CFA8

October 2012

 Improper fuel management, contamination and poor preflight planning cause far too many GA accidents; statistics reveal nearly two accidents per week on average. Whether the result of fuel exhaustion, improper planning or mechanical issues, the majority of these fuel mishaps are easily preventable.


Improper fuel management

However basic a fuel system may seem, as pilot in command it is important to know the system’s design and operation. Figures such as unusable fuel and total capacity, what fuel is considered part of the empty weight of the aircraft, and what type and grade of fuel is approved for your aircraft are essential information.

All aircraft fuel tanks must be marked to indicate the fuel capacity, type, and grade of fuel required. Aircraft modified by STC for the use of auto fuel should include this information as well.

There are operational issues specific to a make and model of aircraft to consider when operating an aviation fuel system. What fuel tank will be used for takeoff and landing? Does the center of gravity change with fuel burn? When is an auxiliary fuel pump used? What is the recommended sequence of fuel burn from multiple fuel tanks, and why?

October 2012

 The new Cessna model T240 Corvalis TTX is now touring the United States prior to deliveries scheduled for 2013. This is the latest refinement of the carbon fiber and fiberglass airframe Cessna purchased to enter the high performance single engine market.


The “TT” stands for twin turbo with an intercooler feeding a 310 hp Continental Motors TSIO-550-C engine. The “X,” well, maybe it stands for a little extra—such as the all-new Garmin G2000 panel that takes the user interface to a new level.

 

WALKAROUND

Kirby Ortega, my Cessna host and chief pilot for piston operations at Cessna Aircraft Co., provided me with a walkaround of the Corvalis TTX. My first impression was that the TTX is a “go fast” aircraft—the small frontal area and raked windscreen are hard to miss. Starting at the nose of the TTX, the bug-eye cooling air inlets optimize cooling air through-put and minimize drag. The prop has heated pads at the blade base for de-icing.

Moving to the left wing leading edge, I could see the shiny TKS de-icing leading edges (so-called “weeping wings”). There is no windshield heat, so this de-ice system is not certified for known icing; it is only useful to get out of unexpected icing encounters.


Flight into known icing (FIKI) is slated for future models and will include a TKS for the windshield. The horizontal stab TKS panel will be fully recessed that will increase cruise speed slightly.

The drooped leading edge in front of the ailerons modifies the chord to reduce the angle of attack in relation to the inboard wing section’s angle of attack. This ensures that the inboard wing section will stall first. The drooped leading edges—in conjunction with the rudder limiter and features incorporated into the elevator—provide docile low-speed handling characteristics with full aileron authority.

Recessed electric spoilers are located on the center rear of each wing and deploy on command to slow down this low-drag airframe. Low-drag wheel pants help you go fast, but are brutal on brake cooling. Differential brake steering adds to the need for additional cooling. The aft-facing hole near the top of the wheel pant draws air over the brakes and exits the wheel pant through this opening.

I stepped up on the wing and entered the cockpit through one of the gull-wing doors—similar to what you find in an upscale sport car. Once you close the doors (held up by a gas cylinder) and activate the pressurized door seal, the cabin is whisper-quiet.


FLIGHT

When you slip into the TTX’s cockpit, the seat folds around you like a glove. Buckle up the three-point shoulder and seat belt, and you are truly part the airplane. With side-stick controllers, you’ll have a full view of the G2000 panels. Engine start is straightforward, and then you follow the checklist to bring the aircraft systems to life.

Gradual power adjustments are easy with the vernier throttle to taxi out of the chocks. Differential braking is a change from what I’m used to, and it takes some time to adapt and get the feel for how much to brake is required to initiate a turn combined with rudder movement to assist this maneuver.

The flaps have three positions: up, takeoff, and landing. Set the flaps for takeoff, line up on the centerline and smoothly apply power to the 310 hp turbocharged Continental engine and down the runway you go. Differential rudder keeps you tracking until you reach liftoff speed—and then you are flying. Raise the flaps and continue your climb.

Fingertips can control the TTX nicely. The side-stick controller is finger-light, particularly in roll. The stick has electric pitch control, but no yaw trim.

The aircraft uses a rudder hold control that acts like a rudder trim. Change power settings or airspeeds, then disengage and re-engage the rudder hold control. The system works fine.

Cessna calls the Garmin G2000 system the heart of its “Intrinzic” cockpit, which is centered on two 14.1-inch high definition LED monitors serving as PFD and MFD. In the center console is the touch screen controller, which will do all but a few commands you need without touching a button or knob.

