Photo File – Pratt My Ride: The PT6 Cessna 206, S5-DOT

By me
All photos me too, copyrighted

Some choices in life are actually pretty easy to make. Take, for example, my options the other day following a 4 AM wake-up to work a dawn flight: A) get some sleep; B) get some exercise; or C) drive an hour and half (one way) to a neighboring country to try and catch a pretty rare turbine Cessna 206… I mean, the choice is self-selecting! 😀

The machine that had managed to score higher than my own bed (!) is a Turbine Conversions Turbine 206, a fresh crack at mating a mid-life Cessna 206 airframe to a (moderately) powerful low-altitude turboprop engine. But, whereas the most successful attempt so far – the Soloy 206 – is based around the same Rolls-Royce/Allison 250 series engine used on the Bell JetRanger, Turbine Conversions’ mod relies instead on the far more famous Pratt & Whintey PT6A – and is the first time this engine had ever been fitted and certified on a member of the Stationair family. With only three examples flying in Europe so far, delaying sleep was definitely a better call, so I plonked myself into the car and went off to see what’s what 🙂 .

A real Quasimodo: ugly as hell on the outside, but with a heart of pure gold underneath

Born to Haul

The recipe for this sort of thing has always been pretty straightforward: take an older generation utility 206, give it a large improvement in hauling performance as cheaply and simply as possible – and then make it work on paper so that it can legally carry paying passengers. And while sticking in an engine that may be worth three times the rest of the aircraft may not sound like the best way to do it, the idea does have a fair amount of economic sense behind it. Stationairs have always been tough birds with long lives, so even a model several decades old can be reasonably expected to have quite a few years of service left; being several decades old means that they were likely paid off in full ages ago, and have none of the fiscal baggage that newer models are often burdened with; and they can be cheap to buy, spares are plentiful, support is available worldwide – and there’s enough accumulated user experience out there that even a fresh operator can learn the ropes quickly and without undue trouble.

Get all of these right (admittedly, not an easy task!) and the turbine conversion can end up being a pretty cheap, sufficiently efficient and very reliable ticket into the utility turboprop world, especially for smaller operators who cannot afford a bespoke type such as the Pilatus PC-6, PAC 750 or Quest Kodiak – or are in regions where Avgas is fast becoming a thing of the past. Get it right and even the conversion’s many downsides – such as fuselage-limited capacity and higher long-term operating costs – may not be critical enough to offset the advantages of having a turboprop – ANY turboprop – at your disposal.

To try and achieve the above, Turbine Conversions – a longtime PW&C user – decided to bank once again on the company’s most famous engine, which – while heavier and more expensive all round than the RR 250 – has an enviable reputation and true global reach on its side. Initially, the mod started out with the 550 HP PT6A-20, but this was changed before production began to the equally powerful PT6A-21 – the difference being that the -21 is in essence a de-rated version of the 680 HP PT6A-27, which retains the latter’s more potent core for a bit added torque and improved hot-and-high performance.

Being a cheap-and-cheerful “firewall forward” solution intended for the rough-and-tough utility market, the Turbine 206 is not really loaded with features; apart from the new engine and its associated accessories, propeller, mountings and structural changes, the only things that stand out are custom exhaust stacks that eek out a bit more thrust – as well as the company’s own air inlet design with is said to improve the flow of air into the engine. The upgrade is rounded out by an Electronics International MVP-50 digital display panel – which replaces all traditional steam gauges – as well as modified engine control levers to cater for its different operation.

Unlike turbine conversions of touring aircraft – where the interior often has to match the performance – both Soloy and Turbine Conversion mods retain the utilitarian equipment levels of the aircraft they were based on. Really the only dead giveaway that there are 550 horses living up front is the MVP-50 display, located above the right-hand panel guard

Another change – albeit not as easily noticed – are the engine control levers, which now behave differently to those on the piston 206. The throttle lever now has to incorporate a reverse function, the prop has to have feather – while the condition lever is actually simpler, with just two discrete positions (HIGH IDLE & CUT OFF)

On the DOT

While all of this is pretty interesting in itself, the machine I had actually gone out to see is just that bit more special 🙂 . Nowadays called S5-DOT, in its past life as N7351Q it had actually served as the prototype and validation vehicle for the entire Turbine 206 mod, and was the one put to the test in order to receive the Supplemental Type Certificate (STC) needed for sale and commercial use.

