Adding Electric Trim post build

I'm sure many, many others have done this but it's a new project for me. I am the second owner of RV7A 523RM. I want to convert it from manual trim to electric trim and use a "coolie hat" trim button grip with mic, a/p and possibly trim speed switch. I currently have a TruTrack a/p Vision 385 installed.

1. What stick grip works best? I am thinking about the Ray Allen G307.

2. How difficult is is to install electric elevator and aileron trim?

3. Are the Van's trim system kits my best and most economical choice?

4. What about the Safety Trim system on page 55 of the Van's accessories catalog. If I want electric trim on both pilot and copilot sticks is that a good unit to use?

5. Does anyone know of a U-tube video showing how to install this?

6. I want to have trim position indicators, again any thoughts would be appreciated.

7. Does anyone know whether the TruTrack a/p can utilize electric trim during coupled operations?

I guarantee there are no YouTube videos showing this.

Likely require modification to the trim tab control horn. Will require removal of manual trim cable and installation of trim servo in elevator. Power and ground wires to servo, fuse, communication wire to servo/AP/efis. Wiring to stick grip. The Ray Allen grips work well and there are some very tiny wires to solder inside there.

this type of change would be pretty simple for the original builder to perform, or one of our resident RV avionics specialists, but to research and complete yourself..... Would take some time, I'd bet you'd have 60-100 hours into it starting from scratch. So unless you like that sort of thing I'd fly it as is or hire it out. Ymmv.

Why? Will it be better?

I am building with electric, but trained with Mike S with manual trim. It was so nice to just grab that knob and twist it three times in the landing sequence. No time to dial it in. I was reminded that IMC training in a 182 was the same, don't "trim" just adjust it the same offset and it is very close. Just fixed amounts for TO-to-climb, cruise-to-pattern, 1/2 flaps, full flaps. Especially helpful for missed approach. OK, maybe not in a light controlled RV, but a throttle off full flap descent to full power ascent in a 182 is a LOT of control force.

How do you electric trimmers get that perfect trim quickly for the transitions of flaps? Black Box? Feel? Time - one - - - - two - - ??

I went from manual to electric on my RV9 and it wasn't difficult. Order the parts from Vans. The kits and installation are fairly straight forward. Use the search function on this site for some installation pictures. I used the manual trim tab arm and it works fine. You will need grips, indicators, and a controller that slows the trim speed down as you go faster.
Everyone has an opinion about trim preference. All of my previous planes had manual trim and they all worked well. I wanted the use of auto trim with my Dynon system so I made the conversion for that reason only. The auto trim works well but it was a lot of work just to achieve the auto trim. Also if you are away from home and have a servo fail you may not be able to safely fly the plane back home to make the repair as the elevator pressure might be too much to overcome on a long flight.

Response from TP75

"fly as is" is not going to happen much longer. I've experienced two occasions where the nut cap at the base of the trim knob that connects the cable to the knob control has come unscrewed and caused full nose up trim in flight (something that can only be addressed after landing due to two hands required for aircraft control). Manual trim is going to go!

I will examin the trim tab horn to see if modification or replacement is required. I do enjoy working on the plane (sort of) and already have had to do major work on the flight control system to correct mis-aligned elevators, incorrectly rigged ailerons due to the elevator problem, adding two wires between my two G430's so they could "cross fill" each other, moving two magnometers to avoid communication interference with the heading system because of original misplacement near the comm antenna, and a whole host of other build issues that needed "improvements." Just because I am not the original builder (or have ever built an airplane) does not mean I should not tackle issues that need to be addressed. People who buy used RV's often buy them because of the freedom to "work on them".

I appreciate your wise cautionary statement but changing to electric trim is going to happen! If folks will address the questions I ask I would appreciate it.

