The following is in response to several queries about Twin Navions made on Facebook.

Performance wise, the D-16 is the least desirable - think of it as a 225hp Navion with twice the maintenance bills. At 2,950lb MTOW it's only slightly more than an A or B single and the speeds don't change. Other downsides include a low single-engine ceiling, additional fuel tanks needed on almost every flight are under the seat or in the rear baggage compartment, and the throttle quadrant sits between the seats making getting in/out of the front seats cumbersome.

The D-16A is (in my opinion) the all-round best Twin Navion out there. With a MTOW of 3,600lb and honest, but not amazing performance with a single-engine ceiling of about 5000 ft. Speeds are the same as a single, but the extra fuel was moved to bladder tanks in the nacelles and tip tanks that Osborne later copied. D-16As have baggage doors to the rear compartment, so one doesn't have to reach over the back seat. The throttle quadrant moved under the instrument panel, making it slightly easier to get in/out of the front seats.

The Camair 480 is a completely different animal than the D-16/-16A. The conversion is beefier, which raises both the empty weight, and the MTOW, as well as the airspeed.

Having flown both D-16A and Camair, I can honestly say that I did not like the Camair. They're fine when both engines are working, but the Camair has a small vertical fin and rudder extension so when you're on one engine you either have to drop a wing (10-degrees or more) or fly around in circles. By comparison the TEMCO birds are over-ruddered because they use 1/2 a horizontal stabilizer and elevator in order to get a trim tab. Fuel burn in the Camair is 24-26gph verse 16-20gph in the D-16A.

Now, despite my preference for the D-16A, it has a massive drawback, and that's the O-340 engine. Even 10 years ago, there were parts available for this orphaned engine but that appears to have disappeared. Today, the Achilles heel is the crankshaft - they're worth their weight in gold (so to speak). I know of at least three otherwise complete D-16As that were parted out because one of the engines failed inspection. I have anecdotal comments from the chief engineer at TEMCO the nacelle was designed for a 200hp engine, and the O-360-A1A should match up perfectly with the O-340 mounts, but no one has invested the time and money to prove it.

So what's better?

The D-16 was a hodge-podge, first generation conversion that really won't improve on what you'd experience with a basic 225hp Navion. It will give you bigger bills.

The D-16A is a no-frills light twin that won't break the bank (at least as light twins go). Performance wise, it's comparable to a 260hp Navion with a higher MTOW and no limit on the fuel being in the tip tanks like it is on the singles.

Want to go faster? Then the Camair is the solution. Think 285hp Navion. It gets there with bigger engines and more gas.

Honestly speaking, as much as I love these planes, I can't recommend people go out and buy one unless they're absolutely determined to have a Twin Navion and don't care about the finances. If you hope to keep your D-16A flying, then you'd better make sure you have two strong engines, and hopefully a spare (or two). Otherwise, it's life could be limited to the next overhaul. If what you want is a light twin, look at the far more plentiful offerings from Cessna, Piper, Beech and Grumman. Light twins from all these manufacturers have dropped to record low prices since 2008, plus the Wichita Wonders have A) loads of parts to keep them flying, B) brand recognition for when it comes time to sell, and C) a much better chance of finding insurance and flight instruction. (Note: After these comments were posted in 2023, a prospective Twin Navion buyer commented that despite having more than 1,000 hours in multi-engine airplanes his insurance provider was unable to find someone willing to underwrite his policy!)

Note: In the interest of transparency, the following are my original comments.

Should you consider buying a Twin Navion? Absolutely. As far as I'm concerned, they're the best bang for your buck when it comes to light twins. Don't let their "rarity" scare you off. That's a label applied by people who don't know what they're talking about. 120 were converted in a factory, and they all use the same airframe as the single Navion, meaning more than 3,000+ airframes to source parts from. The goal of TwinNavion.com was to dispel this myth and answer questions just like yours.

I've been asked this question before, and I thought I'd saved the response, but apparently not. I'll try to remember what I've said before, but forgive me if I send a follow up message to fill in the blanks.

I believe you're probably considering NXXXX, a D-16A that's back up for sale. That airplane was previously owned by a doctor, and I believe it has been kept in pretty good shape throughout its life. I haven't purchased that plane's records from the FAA yet, but there's a 50/50 chance you'll find some damage history. As a type, the Twin Navions were either babied, or ridden hard. The ones that are left are usually the babied ones.

The first thing I try to tell people is that they have to understand a Twin Navion is not a Baron, and never will be. If you're looking for a fast plane, or something you'll take up high, this is not the plane for you. If you want to add another 800 lbs on your Navion's gross weight and are willing to pay the extra fuel burn then you're in the right market.

