Maintenance

List of Maintenance Items

When you own an airplane especially a homebuilt airplane you ended doing maintenance work year round. Some of them are routine and some unexpected. I take all of them as learning experience/challenge. So far I have learned a lot. Think about the supposed purpose of experimental aviation that is "for education". I am being educated every time I fly or maintain my airplane. Following are list of maintenance tasks I encountered.

Index

AHRS and magnetometer (3/22/2007)

I have noticed that my GRT EFIS attitude display often leans slightly to one side and the ball display is opposite to that of my turn-and-bank ball. I finally decided to do some tests. After talking to Mark Allen at GRT, I re-measured the alignment of AHRS and magnetometer and found them correct. I sent Mark a log file from a test flight. After reviewing it he told me that one of the sensors is out of tolerance and he will fix it for me. After sending my AHRS in, he sent me a new set of AHRS/magnetomer. Now the new ones are in and there is no more leans and the ball is centered.

Idle Mixture (4/10/2007)

Well, during my phase I flight test I have tried to set the idle mixture and ended loosing the idle mixture needle. Today, I removed my fuel inlet screen and found some gooey stuff that must be from the fuel tank. I also take the opportunity to readjust the idle and idle mixture. After the scare during my phase I, I set my idle back to 650 rpm. It sure make landing floats. I asked my friend Kyle to help adjusting the carburetor and I run the engine. Last time I did all by myself. For each try, I have to run the engine, shut it down, climb out, adjust the idle, climb back up, then, start the engine. With Kyle's help, it is much easier. Following is the procedure we used:

a. Turn the idle mixture screw all the way in (lean).

b. Run the engine warm

c. Run engine to 2000 rpm then pull throttle to idle, wait a few seconds to allow the rpm to stabilize.

d. Observe the idle rpm and use it to adjust the throttle stop screw to either increase (clockwise) or decrease (counterclockwise) the idle rpm.

e. Slowly turn mixture control to lean, observe the rpm change.

f. If before idle cut off engine runs up 50 rpm before shutting down, the idle mixture is just right. If rpm gradually drop without rise, idle mixture is too lean. If rpm rise more than 50, idle mixture is too rich.

g. If idle mixture is too lean, turn the knob counterclockwise. If idle mixture is too rich, turn the knob clockwise. Each time turn the knob only 1/4 turn.

h. When enriching the idle mixture, the idle speed with drop. It might be necessary to turn the throttle stop screw clockwise (in) to raise the idle speed. Leaning the idle mixture has the opposite effect.

i. To obtain the desired idle rpm and the correct idle mixture, you will have to adjust both the throttle stop screw and the idle mixture screw.

j. Repeat steps c to i.

Always make small adjustments. Today, I was able to see both lean and rich conditions. At rich condition, one time the idle rpm rise was more than 200 rpm.

Fuel leaking down the airbox (4/10/2007)

Today, when I was doing the idle adjustment Kyle noticed some fuel dripping down the airbox. I did not pump the throttle during engine start so it is not the throttle motion. (When pumping the throttle the accelerator pump in the carburetor injects fuel into the carburetor. If the engine is running, the fuel mixed with the incoming air gets sucked into the engine. If not, since the carburetor is mounted vertically, the fuel drips directly down to the airbox.) Kyle said that fuel began to drip only after I shut down the engine. In the past few flights I noticed some black streaks on the nose wheel pant. I thought they were from the oil dropped from the oil filter during last oil change. Now, I see that was accurately the dirt washed down by the fuel. I have no clue as what has happened. I have sent an email to the Matronics RV-list looking for answer. Hope someone will help me to solve this problem.

No one replied. Well, I will continue to observe.

4/23/2007 I came back from an oversea trip on Saturday and on Sunday afternoon flew to Put-in-bay. I noticed that at idle, the engine was running rough. Today, I remove the cowl and try to reset the idle. Mike Fisher, the designer of several biplanes was working on his 1946 Cub across from my hangar. I asked him to observe the carburetor as I run the engine. He noticed that at idle cutoff fuel stream down the airbox. I also noticed that the idle speed was down to 400 rpm and when I pull the mixture back, the engine run up to more than 1000 rpm and refuse to stop. I called Bart at Aero Sport Power and he immediately told me that the float is heavy and he is Fed Exp a new carburetor to me. Now, the problem is identified. I will replace the carburetor when I receive it on Wednesday. Hopefully the problem will go away for good.

An engine expect on RV-list sent me the following explanation:

"Ted, vibration is the cause. The float is heavy enough to let in more fuel when the carb is being vibrated by the engine, but it will shut off under still conditions with the electric fuel pump pushing fuel." (W. North)

4/25/2007 Received the replacement carburetor and install it. Engine runs well and without any fuel dripping.

Starting problem 5/1/2007

4/30/2007 Made a short flight to Jackson, OH. When started the engine at Jackson, the starter made some grinding noise. The first time propeller did not turn. Tried again and engine started. Today (5/1/2007), the same thing happened again. Need to investigate as what is wrong.

Talk to Skytech and the service rep told me to do diagnostic measurement to detect what was wrong. There is a document on their website showing how to do it. Unfortunately, it has to be done in the failure mode. I just can not generate the failure mode to do it. The service rep said that their starter either works or die. The measurement is done when it died. Well, my problem is intermittent. He suggest that it might be the battery is too weak.

5/29/2007. It still takes a few tries to get engine started. Now I suspect the problem is the battery (batteries). I ordered a new Odyssey PC680 from Van's. I will give it a try after I have received it. However, I can not figure out why the batteries became weak so quick. My charging voltage seems to be normal (14.2-3 volts). Later on, it is proven that battery is good. I am still on the old battery.