As Ortega explained to me, “Touch the Home icon on the controller, then touch what you want to do.” It really is that easy. During our flight I don’t believe I made any changes to frequencies or pulling up data except using the very intuitive touch screen controller. This touch screen architecture follows the same logic as the Garmin GTN 750 and other new Garmin hardware and software (Garmin Pilot) offerings.

Flying at 8,500 feet, Ortega demonstrated the two power settings. Setting power at rich of peak showed 195 knots TAS burning 20 gph. Leaning to lean of peak indicted 184 knots TAS burning 15 gph. These numbers are close to what you will see in the checklist power settings.

While the TTX is certified to FL 250 with 235 knots TAS, most pilots will typically fly between 12,000 to 18,000 feet. The flight manual shows 207 knots TAS at 12,000 feet. At these altitudes, if you have oxygen problems you have more time to recognize the situation and less altitude to lose in descending. Located in the lower left side of the panel is a CO monitor and pulse oximeter. When you register a low oxygen level on the monitor, descend to a lower altitude.

The MFD can display in single view or in a split-screen mode. On approaches, the plan navigation display gives you the big picture and the georeferenced approach plate plus the GFC 700 autopilot make approaches hassle-free.

Landing takes preplanning in order to slow down to approach speeds. The speed brakes are there to back you up in case you need to slow down faster. Lower flaps to the landing position and then fly the visual approach, being careful to not over-control the sensitive control stick.

After landing, the SafeTaxi airport diagram shows you exactly where you are on the airport and gives you an easy to interpret method to follow the ground controller’s instructions.

After our flight, I got out of the aircraft and didn’t realize that I had been in a cockpit for an hour and a half. That is the sign of a truly comfortable cockpit seat!

SYSTEMS

Any aircraft in the TTX class needs redundancy to travel long distances at high altitudes and speed in all types of weather.

The TTX is an all-electric aircraft making redundant 70 amp alternators a smart design decision for safety of flight. Either alternator can handle the entire electrical load with no load shedding required to continue the flight. One alternator is gear-driven from the front of the engine and the second unit is belt-driven on the rear of the engine. These alternators feed a split bus that is cross-tied in case of an alternator failure.

The Garmin G2000 has the same displays and controller hardware announced for the Citation M2 (Garmin G3000) and Citation Ten (Garmin G5000). Programming for the G3000 and G5000 will be slightly different to accommodate the different aircraft system requirements, but the basic hardware and architecture is the same.

Again, the TTX has two of everything that is necessary for safety of flight—and one of everything else you’ve ever dreamed of for a high performance single engine aircraft. If either the PFD or MFD fails, you can create a composite display on the remaining active display. Dual WAAS GPS Nav/Coms, VOR receivers, AHRS and magnetometers are standard. All of these systems use solid-state electronics, which have exceptionally long mean time between failure (MTBF) statistics.

Other redundant systems include dual TKS fuselage pumps, where the pumps alternate to prevent latent failure with one able to provide the necessary TKS flow. The dual turbocharger intercoolers are connected to balance flow between the two units. While one turbocharger is not sized to maintain the total boost needed throughout the flight envelope, the one operating turbocharger will maintain boost in a reduced operating envelope.

Cessna has not quantified this reduced performance envelope since numerous failure modes will impact engine performance in unique ways. It is comforting to know that there are two of these essential flight safety items on board to help you land safely under virtually all of the most serious scenarios.

Traffic and weather units are standard. A GTX 33ES Mode S Extended Squitter transponder coupled with the GTS 800 Traffic Advisory System provide today’s TCAS advisories along with ADS-B Out and In capabilities. NEXRAD by Sirius XM satellite weather (plus Sirius XM satellite radio) comes via the GDL 69A satellite data link receiver.

Garmin’s Synthetic Vision Technology (SVT) uses GPS location information combined with a terrain database to depict a three-dimensional view of terrain and water (including obstacles). This synthetic view combines with traffic inputs to provide a 3D perspective of the surrounding traffic in the area. SVT provides additional situational awareness, regardless of weather conditions surrounding the aircraft.

The Corvalis TTX’s Electronic Stability Protection (ESP) coupled with the GFC 700 autopilot monitors pitch and roll parameters plus stall onset, steep spirals and overspeed conditions. Monitoring all these and other loss-of-control conditions may assist the pilot in recovery from most situations outside the aircraft flight envelope.