I can certainly understand the concern that your issue would cause, however this is something that I have never heard of happening on all of the other RV's flying with manual trim (a lot). This would lead me to suspect there is some type of problem or failure with your particular installation and hardware, and I am betting that fixing it would be much easier than changing to electric trim. Have you had a local RV-guru take a look at it? Sometimes without having seen a proper installation, it's impossible to notice an improper one. Perhaps you just have a defective vernier cable assembly.

Also, going to electric trim does not reduce the risk of any problems, in fact there seem to be many more instances of electric trim issues than manual. Any time you add more wires and electronics and tiny switches, there are opportunities for more failure modes. The manual trim is generally a simple, robust, design.

Just my $.02 but the simplest solutions are usually the easiest and best...

Chris

I agree with Chris. Something isn't right with your trim knob/mechanism. Thousands flying and this has never been reported to my knowledge.

My setup includes pitch/roll trim with Infinity grips, which have several buttons and the trim hat. I had previously purchased a speed switch but opted, since I was already all Dynon, to go with their AP button panel, which handles the speed control and adds other safety features.

I have only owned a Cherokee 140 that only had pitch trim on the ceiling via old window knob. I would not want to go back to that setup or anything like it.

You can purchase the trim servo kits from Vans or directly from Ray Allen's site (they are the same kit). The pitch trim was already installed on my emp by the previous builder. I installed the roll setup, which took a couple days, if I recall. The Ray Allen indicators are known to be problematic (led failures) and many find they do not use them, once installed. Something to consider and research here.

The Infinity grips are more pricey than the Ray Allen grips but, having a past in Blackhawk helicopters, I wanted that look and feel. Tosten is another many like.

Wiring the sticks together is a bit complicated, mostly due to routing around flight controls. You'll need a couple trim relays to handle the switching. I recommend the PH Aviation relays; he is a RV owner and is present on the forum. Another is Composite Design. They have single and 3 axis relays that are commonly used.

TruTrak has an auto-trim box you might want to consider for your setup. I don't know if it works with your current setup but you might be able to upgrade at the same time and put it in. I installed the entire system in a RV-6A recently. Just the wiring took over 20 hours.

Don't forget that if there is more than one control 'switch' (e.g., top hat plus autopilot, or two top hats) you will need some sort of relay logic or switches to prevent short circuits should both switches be activated, but in opposite directions, at the same time.

Thank you Ray

Ray, I really appreciate your advice and attention to my questions. Today I called both Ray Allen and Van's tech support. Ray Allen suggested that while the servo's are their's I probably should order the kit from Van's because of mounting considerations that Van's kit addresses. The Van's tech support rep encouraged me to consider the Safety Trim Intelligent Servo Controller also because it will make wiring easier when using two sticks. Ray Allen also suggested I purchase the wiring harness. Now it appears my next big installation is the stick grip. Ray Allen and Infinity both offer what look like nice grips. Infinity appears to be more along the line of a military style grip which I really like (being ex-military with some post UPT time in the T-38), comes pre-wired, but it has more switches on it than I need. The Ray Allen G307 is well designed, less expensive and I can order the type of switches I want (the speed controller has a high and low speed rate that can be controlled by a switch) but does require that I wire the switches myself. I will also look at the Tosten grips, and PH Aviation and Composite Design relays.

I found out today that my GRT Horizon WS EFIS can be configured to show elevator trim position if l wire up the elevator position servo lead to one of the analog inputs on the EFIS.

Your pictures of the aileron servo installation were very helpful!

BillL said:

I am building with electric, but trained with Mike S with manual trim. It was so nice to just grab that knob and twist it three times in the landing sequence. No time to dial it in. I was reminded that IMC training in a 182 was the same, don't "trim" just adjust it the same offset and it is very close. Just fixed amounts for TO-to-climb, cruise-to-pattern, 1/2 flaps, full flaps. Especially helpful for missed approach. OK, maybe not in a light controlled RV, but a throttle off full flap descent to full power ascent in a 182 is a LOT of control force.

