First flight / Phase 1 issues

So I am about 60% of the way through with the hours and items on my phase one test program. Several issues have been exposed during this time and it would be great to have a Thread or Category for listing of these and how they were dealt with or solved.

Such as, I need a rudder trim on my 7-A because the ball is out of center when everything is trimmed for level flight. I also know it is crabbing slightly because I can't fly a straight line without rudder input. This is a simple one but what is the process to fix it? I know people add trim tabs but what is the process for attaching, positioning, etc? (I ordered a piecs from Avory and hopefully it will come with some directions)

Next:
-Why do my fuel tanks take so long to fill the last 3 or 4 gallons?
-My SL30 is full of static but the VOR works. Just the com side is out. Is this an antenna problem?
-My TT autopilot doesn't want to plan nice. I checked all the values against the book but what are others experiencing?
-I've lost about 50 RPM on my prop compaired to when it was first flown. The only thing that has changed is the OAT is about 30 degrees hotter?

You get the point. Is there a clearing house for phase one questions?

I can answer the trim tab question....

What I did was to take the Avery plastic trim tab and duct tape it to my rudder. (left side in my case as I needed right rudder trim)

I wanted the ball to be centered at 155 kts (my typical cruise speed), so I just incrementally cut down the trim tab until the ball was centered at that speed. If I go faster, the ball moves a slight amount to the left, slower and it goes to the right, but at 155 kts its dead nuts centered.

Once I had it the correct size, I attached it with some 3M heavy duty exterior double sided tape. Its been on the plane now for several months and seems to be very firmly attached.

Good luck with the rest of your issues.

Jason

Since there are no other replies, I'll give it a shot on these issues. I can't speak to the thread idea.

On the trim, I like having an electric rudder trim. From what I have heard, most people just do a trial and error with the wedge. Put it on, see if it's better, not quite enough, too much, and go from there.

On the fuel tanks, on the -10 they have holes in the top rear corners of the ribs that are about 1" in diameter. If yours doesn't have these holes or if they're too small, that might make the last couple of gallons fill slower. Other than that, I've never seen that problem.

Does the SL-30 give a lot of static on transmit and receive, or just one or the other? If one is clear, then your antenna is probably fine. It also could be a short in the antenna cable. Disconnect both ends and check for continuity (short) between the center pin and the shield, then check continuity between the center pin on both ends and the shield on both ends. It is not hard to get a bad crimp that shorts the cable out. If it is only transmit or receive that has static, then you probably have a short in one of the pins between the audio panel and the radio, or, if you only have one radio, a short anywhere between the headset jacks and the radio. Also, make sure your jacks are isolated from ground where they mount. They should have little plastic shouldered washers that isolate them in the hole.

We need more detail on the Auto Pilot to be able to help. You could have a wire wrong or something like that. If settings are off, it will just be too twitchy or too lazy. You need to make sure you're getting good information from the control source.

I wouldn't be surprised if you lose some power with an additional 30 degrees, which would reflect in RPM, especially if you are fixed pitch.

Thanks Jason,

That's exactly the type of information I'm talking about. Very helpful but not necessarly easy to find in a search. We need a clearing house for this information.

Paul

Double sided tape works good for the trim wedge, although I just looked at one that had a piece of duct tape over it. Its been on there for 20 hours. Check your prop cable for full travel, of course. Has oil pressure changed?

Paul K said:

I need a rudder trim on my 7-A because the ball is out of center when everything is trimmed for level flight.

Click to expand...

So I've never understood the need for trim tabs to correct this. On my 9A I was able to easily steer left and right with the gear fairings. You can simply put a little bit of turn in to the main gear fairings and it easily corrected for my 1 width ball offset. Not sure if that's the most efficient, but it was easy and didn't require anything attached to the airframe.

Thanks Jesse,

The issues I put out there are just a sampleing of some if the information I am looking for. What Im really trying to do is get a dedicated Thread started if possible to make is easier to find good information such as your SL-30 suggestions. (I didn't of checking the crimps)

The Auto Pilot is really puzzling me. I follow all of the directions in the manual and it still has a mind of it's own! For example, When I engage it in the alt hold mode, it holds for about 30 seconds and then goes into a very steep climb! Doesn't seem to make any difference how anything is set up or what altitude and speed I am at or what the Garmin or GRT's are set at or even turned on. Everything indicates per the manual that all is correct until about 30 seconds after it is engaged. Tried everything in the book! I havn't called TT yet but when I have time and if I can't solve this, I may have to.

