A Short History of the Groundbreaking Williams FJ44 Engine

The Williams FJ44-3 engine. The fan is 23 inches in diameter

The Williams FJ44 engine of the CitationJet family has a fascinating history as it's based on the F107 turbofan used on American cruise missiles like the ALCM and the Tomahawk. Williams International started out with marine turboshafts and APUs before getting into small turbofan engines. Sam Williams and his namesake company would rise to prominence in the aviation industry with miniature turbofans but his real dream was a civilian turbofan for general aviation. In the 1980s Williams envisioned a new class of turbofans based on the F107 design that would allow for a new class of general aviation aircraft that were jets half the cost and size of current bizjets with the field performance and economy of turboprop twins. 

Sam Williams believed so much in his FJ44 engine design that development continued through the 1980s in the absence of any launch order or production application. Keep in mind that this class of engine had never been used in general aviation and Williams International had never made a civilian production jet engine. Through the 1980s, Williams lobbied numerous general aviation manufacturers about his concept for a light jet aircraft and how he had a superbly economical engine to make such an aircraft feasible. The first manufacturer to agree was Rutan's Scaled Composites who flew the Triumph in 1988. Rutan's design never entered production but it did mark the FJ44's first flight. The next manufacturer to agree to use twin FJ44s was Swearingen in its SJ30 design- even though the aircraft flew, Swearingen and the SJ30 have passed through many ownership changes serial production has yet to occur. Williams' big break came with the third manufacturer- Cessna was looking for an efficient and higher performing successor to its iconic Citation line and launched the Cessna 525 CitationJet family in 1992 with a very substantial order of Williams FJ44 engines, vindicating Sam Williams' dream.

Sam Williams

The FJ44 is a joint venture between Williams International and Rolls-Royce and was the company's first civilian engine and first manned aircraft engine. Simplicity and reliability were key to this new class of aircraft and as such, the FJ44 engine has only 700 parts total, 1/4 that of many other bizjet powerplants. The Cessna CitationJet series was the first production application for the FJ44 engine. It wasn't enough to have a simple engine, it also had to have performance and basing the FJ44 on the F107 cruise missile engine gave the FJ44 that foundation. In fact, the F107 that the FJ44 is derived from was such an impressive accomplishment that it won the Collier Trophy- it has 1/10th the weight of the Pratt & Whitney JT8D engine but has the same specific fuel consumption and thrust-to-weight ratio. That performance pedigree translated over well into the FJ44 and it made the engine successful. On the Cessna CitationJet series, the economy and performance of the new engine made the new jet a leap in performance over the Citation 500 series it replaced. While aerodynamic improvements are part of the equation, the FJ44 engine's performance and economics are a large contributor. Compared to a Citation 500 at an identical mid-cruise weight, the CitationJet goes 13% farther with 17% less fuel and it does this 40% faster than the original Citation with the FJ44s having a lower thrust output than the JT15Ds used on the first Citations.

There are four engines in the FJ44 family. The lowest powered one was the first one, the FJ44-1 and it powers the Cessna CJ1 and CJ1+ of the CitationJet family and is also used on the Cessna Citation M2 as well as the Swedish jet trainer Saab Sk60. It has a thrust rating of 1900 to 2100 lbs. The FJ44-1 series first flew in 1988 and went into production in 1992. 

The second engine in the family is the FJ44-2 and is based on the core and LP turbine of the FJ44 paired up with a larger fan and new compressor section for increased thrust. Its applications include the Cessna CJ2, the Beech/Raytheon Premier I,  and the latest incarnation of the SJ30 design, Syberjet SJ30. Two of Rutan's designs fly with the FJ44, the Scaled Composites Proteus and the Virgin Atlantic Global Flyer that Steve Fossett flew around the world in solo nonstop in 2005. It's also used on two re-engining programs for the Citation 500 and the Learjet 25. The FJ44-2 has a thrust rating of 2300-2400 lbs thrust and went into production in 1997.

The next engine in the family is the FJ44-3 which has a new fan and compressor section for an increase in thrust rating to 3000 lbs. It powers the Cessna CJ2+ and CJ3+ and is used in Nextant's re-engining and remanufacture program of the Beech 400 as well as on a re-engining program for later Citation 500 variants. It went into production in 2004. 

The top end member of the FJ44 family is the FJ44-4 with an increase in thrust to 3600 lbs with a larger fan and enlarged compressor. It also features a dual-channel FADEC for more efficiency. It powers the Cessna CJ4 along with the Beech 400XPR remanufacture/upgrade program for the Beech 400. The engine will also power the upcoming Pilatus PC-24 jet. 

There is also a scale down of the FJ44 engine, the FJ33, which went into production in 2004 and has a thrust rating of 1000 to 1900 lbs. The fan is only 19 inches in diameter and it powers the Diamond D-Jet and the Cirrus Vision. 

Unlike other manufacturers of small jet engines, the FJ44 has no turboprop derivative and there are no turboprops in the Williams portfolio. This is a reflection of Sam Williams' philosophy that given time and technological progress, light turbofans like the FJ44 will displace turboprop engines for most civilian aircraft applications. The FJ44 is one of the landmark engines of aviation history and Sam Williams has earned honors for creating an engine that gave rise to a whole new class of general aviation aircraft.

