King Air Rules – OK?

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Still in production after five decades, the King Air combines modern technology with the traditional qualities that remain the essence of its greatness

Early in the 1960s, Beechcraft developed a twin-turboprop concept based on the piston-powered Queen Air. In 1964 the new type entered production as the King Air and a variety of models followed – speaking to EVA in October, Tom Perry, Textron Aviation’s Vice President of Sales, Europe, said more than 7,300 had been delivered and noted: “Over the years, the King Air products have continually been improved and upgraded to meet the evolving needs of customers and the market.”

​In more than 50 years’ production, the King Air has changed ownership at least three times. During the early 1980s, Beechcraft became a subsidiary of Raytheon, the abbreviated form ‘Beech’ coming onto regular use, while product development proceeded as previously.   Today, Beechcraft sits alongside Cessna under Textron Aviation, the two distinct product lines enabling Textron to offer the widest range of business aircraft options on the market, from the Cessna Skylane, through the company’s single-engined turboprops, to Beechcraft’s King Air and on to the Citations.

​Current models

The current King Air range includes the eight-passenger C90GTx, in the classic configuration with low-set tailplane, and offering 1,260nm of range. The T-tail is introduced on the King Air 250, which flies a maximum of 1,720nm and seats ten passengers. Both the King Air 350i and 350ER accommodate a maximum 11 passengers, the 350i covering 1,806nm, while the 350ER’s additional fuel capacity takes it out to a whopping 2,692nm.

​All four models employ Pratt & Whitney Canada’s PT6A turboprop, the 550shp PT6A-135A powering the C90GTx, with the 850shp -52 in the King Air 250, and 1,050shp -60A in the 350i and 350ER.

​Rockwell Collins Pro Line Fusion avionics are standard across the range and although the cabin doesn’t offer stand-up headroom, seated passengers will find it extremely comfortable, the large windows making for a bright interior and carefully designed vibration absorbers maximising ride comfort on the C90GTx. The larger models all feature electronically dimmable window shades and Wi-Fi is a standard fit on the 350.

​Perry is excited about the options the King Air range offers customers. “Each model is well suited to meet the needs of a particular range of missions. They offer unique performance capabilities, cargo and cabin space, and can be configured to best meet customer needs. Charter operators and membership companies, including Wheels Up, rely on the King Air 350i for example, with its comfortable and productive interior. While the King Air 350ER, with its extended range and additional payload, is often used for special missions, including air ambulance and surveillance.”

​That special mission capability has proven particularly attractive to military customers over the last decade or so, expanding on a long tradition of military King Air applications and, Perry noted: “The use of the King Air in the worldwide military and special mission market place has proven and enhanced the ability of the aircraft to perform in challenging and rugged environments. The civil market has greatly benefitted from improvements in payload and increased reliability and durability as a result.” He was careful to note that these enhancements complement additional work directed specifically at the civilian market.

​These improvements add to an already respected passenger experience; Perry confirmed: “King Airs are renowned for their comfortable cabins. Standard features include inflight-accessible baggage, adjustable seats, pull-out worktables, power outlets, a refreshment centre and a belted lavatory, while proprietary sound proofing technologies provide passengers with a quiet, comfortable ride. The King Air also offers Wi-Fi capability, which is standard on the King Air 350i, allowing passengers to stay connected in flight.

​Modern marketspace

The marketspace in which the King Air competes has evolved immensely over five decades of production. Comparisons by price and/or capability reveal competitors in the single-turboprop, twin-turboprop and light jet categories. Yet Perry is confident of the type’s position: “When comparing similarly priced jets and turboprops, a turboprop often offers a larger cabin, more payload capability and superior runway performance to the jet. But Textron Aviation recognises that each customer has a unique mission and therefore offers a full range of jets and turboprops to best meet customer requirements.”