6/13/2007. So far most of the time it takes at least two tries to have engine start. Recently on VAF forum several people talked negatively about Skytech starter. It probably influenced my thinking. Today I thought about the starting problem and concluded that it might be my engine start technique. Last Fall when I started flying, I never used electric fuel pump. Engine started right away. Over the Winter, I began to turn the electric fuel pump on and prime the engine. Again, engine started without any problem. My problem really began when the weather turn warm again. Unfortunately, this time I kept my Winter technique. Now I see that the problem is pretty much engine flooding, instead of starter/battery. Today I started engine without electric fuel pump neither pumping the throttle. Engine started after a few turns on the first try. Hope I have the problem solved.

7/10/2007 (scroll down and see water in fuel section). My starting problem is compounded by the water in gascolator/fuel sump. After emptying water, I no longer have starting problem. I continue to learn from the problems I encountered.

1/19/2008. Today I had my airplane parked outside for 5 hours in low 20s. I asked line person at KLOU to plug in my preheater for me. When I came to the airport, the oil door is open and a 11 kts wind is blowing directly into my air inlet. When turn the power on, I noticed a 50 degree oil temperature. I tried to start the engine many times and it did not try to start at all. Finally, I decided to plug the air inlet with towels and plug in the preheater again for 30 minutes. Tried again for another 5 times and finally the engine got started. I did prime the engine before trying to start it. Well, I still have not figured out how to handle my engine in cold. By the way, it is carb engine and should be easy to start.

Crank seal leak - 5/22/2007

After oil change I noticed oil leak behind the flywheel. Kyle happened to work in Mike's hangar in front of mine. I asked Kyle to take a look. He suspected that the crank oil seal has a leak. I called Bart at Aero Sport Power and he suggest that I get it changed locally and send him the bill for reimbursement (3-year warranty). This morning Kyle helped me to replace the seal. First, we removed the spinner, propeller, and flywheel. Now we can see small amount of oil at the bottom of the crank shaft at the seal. The seal is a piece of black rubber. Using a screw driver, Kyle was able to pry the seal out. It is a split seal (a ring with a split). We went to our local AP - Fred and he gave us a new seal ($11.95) and lent us glue for the seal. This one is one piece with a coil spring looped to keep the ID tight to the crank shaft. We are supposed to stretch the ring seal to pass the flange for the propeller mount. The flange has a much bigger diameter than the seal. After carefully cleaned out old glue from the crank shaft and the engine case, Kyle applied grease to the flange and the seal. Using two large pins, we stretched the seal ring and managed to force it over the flange. After letting it spring back to its original size, we removed all the grease out of the seal, the flange and the crank. Solvent and compressed air were used to do the cleaning. After applying a coat of industrial glue to the OD of the seal, Kyle pushed the seal into the engine case using a piece of wood. The job is done and no more leaks for now.

At the same time when we discovered the crank seal leak, we also saw some oil around one of the nuts on the underside of #1 cylinder (for cylinder stud). Since we did not intend to remove the cylinder to re-apply thread seals, Kyle removed the nut and used solvent and compressed air to clean up oil around the bolt. After solvent dried, he applied high temp RTV around the bolt and put the nut back. Hopefully, it will stop the leak.

5/29/2007. Flew a few times. Open the cowl and check, I found the crank dry and no oil around the leaking nuts. However, there are some oil on the engine parting line around the aft side of the engine (on both side). It turns out that several nuts are slightly loose (could be turn without too much torque). Tightened the nuts and the leak seems to stopped.

Bad magneto timing - 5/22/2007

At few days ago I changed the oil. At that time I tried to remove a plug below the oil filter adapter to drain the oil from the filter and failed to move it. I ended removing the 90 degree oil filter adapter. In the process I had to loosen the left magneto. I thought I knew how to do the timing. How wrong I was. After the oil change, I took the airplane up for a short flight. I noticed that #1, #2, and #3 cylinder CHTs were above 480 degrees F. They do not dropped too quickly even after I level off. I came back quickly and told Kyle and Mike about my problem. They suspected that my timing was off. Today, after changing the crank oil seal, Kyle checked the timing and found my left mag is off a lot. Only at that point, I realized that I did not put the engine to the compression cycle at #1 cylinder. My timing was done based on an unknown cycle. After re-timed left mag, I went to fly and now the temperature is back to normal.

In the future I will first remove the top plug on #1, put my thumb over the hole and rotate propeller until I feel the compression on #1.

Propeller dynamic balancing - 6/13/2007

Today I flew to Athens, Ohio and had my propeller dynamic balanced at Ohio University airport service for a grand total of $166.53 (including tax). Kim White was the A&P who did the balance. At 2,200 rpm, my propeller had 5 IPPS. After the balance, it is 0.14 IPPS. The process began with removing the upper cowl. A sensor is attached to the front top bolt on the engine. I started the engine and run it to the max rpm (2,240). We decided to balance at 2,200 rpm. A measurement was taken and the out of balance position is determined. After engine is stopped, Kim removed spinner and drilled a hole on the spinner backplate and attached a few washers with an AN bolt. Spinner is put back, engine run again and measurement taken again. Don't ask me what does IPPS mean. I was side tracked and forgot to ask Kim the meaning. After coming back, I read that vibration are measured in ips (inch per second). The limit 0.2 ips. Several RV builders had their propellers balanced to under 0.02 ips. Does this mean that I did not get a good deal? I don't know.

Tire rotation - 6/17/2007

After 183 hrs and 268 landings I have not done anything to my original Van's tires. This afternoon I open up the wheel pant and took a look. Well, the outer edge of the tire wore a lot!

It is time to rotate the tires so I can get a little more life out of them. Unfortunately, the temperature in my hangar is in the upper 90s. Without a fan, neither water to drink, I decided to come back tomorrow morning when it is cool and possibly a storm.

