Used Aircraft Guide: Diamond Katana

A sleek if low-powered trainer that has proven durable and safe. The Rotax version is a bargain buy.

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Climb into your WABAC machine and set the dials for the mid-1990s. Once the whirring sounds and flashing lights stop, get out and glance around at what was then your local airport. Very different from today, huh? A lot of all-metal airplane designs, which hadnt changed much in 40 or so years, right?

If youre lucky-or if you mis-set the machines controls for a couple of years later-you might see a curiosity: A T-tailed, all-composite, canopied two-seater

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with sailplane-like wings pulling duty as a trainer. Thats Diamond Aircrafts DA20-A1 Katana, a sleek little machine with unmistakable European roots.

The early, 81-HP Rotax-powered A1 Katanas at takeoff sounded like a sport motorcycle with a stuck throttle. Transitioning students steeped in Cessnas carried way too much speed into the flare. Good times.

Since then, the DA20-in its C1 version-has evolved into what some might consider a more serious contender, thanks in part to a Continental IO-240B sporting 125 HP.

Today, the DA20 soldiers on, training the next crop of pilots in fleet situations and in the traditional FBO/flight school environment. Gone is the Rotax, which on hot days made climbing to altitude a time-building experience, although you can still find A1 versions powered by it.

On the used market, its years of service and by-now well-known maintenance and pilot requirements make it a worthy contender among the two-seat, tricycle-gear competition for a personal airplane.

A New Trainer

Stepping out of your WABAC machine back in the present day, its a good time to reflect on North Americas general aviation market in the mid-1990s. The general economy was strong and GA was showing signs of a modest recovery in the wake of disastrous sales figures posted in the late 1980s. The watershed General Aviation Revitalization Act and its 18-year statute of repose on product liability lawsuits became the law of the land in 1994, but Cessna wouldnt re-enter the piston-single market until 1997. Simply put, there were few new trainers on the market.

The company that eventually became Diamond Aircraft had been building composite aircraft for quite some time before the DA20. Austrias Hoffman Flugzeughbau was formed in 1981 and began producing the H36 Dimona motorglider, which has evolved into the HK36 and HK36R Super Dimona, better known in North America as the Katana Extreme motorglider. Diamond says its now the best selling motorglider in Europe.

With that motorglider as a base, the companys management bought the fledgling airframer and renamed it HOAC-Austria Flugzeugwerk in 1989. Two years later, HOAC was acquired by Diamonds current owners, a family well-established in the automotive business in Europe. The new owners soon began developing the Katana DV20 by shortening the HK36s wings, adding flaps and tricycle landing gear. This design evolved into the DA20 Katana.

The company set up shop in 1992 in London, Ontario, as Diamond Aircraft Industries. The intent was to develop a North American version of the Katana. The next year, DV20 production went into full swing in Austria. In late 1994 and based on its European paperwork, Diamond received full FAA certification of the DA20-A1, and U.S. deliveries began.

Basic Design, Safety

Even with its slightly bulbous nose, one way to describe the first Katana is “Eurosleek.” Diamond has improved and tweaked the basic DA20 over the years, but it seems the Katana was mostly right the first time.

The “plastic” design includes a pair of fuselage halves joined longitudinally down the airframes center. The wings are similar in construction, with upper and lower halves joined in a lay-up and vacuum-bagging process. These methods yield accurate, consistent airframe parts. After assembly, the parts are hot-cured in ovens.

The wing spar carries through the fuselage in a box structure designed to accommodate the spring-steel landing gear. Both seats are essentially attached to this structure, which has proven itself over 14 years in the rough-and-tumble world of flight training.

Although the DA20 has suffered its share of accidents and incidents, only two have been fatal, according to the NTSB. As sister publication Aviation Safety said in an August 2006 look at trainer safety, “Diamond has set the standard.” It is a very strong, well-built aircraft, in our view.

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The Katanas slender wings span 35 feet, 8 inches (cut down from the 53-foot wings used on the HK36), reinforcing its motorglider roots. Despite their looks, the wings are only 28 inches wider than the Cessna 150/152. The wingtips have a slight winglet-like upturn to help reduce drag.