How do you electric trimmers get that perfect trim quickly for the transitions of flaps? Black Box? Feel? Time - one - - - - two - - ??

Click to expand...

I have electric trim and adjust by feel when adding flaps. It seems natural for me. My only complaint is the ratio/speed of the servo. You quickly get a sense for how long to hold the up trim switch when adding flaps. Trim adjustments at cruise are difficult, as the servo is too sensitive.

Larry

Tosten Grip

Jim, my purchased -8 came with the Tosten grip and I like it but it seemed a little "dinky" in my hand. I wrapped black electrical tape around it and now feels more "manly" like a T-38/F-4 grip.

Thanks Jim and Larry

I appreciate both of your comments. Jim, you said the Tosten grip were a bit "dinky" and that wrapping electrical tape gave them a better feel. Do you have another grip you would recommend I check out? Have you looked at the Ray Allen G307 grip? It's not a true military style grip but it does appear to have a "fatter" profile. Your thoughts would be appreciated.

Larry, it appears from your comment that you might recommend a two speed elevator trim control function. Am I correct? One of my concerns is cruise flight and the ability to correctly trim the elevator at higher speeds. Do you have a speed control function on your trim system?

Tankerpilot75 said:

I appreciate both of your comments. Jim, you said the Tosten grip were a bit "dinky" and that wrapping electrical tape gave them a better feel. Do you have another grip you would recommend I check out? Have you looked at the Ray Allen G307 grip? It's not a true military style grip but it does appear to have a "fatter" profile. Your thoughts would be appreciated.

Larry, it appears from your comment that you might recommend a two speed elevator trim control function. Am I correct? One of my concerns is cruise flight and the ability to correctly trim the elevator at higher speeds. Do you have a speed control function on your trim system?

Click to expand...

I would say it's a nice to have, but not required. I have been "bumping" the hat switch instead of pressing it and that seems to work well enough (usually takes 2-3 adjustments to get right). I have built a little voltage reducing circuit and will feed it through a second switch to the servo. The lower voltage will be used at cruise and the hat switch at all other times.

Larry

Tankerpilot75 said:

I appreciate both of your comments. Jim, you said the Tosten grip were a bit "dinky" and that wrapping electrical tape gave them a better feel. Do you have another grip you would recommend I check out? Have you looked at the Ray Allen G307 grip? It's not a true military style grip but it does appear to have a "fatter" profile. Your thoughts would be appreciated.

Click to expand...

Jim, I have not looked at any other grips. Now that I have the tape on the Tosten I am happy with it and looks fine even with the tape. It has everything I need; coolie hat trim, mic switch, a/p disconnect, and freq change buttons. To show you how far we have come when I built my RV-4 in '87 there were few grips available so I used a dirt bike motorcycle grip that felt great.

Hat switches on two sticks is a ton of work, with a mess of wires plus runs to the servos being the greatest percentage of effort for the entire installation. The mechanical effort is straightforward and easy. Think about where you might mount two rocker switches accessible to both seats. My latest build located them close around the throttle where they could be poked or pushed by extending the index finger of the throttle hand. Between the seats in one of the floor pans would be downright simple and no more of an inconvenience than a trim wheel or crank in a spam can.

John Siebold

Trim Switches on Panel

John, I appreciate your comments on the challenge of wiring up two "coolie hat" trim buttons. My problem with your recommendation is panel space. On my panel I've got two G430s, G330 transponder, G340 audio panel (all above the throttle, prop and mixture assembly. I've also got installed dual GRT Horizon WS EFIS systems, Trutrac A/P, independent CDI, Dynon D10A battery backup EFIS, nine panel rocker switches, three dimmer switches, two cigarette lighter plugs for plug in accessories, a bunch of circuit breakers, oxygen connections and a GRT EIS panel. I don't even have room for trim indicators so I am going have to feed position information from the elevator trim module to my #1 GRT EFIS for display on the PDF page. Panel space was hard to find for the A/P emergency level button. The panel is what convinced me to buy the plane.

