-off. Cooling in the air is another unknown. I am going with the idea that if it is controlled on the ground with hardly any air through the radiators, it is going to be within temperature and pressure limits for initial flights where I’ll have 100-200 knots of air blasting through the cowls.

At the moment I am gathering data in various configurations in the runup bay. From here I can make decisions and retest. It might be a long road again. Of course there is nothing to do but continue.

After 18 years and a lot of flying, JZE will be sold soon and my new ride will be ‘The Beast’, XEZ. I’m looking at just a few more flights in the old plane to retain my currency. It is time to move on.

Taxi Tests 4 – Not Good

Date:  11-26-2024
Number of Hours:  0
Manual Reference:  

This is taxi run #11 I think, who’s counting anyway?  I wanted to try and sort out the radio problem AND see how the cooling goes with the cowls on. I’ve just added the heat shields, the top cowl stiffening works a treat and I was expecting a good result and even start runway tests the same day. On to first flight in a week.

Not so…

Previously at low RPM, cowls off I could maintain temperatures on the ground. This is my big goal for the plane so I can sit in a queue at airports for as long as I need without shutting down the engine because it got too hot.

Yes I could then use a handheld and do a hot start as required but this is a pretty awful way to operate. Its a lot of extra pilot stress too and I’d be hot on the take-off roll when I finally got there. There may also be problems restarting the engine when it was my turn. I’d have to restart each time the queue moved too.

Cowls on and my cooling is an epic FAIL. Even at 860rpm the temperatures kept slowly going up. I got to 212F after the radiators although the temps before the radiators where not much better. I have three sensors for all this. I was also up to 13psi coolant pressure when I pulled the plug and taxied back to the hangar.

The cowls were REALLY hot to the touch when I got out. Oh and no joy on the radio problem either. Anyway that puts a big stopper on my imminent first flight. I could go ahead and fly, but then what? It’s going to be far easier to solve this problem at Moorabbin that relocating to Leongatha where resources are only what I bring in the car and things like wiring would not happen easily. Given it just doesn’t seen to cool down quickly after the engine is stopped that idea of shutting down and restarting in a queue is not really viable either.

What to do? How to fix this ground cooling problem?

Get data. I need to do a lot of testing, timing how long it takes to get hot. First cowls off, then bottom cowl on with top cowl off then bottom on top cowl off. I need the numbers. I am expecting to find it OK bottom on, that would tell me that I need a huge vent in the top cowl. What I expect might not be what the data tells me.

Get data. Fans do not work properly without shrouds. Testing last night with bits of paper revealed that air is getting pulled in from the HOT side into the fan at the sides. As a quick and dirty test I need to block off the areas around the fans at the back of the radiators and see if this improves my test numbers. If it does, I am looking to add a third fan and test this too.

If that works I have an idea for louvers at the back of the fans which are closed on the ground but open in flight. This is a common automotive practice that someone smarter than me pointed out. So if the blocking off thing works I have a plan to make it useable.

If all this fails, what comes next is ugly. The tests should tell me if I need to vent just the top cowl or both top and bottom. How big to make the vents? How to I find out without cutting up the existing ones and cutting too little or too much or in the wrong places??

Yes I’m going to have to make a test cowl or even several cowls. I’d use the existing ones as a positive plug (mould). No small task. It doesn’t have to be flight worthy, just strong enough to sit in place while I taxi around slowly. It will probably have to be three ply of carbon too so I can get it to hold shape as I cut bits out. What comes off could be re-joined as I get the shape and size worked out.

If big vents work I am going to have to have doors that open with linear actuators and they don’t like heat at all. Remotely locating one would be very challenging and if its via cable it may need to be a push pull. A real can of worms, maybe something like the gear doors that spring open and are then held closed. Essentially I’m looking at cowl flaps that some GA planes have as standard. Maybe I can rig up a manual cable and set it so the airflow will tend to keep it closed.