I have alots of other less important questions about stuff in general but mostly I'm just making a lot of adjustments and calibrations. The airframe is proving to be very solid.

Paul

Phase 1 findings

You are experiencing exactly why Phase 1 exists, and the "tweaks" you are making along the way will result in the Phase 2 being a reliable, trimmed completed aircraft. The trim often takes a few tries as others have also commented on. The fueling issue is fairly normal with my -4 also, as the baffle holes only allow so much fuel transfer between ribs. You wouldnt notice it if you fueled with 5 gallon cans as I often do, but the pumps have very high volume. You will likely find a lot of advise on this site for most of your quirks, and I will bet the last 20 hrs. of your Phase 1 will seem mundane..just enjoy it!

On the auto pilot, one thing that comes to mind is the possibility of having the pitot and static lines switched on the back. I don't know that this would happen, but if it goes into a climb when in altitude hold mode, then it sounds like it is having a static pressure problem. I realize you said it's having other issues as well.

When I run into something weird like this, I try to find a way to establish where the problem may be, whether the installation or the unit. I try to find someone with a known good installation and put my unit in there to test, or find someone with a known good unit and put it in my installation to test. That will narrow down the problem to the installation or the unit very accurately, so you will know if your unit needs to go back to TruTrak or if you have wires crossed somewhere.

It is also possible that you have your pitch reversed, so if it is trying to descend, it climbs, then it tries to descend harder and in turn climbs harder, and so on. Ground checks should be able to determine if this is the case. Just turn on the auto pilot on the ground and tell if to roll left and see if the stick moves to the left. Tell it to climb and see if the stick pulls back.

As far as a clearing house thread, there are so many different issues that people run across, that trying to organize something like that would be very difficult. There are threads for specific EFIS systems and so on, but for the stuff that you are talking about, doing it this way is a good way to go, IMHO.

Paul K said:

... I need a rudder trim on my 7-A because the ball is out of center when everything is trimmed for level flight.

Click to expand...

We used a short piece of the aluminum wedge ( ) and taped it to the trailing edge of the rudder with aluminum tape. After verifying the correct length ... removed a couple of rivets, match drilled it, then riveted it in place.

Small, effective, and blends right in.
Works like a champ.

So I've never understood the need for trim tabs to correct this. On my 9A I was able to easily steer left and right with the gear fairings. You can simply put a little bit of turn in to the main gear fairings and it easily corrected for my 1 width ball offset

Click to expand...

100% agree. My RV-7 flew great with no gear fairings, put them on had the ball about 1/2 out of center. Just adjusting the gear fairings brought it right back in.

Gear leg fairings provide perfect control over the rudder trim.

Thx

Great information! Looks like I have a lot to do this weekend.

I talked to Todd at American Propeller / Ameritech Industries and discussed whats going on and will make some ground test confrimations followed by some possible gov adjustments. The linkage is all correct etc.

I am barrowing a working AL-30 from another plane on the field and will do a switch to see if the issue is in the unit or external before I go digging.

Looking at the 7 from a distance, looks like one of the gear fairings may have a little twist in it Will be looking at it this weekend. I have to admit though that the plane flys the same with or without the pants on. However, I didn't test it without the gear fairings OK, by bad!

The installation of the AP will get a good look at with attention to checking the Pitot / Static connections.

I have much apprecitation and respect for the contributors in this forum, just having this large of an experanced pool of talented builders/pilots is an asset that can't be purchased. Thanks all.

Try adjusting the left mainwheel fairing first.
The prop slipstream will mainly hit that one.

My -7 flew straight during phase 1 with fairings off.
When installing the fairings later on, we made sure we installed them straight too.

To my surprise we found that the ball was out one width during cruise.
Then somebody told me why: it works like a rudder when the engine is running.

All it took was to adjust the TE of the left fairing one (!) centimeter and then the plane flew straight again.

ao.frog said:

My -7 flew straight during phase 1 with fairings off.
When installing the fairings later on, we made sure we installed them straight too.
To my surprise we found that the ball was out one width during cruise.

Click to expand...

So .... we were 1/4-1/2 a ball off with out the fairings...
Still .... 1/4-1/2 a ball off with the fairings...

Must have got the fairings on stright

Rudder Trim

Ditto to the comments about trim changes when the gear fairings are installed. I flew without gear fairings for the first 10 hours. Centered ball at 140 KIAS. With gear fairings on about 1/2 ball out to the left. After a lot of tweaking on the gear fairings I got it to nearly centered. Instead of Avery I went to the local hobby shop and bought a balsa wedge. I started with a piece 6 inches long and have trimmed it down to 3.5 inches. Centered ball again at 140.