People at Van's and PH Aviation assure me that if I purchase a trim servo relay package that wiring the sticks up to the trim motors shouldn't be an unmanageable situation. In reviewing the wiring diagram for my current pilot stick it appears Aerotronics (the builder of my panel) included a plug for that stick that has ground fault wiring for A/P engagement/disconnect and transponder ident. Since the current stick button labels are missing I will need to experiment to identify those functions on the stick. If nothing else this exercise is teaching me more about the plane I bought.

Jim, thanks for contacting us about wiring your sticks for electric trim. Just to demonstrate how straight forward the process is, and/or to illustrate what the task involves, here are a couple of photographs of our setup for testing our relay boards. You can see the blue cable coming up each side of the Infinity grips. This is the wiring harness that comes with the grip. You just terminate the wires with machined pins and insert them into the D-Sub connectors as shown. Additional wires are for the trim motors themselves and for the power and grounds.

The trim switches on the grips will cancel each other out. This is the way it works in most large commercial jets. So, if the pilot is trimming down and the copilot trims up, the trim will stop. If both are trimming in the same direction, there is no effect. As a matter of fact, the first step in a runaway trim procedure in the airplanes I flew was to trim the opposite way on the grip to stop the motion--and then pull the breaker.





Shown are the Infinity grips, but we have installed the Tosten grips as well and like them a lot. Hope this helps you in your decision-making process.

change of trim

i installed electric trim via coolie hat on an infinity grip.
then i went and flew it.
i recommend staying with the manual trim, particularly if you already have it.
other comments here have embellished and I would add that a coolie hat switch will probably require relays because the wiring can only handle milliamps and this can be a complicated wiring challenge. furthermore the roll trim is mounted in the tunnel where there is little real estate to spare after the push tube and any wiring bundles going up the sides.
having flown them both and installed the electric coolie hat arrangement to supplement my already-in-place panel mounted switches, I definitely recommend keeping what you have.

best of luck.

jrh

There was a thread a couple of years ago with an alternate method for retrofitting elevator trim to electric. I will try to find it and add a link later. The guy kept the manual trim cable but cut it back so that the Ray Allen servo could be mounted under the empenage fairing. There may have been a kit for doing this at one time. It looked like a pretty good approach to me. IIRC he pulled the cable out through the elevator, cut the sheath back and anchored it with an adle clamp, then fed the cable back through, cut it to length and added a connector of some kind on the newly formed end.

Also, I know this is about -7's but I have been considering going to electric trim in my -8 for safety reasons. Should I be incapacitated in the front seat the back seater could control trim and have an easier time getting down safely. I already added a rear seat throttle so the most critical part is done. Without a throttle in the back seat the gib better be a great pilot and cool thinker.

Update - here is one reference to adding it under the empenage fairing: http://www.vansairforce.com/community/showpost.php?p=887223&postcount=5

Update 2 - I think this thread has a lot of the info on under the empenage fairing installation. Gretz was the company who had the kit. I tried to contact them a couple of years ago to see if they had one kit left but I did not get any response. http://www.vansairforce.com/community/showthread.php?t=106121&referrerid=6282

Randy Lervold did it under the fairing too. http://www.romeolima.com/RV3works/Airframe/airframe.html#Empennage He even gives the ACS part number for the cable, his reasoning for doing it the way he did, and included two great pictures that tell it all.

Bubblehead said:

There was a thread a couple of years ago with an alternate method for retrofitting elevator trim to electric. I will try to find it and add a link later. The guy kept the manual trim cable but cut it back so that the Ray Allen servo could be mounted under the empenage fairing. There may have been a kit for doing this at one time. It looked like a pretty good approach to me. IIRC he pulled the cable out through the elevator, cut the sheath back and anchored it with an adle clamp, then fed the cable back through, cut it to length and added a connector of some kind on the newly formed end.