Secondary to this is to get more control over the water pumps and fans. At the moment it is automated so the fans and pump at full power kick in at 170F or whatever I set it at. I do have an aux pump on a manual switch. However at the moment it is only circulating coolant that has not been cooled well at the radiators so it does nothing much at all. That’s the blocking off thing I need to look at. The other thing is to may have the third fan also just an on/off so I can at least get the fan and pumps going early if I need to. It would be on me to get them off once I’m in flight. This might help stop the heat build-up that seems hard to get rid off.

It looks like I’m not flying this year after all. That leaves questions on my pilot currency for first flight as I want to let the old plane go by the end of the year. I have decisions to make in a week or two.

 

 

 

Cowl Heat Shielding

Date:  11-24-2024
Number of Hours:  8
Manual Reference:  ch23

My heat shielding finally arrived.

It took a bit of planning to work out where it needed to go and the sizes required. I just used plastic as templates and drew on them. Next up was to trim the plastic, mark the insulation and cut them out .

This stiff is meant to be good to 1750F and should protect the cowls. Given I had some heat damage from when I lost the Wesh plug and shortly after that…the coolant, there were a few clue on where to put the stuff. I added a bit for the heat exchanger as this sits right next to the cowl with very little clearance. Despite the pipes being coated it is going to get pretty hot in there.  Particularly before I have some ram air pulling the heat out.

I have the shielding also running on the top cowl the length of the pipes, both sides.

All in place both sides and the lower cowl.  I’ve also spent a few hours trying to get the top cowl sitting better by moving one fastener. It took a couple of goes and its ‘better’ but not quite as I’d like. Onward for now. It is something I can revisit later.

Taxi Tests 3

Date:  11-21-2024
Number of Hours:  0
Manual Reference:  

This is the 10th taxi test now. Still just around the parking area and not yet on the runways. The cowls are still off as I evaluate the cooling, radios and engine further.

I’m now using a ‘fuel map’ from another LIO-390 engine what has the same Superior cold air induction. I did try the map from the test cell for this engine but it had the Skydynamics sump at that time. First up, the fuel map that was with the plane when I received it was unusable and the cause of many expensive and serious problems. I do not believe I altered it by accident, I don’t even think that is possible given it was so far wrong.

The current map is usable but nowhere near right. The idea is to have an air/fuel ratio (AFR) at 14.4-15 for cruise and 13.2 under load. So I need close to those numbers where I read the AFR in the cockpit over the whole rpm range. You can download the file to a PC, adjust each parameter for each 100rpm and each map setting manually and then upload it again.

I can tweak in the cockpit  with the ‘Tune’ function but not so precisely. It takes the numbers and averages them. Another way is to see what I have and use the Fuel Trim knob (FTK) to tweak on the fly. Those changes aren’t permanent and as I change the rpm or the MAP changes in the climb or descent, I’d have to readjust the FTK again. A bit like a mixture control so no big deal.

For now what I have is useable but a little rich over the range. I’m still having problems starting the engine. This may be the rich/lean settings at very low RPM  or it may just be me learning what the engine likes in terms of using the accelerator pump which is a fast throttle movement.

The last run I got the engine to 2300RPM in the runup bay. The brakes held but I really stood on them. This is close to what I’ll be using for take-off so we are good here. However as expected the engine got really hot as did the coolant and oil. The coolant pressure was right up close to maximum before the overflow is engaged as well. I backed right off of course, warnings were on the panel and I got a nice female voice in my ear telling me that certain pressures and temperatures were in the red. Not in those words however.

Despite returning to idle levels the oil stayed pretty hot, the coolant levels and pressure came down slowly. What I have found is that if I stay at around 1000RPM or less I can sit there without the temperatures rising. The two fans are doing the job given we have no air through the radiators from forward motion. I looked at the data as there is room for another fan which I thought might be needed with the cowls on. However with the fans and two pumps running, current draw gets to 54 amps and that is almost the limit for the 60amp alternator. The 5.2″ Spal fans draw a maximum of 5 amps so I’d be getting very near the limit if not over it at low RPM. We might be able to tweak the regulators up a fraction however. Without the fans, one pump hardly running and flight instruments and lights I’m at 34 amps.