The Corvalis structure has a rollover cage that provides for occupants’ safety. The wings contain dual spars certified to a significantly higher wing loading than what is required for the aircraft’s Utility Category certification. The dual wing spars provide rupture protection for the fuel cells (the cells are located between the spars). Finally, using liberal carbon fiber composite construction throughout the airframe can provide up to three times more strength for a given material weight than traditional materials.

COMPARISON

How does the Corvalis TTX stack up against the competition?


• Speed: Fastest in its class. 235 knots at FL 250; 195 knots at 8,000 feet.


• Ceiling: Certified to FL 250. Higher ceiling than any other high performance piston single engine aircraft.


• Avionics Technology: First to offer Garmin’s G2000 avionics system. Cessna calls it the Intrinzic cockpit.


• Aerodynamics: Certified in the Utility Category with docile stall characteristics.

CONCLUSION

For a $650,000 price tag, an owner should expect to receive a world-class aircraft. Cessna’s entry into the high performance single engine market with the Corvalis TTX is a most worthy product. I was impressed with how the TTX flew, as well as the company’s attention to the multitude of standard redundant systems installed in this aircraft.

 

 

Charles Lloyd has logged 10,000 hours since his first flying lesson in 1954. He worked for Cessna Aircraft for 16 years. Lloyd retired as captain of a Citation Encore Plus for a major fractional aircraft ownership company. He flies a tricked-out 1966 Cessna 182—also known as Bill—that is a great business tool for his real estate investment company. Send questions or comments to .

 


RESOURCES
Cessna Aircraft Co.
(800) 423-7762
cessna.com/single-engine/
corvalis-ttx.html

 

 

Cessna Corvalis TTX

 

Performance 

Maximum Cruise Speed: 235 ktas

Maximum Range: 1 1,250 nm

Takeoff Distance (S.L., ISA, MTOW) 2: 1,900 feet

Ground Roll: 1,280 feet

Landing Distance (S.L., ISA, MLW): 2,640 feet

Ground Roll: 1,260 feet

Maximum Operating Altitude: 25,000 feet

Maximum Climb Rate (Sea Level): 1,400 fpm

VNE: 230 kias

Stall Speed: 60 kcas

1 45 minute fuel reserves, 45 percent power at 25,000 feet.

2 Distance to 50 feet above the runway.

 

Specifications

Avionics: Intrinzic (Garmin G2000)

Powerplant: 310 hp Continental Motors
TSIO-550-C

Propeller: McCauley, 3 blade metal, constant speed

Maximum Takeoff Weight: 3,600 pounds

Usable Fuel: 102 gallons

Typically-Equipped Empty Weight1:
2,600 pounds

Useful Load: 1,000 pounds

Maximum Payload: 700 pounds

Full Fuel Payload: 388 pounds

           

Dimensions

Exterior Length: 25 feet, 2 inches

Wingspan: 36 feet

Cabin Length2: 11 feet, 8 inches

Maximum Height: 49 inches

Maximum Width: 48 inches

Seating Capacity: 4

           

Pricing/Operating Cost

Base Price 3: $733,950


1 Empty weight does not include a pilot. Actual empty weight can vary based on installed options.

2 From front bulkhead to rear bulkhead.

3 Price represents 2012 U.S. dollars.

 

 

October 2012

The sun was casting long shadows on the dry Arizona lake bed. A gathering of engineers stand restlessly behind a battery of cameras, their long jackets zipped to their chins to keep the early morning chill at bay. Above them a giant C-123 military aircraft flashes in the morning light as it rolls out on a heading into the drop zone. A heartbeat later, an instrument package slides off the back ramp of the airplane and is quickly heading for terminal velocity and the desert floor below.

Boris Popov, founder and vice president of marketing for Ballistic Recovery Systems (BRS), the world’s leading manufacturer of whole-airframe parachutes, watches through a pair of binoculars. After a few seconds of free fall, a giant orange and white parachute deploys and the payload slows to a crawl across the sky.

Popov can’t conceal his satisfaction over the successful test drop. “We’re seeing a real surge in demand for our systems, especially for Cessna aircraft,” said Popov. “That’s probably because of John Farese.”

