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Seneca Throttle Quadrant Upgrade

Seneca Throttle Quadrant Upgrade Featured

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July 2014- I have heard it said many times by many boat owners that the two greatest moments of boat ownership are when you purchase your boat, and when you sell it. I understand the message completely although I've never felt that way about any of the seven airplanes that I've owned over the decades. I've enjoyed every moment of airplane ownership.

Regrettably, I wasn't born a millionaire, so I've found great joy in restoring older airplanes—and my current Seneca restoration project has been a great example of what can be done without spending a huge amount of money.
First, the history lesson

My Seneca II was born in Vero Beach in 1977 and was transported to Norway for the first years of its life. It was then owned by a flight school for a couple of years in Venice, Fla. when I found it resting in a field alongside a hangar in 2004.
It looked very neglected but was structurally sound. It had only 3,000 hours on it and the price was $65,000. I was looking for a plane that I could restore and configure the way I wanted.
I proceeded to purchase the airplane and flew it back to Wisconsin—with oil pouring out of both engines. The props wouldn't stay in sync, the rigging was way off, and I had to hold the yoke 15 degrees to the right for a thousand miles.
Ultimately, I got it home to Milwaukee and in a hangar. My mechanic and I went over the plane and we came up with a five-page (single-spaced, typed!) squawk list.

The engines went out for overhaul; the engine mounts were replaced; the props and governors were overhauled; the instruments went out for overhaul; all of the avionics except the autopilot were replaced with new, modern units; the glass was replaced; and I gutted the airplane and put in an Airtex interior kit.
I managed to do this all in the first year. What I accomplished gave me an airplane that was safe, reliable, and a joy to be in for what is now 10 percent of the cost of a new Seneca.

Most recent changes
Wind the clock forward eight years to 2012. I started the restoration process again and here is a brief recap of what I've upgraded in the last two years: I replaced the old Century original autopilot with a new Century 2000 autopilot with altitude hold, altitude preselect and GPSS. The new autopilot is coupled to my Garmin 530W—and LPV and LNAV approaches are a snap.
As a result of all of these wonderful, very modern improvements I'm using the airplane more, especially for trips. The unfortunate part of my trips now is the IFR portion. Don't get me wrong, I don't mind light IFR, but every time I get in the clouds and it's raining, I can watch the paint peeling off in large sheets.

Obviously this means that paint is in my Seneca's future, but I have to replace all of the exterior plastic before I can paint. So far I've replaced the Seneca's nose bowls with LoPresti nose bowls and all of the other exterior plastic (wingtips, gap seals, gear doors, etc.) with Knots 2U products.
I now have everything so that I can proceed with the painting. Unfortunately, I had an annual inspection bill that was a bit larger than I expected, so the paint project will be put off for another year. I'm sure that each of you has a similar story about your airplane, too.

A project under $500
With the painting project deferred, last spring I began looking for a small restoration project. The criteria were that the project had to be something that I would see every time I used the airplane, and it would have to cost less than $500.
After researching some of the options, I decided to restore my throttle quadrant. My PA-34-200T's quadrant was all original and was well worn. The knobs looked bad and the upper and lower cases were worn. I replaced the original throttle quadrant with a brand-new, looks-like-a-million-dollar-Seneca-V quadrant.
Where to start?

1. Lesson number one in any restoration project: refer to the parts catalog for your airplane. This is paramount to making your project easier and accurate. If you don't already have a parts manual, there are various vendors you can check with. One company, eFlightManuals.com, may stock your aircraft and its products are economically priced at less than $50. (See Resources for more information.) In the manual you will find drawings of every part of your airplane with each part identified in a sidebar/parts list.
Note: Some part specifications have changed over the last few decades. Piper from time to time improves certain parts (as they did on the throttle quadrant) and issues a new part number. The parts manual that you purchase will be dated when your airplane was manufactured and won't have updated parts numbers. If you have trouble finding a part number, be on the lookout for a new part number.

2. Define the scope of your project. If you're not generally project-oriented, try to be realistic about your restoration skills and budget. If this is your first restoration project you'll find this one to be very easy—and a great way to stick your toe in the Avgas and see if restoration is for you. Worst case scenario is that your A&P mechanic can finish the project in an hour's time.

3. Identify and source the parts. For a general list of the parts needed to complete this project, see "Required Parts" in the July issue of Piper Flyer. The companies included on the "Parts Inventory and Vendor List" are quality companies that supply great products. However, if you get a part number wrong and have to return one of the items, you'll run the risk of paying a restocking fee in addition to shipping.
On this particular project I did just that—and learned a valuable lesson. Much like carpentry where you measure twice and cut once, for aircraft restoration projects, double-check and confirm your part numbers before placing an order.
If you run into confusion, call or email the supplier, check with your mechanic or other competent pilot/plane owner, or use the PFA online forums or Parts Locating service. Personally, I rely on the PFA forums for all kinds of aviation-related information and help. You should give it a try!