I have some heat shielding for the cowls on order. I need to adjust a fastener and a few other configuration jobs. I’m still trying to sort or the squelch levels on both radios. They break through with the engine on, its perfect engine off so I need to tweak that while its running. To do this I need ‘config mode’ and to turn off the engine instruments. The GTN750 radio can be done OK instruments on. This is my next task in the runup bay. I will put the cowls on for that but I’ll keep things at 1000rpm so nothing gets too hot.

Once the radios are sorted out AND the heat shielding on the cowls is installed I can contact the tower and see when I can use the active runways for slow and then fast taxi.

 

Headrest Support

Date:  11-20-2024
Number of Hours:  5
Manual Reference:  no ref

Such a simple thing. I had a padded headrest done to fit the rollover. It wasn’t as I’d hoped but I thought I’d work something out to make it more secure. The velcro wasn’t enough and it kept sliding backwards.

I found a bit of hard foam with glass on one side. The idea is to secure it to the bottom with hose clamps and that would stop the lower part of the headrest falling backwards.

I glassed the other side, then made holes in the side so where the hose clamps were bolted on that part would be reinforced with flox. I cleaned it all up, painted it, installed it. Nice job.

Epic fail. There it is on the bottom right. Looks really nice but it tended to rotate on the hose clamps backwards, not what I expected.

Version 2. That’s the big piece above. Yes now hose or P-Clamps top and bottom. Four of the things! At least I had found an old bit of foam with glass both sides. That’s why I keep scraps.

Looks pretty nice eh? Rock solid and weights a lot more than it should for just a headrest support BUT… As I was thinking how to do this I realised that if I store things on that tray for cockpit use I need to make sure they are secure and that they don’t fall forwards in turbulence. I needed a back board that I could velcro a nice big bag onto.

Perfect, I get a two of one here and I can now self justify the extra weight!

Headrest secured, problem solved.

 

RTW Route East #11 rev1 via the Azores

Date:  11-17-2024
Number of Hours:  0
Manual Reference:  no ref

My route for this first Round the World flight keeps changing as the world situation does. I’m also getting great information from ferry pilots and internet searches on fuel availability, airport charges and places with ‘customs’ or ‘ports of entry’ for international flights.

Here’s a flat earth overview. Each ‘stop’ is a single flight.

If the earth is round after all, the lines don’t look too straight.  This view shows the ICAO airport names that I’m currently planning on.

That does look all over the place!  Here are some rough numbers based on a very conservative 170kts and 35lts per hour and nominal winds which will change, I do hope to get much better numbers.

Flights

YMMB YSNF
Moorabbin to Norfolk Island  1,303nm, 7hrs 30mts, 339lts,

YSNF NSTU
Norfolk Island to Pago Pago, American Samoa. 1,320nm, 10hrs 8mts, 254lts

