November 14, 2019

July 25, 2019

Please reload

Recent Posts

ZS-OFH gets her Prop Overhauled

July 21, 2017

1/10
Please reload

Featured Posts

Pilatus PC 24 - Love at first sit

November 19, 2018

Pilatus have dubbed their new PC-24 the ‘Super Versatile Jet’. Just how closely does the reality match their promise?

 

 

 

The PC-24 is the logical outcome from Pilatus’s phenomenally successful PC-12. With sales of more than 1,600, the PC-12 single engine turboprop broke the mould that said corporate aircraft had to be multi-engine. Equally, the PC-24 refutes the paradigm that bizjets must operate from long, hard-surfaced runways.

 

Pedigree and positioning:

The Swiss are not known for messing with a successful formula, so the PC-12 design has remained remarkably unchanged for the 24 years it has been in production. The huge success of the PC-12 laid the foundation for Pilatus to develop a step-up product, and customers had indicated that they wanted a Pilatus with a greater range and top speed than the PC-12, while retaining its overall ruggedness and rough runway capability. So when Pilatus first announced the PC-24 in May 2011, many in the aviation world expected it to be little more than a turbofan-powered version of the PC-12, which would have placed it in the already overcrowded ‘small jets’ market segment.

In October the first PC-24 arrived in South Africa. We put it under the microscope – and found that it really is in a class of its own. Its ability to operate into and out of unprepared runways, and its amply-proportioned cabin places it more comfortably into the utility midsize jet niche; which is quite sparsely populated now that the G150, Hawker 900XP and some of the midsize Citations are no longer in production. And the PC-24 is not only suited to the bizjet-traditional metropolitan airports, but also satisfies the far more demanding requirements of users in Africa and other developing countries. This alone made it worth a closer look.

 

Operational features:

When the PC-24 was certified in December 2017, Pilatus promised that its functionality would allow operators to fly closer to their final destinations, use smaller airports and reduce ground transfer time when compared with most other business jets.

Unlike other bizjets that need to be ‘ruggedised’ for off-road work, the PC-24 was designed from the outset for unprepared runway operations. The robust double-wheel trailing link main gear has large tyres and each wheel is fitted with a triple disc brake for rapid stopping on short strips, and the nosewheel tyre also comes standard with a water-chine to deflect the softer stuff from the runway away from the underside of the aircraft. Its Williams FJ44 turbofan engines are high-mounted aft on the fuselage to keep them clear of whatever debris the wheels kick up and its large flaps have heavy-gauge aluminium on their under surfaces.

While each wing can be fuelled via an over-wing port, the PC-24’s operational capability extends to a convenient single-point refuelling aptitude and also its thoughtful externally-placed ‘potty servicing’ point, both of which minimise ground turnaround time and also disruption to cabin residents – aka the well-heeled pax.

On the subject of the cabin, like its utility PC-6 and PC-12 siblings, the interior of the PC-24 was designed for quick and easy reconfiguration. Each passenger seat has a quick-change capability enabling its addition or removal in just a few minutes, and the cabin can be configured into six or eight seat ‘executive’, ten seat ‘commuter’ seating, cargo only or combi with minimum turnaround time. The aft partition is also movable so either the passenger cabin or the baggage compartment volume can be enlarged for each flight. This versatility means that should the aforementioned pax wish to take their jet skis with them to that rough, dirt-runway hideaway island in the Maldives, the PC-24 is up to the task.

Onboard APUs are virtually a must on any midsize jet with executive aspirations, but once start-up is over, they become deadweight and reduce the aircraft’s load-carrying capability. So Pilatus worked with engine suppliers Williams, and developed a Quiet Power Mode (QPM) functionality for the right engine. This reduces ground-idle rpm on the engine to the point where it’s just enough to provide sufficient electrical power to drive the air conditioners, internal systems or electric cabin heaters without the need for an onboard APU or ground power. When engaged, QPM is also quieter than an APU – which should keep the airport noise abatement people happy.