Rotating airplane tire is not as simple as rotating car tires. Basically, we are flipping the tire. Since one side of the wheel half has a hole for inner tube Stem and the other side has brake, to flip the tire one has to take the wheel apart and flip the inner tube. After removing wheel from the leg, air is deflated. By pushing the half with tube valve stem, the half is loosen. Push the valve stem out of the hole in the wheel half, the wheel half is separated from the tire. The other half is set quite tight with the tire. I pushed a piece of flat plastic between wheel half and tire to separate them. Then, I used two wrenches to pry them apart. The rest of the work is not very difficult.

12-17-2008. A better way to separate wheel halves is to use a bead breaker. You may find one ($19) from Harbor Freight for motorcycles.

Remove right side wheel and axle sat on 2x4.

 

 

 

 

 

 

 

 

Remove wheel half

 

 

 

Number of Landings from each tire:

Manufacturer	Left	Right
Air Hawk (8/2006)	440	329
Dresser Retread  (7/2007)	268	440
Air Hawk (10/16/2008)	416	416
Air Hawk (5/10/2010)

I replaced the first set of tires from Van's at 301 landings. Later on I realized that these two tires are still usable so I reused them. The most puzzling is the Dresser Retread I used on the left side lasted only 268 landings before it is totally worn out.

Tire change photos can be found below:

Wheel change

Nose wheel pant damaged (small) by FBO - 7/3/2007

At Charleston I ask the FBO to keep my plane inside the hangar. I should have left my towbar outside but forgot. When I came back, I noticed that they have torn my wheel pant (cut an half an inch slot at the aft side of the towbar hole). Since I have not painted yet, I decided not to make a big deal. After came home I sanded the area and lay five layers of glass over. Now the damage is fixed.

Master switch - 7/9/2007

Last week when I flew to Indy I noticed once the master did not turn on. Today I flipped the switch and indeed power was not on. Auxiliary master did work though. I checked my wires and did not find any loose connection. Flipped the switch and everything is working. Well, better keep the auxiliary battery there. I hope that I will never be that "lucky" to have both go bad at the same time. I could not find any problem. All wires are fine. This problem has not repeated yet.

Water in the fuel - 7/10/2007

I have had start problem for a while. I checked everything and yet still could not solve it. Today when the cowl is off, I tried to drain the gascolator sump. Wow, it is full of water. After removing the sump and dump the water, the engine seemed to start right away. Luckily my engine did not quit in flight. When I think about it, I did fly in the rain and parked in the rain several times in the past two months. I have not checked the gascolator sump for several months. Water must leaked into the fuel tank through the fuel cap. I better check the sump more frequent.Now engine starts without any problem.

Tire change - 7/26/2007

Since tire rotation at 183 hrs I paid more attention to the tires. I notices that threads on the inside (used to be outside) are almost gone. It makes me feel uneasy. Finally, I decided to replace the tires. I have always carried in my  airplane a nose tire/inner tube and a main tire/inner tube. I also have one main tire/inner tube in the hangar. Now at 214 hrs, I retired both mains. Although the inner tubes are probably still in very good condition, I decided to replace them with the tire. It is a small cost to pay to get a peace of mind. I am not throwing them away. They are perfectly fine for spare. The nose tire looks ok and I keep it on for now. Also, in the future I shall do the 100 hr tire rotation so I can get more even wear on the tire. By doing so I believe I should get more than 400 hrs out of the new tires. Now it is time to buy two main tires.

Condition Inspection - 8/13 to 8/14/2007

This is my first condition inspection. Everything workout well. I opened all access panels and checked inside, lubed whatever needs lub and checked the torque seal of all nuts, cleaned then oiled air filter, cleaned, gaped (0.020"), and rotated all plugs, and did a engine compression test (75, 76, 76, 76, compression at new were 79, 78, 76, 79). Problems found are: poorly crimped right strobe connector and left aileron pushrod binding on the exit hole, fuel line from mechanical fuel pump to the carburetor touching engine mount. All problems fixed.

Nose Wheel and Spacer Rotation Stop - 8/17/2007

A few months ago I built a tail weight using a round plastic dolly and cylindrical cardboard form then poured two bags of 80lb concrete into it. Two days ago when I tried to lift the nose using the weight, instead the weight got lift into the air. Yesterday I brought two more bags of concert and poured a bag and a half onto it. This morning I went to the hangar and now the nose got lifted. I removed front half of the wheel pant and put several 2x4s under the front gear nut. It was very difficult to get the axle bolt out. I had to use a smaller bolt as the punch to punch the axle bolt out. After taking the nose wheel off and checked it, I found the tire is still in the good shape. I removed two bearings and repack them with new grease. Before I put everything back, I put the wheel and axle bolt back on and drilled, countersunk and taped one #8/32 hole each on  the trailing end of the nose wheel folk. The purpose is to secure nose wheel spacers. I read from VAF forum and observed this time that when the wheel turns the spacers turn too. The spacers are not supposed to rotate. The screws I put in stop the spacers from rotating. The screw head is secured by the wheel pant brace.

Update: After I changed to the new nose wheel fork, I did not put the stop on. I didn't really have problem with the nose wheel. What I did before was based on other people's recommendation.