NSTU PLCH
Samoa to Kiribati, Christmas Island 1,265nm, 7hrs 34mts, 312lts

PLCH PHTO
Kiribati to Hawaii, 1,071nm, 7hrs 51mts, 199lts

PHTO KHWD
Hawaii to Haywood Executive, California, 2,025nm, 11hrs 47mts, 483lts

KHWD KSAF
California to Santa Fe, New Mexico, 938nm, 5hrs 39mts, 206lts

KSAF KMKL
New Mexico to Tennessee, 857nm, 4hrs 51mts, 206lts

KMKL KMRH
Tennessee to North Carolina, 607nm, 3hrs 23mts, 148lts

KMRH TXKF
North Carolina to Bermuda, 618nm, 4hrs 10mts, 110lts

TXKF  LPAZ
Bermuda to Santa Maria, Azores, 2,039nm, 11hrs 13mts, 398lts

LPPD LEST
Azores to Santiagio, Spain, 849nm, 6hrs 4mts, 248lts

LEST LMML
Spain to Malta, 1,225nm, 6hrs, 25mts, 248lts

LMML HEGN
Malta to Hurghada, Egypt, 1,332, 7hrs 48mts, 324lts

HEGN OMAL
Egypt to UAE, 1,193nm, 6hrs 41mts, 243lts

OMAL VOCI
UAE to Cochin, India, 1,448nm, 8hrs, 58mts, 364lts

VOCI WIMM
India to North Sumartra, Indonesia, 1,396nm, 8hrs, 39mts, 351lts

WIMM YPXM
Indonesia to Christmas Island (Australia), 935nm, 5hrs, 38mts 231lts

YPXM YPKA
Christmas Island to Karratha (Aust. Mainland), 887nm, 5hrs 25mts, 222lts

YPKA YNUB
Karratha, WA to Nullarbor Roadhouse, SA, 996nm, 6hrs 01mts, 246lts

YNUB YMMB
Nullarbor to Moorabbin, VIC 820nm, 4hrs 31mts, 193lts

21 Flights of about 26,000nm (48,000km) and 5,400lts of fuel

 

 

 

 

Cowl Stiffener

Date:  11-16-2024
Number of Hours:  11
Manual Reference:  23

Do we have a problem?

 

Yes the cowl is vibrating a little too much for my liking. It isn’t touching the ‘lampshade’ around the prop extension yet but it is certainly close. This is another thing I had put off to see if it was an issue or not. It is.

I had a pretty good idea how to fix this using a technique that goes all the way back to the Education Chapter 3 in the plans where you make a ‘confidence’ piece. I also looked to my good friend and build buddy in the US, Wade Parton, who did a sterling job in roughly the same place addressing the same problem. Of course no two builds are the same and mine came out a little wider and higher as I may have had a touch more room.

The first issue is how little room there is to put a stiffener in place and have a healthy gap to the bottom of the top cowl. It turned out to be even less than this blue block in total.

It took a couple of hours of sanding to get down to the carbon as that skilfully applied undercoat and two pack top coat really wanted to hang on.

I eventually got there without loosing much thickness at all. That’s why it took a while.

I made a less than elegant dam with scrap cardboard and duct tape.

Even uglier is the pour foam. This stuff is great. Nice and light, you just have to contain it. I do something like this in several layers or you know its going to go everywhere.

I like to progress evenly and then keep putting the cowl on to check the height.

With the cowls done up and the clearance height confirmed, I went ahead and rounded the foam to make it ‘nice’.

Then I went ahead with a sort of pseudo hard shelling procedure. I knew putting micro on to transition the edges and then the carbon, it could get out of control. Here I have spent a while getting the micro smoother than it looks in the pic. I wanted it to be sticky but not fully cured for when the cloth went on.

I’m going for three plies of BID at 45 degrees. Each piece is 4.2″ wide and 33″ long. The easiest way to do this is wet out the carbon in one piece, then cover it with another piece of plastic and squeegee all the air out. Then its a simple matter of cutting out the three long strips so you end up with exactly sized wetted out carbon with plastic both sides really for the layup.

With all that prep work done, getting the carbon on is a piece of cake. I did peel ply just at the edges for a smooth transition. This often takes as long as putting the wet cloth down.

It looks like I have enough clearance in the middle. It is certainly too hard to photograph without breaking out the endoscope. Being cured enough and still at the ‘plastic’ stage I put the cowls on and let it go really hard in the correct position. This way the bend in the cowl should match where its going rather than fighting me every time I put it on.

While the carbon looks great, I’m going to clean it up after the cure and hit it with some high temp paint to finish off.

Despite all this masking care I did, there was some clean-up needed after a little ‘blue bleeding’. Paint doesn’t care how much time you put in. It shows no mercy, you have to get things absolutely perfect.

Why blue? Well it matches the registration marks on the sides. You can’t see it when the cowl is on AND it was easier than going to a spray booth and trying to match the white. Yes, I should have done this before paint. Here’s turning a mistake into a feature. Oh, and someone else suggested the colour too, so I can’t even take credit for the idea.