Dave
Phase I complete

Gas.
Mine fills slow at the end. I think it is not as slow as I have heard the tail draggers are due to postion of the holes in the ribs and craft attitude.

Trim.
As previusly suggested, remove the gear fairings and fly it. If it is out, you have a rigging issue. It might be fixed via gear leg fairing install. This is speculation on my part. I was lucky to get both conditions straight but I imagine the gear fairing will have considerable influence.

Autopilot.
Please let us know if the AP is still in alt hold mode during the aberrant climb or whether it has simply tripped out. It will do so if the elevator trim is still in a climb setting and you level out, hit the AP button, and expect level flight. Trim it level and then turn on the AP. This happened to me once before I learned.

which fairing?

just to clarify; wouldn't the nose gear fairing have a LOT more effect on the trim than the mains? basically, it's a rudder, at the front!
I agree that truing them up would have a significant effect, with the observation that one might be more critical than the other in the propwash.

a question; if in level cruise, my elevator trim is slightly nose down, and thus the balance horns are up in the slipstream, should I re-adjust the incidence of the stabilizer?...or am I going to end up with the same net effect within a few %???

all this might explain why some otherwise 'identical' RV's are faster than others eh?

On the auto pilot, one thing that comes to mind is the possibility of having the pitot and static lines switched on the back. I don't know that this would happen, but if it goes into a climb when in altitude hold mode, then it sounds like it is having a static pressure problem. I realize you said it's having other issues as well.

When I run into something weird like this, I try to find a way to establish where the problem may be, whether the installation or the unit. I try to find someone with a known good installation and put my unit in there to test, or find someone with a known good unit and put it in my installation to test. That will narrow down the problem to the installation or the unit very accurately, so you will know if your unit needs to go back to TruTrak or if you have wires crossed somewhere.

It is also possible that you have your pitch reversed, so if it is trying to descend, it climbs, then it tries to descend harder and in turn climbs harder, and so on. Ground checks should be able to determine if this is the case. Just turn on the auto pilot on the ground and tell if to roll left and see if the stick moves to the left. Tell it to climb and see if the stick pulls back.

As far as a clearing house thread, there are so many different issues that people run across, that trying to organize something like that would be very difficult. There are threads for specific EFIS systems and so on, but for the stuff that you are talking about, doing it this way is a good way to go, IMHO.

Jesse said:

It is also possible that you have your pitch reversed, so if it is trying to descend, it climbs, then it tries to descend harder and in turn climbs harder, and so on. Ground checks should be able to determine if this is the case. Just turn on the auto pilot on the ground and tell if to roll left and see if the stick moves to the left. Tell it to climb and see if the stick pulls back.

Click to expand...

This is what I think you have going on and is a common thing. You can easily check the servo direction by using either the vertical speed function on the autopilot or simply by engaging the altitude hold on the ground and pushing the tail of the aircraft down. The elevator should move down with the tail. If it moves up, it's backwards. Just use the pitch servo reversal circuit on the back of the autopilot. Let me know if you have any questions. Thanks!

Perry: I have a taildragger so no nosewheel fairing here... but your comment makes sense though: the nosewheel fairing must have a rather large effect. Anyone having an A can comment this?

Jesse and Lucas,

That sure describes what it's doing! It's down for a few days due to weather and an oil change / inspection. I,ll do the ground test suggested and let you know.

Thanks

ao.frog said:

Perry: I have a taildragger so no nosewheel fairing here... but your comment makes sense though: the nosewheel fairing must have a rather large effect. Anyone having an A can comment this?

Click to expand...

I offset the nose gear leg fairing to center the ball at cruise. Works great but a number of people on the list felt I was introducing too much yaw instability. My stability tests indicate that I have a very stable plane in yaw. I am happy but you need to convince yourself that offsetting the nose gear fairing doesn't create a yaw stability problem.

I had a bunch of noise on my SL30, I heard very little noise but got a lot of complaints about static on transmit. Tracked it down to the tach lines between the ACS ignition switch and engine module. Moved the wires, better. Shielded wires, noise gone.

I think you're far better off adjusting the yaw by by adding a wedge to the rudder than you are using the gear leg fairings to compensate. The rudder has a lot more leverage than the gear leg fairings do and a small amount of deviation in the rudder has a big effect - with a lot less added drag.