High CHT - 8/21/2007

My TO and climb CHT has been very high. #3 always go beyond 430 degree during climb even at 100 kts. However, it drops down to below 370 degree (depending on the power setting) at cruise. When I look at the engine log during test stand runs, the temperatures were high too. In the past year I just put it aside. In the past few days there are discussion on VAF forum on CHT issue again. I did a search and found the following information from gmcjetpilot:

O-320's are known to run lean in RV's with the free flow airbox and exhaust. The stock MS carbs just don't have enough jet to feed the extra air flow at higher power. There is no screw to adjust, it's the main jet. I can help you with that if you like. Look up the serial # on the carb and write me. Not all MA-4SPA's are the same. The fix is pretty simple. It does require partial dis-assembly (drop the bowl and remove main jet) and a "mod" drilling-out of the main jet slightly. A very common problem and even more common fix. Typical carbs for a Cessna or Piper are not rich enough for RV's. All this is well documented. Precision Airmotive (the owner of the Marvel Schibler carb line) will officially say no, but on the side they know all about it, they just can't "approve it". In the spirit of full disclosure you can trade in your carb for a richer on (if that is the problem), but that fix might cost $1,600. You can get the richest carb they sell and still have issues. Drilling the main jet works and cost about $5-$10 for new clips, washers and gaskets.

Have you done a LEAN test?

At WOT at approx 75% power (8,000 ft approx altitude) you should see at least 100-150F EGT rise from full rich to peak.

On the ground at run-up RPM (1,700-2,100 rpm) slowly lean, note or detect an rpm increase (75-100 rpm) as you lean. If the engine just dies you are too lean. The EGT should also rise about 150F.

At idle engine rpm (say 1000 rpm), you should see RPM rise slightly as you go to cutoff (slowly). EGT will rise as well, say 25-50F.

I went to the airport and flew. During the climb to 3,000 ft #3 maintain at 420 degree. From 3,000 to 6,500 ft #3 temperature increased to 437 degrees. All the time I was doing from 100 kt to 107 kt at a banking climb. I also noticed that as I vary my speed the temperature did not change. At 6,500 ft I saw on my EFIS that the wind speed was 60 kts. I turned downwind and was cruising at 215 kts ground speed (GPS) for a few moment before the wind speed dropped to the 40s. I did the test and did not notice any rpm drop. Upon landing I did the 1,200 rpm test and no rpm rise neither. Now I know that I have a lean carb and need main jet drilling! Tomorrow I am going to file the flashes out from cooling fins around spark plugs. Actually flashes are very small at parting line. I will see whether they really make a difference.

8/22/2007: Today I filed flashes on the cooling fins and drilled the carb main jet to #38 size. Went out to fly at 98 degrees OAT. During the climb out at 87 kts the #3 CHT kept below 380 degrees. After a touch and go, I climb in a turn at 88 kts to 8,500 ft (clouds at 6,000). CHT goes up after 3,000 ft. Eventually, #3 got to 441 degrees. The oil pressure is 79 and temperature 203. I do believe that the enlarged main jet helped. I need to enlarge it more, since I only observe 50 rpm rise during lean out. Some pictures can be found at : Carb pictures.

Checked baffle and I really can not find any more gaps to seal. The temperature during cruise at 65% power is still around 370. Read Tony Bingelis on Engines book and he seems to say it is okay as long as the cruise CHT temperature is between 360-400.

7/15/2008. Only today I read an article on Kelly Aerospace's site. The article warn mechanics not to bore the main jet. Before you increase the jet size, read the article and see what do you think. Of course, it is too late for me. I do see my lower spark plugs get fouled more than before. Well, more aggressive leaning is a solution now. According to Lycoming leaning could be done at any altitude as long as the power is below 75%. Since my engine monitor does display engine power, it is safe for me to do the leaning.

AP problem - 8/22/2007

During my last flight (8/15/2007) I noticed that when I engaged AP, it made a left banking dive. However, on my return flight, the AP worked perfectly. Yesterday I tried AP again and the same thing happened. Today I went up and calibrated AP. Unfortunately, it did not help. I called TruTrak and they said that it must be the gyro problem. I packed up the AP and UPS it over to TruTrak. Well, I have a fly-in to go to this weekend and a three day cross country next week. Hope the repaired AP will be back in a week so I can have AP on the long trip.

8/28/2007: Just received an email from TruTrak customer service inform me of the shipping of my AP. They have replaced the display and all gyros, and updated the software. All these are free!

10/13/2007: On my way to Columbus the AP quite working again. Tried several times over the week and it worked sometimes and not working some other time. On 10/19 I made a >200 nm IFR trip (round trip). I had to fly by hand. This time the AP wanted to make left turn while it is supposed to fly straight and level. At one time I engaged it while straight and level, it started to make shallow bank left turn. I watched it to turn about 270 degrees before it steeper the turn and started to dive. At this point I turned it off. On another occasion, under track mode, I dialed in 130 degree and it flew 150. I finally call TT and talked to several people include Jim (the boss). AP is sent back for more service. Hope they will find the problem.

According to TT the problem was a gyro. They replaced it free of charge. Now AP is working perfectly.

Cap pitot and static lines - 8/22/2007

When I took out the autopilot both pitot and static lines are open. Since I do intend to fly, I need to cap both lines. I dipped the end of the fitting that was screwed into the instrument into releasing agent before dip it into epoxy paste. When it dries overnight the cap seals the fitting pretty well. The beauty is that I can unscrew the epoxy cap when I get my AP back.

Flap Push Rod End Bearing - 8/28/2007

Yesterday I got an email from a 6A builder telling me that he saw my 9A at MERFI on Sunday and found my flap push rod end bearings were installed wrong (see picture below):

When I think about it, it is so clear what the problem was. But I did not catch it over the past 230 hrs. My FSDO inspector did not catch it a year ago neither. I am grateful to Tony for his keen observation. It might have saved my life if one of the rod end bearings fails.
This morning I spent an hour correcting the problem and test flown the airplane. The bearings are still in good shape without any free play. Here is the correct installation:

Since I have to readjust the push rod length to make flap at the up position at the same angle as the wing top surface, I used a bungle cord to hold the flap while reinstall the bolt at the actuator ends.