 

Post ‘adding the stiffener’ test. I’m really pushing on this and it is nice and solid compared to before. I don’t think it will be a problem with the engine running now. A bonus is that the top cowl is a bit easier to put on as it is more stable across the back. I’m calling this one done.

 

 

 

 

Exhaust to Cowl Correction

Date:  11-13-2024
Number of Hours:  10
Manual Reference:  23

I’ve know it for a while. Those exhaust pipes are too close to the top cowl.

Is there any doubt?

I put this off as I really didn’t have a welding person who could just come and do it.

Now its really time to do taxi tests with the cowls on and as my luck would have it…. Hold on, Murphy has been co-building this plane from the start so where is a welding person? Despite this trend, my delaying worked and a very skilled welder has appeared.

Even better, a mobile setup so we would work ‘in situ’. I can’t show you his face, he is of course, very busy.

I’m not going to tell you how many times the exhausts came off and went back on. We needed two sessions in the end. He made a cut and we would assess. Then another cut and again rechecking. Finally a tack or two. Cowls off and on many times. The idea was to loose the minimum amount of material and just ease into the right position. I also discovered that you need the exhaust nuts done up tightly as almost tight makes a few degrees of height change.

Given I had the pipes ceramic coated inside and out, that had to be removed for the welding, but only in a small area. Yes you can buy 2000F paint, do you think I can get it is satin black? Matt black had to do. I didn’t want to wait a week or two.

With the masking tape making clean lines its not too horrible and you can’t see it with the cowls on anyway.

This is where we ended up.

Well clear of the top and bottom cowl.

I really did want the pipes a bit closer to the prop and pointing in but realistically that would have made them quite a bit shorter. This may or may not have been a problem as no one seems to know the ideal distance from prop to exhaust. I don’t have the time for extensive testing and multiple exhaust pipes of various lengths and angles to find out the truth. I suspect what I have will work OK if not the absolute optimum. I’m not racing, my mission is of another flavour.

 

 

 

Taxi Tests 2

Date:  11-09-2024
Number of Hours:  2
Manual Reference:  no ref

So far, four taxi tests of 15-20 minutes each have been completed. These were just slowly around the parking area and runup bay, getting a feel for the plane. I’ve also calibrated the magnetometer so the ADAHRS has stopped showing error messages.

I have been at the front of the hangar for a change so able to get the plane out. The weather doesn’t matter for these tests.

The last test was with the cowls on. When the engine starts I get a general coolant pump warning, low coolant pressure warning, low pressure from the oil and so on. This tends to inoculate a person to these messages and given I’m not above 1300rpm I pretty much ignored them.  The pump warning did go off and come on again so I turned on the backup water pump just to be sure.

When I stopped the engine back at the hangar there was a LOT of coolant on the ground. It turns out I’d blown a Welsh plug! This was the one we replaced that was leaking from when the engine was delivered. Clearly the installation technique needs improvement.

Of course I was not going to get of lightly. This failure in the air would mean I’d have to shut down the engine or wait for it to seize. On the ground it meant the engine just got hot… but the coolant temps were constant as there was nothing to show the sensors with no water present. I didn’t know. Given the water pressure is zero at start-up with a warning, then it slowly climbs towards 15psi. I missed any message that it must have dropped from that.

So the engine got hot and the cowls hot enough to blister the paint both top and bottom. <sigh> At some point these cowls will need a complete repaint. You can see the marks above like a case of the hives. Review of the engine logs showed nothing catastrophic so I really got of lightly if you consider the big picture.

These glorified bottle tops are cheap but losing an engine isn’t.

I googled how to put them in, I watched five videos and each one had its own method. After a bit I understood what to do rather than follow the instructions like a robot. Every single person also had a favourite sealant too. The more I looked, the more options were presented.

I went for the anaerobic sealant I have used on the water system sensors. This has worked well where others have leaked, so more of the same seems a good thing to try.   The important part seems to be getting the plug in via the edges and not touching the middle. The wedging holds the plug in under pressure, not the sealant.