 

The Walkaround

ZS-YTB is being managed by ExecuJet South Africa. We first met the 24 on its arrival at Lanseria Airport and then had the opportunity to study it in detail before its ExecuJet Cape Town launch.

At first glance my pilots eye noted that for a utility aircraft it’s sleek. Every structural ingredient seems to be integrated into the whole; and thinking of its PC-6 and PC-12 siblings, my immediate reaction was that it doesn’t look Swiss at all. Its styling has a Euro-Latin flair with very little Teutonic utilitarianism, other than the dorsal strake, which was a tad squared off and solid.

A few steps towards the wingtip disclosed the flush integrated LED wingtip lights and the interesting wing planform with a perpendicular-to-the-fuselage, straight trailing edge and a cranked leading edge which begins quite steeply swept at the root and reduces sweep-back about a third along the span. The wing posed a hefty problem for Pilatus design engineers who had to meet a target cruise speed of 440 KTAS and a landing speed of less than 100 KIAS and the resulting variable sweep leading edge and a large flap trailing edge was the solution.

Like a Swiss army knife, function has been integrated with form. The baggage door follows the PC-12 standard and is huge, by that I mean pallet-sized huge. It’s a unique feature on a bizjet. The door  slots neatly into the space between the LH engine nacelle and the wing trailing edge – no problem loading those jet skis. Also, the main gear is quite far aft of the CG to facilitate a stable stance, without a tail stand, while loading heavy cargo via that massive cargo hatch, and as a bonus, the wing’s right-angled trailing edge provides an unimpeded path for cargo-loading vehicles.

Then I noticed the flaps. Quite simply, they’re enormous – not quite barn doors, but suffice to say that Cessna pilots would be quite at home with them. The flaps are particularly titanic when viewed alongside the ailerons, which are quite dinky by comparison, this raised some low speed handling questions – but more about this when we go flying.

A slow second walk around the fuselage revealed the air conditioning vents under the engine nacelles, the single-point refuelling port ahead of the RH leading edge and the flush-mounted hatch for the potty servicing point. A U-turn past the sleek nose brought me to the airstair boarding door which has a sturdy side handrail and a telescoping support strut that, in true Swiss tradition, thoughtfully avoids the irritating entanglement issues when a windy apron causes havoc with support chains or cables. A few quick steps up the stairs brought me into the PC-24’s comfort zone.

 

The comfort zone:

My first impression of the cabin was that it’s much roomier than the plane’s apparently modest exterior dimensions had led me to expect. The second impression was that it reeked of luxury – I mean that literally. The cabin odour was that rich leather incense of a new Rolls Royce or a bespoke saddle-maker’s shop and it was a perfect match to the bouquet of a ’96 Dom Perignon.

The PC-24’s cabin windows are the largest in its class and they’re well-placed for outside viewing. Along with upwash, downwash and aisle lighting, they also contribute to making the cabin appear more spacious than its dimensions, even though it has a flat floor rather than a drop-aisle setup.

ZS-YTB is configured in double-club eight-seat ‘executive’ arrangement. All the seat pairs have fold-out working tables, their own power outlets and an overhead passenger service unit with a discreet reading light, eyeball airflow vents and a drop-down oxygen mask. Lined side pockets in the seats provide occasional storage for personal items like smartphones. The seats are also multi-way adjustable, including a pop-out calf support or footrest; and all the cabinetry, interior doors, bulkheads and cabin fittings are sheathed in mirror-gloss wood veneer – probably Swiss Maple or Ash – I’m unsure which, but it looks exquisite.

There is a convenient coat closet immediately behind the pilots seat. The toilet is forward, aft of the flight deck and solid partition doors on both the cockpit and the cabin side can be closed to provide privacy. The toilet is also discretely concealed as a pull-out unit below the vanity mirror and the washbasin, which, I’m told, dispenses its water at a comfortable 32 degrees centigrade.

The PC-24 has no dedicated galley, but it does have insulated storage units forward of the cabin to house the Swiss cheese, biscuits, Perrier water and the aforementioned Dom P.