Originally a stock U206F manufactured in January 1973 with the serial U206-02179, DOT is a fresh addition to the fleet of Letalski klub Šentvid, based at the picturesque airfield of Šentvid pri Stični – the same place I had gone last year to have a one-on-one with another Cessna turbine mod. Replacing the smorgasbord of outside aircraft that previously had to be leased at significant cost, DOT has arrived right on the dot for the beginning of the commercial skydive season – so with any luck, it should be a frequent dot on the Slovenian sky!

Rolling full laden toward RWY 14 for another afternoon run. Though turbine power could not change the type’s hauling capacity all that much, it did wonders for both take-off and climb performance at high weights – not an insignificant feature given the close-in hills in all directions and high daytime temperatures…

Like all piston-to-PT6 conversions, the Turbine 206 looks quite brutish from the front. Note also the offset propeller (and engine) installation, designed to reduce the adverse gyroscopic and aerodynamic effects of the new powerplant

Waiting for the next load. Like any self-respecting skydive machine, DOT has a full set of handles, steps and door covers, and can comfortably accommodate up to six skydivers at once

The Dependable Engine (unless you’re talking about the GTF!). An interesting operational feature is that engine starts are performed with the assistance of an outside battery kart, since the huge current draw from repeated spool ups would drastically shorten the service life of the on board battery

As always, I would like to thank the people who made this photo shoot possible – in particular Mr. Tone Dolenšek, who spent quite some time keeping me company and answering my Achtung, Skyhawk!-y questions!

Sources:

Photo File – The Heat Is On

By me
All photos me too, copyrighted

While I often rant here about Croatia’s summer weather – an eclectic mix of searing heat and violent thunderstorms – these past few months have seen thermometers run off their scales, with several airports reporting temperatures in excess of 40 degrees Centigrade… no small feat, since readings are taken two meters above grass and in shade. Out on the tarmac, 55+ was nothing out of the ordinary, making life out in the open particularly unpleasant.

Thankfully though, the heat and humidity had not deterred the brave men and women of general aviation from their passion, with the region’s airports chocked full of everything from cheap-and-cheerful ultralights to high-flying, million+ Euro turbine singles. So having already come to terms that my summer would consist of flying from one oven to another, I’d decided to make the best of it and see what’s on offer on the country’s GA aprons… 🙂

Whenever I’m in a rut for not having snapped a light aircraft in awhile, I can always count on Dubrovnik Airport (DBV/LDDU) to come to the rescue! Even though both GA aprons had on this day been overflowing with various private and business aircraft, G-UAVA was the one that had instantly caught my eye – if anything for being one of the very few Twin Comanches still flying in Europe. Born in the early 60s, the PA-30 was an extensive twin-engine conversion of the earlier PA-24 Comanche, a “heavy cruiser” that had been the top of Piper’s single-engine offering all the way until the late 70s and the appearance of the PA-46 Malibu. Even though it is far from the most elegant twin out there, the Twin Comanche nevertheless has several aces up its sleeve – the biggest of which is a design penned by the legendary Ed Swearingen, a freelance engineer known for his passionate love of speed and low fuel consumption. Most famous as the father of the Merlin bizprop and Metro feederliner, Swearingen had used all of his talent in designing the PA-30, creating a 300 km/h aircraft powered by engines of only 160 HP that together drank just 17 USG per hour. While they do not sound like something to write home about, these numbers are identical to what the SINGLE engine Cessna 210N could manage on its 310 HP – and all the more amazing given the extra drag and weight penalties of the second engine. G-UAVA itself had been manufactured in 1967, and can additionally boast so called “turbonormalized” engines, a special variant of the classic turbocharged setup running at lower manifold pressures and cylinder temperatures – thus increasing engine life and durability with very little loss in performance. Another interesting detail is the slope of the apron and runway; my camera’s internal balance had said that this shot is perfectly level! Built on an undulating plain that is the only suitable piece of flat land for dozens of miles around, the airport is well known for its “uneven nature”, which can cause problems if you’re not prepared for it.

After Dubrovnik had served up its best offer, Split (SPU/LDSP) had also decided to deliver! Cessna’s first post-war twin, the 310 had remained in continuous production for 26 years, and spawned such a number of versions that they ate up half the alphabet. The Q model pictured here was the type’s last snub-nosed variant, with the subsequent 310R – the last series to go into production – receiving an elongated and aesthetically far more pleasing job that had included a lot of additional storage capacity. A fine example of a classic 70s Cessna paint scheme – proudly advertising the fact that the engines sport a fuel injection system and not the common man’s carburetor – D-IBMM had been manufactured in 1973, and can still be seen happily flying all over middle and southeastern Europe.