With that sorted out, the next day I drained the coolant which was only about 2 litres despite the sight tube level indicator showing full!  I filled again with the 50:50 fresh green stuff by pulling a vacuum at the cap this gives me a much better chance of having no air pockets in the liquid.

What to do about these CAS messages that are false on start-up? It turns out that with recent software changes to the G3X you can make messages ‘conditional’. We have set things up so many of these messages happen after the engine has been started and running for a bit. This should make them appear when they are REAL warnings, not false ones so I’ll take more notice.

We also reconfigured the fuel level system to now display on the G3X rather than the AG6 annunciator button that I had spent a huge amount of time and money on. When taxi testing it seems stuck on low sump despite there being 60 litres of fuel in the plane. It’s just been a PIA to program and hook up.  With software updates to the Garmin G3X it can now  accept different voltage levels for fuel annunciations.

Here’s the AG6 button which is currently disconnected and dark. I’m thinking maybe it could be a Master warning for all the major CAS annunciations but I’m reluctant to go to my long suffering avionics guy right at the moment!

Next up is getting the exhaust pipes tweaked again so the sit in the middle of the cowl openings. This is a cut and shut procedure. Then its back to the engine fuel tuning issues which are not yet resolved. I also have to stiffen the top cowl. I’ll do a separate blog entry on all that. Its a bit of work.

 

Taxi Tests 1

Date:  11-06-2024
Number of Hours:  0
Manual Reference:  Taxi Tests

My Long-EZ build moved under its own power for the first time, November 1st 2024. It has been 12 years and 11 months since this marathon began and over 16,000 hours of logged build time.

We had finally found the cause of the latest engine problem which was the fuel mapping and with a little difficulty the engine started.

Here’s a link on my YouTube channel with slightly better resolution.

Since then I’ve done 4 runs in total of around 18 minutes each. The steering was quite stiff which was a concern but that only needed some lubrication on the nose gear and now it really turns well and feels much better in the taxi. It is extremely sensitive so I need to be on my game on the runway.

I also found that with about 2mm off the nose gear cover and one AN size shorter bolt down there with a washer removed I can now rotate the nose wheel 360 degrees on the ground. This makes pushing it backwards where the nose must rotate 180 degrees much easier.

The cowls are not on yet so that will effect the temperatures in a negative way. We are starting on a cut and shut for the exhaust pipes today. The ends are too near the top cowl for my liking and I have found a gun welder to do the job.

The temperatures hasn’t reach maximum at low RPM after 20 minutes so that’s going in the right direction. However the Delta T is only 6 degrees. I need this higher. That’s the difference between the coolant temp from the engine and then measured after the radiators before it returns to the engine.

Min coolant temp for take off operation:
Normal operating temp range is 170F ~ 210F, it should be stable, i.e. +-5~7F during climb and decent but should not drop or increase dramatically.
Min temp for cruise, same 170F ~ 210F, should not change  at cruise speed or OAT’s it should always be constant.
In light of this information from the engine designer, I might change my minimum temperature for the fans and pump to start operating to maybe 160F and see how that goes on the ground. That will give them a little buffer to get to the 170F.

The only control I have with the Coolant temperatures in the cockpit is a switch to turn on the second water pump. This is why I will try setting the fans a bit lower for when they cut in. Mind you, we have no airflow over the radiators really at taxi speeds so its just when the fans cut in and I don’t know how effective they are yet.

There is an issue with the rudders not returning to fully closed. This is easily fixed by pulling the pedals forwards in the cockpit with my feet. The problem is that the angle from the pedals to the cable run is too severe to allow the rudder springs to pull back into line. It is likely that the airflow in flight will fix this but I will have a look at dealing with the angle involved. Its a bit of work and would need a new bracket on the pedals a bit higher and perfectly set up so I don’t have to alter the cable length. I wish I’d picked this up earlier, I thought it was paint too thick on the rudders preventing full closure. At least I know exactly what’s going on now.