Flying:

I'm a low time pilot with only 300 hours total time. About 200 of those are in our Twin Navion, a D-16A. I literally went from flying in the flying school's Cessna 172s, to the Twin. I had absolutely no problem with the transition. My problem was getting used to all the extra radios and instruments.

A single Navion will burn 12-18 gph based on the size of the engine installed. The Twins will burn 15-20 gph. If you're light and use lower power settings, you'll see the bottom number. At gross weight, you'll be at the upper end. I've gotten it as high as 22 gph - don't ask. According to my father, who's flown way more planes than I, the D-16A performs identical to a 260hp Navion (I've only flown a 225hp Navion).

Cruise is about 145 mph at 25-squared, and gross weight. Fuel burn at 20 gph. I've been trying to fly lighter to get the gph down, but I still do all my flight planning at 20 gph. Takeoff and landing performance is typical Navion - very good, better than a Bonanza. We used to take ours into the mountains and the grass strip at Banff (before the government tried closing it). That required a one-way approach down the side of a mountain, at about 2,000fpm descent. You get that with gear and full flaps, fine pitch and idling engines.

Navions are very stable in turbulence, and the Twins only more so, because of the higher wing loading. We've been in 45+ knot winds and had no troubles. My grandparents used to deliver passengers to Lethbridge when the winds were too high for DC-3s to land. They simply landed the Navion right in front of the terminal. The big tail will cause weather cocking, so watch for it and be prepared. Steering is done with the nose wheel and not differential brakes. This instills the Navion with a solid feel on the ground.

As far as twin airplanes go, the Twin Navion and Piepr Apache are as basic as you can get (I think the big tail makes the Twin Navion easier to fly than the Apache). The engines are normally aspirated and carbureted. There's no anti-icing, no, cowl flaps, no fuel injection, no super chargers and no turbo chargers. All you have to worry about is throttling back to keep the manifold pressure and keeping the propeller rpms under the red line. Out here in Alberta, I don't even have to worry about the MP. I'm too high. My last flight, was the first time in two years I had to throttle back after takeoff, and that's because I was flying in Saskatchewan.

Single engine performance is quite unexciting. Because the plane has such a large vertical fin and rudder there's effectively no critical engine. You just overpower it. Stalls are predictable and straight forward. There's a noticeable buffet before, the then the stall. The outer wing keeps flying, and you can maintain aileron effectiveness. I had a chance to fly a Beech 18 and it was almost identical for numbers (except the engines). Not that everyone's flown a Beech. The ailerons are heavier than any Cessna or Piper I've flown, and it gives the Navion a "big airplane" feel. Elevator is only slightly heavier than in other planes, but much less than an Aztec, and the rudder is interconnected with the ailerons to help co-ordinate your turns. I flew an Ercoupe, which is the pinnacle of this system, and I thought the Navion had better co-ordination. I really believe that if you killed yourself in a Navion, you did something to deserve it, and you would have been dead a lot quicker in something faster, or more high-tech. Looking at the accident reports supports this. Most crashes were caused by fuel mismanagement, or flying into IFR conditions.

I talked with the chief designer at TEMCO about the work they'd done to upgrade the D-16 into the D-16A. The whole goal was to create a single engine service ceiling of 5,000 feet ASL. They started at 4,000 lbs and removed weight until they got there - at 3,600 lbs. Recently my father was doing his IFR check ride. They were easily at gross weight out here in the foothills of the Rocky Mountains, at about 6,000 feet ASL. They pulled one engine back to zero thrust (simulated engine failure) at 13" MP. They then continued to fly in simulated engine out conditions for another 45 minutes - without loosing altitude. Thinking about it later, my father discovered that they'd also been using the older engine, approximately 500 SMOH. With 5,000 hours in 200+ aircraft types, it was something that really impressed him, and he still tells people about what his old girl can still do.

I mentioned the weight experiments, because with the two baggage compartments, four seats and five fuel tanks, its easy to overload the D-16A. As long as you take off in the fore/aft limits of the C of G envelope, you'll be okay. All of the fuel tanks are on the C of G, so as fuel burns, it descends straight down, into the legal envelope. I try not to exceed this, but I have been above it. The worst I've heard of was an 800 lb overload. It used up a lot of runway and struggled for a long time before it burnt off about 400 lbs of gas. Then it started to pick up and behave. We typically keep the main tank full and run with 15 to 20 gallons in the nacelle tanks to give flexibility. We only put fuel in tips if we're going to burn it off right away.