A cute little canary coming in to make an already fun day of flying and photography at Split Airport (SPU/LDSP) all the better. A pretty rare bird, the Do-328JET is – as it says on the tin – a turbofan variant of the 33-seat Do-328 turboprop, a sleek and sexy design that can still today be seen flying with smaller regional operators in and around the Alps. Even though it had always been a well designed, robust and quality product, the Do-328JET had one fatal flaw: it was the brainchild of two small companies (Fairchild and Dornier) that went head-to-head with the likes of the much more established ERJ-135 and CRJ-100/200 in a market that does not easily forgive design missteps. Dornier’s wobbly financials had further deepened the hole being dug under the design, the result of which are only 83 examples of the type ever made. Today however, it is enjoying a small Renaissance as a business jet – as well as a speedy and capable utility aircraft for both civilian (such as ADAC) and military operators (including the USAF).

The second oldest airworthy Skyhawk in Croatia – manufactured in 1966 – observing proceedings at Split (SPU/LDSP) from its elevated position halfway up the airport’s famous hill. Located just a 100 or so meters from RWY 23, the hill tops out at just 10 meters above the airport elevation, and in addition to a GA hangar and fuel farm features an olive garden – as well as a small church that predates the airport by a couple hundred years… not a bad feature to have INSIDE the airport fence! BDM itself is similarly native, having flown in country ever since the early 70s and the first of the Yugoslav government’s aeronautical shopping sprees (intended to equip flying clubs and schools with modern Western machinery). As an H model – Reims-built no less – it still sports the Skyhawk’s original six-cylinder O-300 engine developing 145 HP, quite a more charismatic (if inefficient) package than the modern fuel-injected four-pop IO-360.

Enjoying a bit of sun and fresh sea air on Croatia’s highest – and most challenging – airport. Perched on a high plateau surrounded by hills near the top of the eponymous island, Brač Airport (BWK/LDSB) sports a cocktail of characteristics that requires you to be very much awake on landing, including a 1750 ft elevation, a 1.4% runway gradient (1.7% in places even), notorious rotors and turbulence on all approaches, summer temperatures well above 30 degrees Centigrade – and a tight 1600 by 30 meter runway that often gives bother to business turboprops and jets, let alone the occasional airliner. On this day however, the stars of the show were the lighties, here a typical “summer holiday mix” of aircraft from Hungary, Romania, Germany and Slovenia. Type-wise, there was a lot to choose from as well, with just this lineup boasting one of the more powerful Morane variants, the Mudry CAP-232 aerobatic single-seater… as well as six-cylinder Mooney and a mint Skyhawk that – despite being 35 years old – looks like it had just rolled of the production line.

Taking a quick stroll through Varaždin’s (LDVA) small corrosion corner. Already disused and mostly abandoned prior to having been flipped over in a storm in 2012, CDZ is one of Croatia’s oldest Skyhawks, manufactured way back in 1967. Unfortunately, despite quite a bit of history in its logbooks, this is as far as it will ever get, since repairing it would actually cost more than buying an airworthy late 70s/early 80s example. Indeed, the extensive buckling down the tail (evident on both sides) is a telltale sign of major structural failure in the underlying load-bearing frame, requiring the whole back end of the airplane to be replaced at the very least. Though it had, damage-wise, fared much better, the country’s sole PA-28-235 hiding in the background – and registered, rather ominously, 9A-DIE – is pretty much in the same boat. Completed in 1965, it too had not seen much air these past few years, and looks to be another candidate for a “Coke bottle conversion”…

Just when I thought I’d used up all of my luck for finding rare piston singles, I stumble upon this magnificent Sierra at little old Lučko. Fairly atypical by the standards of the company, the Sport/Musketeer/Sierra family was Beech’s attempt at replicating the success of Piper’s legendary PA-28 Cherokee series. Standing at the top of the lineup, the 24 Sierra was essentially a 200 HP Musketeer with retractable gear that had hoped to take on the extremely popular PA-28R Arrow. Sadly though, none of these models had managed to make a significant impact on the market, partly because they were made to Beech standards – and therefore more expensive – and partly because this segment of the market had never really been the company’s forte. But more on the 24 in a separate post!