 

The pointy end:

The convenient grab handle in the flight deck upper binnacle was a great help to get my slightly arthritic six foot two ensconced into the RH seat, but once there, it was love at first sit. The crew’s seats have adjustment for height, track, and recline as well as headrest height, thigh and lumbar cushion support, so it was a doddle to get comfortable. My long legs were not an issue either because the rudder pedals are adjustable via a little crank handle between them. The view from the pilots’ seat is excellent though the broad, swept front and side screens and the very slim pillars barely impede a 270-degree visual sweep.

But it’s when I focused my attention below the glare shield that the PC-24 finally revealed its Swiss origins. From left to right the fascia panel is Teutonically clean, uncluttered, logical and pilot-centric. The flight deck ergonomics are the best I’ve ever seen. The ‘ram’s horns’ yoke is exactly where it should be, and every control is predictably placed, falls naturally to hand or eye; and ‘normal’ is 12-o-clock for knobs, up for switches and forward for levers. If I have a minor criticism, it’s that the thrust levers (the PC-24 has auto-throttles plus TOGA button so they’re not ‘throttles’) are a tad too far back on the centre console for my creaky shoulder joint and it takes a neck twist to see the flap lever which has detents at zero, eight, fifteen and thirty-three degrees.

The good stuff happens across the four 12-inch glass screens which display the functions of the Honeywell Epic 2.0 avionics and, to talk me though them, I was joined in the left seat by a senior pilot and PC-24 guru.

The PC-24 is certified for single-pilot operations and its Advanced Cockpit Environment (ACE) is a close fit to that of the PC-12, so the upgrade path for flight crew is a relatively easy one. All the functions in the avionics suite are selectable via direct ‘select and click’ or the pilot can step though them via a button on the yoke. I found the menu system, via the keypad below the centre screen, to be intuitive and each function is accompanied by an appropriate graphic display on the large centre screen, so the crew can verify the correct configuration or functionality.

An interesting facet to the avionics and a contributor to the uncluttered appeal of the cockpit is that there are only a few mechanical circuit breakers to protect essential systems, and these are placed behind the pilot’s left elbow on the side panel. Most of the electrical systems are protected by electronic ‘virtual’ breakers which can be selected and re-set via the click function on the yoke button. A few of these virtual circuit breakers, however, are ‘protected’ and cannot be re-set.

The ACE uses the standard Honeywell Epic hub and spoke layout with dual modular avionics units at its centre. The system has dual KTR 2280A multi-mode digital nav/comms plus UHF glideslope receivers and a single ADF unit. The avionics also includes a KN-63 DME and dual satellite-based augmentation system (SBAS) GPS receivers which are true multi-sensor in that they accept inertial reference system (IRS), GPS, DME and VOR inputs. A radio altimeter, weather radar, TCAS and ELT round off the avionics package.

The ACE makes the use of its own pre-flight checklist mandatory and I easily tracked though the pre-flight ‘click and verify’ steps before getting onto the big question – what’s it like to fly?

 

Flying the PC-24

Start-up is easy, it’s merely a case of selecting Run on the overhead Run/Stop button and pushing the start knob, after which the dual-channel FADEC takes care of the light-up. Once the systems say that all is turning and burning as expected, taxiing is simple as the response to rudder inputs is crisp and positive, but differential thrust and braking helps for the tighter turns.

According to its pilots, the PC-24 delivers more than the book says it should, in fact, it’s either conservatively under-spec’d, or its been over-engineered. You immediately notice this when you advance the thrust levers for takeoff as the push in your back is unexpectedly impressive – you’re left in no doubt that this is an aircraft designed with the necessary get-up-and-go for short-field operations.