Source: The History of North American Small Gas Turbine Engines by Richard A. Leyes and William A. Fleming. American Institute of  Aeronautics and Astronautics/Smithsonian Institution Press, 1999, pp383-429. Williams International http://www.williams-int.com/. Photos: Williams International

Despite an overall decline in accidents by airline operators in the last several decades, the general aviation accident rate has not changed as significantly. While it's obvious that those are two different worlds of flying that contribute to that difference, efforts to improve general aviation safety in the last several years haven't had the desired impact. The insurance company Avemco only insures piston aircraft and has embarked on a significant study to determine what can be done to improve general aviation safety. While admittedly that's financially self-serving for them, the preliminary results have lessons to be learned for the GA community.

Given that Avemco has very detailed information on the pilots they insure as well as on the exact nature of claims made, they are in a unique position of having a database that is more comprehensive than what the FAA and NTSB would otherwise have access to in any accident investigation. In addition, the FAA and NTSB databases only have information on accidents while Avemco's database also includes insured pilots who have not filed claims.

Their findings so far have been interesting. First of all, advanced ratings make no difference in the overall risk. It makes no difference in the accident rate by their data if the pilot has an IFR rating vs. VFR rating, or even an ATP certificate. Also, after several hundred flight hours, overall flight time doesn't make a difference either. While recent type experience does make a difference, the overall hours in a pilot's logbook have no influence on the accident rate either. It may be that what one gains in experience from advanced ratings is offset by new risk exposures. As a result, Avemco has focused on the psychology of the pilot as the primary difference between pilots who have accidents and those who don't.

Bill Rhodes, a human behavior specialist retired from the US Air Force Academy, is heading the research effort at the company. Though the work is far from complete, some overall patterns are starting to emerge from an exhaustive analysis of their database.

It seems that overall experience, skill, and level of training are important in preventing minor accidents. Usually these accidents don't meet the NTSB's criteria for reporting, so they don't appear in the federal safety investigation databases. But minor accidents are reported to the insurance company in the form of claims for a variety of incidents from fender-benders on the taxiway to a hard landing. These are typically accidents that are injury and fatality-free and more often than not, the more experienced the pilot regardless of ratings, the lower the minor accident rate.

In major accidents, however, involving injuries, fatalities or an aircraft write-off, the contributing factors are a bit less clear. Considering that on the average 500 people a year are killed in general aviation accidents in the United States means that finding a way to prevent major accidents doesn't just improve safety, it also helps the insurance company's bottom line as those accidents are its priciest claims. It seems that there's no difference between high-time and low-time pilots when it comes to the major accident rate.

Being a human behavior specialist, Rhodes has put a series of pilots through stressful simulator sessions that tax their abilities in an effort to understand the human factors in emergency and complex situations more clearly. It appears that one group of pilots is able to prioritize tasks quickly and effectively in such situations. He also measured physiologic parameters such as heart rate, breathing rate, and changes in speech patterns and this group of pilots were clearly under stress but adapted and handled the stress easily.

The other group of pilots it turns out don't handle stressful situations well. They unnecessarily try to multitask and are unable to filter out what is important and what's not in a given situation. It appears that this group of pilots may also be taking on additional risks that the first group of pilots won't because that first group will make conservative decisions at the outset to minimize their risk exposure.

While this information might seem intuitive, the key in improving general aviation safety lies in finding a way to identify those pilots who are more at risk as well as making risk assessment an important part of general aviation pilot training much in the same way it's universally applied in military flying which boasts a lower accident rate with low-hour pilots operating higher performance aircraft than most general aviation pilots will ever command.

Source: Flying, June 2010. "Left Seat- The Psychology of Safety" by J. Mac McClellan, p8-10.

Before the Rutan Voyager: The BD-2 LOVE ONE

Although he had his career begin at North American Aviation, Jim Bede's real passion was for light aircraft- more importantly, light aircraft that were within the reach of most Americans at a time when ownership of even a two-seat Cessna or Piper was out of reach for most private pilots. In 1961 Jim Bede formed Bede Aviation to produce the BD-1, a two seat low wing monoplane that would be kit built, something that had never been tried before in the general aviation market. Changes in the business plan at the time pushed him to offer the BD-1 as a fully-built aircraft instead of a kitplane. The new company was called American Aviation but a conflict between Jim Bede and the shareholders resulted in Bede being forced to relinquish leadership of his company. The BD-1 became the AA-1 Yankee with Russ Meyer as its president. Russ Meyer would later go on to become president of Cessna and American Aviation was acquired by Grumman in 1972 and the AA-1 would set the pattern for a series of light planes from the company in the 1970s.

Jim Bede, however, decided to refocus his efforts on one of his other aviation dreams- to fly around the world, solo, nonstop, and without refueling. Long before Burt Rutan's Voyager accomplished the same feat but with two pilots in 1986, Jim Bede started work on his aircraft twenty years earlier in 1966.