Landing gear and flaps are hydraulically actuated. This can scare people away, but that's only because they're used to electrics. I've only had one problem with the system in 11 years. I was practicing emergency gear drops at the time and that's when the pump decided that it wanted to die. No big deal. We flew back home with the gear down, taking about 45 minutes to do so, and did a flapless landing. Had the gear been up, I would have flown home and simply dropped the gear using the emergency release, which pulls the uplock hooks. I could have pumped them up or dropped the flaps using the emergency hydraulic pump, but I didn't bother.

Maintenance:

Once again, the plane's simplicity becomes a great strength.

The engines behave just like any other Lycoming engine (although I'll make some comments later).

The airframe is bullet proof. Navions were overbuilt and as a result they keep on going when their contemporaries are getting tired. You'll have a hard time finding a 1955 Apache that isn't worn out, but the Navions just keep on trucking along. Just don't forget they are 60 year old machines and have a really good pre-inspection done. We do preventative, on-going maintenance on our plane. The annual usually only takes one day and that's mostly because our AME likes doing pressure tests on the cylinders. We typically keep a couple thousand dollars for those problems that creep up throughout the year, and another couple for one or two specific tasks. In that way we've installed a new windshield, rebuilt the nose gear, and removed, stripped, inspected and repainted the ailerons and flaps. Main gear are probably the next ones we'll tackle, but its hard without a hangar.

Twin Navions have their own type certificate, so we're not immediately connected with ADs against the single Navions. Recently there was a huge battle over the Navion's fuel selector. Many argued it wasn't warranted. No D-16, D-16A or Camair is affected by this AD. Off the top of my head, there are no structural ADs against the type. There was an AD against the propellers a couple years ago. Make sure this has been done before you buy. It was against the Hartzell blade clamps and affected tens of thousands of light planes.

Maintenance of the Navion is simple and straight forward. Maintain per the single Navion manuals, except for the Twin's supplements. Airframe parts are available for almost everything, except the fluted aileron and flap skins. I've seen photographs of one Navion with a traditional built-up flap with flat skins, but I hope the owners of the Navion type certificate decide to start producing new skins soon.

The Lycoming O-340-A1A engines are the only down fall of the D-16A. They're an odd-ball, built in low numbers before the O-360 started. That's not to say they're bad. No. It does mean that you should keep your eyes and ears open for parts though. In the last ten years, we've picked up three spare engines. One from an STC'd Cessna 170 that the owner was changing to an O-360, and two from an STC'd Apache that was being parted out. In both cases the owners asked our local engine shop if they knew anyone interested, and they passed the word to us. I won't tell you what we paid, but all three were less than an overhaul. Many people are scared away because they think its impossible to get parts. Its not impossible, you just need forward thinking.

Back in 1975, when my father was rebuilding our plane, he wanted to upgrade to O-360s. At the time, Transport Canada allowed you a 5% hp increase without paperwork. 5% of 170hp is 8.5hp. A 180hp O-360 was 1.5hp too much, and Transport Canada wouldn't allow it. He tried arguing it but Transport Canada wouldn't budge.

Canada:

At the moment there are only two Twin Navions and one Camair in Canada. Ours is the only one flying regularly. C-FKLB and C-FDEC were in Southern Ontario for decades.

Twin Navions aren't in the Nav Canada "big book of airplanes" so we used to get all sorts of pointless clearances when flying into Calgary International. Occasionally this resulted in 737s getting hold short orders incase we couldn't land in 2,500 feet. We tried several times to add the Twin Navion to the book, but no one knows how to do so.

Another Nav Canada quirk is flight planning. We're now NA16s in the computer, but for a while it seemed like we were getting different designators every time we took off.

Watch your landing fees too. D-16As weigh 3,600 lbs. Camairs are 3,930 or 4,323 lbs. Depending on who's looking at the book when they're billing your landing fees, you could get a bill you'll have to argue. Medicine Hat was doing this to us for about a year.

General:

Navions in general, have been extensively modified throughout the last 60 years. And since most are American, watch the number of repairs and modifications done on FAA 337 forms. Canada doesn't accept these and you'll have to get them covered, usually via Canadian LSTC.

We whole heartedly recommend membership in the American Navion Society (Navioneers), as they have an extensive parts and maintenance network. Most of the maintenance tips for the singles transfer directly over to the twins. You used to be able to order all their technical articles as a package.

Because Twin Navions are only four seaters, you won't run into the insurance and landing fee problems that can come with six seat Barons, Senecas, Aztecs, 310s, etc. Also, consider that turbo chargers, super chargers, and bigger engines used on those planes will bump you to the 25-30 gph range, and add thousands to your overhaul and maintenance costs.