Tuesday, 12 February 2013 11:52

AirVenture 2012: Observations and Musings

October 2012

Walking through EAA AirVenture’s exhibit hangars and aircraft manufacturers’ displays is always fascinating to me. Whether you head to Oshkosh with a detailed checklist or employ the good old “I’ll know it when I see it” approach, I don’t think you’ll be disappointed. Over 800 exhibitors were at this year’s show.

My expectation was that 2012 would be The Year of the iPad—and I figured I’d see new iPad apps, as well as a flood of flight planning software upgrades with ADS-B weather in the cockpit. 


iPad Apps

As I thought, iPad apps for pilots’ use in flight planning and to display ADS-B weather were abundant this year. As I walked around the show, I wondered to myself why Apple, the maker of the so-loved-by-pilots iPad, doesn’t have a store in one of the buildings at AirVenture.

Four of the most popular of these iPad utilities (ForeFlight, Garmin Pilot, WingX Pro and JeppFD) returned with improvements over last year, along with one newcomer—iFlightPlanner.

September 2012

Q: Hi Steve,

I’m looking for an all-around Cessna that I will use both in business and for family outings and vacations. I have flown in a friend’s Cessna 182 and I do like the way Cessna single engine airplanes fly.

I also like that Cessna built so many single engine airplanes. I’m in the farm equipment business and know that mechanics sometimes have trouble with machines they aren’t familiar with.

I talked to my local airplane mechanic about buying a Cessna and he told me that he thinks the Cessna 205 would be perfect for me. He described the 205 as a fuel-injected 182 with a bigger useful load. That sounds like a 206.

You know a lot about Cessna single engine airplanes—do you think buying a 205 is a good idea?

Thanks.

—Ready to Buy

Tuesday, 12 February 2013 11:41

Push To Talk – The Hundred Dollar Hamburger

September 2012

Will Fly to Eat. Give me a sectional and dreams of a great burger.

I was walking through all the airplanes at this great little fly-in I attended. There were several classic birds there including a cabin-class Waco, a tricked-out Luscombe 8 and two beautiful Cessna 140s. Admiring the loving restoration, I couldn’t help but notice how tiny the cockpit was and how close the seats were back then. Were people that much smaller five and six decades ago? The answer, I discovered, is you betcha.

Our country’s prosperity, which brought with it a better diet and better health care, has resulted in Americans growing taller and living longer. Twenty years ago, America had the tallest people on the planet. Now, with the rest of the world catching up, folks in the United States are only the ninth tallest folks on earth. Before you chalk up just one more thing America has fallen by the wayside on, we now have another category in which we are number one. Americans are officially now (drumroll, please) the heaviest people on earth.

As aviators, of course, weight is a huge part of our sport. We have to weigh things before we put them in our airplanes, and we have to balance that weight relative to the aircraft’s center of gravity lest we become test pilots.

September 2012

 

While I’ve been an aviation magazine writer for the past 40-plus years, some members are probably also familiar with my aviation-themed novels: there have been seven of them since 1979. The first one—“Mayday,” an airline disaster story—was revised and updated in 1997 with my lifelong friend, author Nelson DeMille. “Mayday” was eventually bought by Hollywood and turned into a CBS Movie of the Week that aired October, 2005.

In April of this year my latest aviation-themed novel, “Captain,” was released in a print edition and also in all e-book formats. That novel was reviewed here at Cessna Flyer a few months ago (refer to the June 2012 issue —Ed.), and that’s when the idea came up to share some of the “insider stuff” about this aviation story with our loyal Cessna Flyer readers.

First, let’s talk about the whys and wherefores for having a fireside chat about a work of fiction in a magazine that is dedicated to helping real pilots in moving their real metal through a very real sky. What’s the possible connection? Allow me to quote the jacket copy of “Captain”:

“...a chilling and all-too-real story about a routine Trans-Atlantic airline flight that suddenly turns absolutely insane. In the doomed airliner’s cockpit, inside the passenger cabin and on the ground, a complex array of characters have been propelled at jet speed into a sudden and frantic race for survival. ‘Captain’ is about the individual and collective struggles of each of these men and women as they attempt to deal with and ultimately fight against the odds and circumstances that are stacked against them.”

Tuesday, 12 February 2013 11:38

Visit Europe by Seaplane

September 2012

We were flying through a high mountain pass, a twisting maze of switchbacks across the top of the still-snowing Alps, a pass that may have been the same route Hannibal selected to bring elephants into battle with the Roman Empire. Ahead, the sprawling coastline of Lake Como came into view. The deep blue water was encircled by castles and villas and resorts extraordinaire.