 

 

 

 

 

 

Transponder Antenna - 9/6/2007

Today while washing the airplane the brush bumped the transponder antenna. To my surprise the antenna shared off from the base. I flew to Rose County airport to buy a replacement for $85 ($91.5 with tax). Such an expensive mistake.

9/21/2007. I did it again. While applying alodine (aluminum prep for painting) using a sponge mop, I broke the antenna again! Have to be more careful in the future. This time I am going to order one over the net and not to pay $91.5 for such a simple antenna. I read Bob's book and I could build one myself. Well, I have already saved a lot of money painting the airplane myself. It is better not to spend the time building an antenna.

Cracked Elevator Skin - 9/20/2007

While preparing the elevator for painting, I find three cracked around the rivet. I suspect they were the result of riveting and not the load stress. I stop drill the crack and applied some epoxy to it. After painting, you can not see the cracks.

 

 

 

 

 

 

Replace Panel Label - 12/12/2007

After 16 months of flying my panel labels are fading. Inkjet produced labels just can not take the beating of UV light from the Sun. The new labels are produced on a Brother Label Writer I brought from Sam's Club. I have used this writer to prepare labels for wires. The labels in the engine compartment still look fresh. I am not sure about how they will take the UV light.

 

 

 

 

 

Brake Pad Replacement - 1/8/2008

After 322 hours (480 landings) and it is time to replace break pads. I purchased rivet squeezer die set for break pad rivets from Avery Tools. Replacement break pads are purchased from Van's. The old brake pad is measured 0.14" that is more than the minimum of 0.1" allowed.Details (including pictures) can be found here.

 

Replacing Auxiliary Battery 1/11/2008

In the past week I noticed that my batteries are always being charged (through amp meter). Yesterday I did a simple test. First I cranked engine using main, it works fine. Then, I cranked it with only aux battery. It did not work (very slow turns). Since I have already purchased a new battery in the Summer, I decided to put it in. After BFR this morning, I removed cowling and replaced the battery. I put it on a trickle charge and will find out whether this solve the problem. A few flights following the auxiliary battery change showed that the new battery is working strong.

1-19-2008. On the trip to Louisville, KY today, I noticed a few things. First, when the master is on, the charge rate is more than 20 amps. It implied that the master battery is very low. I turned mater off and keep it off during the trip. I put it on the trickle charge after got home. I have not figured out what caused the discharge yet. Master battery is always hot for clocks. But, all other devices are turned off. Another problem I noticed is the momentary low EFIS bus voltage. EIS voltage seems to be around 14.1 to 14.4 volt (depending on whether mater is being charged or not).

After trickle charged the battery for two days, on my 1/21/2008 flight the battery looks normal. I took the auxiliary battery I replaced home. After a few days I measure its voltage and it is 12.78 volt. According to the battery manual, it is still in a good shape. Now I really need to figure out where do I have a leak (small drain of current).
Finally I determined that there is no leak. Old battery is still keeping the charge after I placed it in my study for a month. The high charge current on board must be due to the error of using E-bus alternative feed.

Carb Temperature Sensor (1/26/2008)

I have been puzzled by my carb temperature. Before engine start, it shows the OAT. However as soon as engine starts, it temperature began to raise. In a few minutes it stopped at 127 degree. When OAT is below 30 degree, it does not reach 127 degree. Early on I talked to Sandy at GRT (my EIS vendor) and she sent me another sensor. The end result is exact the same. I settle with what I have. Recently there is a discussion on where to install carb sensor on VAF. I showed my pictures and mentioned the problem. Someone said that 127 degree is just wrong. Well, today I found my old sensor and did a simple test. I basically connected the output of the sensor to a ohm meter and heat the sensor body up. The resistance value reduces when the sensor is heated. Well, that pretty much proved that the sensor is measuring the carb body temperature. The venturi where carb ice may form is a distance from the sensor and the temperature may differ. One really can not rely on the sensor reading to prevent carb ice.




This is the upper half of the carb body.

Flat Nose Wheel - 1-30-2008

On Monday morning I practiced Cub J3 (I have no taildragger endorsement) with an instructor. upon the second landing the right main went flat and the airplane got stuck on the runway. After getting the airplane back to the hangar (use a dolly and a pick up truck), I flew my RV to Mason County, WV to take Larry to Parkersburg for lunch (engine of Larry's 7A has been in shop for three months). When I returned, the airplane was fine. However, on Wednesday when my son called me to pick him up from Louisville, KY, I found my nose wheel was flat. After pumped air in it, it kept the pressure for a while. I flew to Louisville and back without any problem. On Thursday noon when we arrived at the hangar the tire was flat again. This time I decided to replace it. It turns out the nose tire is much more difficult to change. I had a hard time to get the rims off the tire. Finally took it to the FBO and used their tool to press the tire down to pop the rims. Actually we tried several times before the rims popped out. Since we had to fly to Detroit for David's residency interview, we did not spend much time to investigate what's wrong with the tire. The outside of the tire looks fine. I always keep the nose wheel in the air until I am about the turn off the runway, it does not get to wear much. It must be the inner tub that started to leak. This is after 334 hrs of fly time.
After a while, I took the old nose wheel home dip it in a tank of water. No leak! It must be the valve stem that was leaking. After tightening it before changing the tire, the leaking has stopped. Well, I am keeping the old tire and tube since they are still in good shape.