The Katana retains the T-tail used on the motorgliders and employs a conventional elevator. The horizontal stab and elevator are just a bit above the average persons eye level, so pre-flight isnt a hassle and the airplane handles quite nicely.

About That Canopy

One of the nicest things about the Katana is also one of not-so-nice things about the Katana: it has a forward opening (i.e., rear-hinged) wrap-around bubble canopy. While the resulting visibility is unparalleled for a trainer-and most other aircraft, for that matter-a hot summer day can turn the cockpit into a solar oven.

There is another aspect of the canopy: it can generate massive drag if it comes open in flight. In such an event-usually resulting from failure to latch it correctly prior to takeoff or if it becomes unlatched in flight-the canopy pivots back and presents its entire surface to the relative wind. In other words, it becomes a giant, very-effective air brake.

In later models, beginning with those made after January 1995, Diamond added a warning light to indicate when the canopy isnt latched and improved the latching mechanism for ease of use. Were still not crazy about that aft-hinged canopy but the accident record suggests its not the safety hazard we imagined.

The only other issue raised by the canopy is what happens to the occupants if the aircraft comes to rest upside down. In one of the only two fatal accidents in the NTSBs files, a 2004-model Katana being used for primary instruction clipped unmarked power lines during a simulated engine-out landing. The airplane came to rest inverted and caught fire. The accident report doesnt provide details on the occupants egress, but the CFI apparently was killed outright. The student succumbed to “serious thermal injuries” almost four months later.

Powerplants

North Americas original DA20-A1 Katana is powered by a Rotax 912. As such, it became the first “mainstream” Rotax-powered GA aircraft most pilots and mechanics encountered. Rotax was and is a well-known and -respected maker of quality engines for the ultralight, LSA and light homebuilt market. But at the time, a Rotax was unheard of in a certified airplane.

Initially, the Rotax 912 engine had a 1000-hour/10-year TBO. In March 1999, this was extended to 1200 hours/10 years. Again in April 2003, TBO again was extended, this time to 1500 hours/12 years. These values are generic, however; review a specific engines serial number and maintenance/parts history to determine the manufacturers recommendation. Presently, the Aircraft Bluebook Digest shows the DA20-A1s engine to have a 1200-hour TBO; the overhauls average cost is $8500, installed.

The Rotax engines in the A1 Katanas have delivered generally good service. Over time, complaints about anemic climb made their way back to the factory. For these and perhaps other reasons, Diamond switched to the Continental IO-240B in the 1998 model year, giving it 125 HP and the C1 designation.

First certificated in 1990, Continentals IO-240-series engines-which basically are two thirds of the six-cylinder IO-360-generally have a good service record. Beginning in 2004, however, Continental released a handful of service bulletins and service letters designed to address what were termed an “idle stability problem on the IO-240 engine models.”

Transport Canada (TC) put it more bluntly in early 2008: “There have been a number of rough running/unstable engine events and engine shutdowns occurring on Diamond Aircraft (DA) model DA20-C1 powered by the Teledyne Continental Motors (TCM) IO-240-B series engine.”

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A TC-issued service difficulty advisory noted, “Uncommanded engine shutdowns have occurred during various phases of training flights (stalls, spins and sideslips). Engine idle instability and sputtering at low power have also occurred during the critical approach phase and after landing.”

To address the problem, Diamond issued a mandatory service bulletin (MSB) and Transport Canada Civil Aviation issued AD CF-2007-27R1, mandating Diamonds MSB and specifying incorporation of Revision 23 to the DA20-C1 Aircraft Flight Manual.

We couldnt find any U.S. airworthiness directives targeting Continentals IO-240 series engines. For that matter, we couldnt find any ADs against the DA20-C1, period.

Finally, potential buyers may come across a “Katana 100” variant. This is a DA20-A1 that has been through a factory program costing some $30,000 and consisting of a complete mechanical and cosmetic refit. Part of the bargain was a factory-new 100-HP Rotax 912S and a gross weight increase, to 1654 pounds, providing a 44-pound useful load boost. This variation also is listed in the FAA type certificate and references Diamond Aircraft Drawing No. 20-0100-00-00. The Aircraft Bluebook Digest doesnt list any Katana 100 models.