Lake Como has been a celebrated destination for literally thousands of years for people like Julius Caesar to Hollywood celebrities. But the best Lake Como experience is not reserved for emperors or Hollywood stars—that experience is available to a pilot with a seaplane.

Cesare Baj dropped the first notch of flaps on the Lake Buccaneer as we made our final approach onto Lake Como. A few seconds later, we were floating in front of a villa that recently sold for more than $30 million. We weren’t invited, but we weren’t intruding either. We were enjoying Lake Como. “This is why we like to fly floats,” he said with a very big smile.

Tuesday, 12 February 2013 11:37

Corrosion: When Good Metal Goes Bad

September 2012­

“An airframe contains the elements necessary to turn it into a battery—all that’s lacking is an  electrolyte.” 

—Jim Van Gilder

Founder, Corrosion Technologies

 

When two different metals are near each other and are bathed in an electrolyte, electrolysis occurs. (That’s how a battery works.) Electrons transfer from one metal to the other. That’s corrosion.

Even aluminum skin and aluminum rivets are different alloys; unprotected metals at the places they meet, wetted by an electrolyte, will result in corrosion. Remove a skin from a 30-some-year-old airframe and you will likely find a circle of oxidation around each rivet hole.

Calling an airframe a “battery” may seem like a stretch, but it’s true that all metal-to-metal points can act as tiny batteries, destroying an airframe ion by ion. Just expose these points to moisture or other electrolytic elements, and the action begins.


DEFENDING AGAINST CORROSION

What can we do? There are two basic defenses against corrosion, and we need both.

Manufacturers use primers and sealants (paint) as a corrosion inhibitor, and undamaged paint is the first line of defense. With use, however, paint breaks down. Exposure, vibration, turbulence and other normal activities attack it.

Hairline cracks appear around stress points like rivets and faying surfaces. Chips result from FOD, sand, stones; bug and bird strikes can compromise the finish. Bird droppings, tree sap, bug juice—even sweat—can all eat away at paint.

Owners and maintainers must also systematically use a remedial product to displace moisture and leave a protective film that prevents attacks from abusive elements found in the atmosphere. This is the second line of defense.

Relief from the elements is a hangar’s job. When the aircraft is outside or in service, we protect the painted surfaces with frequent washing using noncorrosive cleaners and waxes.

It’s a start, but it’s not sufficient. We need to keep electrolytes from reaching metal. A protective exterior coating (wax, or proprietary products like RejeX, from Corrosion Technologies) can seal against some electrolytic elements, or at least make them easier to remove.


MOISTURE IS THE MOST COMMON CULPRIT

The most common electrolyte is moisture, contaminated by airborne by-products of combustion produced from diesel/turbine exhausts. Other moisture comes from the lav, passengers’ drinks, and unseen condensation. Exhaust fumes—from tugs, other airplanes, trucks and traffic—introduce corrosive chemicals to common water, and what started life as dew or condensation becomes an aggressive electrolyte (and often, a metal-eating acid in its own right).

Know where to look and what to protect. Nobody is surprised to drain water from fuel tanks; the same circumstances cause condensation to form inside the entire airframe. (For more about “invisible” corrosion, see the entry “Cessna: 208B; Rudder Torque Tube Corrosion; ATA 5540” in ADs and Alerts on page 58 of this issue. —Ed.)

There is no permanent cure for corrosion, and it can’t be prevented without constant attention. When it gets to the point of exfoliation, we must replace the structure, but corrosion can be interrupted indefinitely, even after it has a toehold, by the application of remedial and preventive chemical treatments.


PRODUCTS ON THE MARKET

One coating used for years is LPS 3, essentially a wax dissolved in solvent. When this rust inhibitor is sprayed inside an airframe, the solvent allows it to spread. Then it evaporates, leaving a barrier coat of wax on the surfaces.

Its disadvantages include adding weight to the airframe and making inspections difficult (concealing flaws and collecting dirt). It is hard to remove, requiring a lot of solvent and a pressure sprayer—and atomized solvents in an enclosed structure can be dangerous.

LPS 3 and other similar coatings have another serious disadvantage: they don’t stop the expansion of existing corrosion. In fact, they can lock the electrolytes inside the coating, allowing it to continue.

