Wednesday, September 24 2014 00:00

Seneca De-ice Control Panel Upgrade

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De-Ice Panel Before De-Ice Panel Before

October 2014-

All restoration projects seem to start the same way. There is this one little thing on your plane that doesn't look good, so you restore it... then everything around it looks bad and you start moving from one project to another....

     I was admiring my newly restored throttle quadrant last week when my eyes wandered up a couple of inches—and I noticed how bad my de-ice control panel looked when compared to the new quadrant. (For all the details on Sherer's restoration of the throttle quadrant in his Seneca II, see his article in the July 2014 issue of Piper Flyer. —Ed.)

     While restoration can be most pleasing, it does tend to empty your checkbook if you're not careful. I'd like to say that I'm really careful on this last point, but sometimes I'm not. I get surprises in my checkbook just like everyone else.

     On this project I wanted to know what it was going to cost before I started it. I knew that paint, sandpaper and elbow grease wouldn't cost much—but I was very concerned about the price of switches. I wanted to use only original Piper parts, and I figured that finding new surplus switches for a 40-year-old plane was going to cost a bundle, so I started to get estimates before I touched anything.

     As with most Piper restoration projects, you can't just call Piper Aircraft and expect them to have a brand-new part for you; sometimes you have to spend copious amounts of time.

     Finding all of the vendors listed on the sidebar (see below) was easily a six-hour project, so to save you some time and possibly a little money, take a look at the list—and keep reading.

seneca chart

     Further, if you're not qualified to attempt this job on your own, be sure to engage your A&P in the process. You'll learn a lot—and get a lot of satisfaction out of this inexpensive upgrade.

The price is right
     In my search I discovered the ice wing light switch was less than $10! How cool is that? The boot activation switch was less than $10, too, as was the hot prop switch. And they were all available from one source: Wilco.

     I was excited to think that I was going to be able to do this project for under $50. Surely the airplane restoration gods were smiling on me that day. Since I already had a perfectly good prop de-ice amp meter (I sent it to Century Instrument Corp. a few years ago for a new meter scale), I started the project.

     Of course—I hear you laughing!—I forgot to price the dreaded hot plate switch. I'd ordered everything and removed the panel before I realized I had forgotten that one dreaded switch.

Keep looking
     Of course, this wasn't just any switch. The amazing guys who designed my Seneca way back when I was in grade school had run out of space in the circuit breaker panel for one more breaker and I have to surmise that, not knowing what else to do, the engineers decided to use a combination switch/circuit breaker for the hot plate. Whatever the reason for it 40 years ago, I knew today's cost for this part wasn't going to be $10.

     I searched the web and got five different bids for a new surplus switch/breaker. Two hundred dollars was the low price; $900 was the high price—with many in between. I chose the part that cost $200.

     There are a couple of lessons here. First, don't give up looking for parts. It's frustrating and time-consuming, but it's worth doing. (If you feel lost or overwhelmed, check with Kent Dellenbusch at Piper Flyer Association. Parts locating is a member benefit available to anyone who joins PFA. —Ed.)

     Second, there are aviation parts businesses out there whose scruples are questionable, so I recommend that you take your time and keep hunting. If you're suspicious of any company, ask your avionics guy or a trusted mechanic. You can even check with the folks who use the PFA online forums to get some more opinions.

     In any case, I did get all of the parts that I needed for around $250—which I consider a victory, considering that we're dealing with airplanes here. So let's get this project rolling!

Picture 1

Picture 01. Scott's Assistant

  Step one: removal
     First, see if you can get your assistant to stay in the seat next to you. (see picture 01)  Since I'm left-handed, it's easier for me to work on this project from the right seat. Right-handed folks will probably want to sit in the left seat. The downside is that your assistant might escape out the passenger door, as mine tried to do.

     Remove the three black screws at the top of the de-ice control panel using a medium screwdriver. There are no screws at the bottom as the bottom has been inserted into a flange to hold the panel in place.

     Pull the top of the de-ice panel toward you—about ¼ to ½ of an inch—and lift the panel vertically. If it doesn't want to move, it's probably restrained by the plastic horizontal panels on each side. You may have to remove these two panels to get the de-ice panel to release.