Systems

In a nod to maintainability and its intended use as a trainer, Diamond made the Katana about as simple as certificated airplanes get. For example, theres no nosewheel steering. Instead, theres a castering nosewheel and steering is accomplished via differential braking, which seems to be the trend in modern fixed-gear aircraft. Early Katanas had high brake-pedal pressure. Meanwhile, a shelf-like structure built into the airframe near the rudder pedals made it difficult for those with larger feet to steer and brake the airplane. This was corrected in later models.

Except for the rudder, which is cable-operated, the flight controls are activated via push rods, which generally provide the pilot with more feedback and responsiveness. The flaps are electric with three positions: retracted, takeoff and landing. The flap switch is panel-mounted and includes a position indicator.

Pitch trim is electric, with no manual provision, producing one of the few things we dont like about the airplane. A rocker switch on the center console behind the throttle operates an anti-servo tab on the elevator (A1 models), but fine-tuning the trim can be an exercise in excess.

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We think the Katanas center stick is one of the airplanes strongest assets. Weve always believed students or pilots new to a type adapt more quickly to a center stick, which we prefer over yokes and the more-recent innovation of side-sticks. Even pilots who dont like the Katana for other reasons seem to like the stick.

The Katanas fuel system, while as simple as the rest of the airplane, does pose a potential problem. A single aluminum tank is located behind the seats, forming the baggage compartments floor. It holds 19.5 usable U.S. gallons in the Rotax-powered A1 version and 24 U.S. gallons usable in the C1. In both models, its filled from a cap located on the fuselage aft of the pilots seat.

As a design feature, we dont like the idea of putting fuel lines and hoses in the cockpit space, let alone the entire tank. In our view, the gasoline should be outside the people area, preferably in the wings. Even so, were aware of only two accidents involving post-crash fires: The aforementioned fatal accident in which the Katana came to rest inverted and another one in which fuel exhaustion was blamed.

Since theres only one tank, switching isnt an issue. The single shutoff valve is located on the left side of the center console, near the pilots feet. The tank has one sump drain located on the left side of the fuselage. In Continental-powered C1 Katanas, an additional fuel system drain is installed on the fuel filter bowl. All Katanas are 12-volt airplanes. The airplane is all-electric, but Katanas usually dont have extensive avionics for the simple reason they were never certified for IFR operation, something many flight schools and owners have complained about.

A1/C1 Differences

The Rotax-powered Katana A1 is an easy-to-fly starter trainer, but many flight schools wanted more. The main thing they complained about was poor climb performance. Diamonds first solution to the performance problem was the aforementioned Katana 100 retrofit program.

The second solution involved the C1s Continental IO-240B, with 125 HP. At the same time, Diamond tweaked up the basic airframe, squeezing an impressive 60 pounds out of it. This helped accommodate the heavier Continental engine.

With the lighter airframe, the C1 also got a re-designed horizontal stabilizer, eliminating the anti-servo tab. It also got slotted flaps in place of the A1s hinged flaps and the canopy latch was improved, as were the brake master cylinders. Wing sweep was tweaked by half a degree.

Ergonomically, the instrument panel was moved higher and further forward, creating more knee room. Seatback recline angle was increased to improve comfort. This was a necessity, in our view, because although the fixed seats-the rudder pedal position is adjustable in all models-are comfortable enough for a short training session, they can be excruciating on a long cross country.

There were some name changes, too. The C1 initially carried the Katana name but in 2000, Diamond renamed the airplane the Eclipse and Evolution, with the former being the gussied up airplane intended for private owners and the Evolution the training model. The Eclipse has rear windows, pop out vents, wheel pants, inertial-reel harnesses and Garmin avionics versus Bendix/King products in the Evolution.

Performance, Handling

Stick-force-to-G is a bit on the light side, which is fine for a trainer, in our view. While we dont think manhandling will ever pull the wings off a Katana, students should find it light enough to be easily mastered. The ailerons are effective-and what adverse yaw there is encourages rudder use. But rudder input requirements remain light-pressure-on-the-pedal, not the thigh-numbing stomp encountered in heavier airplanes.

Stalls are quite gentle and even when weve tried to provoke the airplane into something more sinister, it wont go along. Although plenty of students have ham-handed Katanas and broken plastic as result, none of these have been due to stalls or stall/spins, as far as we can tell from reviewing the Katanas accident record. The airplane is approved for spins, with the flaps up, something desirable in a trainer.