Rudder Damage - 5-1-2008

This morning I flew to Clark County Airport just north of Louisville. At 4,500' the strongest headwind I encountered was 44 kts. On the trip there above 4,000' the air was smooth. Down below it was bumpy and gusting. After parked my airplane, tied it down, and inserted my homemade rudder lock (1/8" stainless steel rod) I left for lunch. Upon returning, I notice that the 1/8" rod was totally bent and rudder horn hit rudder stop hard to leave some surface damage. The worst thing is that the low trailing edge of the rudder popped open (rivet shop heads pulled through skin). Check METAR over at KLOU, the wind gust was around 33 kts. I need to fix the tailing edge and device a stronger rudder lock.

After flying with the repaired rudder I decided to build a new one. A rudder kit was purchased from Vans and built over a two week period. I ordered a quart of yellow and a quart of blue paints and painted the rudder before installed it on the airplane. On November 3, 2008, I installed the rudder and test fly it. At 3,000', full throttle, the ball moved to the left by half a ball. At 10,200' the ball actually is not much to the left. For now I will leave the trim off.

 

Bleed Brake - 8-5-2008

After 420 hrs I noticed some air in the brake line (although there is no performance change). Since the air are upstream from the pilot side master cylinders, brake performance has not been affected. Today, during condition inspection, I decided to bleed the brakes. See more details at this page. After I bleed the brakes segments of the tube still looks like to have air. After careful inspection, it really was due to the light reflection. I did not have air in the tube after all. However, my reservior is a little low. I don't regret the trouble. At least it assure me my brake lines are fine.

2nd Condition Inspection - 8-12-2008

Over the past two weeks I have been doing three tasks: 2nd condition inspection, installing Lightspeed Plasma III electronic ignition, comply to nose gear mod. Finally, they are all done except the fitting and repainting of nose wheel pant. In the 2nd condition inspection other than bleed the brake, I did not find any squawks. The engine compression even improved from 76 to 78 (two cylinders). The other two cylinders kept the 76 from last year. I also took the opportunity to organize wires for APRS and Anywhere Map. Now the only instrument on the dashboard is MRX PCAS. I installed black simulated leather on the dashboard. It reduces glare, however, increases heat absorption. For nose gear mod, I sent my gear leg to LangAir a little more than two weeks ago (it takes one full week for UPS to ship it one way). Finally I got it back (with the help of a friend working at UPS) in the morning. It took me about two hours to put it back on, install new fork, torque all bolts, drill cotter pin hole, install wheel, then, test run engine (for the new EI), adjust idle and idle mixture, and put cowling and spinner back. I was surprised how fast I was able to get everything done. Afterward, I took the airplane out for a test flight. EI really make engine run strong.

EFIS Slow to Boot - 10-1-2008

Recently I noticed that my EFIS 1 is booting much slower than EFIS 2. Sometimes it took a few minutes to boot up. Finally I called Mark at GRT to report the problem. He indicated it might be the voltage problem and advise me to swap two EFISs first, if it did not clear up the problem, send it to him and he will take care of it. Swapping did not make any difference, so I send the unit to him. As soon as he received it, Mark called me and told me that it was the compact flash card problem. In GRT Horizon 1, a compact flash interface and a memory card are installed by the user for the terrain option. The compact flash card I recycled from my old digital camera that is in the EFIS went bad. Well, it is time to get a new card. I am glad that I purchased the GRT product. So far their service has been top notch!

Oil Pressure Valve Spring - 12-18-2008

During takeoff my oil pressure is always beyond 90 psi. During high power cruise it is close to 90 psi and sometime even higher than 90 psi. During the first winter operature my engine had a nose oil leak. I suspect it is caused by the high oil pressure. I have ready turned the screw on the oil pressure valve all the way out. The next step is to replace the spring in the valve. According to my engine record, the spring installed is LW-11713 (yellow). I verified it by taking the valve off. I ordered a new spring one size down (#61084 black) from A.E.R.O. for $5.13 (plus $4.97 shipping). This morning I replaced the spring. Unfortunately today is an IFR day and I am not able to flight test the new spring. The ground run showed lower oil pressure.

Light Speed Electronic Ignition Problem - 12-30-2008

Since I installed Light Speed electronic ignition it has worked well until today. When I did my run up on the LightSpeed side, the engine run rough and even misfire. I was on my way back from a short cross country and decided to turn EI off and fly with magneto only. I noticed that EGT of #3 cylinder is 300 degrees F higher than #2 and 150 degree higher than #4. CHT of #3 is 45 degrees higher than #2. However it is about the same as #1 and #4. After arrived home I checked the ignition and found that the ignition wire has fallen off the spark plug. After plug back on the engine run smoothly. LightSpeed uses auto plug and it is not as secure as aviation plug. One more thing to check in the future.

Engine Control Bracket - 1/2009

For a long time I have been puzzled by the short control cables. When I installed my control cables all of them were very tight. It is not until today when I read the January 2009 issue of Van's RVator newsletter I found the reason. Following is a quote from Kent Scott:

Occasionally, we’ll get calls from builders saying that the throttle and mixture cables supplied in their firewall forward kits are too short. This has puzzled us, since we’ve — and the majority of builders — seem to use them without problem. Sharp eyed Gus Funnell spotted one possible reason on the photo below. As you can see from the plans insert below, the F-746 Aft is shown with the vertical face an inch or more behind the instrument panel. In the photo the builder has chosen to mount it flush with the face of the panel. That looks good, and structurally it should be fine, but it does stick the throttle/mixture/prop cables farther back into the cockpit, and could easily change the length of cable(s) required. It might also interfere with full stick travel. Just another example of the ripple effect caused by seemingly small changes.

Yes, I did just that. My engine control bracket is flush with the panel. Next time when I go to the airport I will add another flat piece of aluminum plate to extend the bottom of the instrument panel backward and mount the engine control bracket one inch behind of the instrument panel.