     Once it's released, the entire panel has (at most!) one inch of play before you run out of wire. This is where we get into the challenging part of the project. I would recommend that you take your time, and take a break if you need to.

     As for me, this is why I brought my assistant. Every time an expletive would leave my mouth, my dog—er, assistant—would give me a lick and make things okay.

Picture 3

Picture 03. Old Panel Partially Removed    

     So, starting on the right side of the panel, the hot plate switch/breaker inserts from the back side of the panel. Remove the two front panel screws and let the switch fall back. You'll notice here that working from right to left on the panel has an advantage: the panel comes toward you just a bit more with each device that gets released.

     The next removal task is the hot prop amp meter. It's very important that you do this correctly. Using small pieces of masking tape, identify and label each wire before you remove it. The meter movement has three wires: one ground, one positive and one negative. You must properly identify each wire and make no mistakes.

     I wrote "meter ground" on the meter ground wire. Since I couldn't see the back of the meter and therefore couldn't identify which was positive and which was negative, I wrote "meter left" and "meter right" on the masking tape attached to those wires. Only then did I detach them. You can see my progress in pictures 3, 4 and 5. Take your time, and do a good job.

     After working for about 15 or 20 minutes, you will be rewarded with a big hole in your panel and lots of wires and masking tape sticking out.

Picture 4

     Picture 04. Wires Labeled

     As you disconnect wires from right to left, you'll encounter the leftmost two switches which are the surface de-ice (boot) and hot prop activation switches. You'll notice that there are as many as three wires attached to the same terminal on these switches.

     The only way that you'll keep these wires together is by putting a small nylon cable tie through them in addition to the masking tape label(s). This is critical, as masking tape alone isn't strong enough to keep the wires together. Heed my advice and use a cable tie.

 Picture 5

  Picture 05. Panel Removed

   The de-ice panel you now have in your hand probably looks pretty sad with its worn paint and missing lettering. Now you can remove yourself from the airplane and go to your workbench.

     While I have a workbench next to my plane at the hangar, I didn't think that spraying paint and primer within five feet of my plane would be a good idea, so I took the panel home. There I removed the old switches, lamp and meter. I used a razor knife to remove the gum labels that were affixed to the panel and cleaned the panel with alcohol to remove any traces of adhesive.

     At this point my patience had long since run out for the day. I'd invested about six hours to order parts and one hour to remove the old panel from the plane so far.

Picture 6

Picture 06. Panel Sanded to Bare Metal

Making progress
     The next day, I sanded the panel down to bare metal. Good preparation makes all the difference, so don't skimp on the sanding. Make sure that what's left is shiny aluminum. If you can see daylight through the part of the panel that you're sanding, you've gone too far.

     Following the instructions on the can of primer, apply two coats of primer about 30 minutes apart. Primer dries to the touch rather quickly, but I'd suggest you leave the project overnight to allow the primer dry thoroughly.

Picture 7

  Picture 07. Spraying Primer

   The next day it was time to sand the primer. Even though I've been using spray primer and spray paint on various projects for years and years, my A&P taught me something new and it worked great.

     Get yourself a small piece of 600 grit (P600; extra fine) sandpaper and sand the panel until it's smooth while under running water. That's right, do it under a running faucet.

     Just don't sand too much. You want to sand the primer until it's very smooth—and this only takes a minute or two. Run your finger over the panel to see if there are any rough areas that need re-sanding. If not, dry the panel with a paper towel.

     After a couple of hours, take a lint-free cloth and wipe both sides of the panel and in the holes. Make sure that there is no moisture evident on the panel.

     Following the directions on the spray paint can, apply two to three thin layers of paint to the panel. Allow the panel to dry between layers in a dust-free, no-draft environment. You'll be amazed at how good it looks! Leave the panel overnight to ensure it's thoroughly dry.

Picture 8

Picture 08. Panel Primed

Replacing switches, and...
     The next morning, insert the new switches in the correct order. From the front side and starting left to right, first insert the new surface (boot) de-ice switch. Be careful when you insert the switch so you don't scratch the panel. Leave the ice light toggle switch and the boot activation press-to-test lamp uninstalled.