​Considering its single-engined turboprop competitors, Perry said: “The King Air series offers many advantages, including twin-engine redundancy, superior runway performance, faster climbs, more payload capability, a larger cabin and higher cruise speeds. But for those customers who prefer a single-engine turboprop, we offer the Caravan, Grand Caravan EX and all-new, high-performance Cessna Denali.”

Direct competition in the twin-turboprop space is sparse, but notably includes Piaggio’s Avanti EVO, an aircraft renowned for its high performance and dramatic design. The Italian machine is undoubtedly making progress and winning sales, but Perry reported: “According to market delivery data, turboprop customers have already purchased more King Airs in 2017 than all Avanti sales in the past eight years combined.”

Nextant upgrade With more than 7,000 built, plenty of older King Airs remain in service and a healthy upgrade and refurbishment industry has grown up around the type. For its part, “Textron Aviation offers many aftermarket upgrades through its service network, and works to provide upgrades and improvements to ensure the aircraft are meeting the needs and expectations of customers. These upgrades are also available to those who purchase or modify older aircraft,” Perry said.

​Otherwise, Nextant has developed the Nextant G90XT modification, certified for application to the C90A King Air and more recent models. The type faces similar competition to the new-build aircraft, with the added challenge of the OEM’s C90GTx. Jay Heublein, Executive Vice President at Nextant, says: “Relative to the C90GTx, the G90XT adds digital pressurisation, a new environmental system, and new cabin design and technology, plus General Electric H75 engines and an advanced power control system. Together, they bring considerable performance benefits… and lower operating costs!” As for the Avanti EVO, Heublein reckons: “It’s a different category; you’re comparing a $2.8m aircraft to a $7m+ proposition. I think they’re attractive to different consumers.”

​Nextant’s choice of changing engine rather than upgrading to a more powerful PT6A is interesting. Heublein explains: “The aircraft is limited to 550shp and the GE engine is derated from 850shp – it’s the most powerful engine ever installed on this variation of the airframe. The H75 carries much more power at altitude, which is why you see our 20kt speed advantage relative to the current production aircraft. But most importantly, the GE engine is the only one to offer the new power control system and that’s the absolute game changer.”

​Delivered through an electronic engine control (EEC), the power control system also facilitates an auto-start function. Heublein says: “The real world benefit is enormous – it gives complete exceedance protection (over-temp, over-torque) and linear power application. The prop control goes away and you fly the plane like a jet!”

​A new Garmin avionics suite goes into the G90XT cockpit, while in the cabin, Heublein says: “Our customers are looking for a more bespoke interior that more closely resembles a high-end jet interior vs the typical turboprop cabin that has been available to date. The options for connectivity are identical to those we offer in our jet programme.”

​Post-delivery, Heublein says Nextant offers dedicated 24/7 product support and “the largest AOG network in the industry”. Looking to the future, do the King Air B200 or 250, or even the early-model King Air 300/350 make sense as a focus for the Nextant touch? A canny Heublein responds: “We just announced the Challenger 604XT programme, so I think we have enough to focus on for the next six months… You’ll have to wait and see after that!”

Blackhawk power

For Waco, Texas-based Blackhawk Modifications, King Air upgrade has always been about engines, sticking with the PT6A, but delivering more power to the airframe. Regional Sales Manager and King Air pilot Chris Dunkin explains: “We take a higher-horsepower PT6A and install it on the aircraft. The relationship with Pratt & Whitney Canada began with the Cessna Conquest I, equipped with PT6A-112 engines, which Blackhawk replaced with the -135A. The modification was popular, so we looked for another avenue for the -135A.

​“In the early 1970s, Ed Swearingen had developed the Taurus modification for the King Air C90 and Blackhawk bought that STC, flat-rating the 750shp engine to match the airframe’s 550shp rating. Today we give operators and owners the option of having their factory-fresh aircraft modified, or of having their older aircraft re-engined at close to the same cost, or sometimes better than having the original engines overhauled.”