Also, I know this is about -7's but I have been considering going to electric trim in my -8 for safety reasons. Should I be incapacitated in the front seat the back seater could control trim and have an easier time getting down safely. I already added a rear seat throttle so the most critical part is done. Without a throttle in the back seat the gib better be a great pilot and cool thinker.

Update - here is one reference to adding it under the empenage fairing: http://www.vansairforce.com/community/showpost.php?p=887223&postcount=5

Update 2 - I think this thread has a lot of the info on under the empenage fairing installation. Gretz was the company who had the kit. I tried to contact them a couple of years ago to see if they had one kit left but I did not get any response. http://www.vansairforce.com/community/showthread.php?t=106121&referrerid=6282

Click to expand...

You don't need a kit to do it - a number of RV-3's (including ours) have he servo mounted to the deck under the vertical tail, with a Bowden cable going out to the trim tab. Easy to do with some scrap material and a couple of Adel clamps. On the small tail surfaces, there just isn't much room to mount the servo in teh elevator.

Paul

Use of Bowden Cable for Elevator Trim Control

Paul

I went to the Aircraft Spruce Website and looked up what a Bowden cable was. It appears to basically be the same type of cable used on lawn mower controls. I certainly liked the price but my question is: How do I attach the cable to the trim tab. The existing cable uses plastic clevis push rod assembly that is attached at the elevator trim bell crank. I can see using an adell clamp where the cable attaches to the trim servo but not at the trim tab bell crank. I would prefer a clevis push rod assembly at that point.

I called Spruce Aircraft about making a "custom push/pull control cable" which could be threaded for a clevis assembly but that's around $90 plus shipping. How do you get a "good/secure" connection on the trim tab using the Bowden Cable approach? Also, if the length that I order is too long is it very difficult to cut these down to the "needed length?"

I have received some great tips on this project on the VAF site. I really appreciate everyone's help and insight.

Jim H

Project Update - Thanks, parts ordered

Today, after much deliberation, thought, and technical assistance I pulled the trigger and ordered the parts, supplies and needed tools. I want to express my thanks to Pat Hatch at PA Aviation for his superb technical assistance and encouragement, Jim, Larry and Bubblehead (see their earlier remarks on this thread) for pointing me in the right direction, Keven at Tosten Manufacturing for sending me a free sample grip to guide my switch selection and placement, Jason Smith at Aerotronics for helping me better understand the wiring options of my panel (they built it for the original builder and had no obligation to provide assistance to me but have willingly answered every stupid question I've asked), Mark at GRT Avionics for guiding me on how to wire my EFIS to show elevator trim position, and the Ray Allen company for answering questions about servo push/pull strength and attachment to my elevator trim tab via a push/pull cable even though they knew I was ordering the trim kits from Van's. The VAF network is definitely an exchange group of talented enthusiast and great vendors.

I will try to post my progress as I move forward and hopefully a few pictures if I can figure out how to do attachments.

Electric Trim Installed - finally!

Well it took me two months, over 150 hours of effort, and lots of hair pulling but my trim conversion is finally finished. To answer the basic question of was it worth it? YES!!! YES!!! YES!!!

However my project was more than just trim conversion. I also changed stick grips from a simple three button grip on the pilot's side and one button grip on the copilot's side to two Tosten military style five button grips that include PTT, Ident, Autopilot engage/disengage, Frequency swap, Flap controller (pilot's side), Comm swap (copilot's side) and of course trim positioning (coolie hat switch) on both sticks for elevator and aileron trim.