At Vr, a man-sized pull is needed to rotate – because of that aft of CG location of the main gear – which causes a mild tendency to over-rotate, so a brief check forward was needed. Once climbing away, even at low speed, you feel immediately that control harmony is near-perfect with light and balanced response to both pitch and roll inputs. Spoilers on the upper wing surface assist the dinky ailerons to maintain positive roll effectiveness. However, I was told that at high speed, the roll control becomes heavy while pitch doesn’t become quite as heavy, creating a minor control disharmony. The electric spoilers are missed at higher speeds.

The engines are fitted with Williams’ passive-thrust vectoring exhaust nozzles which use Coanda effect to give up to three degrees of thrust vectoring at high power operations, and this means that, despite the high thrust line, idle-to-maximum thrust changes produce very little pitching moment. The result is that control in steep turns is stable and manageable. Another indication of just how underrated the plane is, was that on the delivery ferry flight, south of Aswan, its rated 45,000 foot service ceiling was tested and it was still climbing at 700 ft per min at that altitude.

Any flight test should include a comment on the aircraft’s stall characteristics, but in the case of the PC-24, this is simply a non-event. In the landing (dirty) configuration, the stall warning (stick shaker and red lights) is triggered at 83 KIAS and the stick pusher fires at 78 KIAS. The pre-stall behaviour as well as the stall are benign and straight forward with no hint of wing drop or adverse yaw and an altitude loss of only a handful of feet.

Another non-event was the airbrakes – my first impression that this plane is sleek and doesn’t lose speed easily was confirmed – as application of the airbrakes only produced a progressive decrease in velocity without the expected feeling of ‘hitting a brick wall’. The flaps, however, are exactly the opposite. Extend those barn doors and you’re left in no doubt that this is a short-field aircraft as the slowing effect is very noticeable. The PC-24’s PC-6 lineage becomes immediately apparent on the landing approach which is slow, stable and predictable and you are comfortable that those big triple-disc brakes will stop you safely inside the MLW-rated 725m.

 

How does it stack up?

Anyone shopping for a PC-24 would be in the price bracket that includes the Embraer Phenom 300 and the Citation CJ4 and, based on manufacturers figures, on price alone, the PC-24 at US$ 8.9m would score over the Phenom 300 at US$ 9.2m and the Citation at US$ 9.4m.

That said, aircraft designers always aim for exceptional results across the board, but the laws of aerodynamics and physics rule that it’s rare for any one aircraft to do all missions with equal efficiency. When it comes to aircraft design, trade-offs are a reality. So what are the trade-offs that Pilatus made to get the PC-24 ahead of its price competitors?  The major trade-off appears to be in speed; as the 453 knots of the Phenom 300 and the 451 knots of the Citation are ahead of the PC-24’s 440 knots.

The range of the PC-24 has also been quoted as a trade-off, but the manufacturer’s figures from all three have no common basis for comparison and I had to resort to figures published by Conklin and Decker who show the Citation at 1,991-nm, the PC-24 at 1,950-nm and the Phenom 300 at 1,937-nm. There is not a lot between the three, particularly as in the real world, average missions are usually significantly shorter than the maximum possible range.

The PC-24 is a much roomier plane than the other two. I mentioned earlier that its more ‘mid-size’ than small jet and the manufacturer’s cabin volume specs are a clear indication; as its 501 cubic ft scores far ahead of the Phenom 300’s 324 cubic ft and the 311 cubic feet of the CJ4.

So, to summarise, it’s a mid-size jet with a small jet price, speed and range; and, with its distinctive characteristic of short-field unprepared runway capability, it creates a new class of business jet.

 

So what do we think of the PC-24?

This is the most difficult question of all for me to answer, as it’s hard to be objective and not ‘gush’ about an aircraft this well-designed, pretty, functional, and from a pilots’ perspective, ergonomically near perfect and balanced. Operators will approve of its versatility, economy and broad operational scope, as it opens destinations previously unvisited by jets. And pax will love its thoughtfully crafted, cosseting and spacious cabin.

The PC-24 lives up to the promise of being a ‘super versatile jet’, and is without doubt, in a class of its own. – so what’s not to love?

Share on Facebook
Share on Twitter
Please reload