2-5-2009. I fixed the control bracket problem last week and found now my throttle knob won't go all the way in. It has too much throw! Since the weather has been bad (snow and ice storms, single digit temperature, etc.) I have not been to the airport to work on the throttle control. This afternoon the temperature was in the 20s, I brave the cold (no heat in the hargar) to do some work on the airplane. I detached the throttle cable from the throttle arm and tried outer holes. I found when using the outer most hole, the cable throw is not enough. Thus I reattached the cable to the middle hole. Now, when full throttle there is still a little on the throttle knob.

Condition Inspection - 8-2009

This is the end of 3rd year condition inspection (annual). The hobbs time is 640 hrs. So far it seems the airplane has less and less problems (squawks). By now I have opened all wings inspection plates and wing tips. All bearing surfaces have been lubricated. Engine compression test was done a month ago, all four are 76-78 out of 80. Fuel filter screen looks clean. Nose wheel still looks new. Bearings are repacked with new grease. Main tires rotated and bearings repacked. Brake pads have 1.2" left. The pad limit is 0.1", however, I don't check pad all the time, it is better to replace it now. Check the record and found this set of pads lasted almost the same as last set: 320 hrs and 477 landings. So far the major problem encountered is a striped AN3 bolt that holds the airbox to the carburetor. It took some effect to get it out. The nutplate is still good and only the bolt is striped. I did torque all the bolts to 25 in-lb. Don't know why this one got striped. Air filter is out and cleaned. The rest of the plane are in excellent condition. The interior looks just like it was when I built it. I did lubricated everything. I am not satisfied with the painting of my replacement rudder, so I take it down and repainted the yellow. While doing it, I repainted the front part of the nose wheel pant. On my Oshkosh trip I flew through heavy rain, there are several small spots of paint chipped off. They are all touched up. I also put threads on rudder lock so I can secure it to the rudder and rudder stop. I definitely don't want it to slip out. One problem that will require a little more work is the fuel vent line join. It was the first flair I did and I did not do it right. It leaks! When the fuel expanses in the tank, it gets push up through vent line. Instead of getting pushed down the vent inlet, it will leak a little in the fuslage. Of course this happens only when the airplane is parked. As soon as it is moving the air is pushing the fuel back into the tank and there is no leak. I put in some fuel lub around and hope it will stop this little leak.

Nose Wheel Pant Repair - 8-25-2009

During our trip to Washington DC, the nose wheel hit a step on the ramp (why is the ramp not level?). The front part of the nose wheel pant hit the step and the rest was pushed up and got shattered by the nose gear end nut. Here are pictures of my repair (click to enlarge).

Cylinder AD and Spark Plug Hole Damage - 1-16-2010

All four of my ECI Titan cylinders are on the AD 2009-26-12 Amendment 39-16151. They are in Group A that requires 50 hr compression test and visual inspection. First test must be done before the next flight. On Saturday I went to the airport to do the inspection. Unfortunately by the time I was putting in the spark plug extension (for Light Speed EI) on upper plug of cylinder #1 I found it won't go in. I knew that earlier on (2 years ago) one time I put the plug in at an angle and damaged the thread. It has been difficult to align the plug and put it in. However, this time the extension just want sit on the thread. I tried chip chaser then an old 18mm plug. Both chip chaser and 18mm plug will go in but after a turn or so it was very hard to turn. I forced a little before backing the plug out. After a few tried I noticed a chip on the plug hole. I was concerned and decided to use a plier to break the chip off. While doing that the chip grew longer and I realized it is an insert. I must pulled 1/4" of the insert off the hole. Not being an expert on engine I went asking people at the airport about this. None of them had any idea. Coming home I immediately did a Google search and found on "http://www.sacskyranch.com/lycoming.htm" a description of special Helicoil for aircraft engine. Then I found it is a serrated kind (match the coil in the photo I took). The coil costs $8 but the special tool costs $1,160 (Aircraft Tool Supply Company)! Initially I thought I need to replace the coil so I searched for rental tools. Unfortunately I was not able to find any. The next thought was to take the cylinder off and ship it to an engine shop for repair. After posting on VAF Forum and advised by a few people I decided to cut the damaged part of the coil off. This morning (1-19-2010) I went to the airport and did just that. Cut off less than 1/2 of a thread. After tapping it with a 18mm tap the thread is fixed. A few lessens learned:

a. Don't force in any screw or plug. If you can not hand rotate the plug in a few turns it is crooked!

b. Always clean up the old antiseize on the plug thread before applying new one. Once in awhile clean the plug hole too.

c. Before cutting the coil off, use a rag to plug the hole. Vacuum the chips off before removing the rag.

d. Use a 90degree attachment of a Dremel tool and worn cut off disk to cut the coil.

e. When use the tap on the plug hole thread apply generously grease over the tap to attract chips to the tap.

ECI SB09-3 - 2-4-2010

I was not aware of the the ECI SB09-3 that was published on 1-25-2010 until last night. Basically it is a solution for the Titan cylinder AD 2009-26-12. If cylinders are shipped back to ECI, they will rework the cylinder and resolve the problem. ECI has not received FAA approval yet, so they offer the solution only to experimental market. As soon as FAA approves, they are going to be flooded with rework orders. Definitely I don't want to continue to do he inspection/compression test and worry whether my cylinder head is going to explode. I am going to bit the bullet and remove all four cylinders and ship them in. It means my airplane will be down for four to five weeks!

I finally received RMA back from ECI. Now it will take 4-6 weeks factory time to get the rework done. Their work must be piling up! On Friday 2/5/2010 I went to the airport and spent 6 hours straight to pull all four cylinders and ship them to ECI.