Problems! There were problems that come from doing something you've never done before and of course making mistakes that screw with your mind. However I will say that Pat Hatch (PH Aviation Services) who manufactures the trim servo hub I used, promised to help me through the process and he was definitely a man of his word. Without his email and phone call assistance this project would have been a disaster. His guidance and encouragement allowed me to succeed even when I thought about giving up. Jason and Andre at Aerotronics Inc. once again came to my rescue when I couldn't figure why my radios weren't transmitting (I had reversed pilot and copilot PTT stick wires). Kevin at Tosten Manufacturing has also been very supportive and will rewire my grips when I send them back in a few months to accommodate two system issues I was unaware of (when I ordered the grips) and tried to wire my flap and comm swap switches using the common ground design of Tosten grips. Those two systems require a circuit completion approach in wiring. Additionally, Pat wisely recommended I view the SteinAir U-Tube wiring videos before starting. Time well spent (I viewed them multiple times).

I installed the elevator trim servo in the empennage just below the elevator using an approach discussed in this form. I also installed trim indicators on the panel to advise me of trim position. No speed controller was necessary and PT Aviation Services Ultimate Hub servo does a wonderful job of controlling the two stick trim inputs and keeping all the wiring issues on one hub using two Dsub connections. I used Molex connections where needed and thanks to Pat's wise words drew up schematics of all wiring changes made.

I would include pictures but I don't know how to put them in this update.

I have a RV-9A with original manual trim which worked great. No problems whatsoever for 6 years, over 1000 hours. I upgraded my Dynon 180 and 100 units to a SV-1000 then upgraded again to the Touch Screen. I have the Dynon Autopilot installed with 2 servos. I wanted the auto trim function that the optional autopilot box offers, so I upgraded to electric trim. I bought the Ray Allen servos, T-something or other, mid length/strength jobbers, two coolie hat thingies, I bought the wire locally, and the electric trim aileron unit from Vans. One note: Since I had built in the manual trim originally, I only needed one part from the electric Vans kit, you might ask them to sell you the one part you need instead of a complete original electric trim kit. I had originally used the righy-handed stick grips from Vans and drilled the holes I needed for the push-to-talk buttons. I modified the grips to accept the additional coolie hat on each and an extra momentary push button on the pilot grip only to disconnect and re-connect the autopilot. I mounted the optional autopilot box at the center top of the radio stack along with the autopilot CB and trim CB. All the wires go to the autopilot box, the servos, stick mounted coolie hats, and power and ground. The entire retrofit took 2 days, about 7 hours total. Best thing since sliced bread. Dan from Reno

Trim trim trim

I've flown RV7a's with manual and with electric trim. I bought my own 7 a with ray allen panel mounted electric roll and pitch trim but decided I had to have the coolie hat for both. Somehow it was not until I flew with the coolie hat did I realize how little trim adjustments seem necessary in the 7a. With the complexity of installation and increase in failure modes I feel the change was not only unnecessary but had i the opportunity, I'd go back to manual rather than adding complexity with the coolie hat.
My impression is that changing from manual to electric will not just add complexity and failure modes but seems, as well, independent of the failure mod you described.
Given your situation with my experience, I'd repair my manual trim and go fly.

Good luck
Jeff H n377cp kwvi

Response to n2b8r

There will always be people who want to rain on one's parade. I started the electric trim conversion because I didn't like manual trim in my RV. I've now flown it three times since the conversion and wouldn't even consider going back. The military style grips with multiple switches do add a new level of complexity to my aircraft but it's one I enjoy and appreciate. I flew military aircraft for over 16 years (not including several desk jobs while on active duty) and personally like the greater "feeling" that comes with the ability to trim off stick pressures as you directly feel them.

My RV has a "complexity" to it greater than a "steam gauge" panel that results from a full IFR dual EFIS system, dual Garmin 430s, a TruTrak autopilot that allows fully coupled approaches, and an EIS system that provides very detailed engine information. I bought my RV from the original builder because it was a good looking RV with a level of "complexity" that reminded me of flying military jets. Electric trim and multi-function military style grip just increase the size of my RV grin. Each to their own opinion - my opinion is the only one that counts with my own RV.