There is also an issue with the fuel level electronics giving a false indication, so that’s another one. I need to adjust the squelch levels in software too. Its always open which is really annoying! That needs a borrowed laptop unfortunately. My old one is pretty much toast.

This is why these early taxi tests are taking a while. Its a good time to find a few gremlins and send them on their way.

Pre Taxi Test Engine Issues Part3 – Resolution

Date:  10-31-2024
Number of Hours:  15
Manual Reference:  23

The problem was still waiting to be found….

I added a pointer for TDC and we confirmed all the spark plugs were firing and in the right order and the right place.

We confirmed yet again, the magnets that trigger the ignition were all correct. That’s the T1 S1 T2 S2 which light up when the flywheel magnets is in position over the pickup. All good.

Why was it running so rich that we keep getting backfires? I pulled the air intact apart to look for a rag I must have left in there.

No rag, clean as a whistle.

I rechecked the throttle position with what was happening down the back with that butterfly. Confirmed, I was getting throttle fully closed and open in sync with the throttle position.

Of course we had gone back to the wiring as well and with diagrams of pinouts at the big multi connectors we again checked everything and buzzed out the wiring. All was correct and connected as it should be.

I gave the new flywheel a lick of paint. The new bolts finally showed up from Texas along with the new insert. They were held up in quarantine by the wildlife people.  Who knew steel was a carrier of things dangerous to the native flora and fauna? I guess they needed to charge some storage fees.

The insert went in the freezer overnight and the licensed engine guy in the hangar made short work of installing it. I don’t think I’d have done so well. Everything is on a steep learning curve for me and there are times when its better not to have a couple of goes.

The bolts and the inserts were again very carefully cleaned. I chased the threads with a tap and die. This will be my new SOP (standard operating procedure) The prop went back on with anti-seize, yes my call,  and I had another go at trying to improve my lockwiring.

Through some friends we had made contact with a race car guy who was very experienced in ignition and fuel systems. Next came another wait for his availability.

THE RESOLUTION!!

Gary, (Mr Fuel and Timing) hadn’t done this sort of thing on airplanes and it took a bit to get him comfortable and explain we were only wanting him as a ‘consultant’ rather than walking away and expecting everything fixed. He knowns what a piston engine should be doing in terms of spark, fuel and air.

I had a print out of the Fuel Map and he gave it a good read. You can’t access all the numbers directly at the plane. You need to download the file and put it on a PC to view and then edit. The file is then uploaded back into the EFII system in the plane.  Here are the first few numbers of the original file.

He didn’t like what he saw. He felt that the settings for starting were overly rich and this was the problem. I am still not 100% on what I am seeing here. The big numbers at the higher MAP end really got his attention.

So rich for starting. Ok here are some of the numbers we ended up with as a quick new setup after the testing you see below. This was based of a fuel may we got from EFII as their standard. It was still a bit rich in my plane. We are going to need a good day of runs  at different RPM up to the higher ranges to set the whole map but the one above is ‘usable’ for low RPM work.

We did more testing with the new settings, plugs not connected and ignitions off of course. The numbers and cockpit indications were promising.

Time to try again. With an abundance of caution I didn’t even prime the engine. I remain concerned about the VERY expensive backfires. As I cranked Gary watched on checking the numbers. All seemed ok.

After a few more goes the engine was starting well with minimal throttle and idling quite low around 660rpm. Gary was monitoring the AFR (air/fuel ratio) very carefully on each start and we tweaked the low RPM section of the fuel table to the one I displayed earlier.

So the problem was found.  The supplied fuel map with the engine was rubbish. Given the log books say it has been previously run for 25hours, I have to conclude it was NOT with the supplied map I got and an error had been made. These things happen. The fault was in an unexpected place and took 3 months and several thousand dollars to find. Of course its easy to say, “Why didn’t you check this day 1?” A lot of people were involved and given the engine run history as presented, it took fresh eyes.

I always move forward. This is now in the past, gone and behind me.  The first taxi happened the next day.