In this episode, we’re talking turboprops with the King Air 90 series. Plus aircraft ownership news, the tip of the week and your feedback.
King Air 90 Series Notes
The King Air series of turboprop aircraft is perhaps one of the most popular airplanes on the ramp. Pilots of all skill levels and owners of all types admire the look and the legend that defines a King Air—and the King Air 90 is certainly no exception. As one of the most affordable entry-level turboprop aircraft, the 90 series can be found in the hands of owner-pilots, small businesses, corporate flight departments, charter operators, and even the military. With more than half a century of proven performance and reliability, it’s no wonder the King Air 90 is still one of the most sought after aircraft on the market. The latest generation of King Air 90s, called the King Air C90GTx sells in the ballpark of $2 million, but fortunately there are many variants of the King Air 90 to fit virtually any mission and almost any budget. You can pick up a well-equipped early model C90 for about $450,000.
But the King Air 90 is not the only aircraft in this category of medium twin-engine turboprops. The 90 series competes almost head-to-head with other turboprops including the Cessna Conquest, the Turbo Commander, Mitsubishi MU-2, The Piper Cheyenne, and Piaggio P180. It’s even a contender with more modern single-engine turboprop aircraft such as the Pilatus PC-12 and the TBM850 and many light jets. But there’s clearly a reason behind the King Air 90’s fifty years of success. Sure, it’s the looks, performance, power, and capability, but that’s only half the equation. The aircraft also has a great safety record, an excellent reputation for dispatch reliability, low operating costs, and maintenance support.
Today there are more than 3,000 King Air 90 and 100 series aircraft flying. It was the first aircraft in its class and has been in continuous production since 1964. As a result, it’s quite possibly the most recognized general aviation aircraft on the ramp. In fact, the King Air 90 series was originally developed as a turboprop version of the Queen Air first fitted with Pratt & Whitney PT6A-6 engines. The modified Queen Air test aircraft was known as the Model 87 and first flew in 1963. After nearly a year of testing, the first Model 87 was delivered the US Army. In the beginning of 1965, the King Air Model 65-90, the first definitive prototype, was built.
In 1966, the King Air 65-A90 came to be equipped with PT6A-20 engines. Over 200 were built by 1968 before production of the B90 began. The B90 saw an increased wing span, improve aileron design, a gross weight increase to 9,650 pounds, new cockpit layout, and enhanced pressurization. Then came the C90 in 1971, which featured the same pressurization and ECS system as the larger King Air 100 and two 550 shp Pratt PT6A-21 engines. The E90 series was produced simultaneously with C90 and served to address some of the performance complaints of earlier King Airs. In fact, the E90 is essentially a more powerful C90. The E90 first flew in 1972 and features two 680 shp PT6-28 engines providing another gross weight increase to 10,100 pounds and significantly better performance. The pressurized three-compartment interior can be maintained at sea-level atmosphere pressure to altitudes as high as 10,500 feet. Both the C90 and E90 versions have full-feathering reversible props.
The next major improvement came in 1978 with the birth of the F90. The F90 is easily distinguished from other 90 models thanks to its slim T-Tail design, similar to that found in the larger King Air 200 and 300 series. The F90 also has dual-wheel gear that are fitted with brake deice systems, and the pressurization differential of 5.0 psi providing a sea-level cabin at 11,000 feet. The F90 also has a shorter wingspan and more powerful PT6-135 engines producing 750 shp per side mounted behind four-bladed props. The F90 can cruise at about 300 true burning 35 gallons per hour per side. The F90-1 was introduced in 1983 and featured a number of improvements including hydraulic landing gear, PT6-135A engines, and a more robust electrical system.
Between 1992 and 2005, the King Air C90B was produced. The C90B-model has a Maximum Take-off Weight of 10 100 lbs, quieter Hartzell four-blade, constant-speed, full-reversing 90-in diameter propellers and dynamic vibration absorber system. Then came the C90GT with -135A engines flat rated from 750 to 550 shp for better climb and cruise performance.
The C90GTi was introduced as a variant of the 90GT. The GTi features Collins Proline 21 avionics system, which has become standard in all subsequent King Air Models. Finally, winglets were introduced to the aircraft in 2010, dubbed the King Air C90GTx.
The C90 an E90 model series is still one of the most affordable turboprop aircraft on the market today. I’ve put a comparison chart between the C90 and E90 aircraft in the show notes. Both aircraft have identical cabin dimensions with about 54-inches cabin width, 48-inches of cabin height, and almost twelve and a half feet of cabin length, making a cabin volume of about 227 cubic feet. Exterior dimensions are also the same, featuring a 50-foot wing span, 14 foot height, and 35.5 feet of length. Both variants can hold 5-6 passengers with a crew of either one or two pilots. Both aircraft also have a MTOW of 10,100 pounds. Zeroing in on the E90 for a moment, it has a 30,000 foot service ceiling, about 1300 miles range, and maximum payload of 3100 pounds. It can cruise between 200 and 240 knots, depending on power settings, and climb up to 1,870 feet per minute.
What about maintenance? Well every aircraft has it quirks, and the King Air 90 is no exception. For example, many King Air 90 series aircraft did not have empennage inspection panels to examine the inside of the empennage. In 2008, Beechcraft issued a service bulletin recommending the installation of inspection panels to fulfill its inspection program. Another area to be mindful of is correct installation of the ailerons. Through 2012, there have been a number of reports of partial aileron separation due to improper installation techniques. Finally, Hawker-Beechcraft reminds owners and pilots to be mindful of fuel leaks from the wing or engine nacelles. Fuel isn’t supposed to leak from these areas, and may be a sign of leaking fuel bladders or loose interconnect plumbing—again, emphasizing the importance of a thorough prebuy.
One great thing about King Airs is owners and pilots get peace of mind knowing they are supported by the factory and Beechcraft’s owner clubs like BeechTalk. There’s even a King Air Magazine!
There are also a wide range of modifications available for the airplane from avionics to cabin, engines, props, and more. Most notably, the Raisbeck swept propellers, aft-body strakes, wing lockers, and high floatation gear doors. Blackhawk also offers modifications for improved engine performance, speed, and range with its XP135A engine swap. There are also engine TBO extensions available from MORE Company. You can also avionics upgrades available from a variety of companies, including a full Garmin G1000 retrofit.
To summarize, the King Air 90 series is an excellent entry-level twin-turboprop aircraft that will fulfill a wide range of missions. It’s proven, reliable, fast, and relatively affordable compared to many other turboprop aircraft. But no airplane is perfect, which is why doing your due diligence or enlisting experts familiar with this aircraft is highly encouraged. I know Don has a lot of experience doing prebuy evaluations and maintenance on the 90 series, especially the E and F 90 versions.
Welcome to The Airplane Intel Podcast, the weekly General Aviation podcast for aircraft owners, operators, pilots and mechanics. We deliver practical advice, tips and strategies to make aircraft ownership simple, safe and cost effective.