4. (a) Remove the old parts. You'll first need to remove the knobs. All you need to do is to remove the screw on the side of each knob. If you're doing this on a twin you'll note that the throttle knobs need to be separated to gain access to the screws; same with the mixture and propeller knobs. Keep the screws, as the new knobs do not come with any.
I chose to replace the old screws with new screws and you may wish to do the same. Keep the old screws to use as a guide for new screws. Your mechanic will probably give you a few screws at no charge if you ask him.
If you have a Seneca with alternate air levers, you'll need to remove the knobs using the same technique used above. The screws are on the side of each knob. Note that alternate air knobs are two pieces and not one, as the throttle knobs are
(b) Now remove the housing. On my Seneca I found two screws on the left side of the housing, two screws on the right side of the housing and three screws underneath the housing. They are all self-tapping screws that can be reused if you wish.
When the screws are off you can gently remove the housing by pulling it straight out. Please note that the levers may have to be moved up and down as you remove the housing. Be gentle!
You'll be putting the new housing in soon so make a mental note of how the old one came out. This would be a good time to take a rag, cotton swabs or a vacuum cleaner to clean up the area.

5. Prepare the new parts. Two things need to happen at this point. First, compare the new housing to the old housing. You'll find that the old housing has screw holes on the sides and bottom and the new housing does not have those holes. You'll need to measure on the old and mark on the new. Masking tape on the new housing will assist you on this.
On my Seneca, there are two holes on the left, two on the right and three on the bottom. Also, once I had the holes drilled I discovered that the new housing had a bit too much plastic around the quadrant friction lock. Fortunately, I have a Dremel that allowed me to trim a bit of plastic from the friction lock area to make it fit. (Dremel tools start at about $30 if you don't have one.) Other kinds of tools will work, too but having a Dremel in the shop is a good investment. Alternative tools are Exacto knives and files.
Note: Only trim a small amount of plastic at a time, then reinstall the housing on the panel to check the fit. It may take several iterations before it's perfect. Patience goes along way here. We're only talking about an extra five minutes to be precise, so don't rush.
Also, Vantage is an extraordinarily good company with outstanding support. With every product you buy from them, you get an installation manual. It is more than worth the 10 minutes it's going to take you to read through the instruction manual. You may save yourself a major blunder by following their directions. 'Nuff said!

6. Fitting the upper quadrant. With the lower quadrant housing fitting perfectly—with the screw holes lining up and the housing fitting flush against the panel—it is now time to fit the upper quadrant over the throttle levers and place it on the lower housing.
Six holes will need to be drilled in the lower housing and the two pieces will need to be screwed together using the screws supplied with the upper housing. While you have the two parts in the airplane, you'll need to mark the locations where the four small lower holes will need to be drilled. Masking tape may assist here, or an awl may be used to mark the hole locations, or you may think of other ways to mark the holes. Note that the upper housing comes with two different kinds of screws.
Next, take the new and old housings to a desk or workbench. You'll need a drill with a small bit for the next task. Drill one hole at a time and check the marks that you made while in the airplane. If they don't line up correctly go back into the plane and try it again. If you go slowly here it will come out okay.
When you have the four holes drilled, screw the top plate to the lower housing and try it back in the plane. At this point in my airplane I discovered that the top of the upper piece needed holes drilled and screws inserted, too. I also had to trim a bit of lower housing plastic using my Dremel as the airplane panel wasn't installed perfectly at the factory.
After about five minutes of careful trimming and comparing to the old housing I had it done and everything fit. Regarding the variety of fasteners that came with the upper quadrant, I chose to use the nuts and bolts rather than the self-tapping screws.

7. Replace the housing in the airplane. This proved to be a somewhat challenging task for me as the throttle levers don't just slide through the quadrant openings. Rather, each lever has to be individually inserted in the assembled housing and moved up and down to get it to fit.
In the case of my Seneca, getting one lever in was easy; getting the other five levers out of the way was most challenging. However, if you take your time and are gentle, it will work out perfectly.
Do not force the housing onto the levers as you'll break the upper quadrant, which is fairly rigid and won't take much bending.
8. Replace the screws. At this point I hope you're still with me and haven't had to dredge up all of those words you haven't used since you left the Navy. I admit that I used a few and you probably will, too. However, we're in the home stretch, so we'll just persevere and get 'er done!
Don't forget where the screws came from: two on the left, two on the right and three below. (Your plane may be different, of course.)
Check the play in the levers and make sure that they don't rub against the upper quadrant. If they do, a bit of grinding with your Dremel tool or sanding may be in order.

9. Replace the knobs. If the quadrant housing is on and the levers move without binding, then it's time to put the new knobs on.
You may choose to use new screws or reuse the screws that came out of your old knobs. In any case, the screws that came out of my airplane were self-tapping screws. As the new knobs have screw holes but no threads, only self-tapping screws will work.
Using the appropriate screwdriver, you'll need to hold each knob firmly in place while you insert the self-tapping screw into the knob and tighten it. On my airplane, the throttle knobs had two screws each and the mixture and propeller knobs had one screw each. The alternate air levers had one screw each.

10. Gloat. Finally, admire your handiwork and call all of your hangar buddies over to see the finished product. This will give you something to crow about next time you're hangar flying and perhaps encourage you to try another project.

11. Share. Don't forget to take a picture and post it on the PFA online forum. It'll make all of the other members jealous. You should have a picture just like this, or maybe even better!

Happy flying!

Piper Flyer Association member Scott Sherer is a mult-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 .



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Last modified on Monday, 01 December 2014 23:37

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