Newer technology can interrupt corrosion’s progress for extended periods. There are two popular products dominating the market: ACF-50 from Lear Chemical in Canada; and CorrosionX Aviation, made by Corrosion Technologies in Garland, Texas. The technology is commonly referred to as FTFC, Fluid Thin Film Coating. (TFFC™, or Thin Fluid Film Coating, is trademarked by Lear Chemical Research Corp., which makes ACF-50.)

These “oily” type treatments, when properly applied at two-year intervals, can actually stop existing corrosion. Mark Pearson, Managing Director of Lear, explained that in 1985, when ACF-50 premiered the technology, it “was significantly different from the passive/barrier films because it actually penetrated corrosion to remove the electrolyte. With the process completed, ACF-50 acts like an ‘off switch’ for the corrosion process.”

These fluids creep into minute, inaccessible areas like those between lap joints and around rivet shanks, forming a dielectric barrier that stops the transfer of electrons, shutting down the “battery.”

Several years ago during a photo shoot, I noticed some dirty seams and rivet lines on an otherwise pristine pair of amphibious floats that I was featuring in an article. I asked the owner why the seams were dirty. He said, “I sprayed the inside a couple months ago with CorrosionX, and it’s still working its way out—but I’d rather have a little dirt than a little corrosion, any day.” It wiped off cleanly, and I continued the photo shoot.


INEFFECTIVE MOISTURE BARRIERS

Some of the things we do that we think are helping really aren’t. Oil, for instance,­­ is not a good moisture barrier. We all know that oil floats, yet we persist in thinking that it won’t float off shiny surfaces when they’re exposed to water. It will.

I also have to mention every person’s solution to nearly every problem: WD-40 has its uses, particularly as a water displacer, adhesive remover, and as a cleaner for small parts, but it is of little value as a preventive for corrosion. Its extremely high solvent content (76 percent) also makes it a fire hazard in enclosed areas—but it can come in handy as a starting fluid for tugs and other equipment. Review the label warnings.


CHOOSING A PRODUCT

When you consider a corrosion protection product, look for the one that will do what you most need it to do. Some are heavier; some contain more solids; some creep into smaller gaps; some last longer under certain conditions. Some are stickier; some “heal” better after being penetrated; some stand up to water better. (CorrosionX is an excellent light-duty lubricant for cables, rod ends and suspension sliders.)

The salespeople for both ACF-50 and CorrosionX know their products—and their competitions’ products.

One last consideration: packaging. Both CorrosionX and ACF-50 are available in aerosols or as bulk liquids for pump sprayers. With the pumps, you get more product (roughly 20 percent of the content in any aerosol is propellant), but you tend to waste more product getting it to atomize and cover surfaces. The biggest disadvantage to aerosols is in shipping: airlines won’t carry them.

Arriving at your favorite anti-corrosion treatment may take a little research and experimentation, but it’s better to apply one right away (and then do the research) than to debate and corrode!

 


Tim Kern, CAM, MBA, has authored features in over 40 aviation publications. He writes technical, publicity and expository pieces for several companies in the aviation industry. Kern is a private pilot with a seaplane rating, and is listed as the manufacturer (“with a lot of help!”) of an experimental aircraft. Send questions or comments to .

 

 

RESOURCES

ACF-50

learchem.com/products/acf-50.html

 

CorrosionX

corrosionx.com

 

Tuesday, 12 February 2013 11:35

The Citation: Eclipsing the Competition

September 2012

 

In the early 1970s, Cessna—along with every other General Aviation manufacturer—was selling airplanes. Vertical marketing was the strategy in vogue, and airframe manufacturers had a step-up program designed to introduce a new pilot to aviation in their brand of aircraft and keep them there.

The business jet market was dominated by Rockwell, which built the Sabreliner; Hawker, which built the DH-125-400; and Lear, whose small but incredibly efficient airplanes had earned them the nickname, “the executive mailing tube.”

Up to this point in aviation history, a small, lightweight, fuel efficient, high bypass turbofan engine applicable to small airframes had not been developed. The Pratt & Whitney JT15 changed all that.

Essentially, the JT15 is a high bypass (by 1970s’ standards) fan version of Pratt’s incredibly successful PT6A turboprop engine. This true high bypass turbofan made 2,500 pounds of thrust and burned a miserly (compared to General Electric’s CJ610 that powered the Lear 23/24/25 series) 500 pounds of fuel or so per hour.

Great advances in aircraft design have always followed great advances in powerplant design, and so it was for the Citation.

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