Since I sent my cylinders in ECI stopped returning my emails. Eventually on March 18th they sent me a "Sales Order" acknowledging the receipt of my cylinders and estimates to deliver on April 17th. Only today (April 23) I read a new release on VAF frontpage from ECI. It stated that since April 21st they have been finishing 3 sets of cylinders each day. They still have 63 cylinders to finish and expect to finish them all by May 15th. It is hard for me to believe, 1. only 69 cylinder sets (out of 18,000 affected) were sent in for rework. 2. They did not work out the manufacturing process until April 21st and they issued mandatory rework service bulletin on January 25th. Also, during this time the customer service is very poor. Although I still believe they have a good product but I don't want to go through this kind of problem again (poor planning and poor costumer service).

On April 28th I got a phone call from ECi telling me that all four of my cylinders are bad and they are sending me four new ones for free. Upon returning from a trip I received four boxes on May 5. I went to the airport and spent two days installing four cylinders and the rest of the "stuff" back on. Two three min run-in was successful. We are going out of the town for the weekend and will do my test flight on Monday.

Flat Nose Tire - 5-30-2010

This Memorial Weekend we travel to Georgia and Florida to visit friends. At Green County Airport, Georgia I gave a ride to our friend. When I lowered the nose wheel down after landing I heard grinding noise. Since I always lower down nose close to the turn off it did not take long until I was off the runway. I stopped and got out. The nose was flat and the airplane is riding on the wheel pant. Fortunately I do carry inner tubes for both nose and main wheels. After line men at FBO helped me towing the airplane to a big hangar I got the wheel removed. It was very hard to split the two halves of the wheel. Thye don't have a bead breaker and we had to use a vise and a wide pray bar (very carefully). Upon removal I found a 1/8" slit on the tube. The tire treads are still in good shape but the side wall has been wrinkled. I will change the tire after coming home and the spare inner tube saved the day. The tube lasted 776 hrs.

Another Damaged Rudder Gust Lock (6-20-2010)

When return from a trip while parked outside at Linden Airport for five days I found my rudder gust lock got twisted again. Two years ago the 1/8" gust lock was damaged and I replaced it with a 3/16" gust lock. Unfortunately it got damaged again. However, this time the trailing edge of the rudder did not pop open. I am not sure whether the damage was caused by strong wind from thunderstorm or prop wash from all those helicopters at Linden Airport. Time to think of some other solutions to rudder gust lock.

Magnetometer Failure (6-20-2010)

After 700 hrs operation magnetometer failed. Fortunately I have backup AP and turn and bank. There was no problem flying VFR back from a X-country trip. Time to get it replaced. Sent magnetometer to Mark Allen at GRT.

6-28-2010. Just talked to him while he bench tested the magnetometer. It turned out it is bad. Mark is sending a new unit to me free of charge.

7-2-2010. Replacement magnetometer installed and it works properly.

Cap screw holes on nose wheel fork (7-2-2010)

Since the nose wheel fork is made of aluminum and the screw steel. After a while the screw hole got damaged. It became hard to hold the screw in. I order a 3/8" dia 1/2" long Heli-coil kit for the fixing the internal thread of the hole. Heli-coil is made of stainless steel and it should hold up for the abuse of the steel screw. After I installed the Heli-coil and decided to install it to my RV10 nose wheel fork too. It is an investment well spent.

A few pictures of installing Heli-coils on RV10 fork. First picture starts here: click here.

Replacing starter (8-5-2010)

A few weeks ago when I tried to start the engine the starter just made click sound without turning. I tried a few times and finally it started to turn. The problem repeated another time a few days later. Since I have the light weight Sky-Tec PM starter, it needs very high current load at start I figure my battery must be too old to provide the starting current. After replacing the battery the problem solved. Since after the first Winter my engine always take two or three tries to start. I tried everything and have not been able to solve this problem. After some research I decided to replace the starter to the NL model. Yesterday I received my new starter from Sky-Tec. It took me an hour to get the cowl off and starter replaced. With the new starter the engine starts after a few turns. I will continue to observe and see how it performs.

The new starter cranks well, however, it still take a few tries to get engine started. Now I have to conclude that my starting problem is due to the carburetter instead of the starter. I am going to put the old starter back and mount the NL starter to my RV10.

Replace Starter Relay (1-15-2011)

Recently several times when I tried to start the engine the starter contact did not engage (starter relay click yet there was no current passing through). After a few tries the contact inside the relay finally engage and starter turned. I ordered a new starter relay from Van's and installed it. I did put a diode on the starter relay and did not expect the contact to wear out so quickly (total hobbs time: 877 hrs).

Upon closer inspection I found the Hall effect current sensor must be hitting the starter relay. The sensor is installed on a fat cable connecting the input side of the starter relay (also the output side of the main and aux relay). It is a ring type (about 1.5" dia) sensor over the cable. Due to the wire routing it is very close to the starter relay. A small section of the ring is missing. Since it is hard to relocate the sensor I am going to put some RTV between the sensor and the relay to hold it in place.

Fix the Crack Left Step (9-19-2011)

I have heard a lot of cracked steps yet thought my steps are fine. A month ago while attending a fly-in another RV9A driver mentioned that it took him 10 hours to replace his left step I told him how lucky I was not having a cracked step (two years ago at another fly-in my steps were inspected by a few other RV drivers). He offered to check the steps. Knowing-behold, he found a big crack on my left step just below the root weldment. It cracked though half of the circumference of the tube. Finally, today I got Kyle, a local expert, to weld the crack. He used a TIG welder and made beautiful weld. Before the weld he mentioned that people said welding will burn diodes in the alternator. I also heard from airplane people that welding will damage avionics and may even cause fire. Now knowing much about TIG welder I tried to learn a little about the equipment. It turns out we were using reverse polarity DC to weld the steel step. Current only flow through a short segment of the step. I did not see any signal strong enough to damage systems a few feet away. It turned out everything was fine after welding.