Though we had already met before several years ago, it is nevertheless always nice to see this old trooper once again. One of the very few early 206s still flying in Europe, HA-CPA celebrates its 50th birthday this year, a fact that had not – in true utility Cessna tradition – prevented it from working hard well into old age. Many moons ago actually a resident of Croatia, CPA had on this day popped into Lučko for a state skydive championship, for which it was the sole official dropship. An interesting detail is the pronounced chin under the nose, a leftover from the early Cessna 210 on which the 206 is based that had housed the 210’s nose wheel when retracted (a bit more info available here).

In common with many Cessna models of the 60s, CPA’s flight deck is, by modern standards, a jumbled mess – but it nevertheless does have a certain odd charm. Interesting details are the flap position indicator (partially obscured by the right yoke) with color-coded fields representing maximum flap extension speed – and a Soviet EGT gauge below the CDI, apparently salvaged and reused from a light transport twin (possibly even the An-14).

Taking a short breather on Croatia’s sole truly private airstrip. Nestled in rolling terrain 20-odd kilometers south of Zagreb, Pisarovina Airfield counts among the more scenic places to land at in the area, ringed by dense woodland and the Vukomerić Hills to the north, vast arable fields and fisheries to the south – and airliners on approach to Zagreb Airport (ZAG/LDZA) above. Indeed, the airfield is within spitting distance from both ZAG’s control zone and the Pisarovina NDB – the focal point for all approaches to RWY 05 – making getting in and out quite a fun and refreshing experience. Though several aircraft – and even a flight school – are based here, on this day we were the only plane in town, which made us feel a bit… conspicuous…

A short & sweet additional feature to accompany the photo above: a “dash cam” video of the approach to and landing on Pisarovina’s RWY 04… a fair bit of thermal turbulence that day, but what can you do (also, the camera shake on landing is exaggerated – the runway is relatively smooth, but the camera was mounted on a suction mount on the windscreen, which is flexible and tends to wobble about with every bump).


Photo Report – Going Up: Cessna U206G 9A-ADV

By me
All photos me too, copyrighted

Given that a number of my topics of late – Dash 8 flight simulators, 80s airport charts and the like – have strayed quite a bit into “commercial airspace”, I felt it would be about time to dip back into the little world of Croatian general aviation :). Even though the flying season has been slow to start this year – with aerial activities still sporadic at best – I’ve nevertheless quickly managed to find the perfect ticket for the job: a short, but pleasant afternoon shoot with one of the newest lighties on the country’s register, Cessna U206G 9A-ADV

While a 206 in itself is (rarity-wise) nothing to write home about, this particular machine represents by far and away the most complete and best-equipped piston skydive platform in the country, which all on its own warrants some additional scrutiny :). Owned by local operator Adventure Driven Vacations (which pretty much does what its says on the tin), ADV is also a prime example of the last of the “old generation” Stationairs, having rolled off the production line in 1983 – just a short while before all piston single production at Cessna would go into a decade-long remission. Bestowed with serial U206-06796, it had actually been a seaplane in its original form, and would be known as N9986Z until 1988. Sold on to Norway in August that year, it would quickly become LN-AEZ and would – still on floats – continue to fly with a slew of local operators right up until its acquisition by ADV in March of 2013.

Before its move south, AEZ would first be converted into a conventional land-plane model, and then dispatched to Portugal (under its own power) to be re-fitted and equipped into a dedicated jump plane. Once the works were completed in July 2014, it would make its way (again with no “outside assistance”) across half the Mediterranean to Croatia, where it would then become only the fourth 206 currently on the register 🙂 (interestingly, this little group also contains a “new gen” 2006 U206H… as well as a fantastic 1966 P206B Super Skylane, the progenitor of the modern Stationair).

Even though it had been in-country and operational for close to nine months now, its normal base at Zemunik Airport (LDZD) – serving the coastal town of Zadar – had meant that it was generally out of range of my camera. However, the current dearth of skydive machines here at Zagreb had forced it inland, proving once more that if the photographer can’t go to the plane, the plane will come to the photographer… 😀

Looking splendid (and quite eye-catching) in its new colors as it cools down following the last flight of the day. A significant capacity increase for the Croatian skydive scene, the 206 is quite a step up from the more usual 182s and occasional 185...
Looking splendid (and quite eye-catching) in its new colors as it cools down following the last flight of the day. A significant capacity increase for the Croatian skydive scene, the 206 is quite a step up from the more usual 182s and occasional 185…

Central to ADV's successful use as a skydive platform, the mods installed in Portugal include a sliding cargo door for easier egress, as well as several handles and steps to facilitate group jumps or tandems.
Central to ADV’s successful use as a skydive platform, the mods installed in Portugal include a sliding cargo door for easier egress, as well as several handles and steps to facilitate group jumps or tandems.