Using a Schweizer 2-32 sailplane as the basis for what he called the BD-2, he fitted it with a modified 225-horsepower Continental IO-360 six-cylinder piston engine in the nose that could run the prop at low power levels. The wings were sealed to form a large fuel tank and special wingtips were added to the BD-2 to increase the aspect ratio of the wing, increase its fuel capacity and ease ground handling. Additional fuel tanks were built into the fuselage as well. During the flight tests, Jim Bede demonstrated that at 20,000 feet, the BD-2 could cruise at 135 mph using only 20 horsepower which amounted to an impressively low rate of fuel consumption. With a takeoff weight of 3,000 lbs, it was an impressive feat of creative engineering.

Bede christened the BD-2 "LOVE ONE" for Low Orbit Very Efficiently No.1" and managed to stay aloft in the BD-2 for over 70 hours flying back and forth between Kansas City and Columbus, Ohio in 1969 before an electrical fault ended his flight having only covered 9,000 miles- while short of what a global circumnavigation would have entailed, it was still an impressive feat for such a small aircraft.

He never attempted the round-the-world flight in the BD-2, having gone back to his ideas of kitplanes. With the more successful BD-4 and BD-5 designs, he would go on to fame as creating the modern kitplane market.

Source: Air Enthusiast, Volume 4, Number 2, February 1972. "Mr. Bede's Dreamboat" by John Fricker, p69-72.

Long before the Cirrus SR22 series of composite aircraft flew, and even long before the composite Beech Starship flew, there was a general aviation aircraft that was made of all glassfiber plastics in an effort to make an affordable two-seat training aircraft that was easy to build. In mid-1958, Piper Aircraft started development of the PA-29 Papoose with the intent of putting an aircraft to market that would cost substantially less to build than other comparable types that used standard construction techniques and materials.

The Papoose was to be made entirely of a honeycomb sandwich material with the top and bottom layers made of 0.79mm glassfiber cloth surrounding a 9.5mm core of paper honeycomb and the sandwich was formed in high-temperature epoxy plastic moulds. As parts and airframe components could be pre-moulded, the entire Papoose airframe had just over 100 parts. The engine used was a 108-horsepower four-cylinder Lycoming engine. Flight trials started in 1963 but details are limited and the difficulty in reliably reproducing the composite components led to Piper abandoning the Papoose project and the sole prototype is now on display in the Piper Aviation Museum in Lock Haven, Pennsylvania.

Now be honest. You were entertained by saying to yourself "Piper Papoose Plastic Plane now in Pennsylvania." I know I did.

Source: Air Enthusiast, Volume 5, Number 3 (September 1973), "Plane Facts" by William Green, managing editor, Gordon Swanborough, editor. Pilot Press Ltd, 1973, p147.

The first electric-powered two seat airplane to fly at AirVenture 2009 at Oshkosh, the Yuneec E430 is an LSA (light sport aircraft) class aircraft that is the first commercially produced electric-powered aircraft. Manufactured by a Chinese company, Yuneec International, headed by Asian entrepreneur Tian Yu, the company already has the first phase of its factory outside of Shanghai operating with 250 workers. The proof-of-concept aircraft first flew just before Oshkosh and by the time of the show had accumulated 40 hours of flight time as part of its FAA certification.

With long span wings and a glide ratio of 25:1, the E430 is more like a motor glider with an empty weight of only 550 lbs and a maximum weight of 1050 lbs. It has a 40 kilowatt electric motor (equivalent to 50 horsepower) spinning a three-bladed prop. Three rechargeable lithium-ion battery packs provide 1.5 to 2 hours of flying time and there is an option for a five battery pack with just over 2.5 hours of flying time.

The E430 is already available for order with a quoted cost of $89,000 ready to fly with a complete electric power package.

Source: Flying, November 2009. "Electrics Emerge" by Robert Goyer, p62-64.

The Hudson River VFR corridor is one of two pathways of airspace created by the FAA in 1971 to allow VFR traffic to operate clear of the busy Class B airspace of the New York City area. The corridor extends from the surface of the river to 1100 feet AGL with controlled airspace at 1101 feet on up. Aircraft in the corridor use a common frequency of 123.5 MHz to announce position and altitude; northbound traffic follows the Manhattan shore and southbound traffic follow the New Jersey shore. More than 200 aircraft use the corridor daily.

The other pathway is the East River VFR corridor which has been closed to aircraft unless under positive control since October 2006 following the crash that killed Yankees pitcher Cory Lidle and his flight instructor.

Source: Aviation Week & Space Technology, August 17, 2009. "Midair Mystery- Collision follows decision to fly river route; Pilots face limits on popular VFR corridor" by Frances Fiorino, p52.

According to the 2008 General Aviation Manufacturers Association report, general aviation contributes more than $150 billion to the US economy each year and employs over 1.2 million workers. About 2/3 of all hours flown by general aviation aircraft are for business purposes. In the United States, general aviation aircraft fly more than 27 million hours and transport 166 million people annually.

Source: Aviation Week and Space Technology, July 6, 2009. "Vision Plan: Cirrus team seeks new financing to fund and revive Vision program" by Frances Fiorino, p30.