In addition to its training duties, the Katana is perfect for low-and-slow cruises across the countryside. The Rotax-powered Katanas cruise in the 110-to-115-knot range, which makes them a bit faster than a Cessna 150. Expect fuel burns of 3.5 to 4.5 GPH, which places the A1 Katana firmly on the positively frugal end of the spectrum

The Continental-powered C1 version burns more fuel, but is quite a bit faster. On 7.3 to 8.3 GPH, itll true out at 125 knots. Also, the C1 comes with a noticeably improved climb rate, easily turning in an 800 FPM initial performance, bleeding off to 500 FPM or so at practice-area altitudes. If you dont think thats a considerable improvement, you havent spent much time instructing.

As should be expected when considering its role, Katanas have adequate but not generous payloads. Early A1s had empty weights of about 1160 pounds against a gross weight of 1609 pounds. That yields a useful load of about 450 pounds. Throw in full fuel and theres barely enough payload left for two FAA 170-pounders. Obviously, a pair of 200-pounders up front wont cut it.

Allowable baggage weight is 44 pounds, which is quite generous considering that theres very little space behind the seat for anything more than underwear and a toothbrush. The Continental versions have a higher gross weight of 1764 pounds for a typical useful load of 600 pounds. That means full fuel and a pair of heavier pilots up front is a realistic option.

Maintenance, User Groups

Given its simple airframe and overall design, Diamond predicted the Katana would be a low-maintenance airplane. Thats true, but the airplane isnt without foibles. Thankfully, none of them are deal breakers, in our view.

Brake wear and replacement rates can be high, which should not be a surprise, since the airplane is steered with brakes. Early in the A1 versions history, there were a number of reports of cracked spinners. One reporter found all nine of his fleet aircraft with cracked spinners, suggesting pilots pushed on the spinner during ground maneuvering.

A recent review of the FAAs service difficulty reports did not uncover a series of related or linked problems. This tends to indicate to us the type has matured and installing revised components-either in the field or at the factory-has resolved many recurring issues.

The DA20 can be thought of as being relatively AD-free. We count only four ADs, all of them on the A1 version. AD 97-13-02 requires a placard prohibiting spins to be installed on the panel and 96-09-05 requires inspection of the aileron circuitry for potential debris that could cause control jamming. The spin placard was a one-time check for a bolt in the rudder circuitry.

The Diamond Aviators Association (www.diamondaviator.org), is a relatively new group, having been formed in 2007. A traditional type club, the organization has more of a virtual presence than a physical one, but acquired the apparently defunct Diamond Owners and Pilots Association and merged its membership. The organization says it is independent from but endorsed by the manufacturer and works closely with Diamond to maintain a two-way flow of information.

Reader Comments

A few years back, I trained flight students in the DA20-C1; its one of my favorite aircraft. Some observations:

Since steering is by differential braking, pilots new to the aircraft find this feature a bit daunting, but quickly adjust to it in a few flights.

The DA20 likes to float in ground effect if the approach speed is too fast, making for some long landings, (especially if flaps arent used). The lesson here is to fly close to the recommended airspeed on approach.

Most pilots over six feet tall didnt seem to like flying the DA20 for long, due to limited headroom.

Having no manual backup, the electric trim was at first a concern of mine. However, the trim proved to be very reliable. I cannot recall anyone in the flight school having even one failure.

The excellent safety record of these airplanes I believe is due in part to this philosophy. The composite prop will start to delaminate very quickly if flown in rain. Had it not been for this and the VFR-only limitation, I would purchase a DA20 today.

John E. “Jack” Demyan
Via e-mail

I am a fairly new pilot and the DA20 is the plane I learned to fly in. Ive really discovered only two weak points:

Sliding storm windows are really wimpy, and break easily. Ive done it.

The seats are fixed in place, which is not a problem in itself, but the lawn-mower-type pull cable that allows rudder/toe brake pedal adjustment is flimsy, and known to break. Ive done that, too.

Other than those two minor weak points, the DA20 is a great little airplane. I love to fly it and I hope to own one someday.

John Vybiral
Pollock Pines, Calfornia

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