The interior is - by necessity - pretty spartan, since skydive ops are not really kind to fancy upholstery! Note also the two black panels (one set against the copilot's station and one folded down behind the pilot's seat) which permit skydivers to leisurely lean back during long climbs without fear of interfering with any of the aircraft's controls.
The interior is – by necessity – pretty spartan, since skydive ops are not really kind to fancy upholstery! Note also the two black panels (one set against the copilot’s station and one folded down behind the pilot’s seat) which permit skydivers to leisurely lean back during long climbs without fear of interfering with any of the aircraft’s controls.

Like virtually all other skydive 206s, ADV accommodates six skydivers in addition to the pilot. Their sitting locations determine the sequence for jumping, which is further indicated by the note on the aft bulkhead.
Like virtually all other skydive 206s, ADV accommodates six skydivers in addition to the pilot. Their sitting locations determine the sequence for jumping, which is further indicated by the note on the aft bulkhead.

In addition to a full IFR suite w/ autopilot, the nicely equipped panel also includes several useful features for skydive ops, including a moving-map GPS (great for putting the jumpers right on target), EGT and CHT gauges (to avoid overheating the engine during prolonged high-power climbs in hot weather) - as well as a stormscope for avoiding summer CBs common in the region. An interesting detail are the two windshield crossbeams, a leftover from ADV's seaplane days (also my apologies for the glare, the sun was low and I couldn't bear to nag with re-orientating the aircraft).
In addition to a full IFR suite w/ autopilot, the nicely equipped panel also includes several useful features for skydive ops, including a moving-map GPS (great for putting the jumpers right on target), EGT and CHT gauges (to avoid overheating the engine during prolonged high-power climbs in hot weather) – as well as a stormscope for avoiding summer CBs common in the region. An interesting detail are the two windshield crossbeams, a leftover from ADV’s seaplane days (also my apologies for the glare, the sun was low and I couldn’t bear to nag with re-orientating the aircraft).

Another remnant from ADV's seafaring days are the vortex generators, located along the upper leading edge of the wing and just in front of the rudder on the vertical stabilizer. By creating a turbulent flow of air just along the surface, they cause the flow to stick to said surface for longer than it normally would, enhancing its aerodynamic properties (at the expense of increased drag). On a seaplane they counter the various pitch and roll moments created by the floats (located well below the CG); on a landplane, they translate into reduced take-off and landing rolls, a lower stall speed and better stall response - and generally improved handling at high Angles of Attack (during low speed and/or high weight conditions).
Another remnant from ADV’s seafaring days are the vortex generators, located along the upper leading edge of the wing and just in front of the rudder on the vertical stabilizer. By creating a turbulent flow of air just along the surface, they cause the flow to stick to said surface for longer than it normally would, enhancing its aerodynamic properties (at the expense of increased drag). On a seaplane they counter the various pitch and roll moments created by the floats (located well below the CG); on a landplane, they translate into reduced take-off and landing rolls, a lower stall speed and better stall response – and generally improved handling at high Angles of Attack (during low speed and/or high weight conditions).

Also frequently seen on seaplanes, wing fences prevent the horizontal spill of air across the span of the wing, making the airfoil far more efficient. Interestingly, ADV's seem modified, since on all 206 floatplanes that I've seen they extend forward across the wing for at least half its chord...
Also frequently seen on seaplanes, wing fences prevent the horizontal spill of air across the span of the wing, making the airfoil far more efficient. Interestingly, ADV’s seem modified, since on all 206 floatplanes that I’ve seen they extend forward across the wing for at least half its chord…

Repainted into the operator's
Repainted into the operator’s “house colors” in December 2014, ADV certainly stands out on the apron. The more eagle-eyed readers will also have noticed that the aircraft now sports the U206’s standard cargo doors; with the skydive version not being the most thief-proof option, the standard set is installed for each over-night stay out in the open.

Always a brutish looking thing, ADV's high-contrast scheme makes it look even more purposeful and powerful.
Always a brutish looking thing, ADV’s high-contrast scheme makes it look even more purposeful and powerful.

I would also like to extend my sincere thanks to my flying colleague Mario Car – one of ADV’s pilots – who had given me a heads up and spent some time answering my nerdy Achtung, Skyhawk! questions!

Other sources:

  • Seabee.info – Norwegian seaplane database (LN-AEZ service history)