​Beechcraft might well have spoiled Blackhawk’s party, at least as far as new C90s were concerned, when it released the -135A engined C90GT in 2005, but many E90 and F90 aircraft were extant and business remained brisk. The engine upgrade improves cruising speed and climb rate, but also delivers savings in direct operating cost. “If you look at the time put on an airplane, direct operating cost over a period of time comes down with the reduced hours you fly if you’re going faster.

​“Some customers choose to have an engine ‘event’ and change immediately, but for others the argument for waiting until overhaul is compelling. Because we buy a lot of engines we offer attractive prices. Engines become due for overhaul at 3,600 hours, that typically represents ten to 15 years of operations, and incorporating all the service bulletins released during that time, on top of doing the overhaul, can be really expensive. That means changing them might be a better option than upgrading, especially since a used airframe with factory new engines is a far more attractive option than the same airframe with refurbished units.

​“As new equipment, the engines also qualify owners for tax depreciation bonus and that can be attractive if the aircraft itself has already been depreciated. And, if someone chooses to upgrade from engines with time before overhaul remaining, we give them credit for that time!”

The engine-change process in itself is relatively straightforward. Dunkin says minor engineering changes and a few additional parts are involved, plus the addition of “… a modern analog/digital engine gauge stack” replacing the original instrumentation. Otherwise, the same engine mounts and cowls are employed.

From a piloting perspective, the difference in performance is immediately noticeable, especially from more challenging strips. “Take the C90 with the 550shp -21 engine. The -135A delivers 750shp, but flat rated to 550shp, which for the pilot comes down to markings on a gauge. Maximum rpm for the -21 is 2,200, for the -135A it’s 1,900, delivering more torque with less noise. But here’s the big issue. On the -21, maximum ITT [interstage turbine temperature] is 695°C, with the -135A it’s 805°C; at sea level on a standard day, they both develop 550shp, so performance is the same until you climb out and reach the temperature limit on the -21, but not on the -135A, which delivers the same power at altitude.

​“Now consider Gunnison, Colorado, up at 7,000ft, where the -135A will give you much better take-off performance on a summer day. And much better single-engine performance, so now you’re looking at safety factors too. Basically, on hotter days, at higher altitudes, you can pull more power and there are no payload restrictions.”

​Blackhawk offers a similar programme replacing PT6A-41s with -42s on the King Air 200, and then, after Beechcraft introduced the -42 on the B200, it added a new product, switching the 850shp -42 for the similarly-rated -61, albeit with a higher thermodynamic range that delivered all the benefits of the -21/-135A Model 90 modification. Then the Model 200GT emerged with the -52 engine, which Pratt & Whitney Canada eventually offered to Blackhawk as a replacement for the similar -61.

​In a graphic illustration of the performance benefits of the -61/-52 over the -42, Dunkin offers fuel flow. “It equates to 2,000ft in cruising altitude. If you’re flying at 26,000ft with the -42, for the same fuel flow you’re at 28,000ft with the -61 and going 20 or 25kt faster.” Now Blackhawk has turned its attention to the King Air 350, re-engining with the 1,200shp -67, derated to the airframe limit of 1,050shp.

The same, but very different

The King Air has come a very long way in terms of design evolution, yet at the same time has changed very little, at least on the outside. So what would a 1965 King Air 90 customer find most different about a 2017 C90GTx? And what features would be familiar?

​Perry reckons: “The improved King Air C90GTx incorporates many new technologies to offer better runway performance, faster climbs and cruise, increased payload, a more refined cabin and more powerful avionics. Upgrades include an 895lb increase in take-off weight, new, swept propeller blade technology, improved aerodynamic features and the upgraded PT6A-135A engine, offering a standard horsepower of 550. The 2017 King Air C90GTx cruise speed has also increased to 270kt, from the original 217kt. But the 1965 customer would recognise the legendary, trusted reliability, quality and service for which the King Air brand has been known for decades.”