     Next, install the hot prop activation switch, also from the front, also being careful not to scratch the panel.

     Next, install the hot prop amp meter from the front of the panel and attach three of the four nuts to the back of the meter; leave the one nut off where a ground wire (removed earlier in the process) will be reattached. Leave the hot plate switch/breaker out of the panel at this time.

     Finally, using a suitable label maker or appropriate decals (I prefer a label maker), re-label the panel as it should be. You may want to use the photo of my panel as a model.

     It is now time to reinstall the panel in the airplane. However, unless you wish to use your entire inventory of bandages listed in the "tools needed" sidebar, I highly recommend that you cover the edges and corners of the panel with masking tape. This will keep you from getting blood on the upholstery and/or scratching other parts of your panel.

Picture 9

Picture 09. New Panel Less One Switch in Transit

Making improvements
     Before you begin to reinstall your panel, these tasks must be completed. If you refer back to picture 5, you will remember that the wires were removed from all of the switches and the meter that install from the front of the panel.

     The three devices that install from the rear of the panel that haven't been addressed yet. First is the ice light switch, which you will need to install using your soldering iron. Make sure you use heat shrink or similar tubing to ensure that there are no exposed terminals on the switch.

     Note that there is no polarity on the switch, yet there are three terminals. Use the middle and bottom terminal and leave the upper terminal empty; this ensures that "up" is "on."

     For the boot activation light, I chose to replace a 40-year-old incandescent lamp with a visually identical LED lamp. The LED lamp is polarized (the incandescent lamp was not), so I had to make certain that I connected the three wires in exactly the same way on the new lamp as they were on the old lamp. You do this by removing one wire at a time and soldering it (again, using shrink wrap or similar tubing) on the new lamp housing. Make sure that you're on the correct terminal. Note that all three terminals are used.

     The third item is the rightmost switch/breaker for the hot plate. Unscrew the two screws, remove the old breaker and connect the new one.

     We're now in the home stretch, but now would be a great time to take a 15-minute break and go for a walk. I suggest you stretch your legs and give your eyes a break, because you must proceed slowly and carefully on this last task.

Final connections and the smoke test
     Holding the panel up near the hole, with the left side in close to the hole and the right side several inches away, carefully read the masking tape wire labels and reconnect each wire to each switch. No mistakes here! Take your time and do it right.

     When this is done, install the ice light switch, boot activation light and hot plate switch/breaker in the panel. Next, carefully remove the masking tape on the edges and corners of the panel and insert the bottom of the panel into the groove at the bottom of the hole. Gently press the top of the panel against the top of the hole and reinsert the three mounting screws. If you had to remove the two side pieces of plastic molding, reinsert those, too. Now take another break before the smoke test.

     After your break, turn on your battery master. Did any breakers pop? Do you smell anything? I'm not trying to scare you, but these are necessary steps to make sure that all is well. You can test the ice light, the press-to-test boot activation light, and the hot place switch/breaker (if the hot plate is installed) without starting the engines.

     If these work okay, start up your engines and test the surface de-ice (boot) activation switch. The boots should inflate and the lamp should light up.

     Finally, take a picture and post it on the PFA forums for all of us to see and admire.

Picture 10

    Picture 10. Finished and Reinstalled

     We just finished our panel and my assistant and I are going for a plane ride—just as soon as I can get her out of the pilot's seat! Good luck on all of your own restoration projects on a budget. If you need help, contact me through the Piper Flyer Association online forums at PiperFlyer.org.

Piper Flyer Association member Scott Sherer is a multi-engine and instrument rated private pilot. He's logged 2,600 hours and is the owner of a 1977 PA-34-200T based at Burlington Municipal (KBUU) in Burlington, Wis. Sherer anxiously awaits the day when N344TB finally gets new paint. Send questions or comments to This email address is being protected from spambots. You need JavaScript enabled to view it..


Aircraft Spruce & Specialty Co.
AeroGraphics, Inc.
KRN Aviation Services
Wilco, Inc.
Last modified on Wednesday, February 11 2015 21:16

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