Chelton cockpit upgrade gives new life to old jets

 - April 3, 2007, 6:41 AM

The Cessna Citation 501 has served nobly in a variety of roles over the course of the last three decades. A smooth-flying machine with decent range and single-pilot simplicity, the 501 (also known as the Citation I/SP) already holds a hallowed place in business aviation history as one of the original entry-level jets. From 1977 through 1984, Cessna built 339 of the Pratt & Whitney Canada JT15D-powered airplanes, familiar to this day at airports around the world and in use primarily as personal aircraft, corporate transports and air ambulances.

A used Citation I/SP in good shape and with mostly original equipment today sells for well under $2 million. And since the end of its production run, there have been a number of engine and avionics modification packages developed for the venerable twinjet, allowing the airplane to ease in to middle age quite gracefully. With so much going for it, it is little wonder that the first single-pilot Citation from Cessna is still one of the most popular light jets ever manufactured.

The latest Citation 501 upgrade to hit the market takes the airplane from respectable to downright cutting edge. Chelton Flight Systems is on the verge of obtaining an STC for a four-display cockpit upgrade that brings the Boise, Idaho company’s synthetic-vision EFIS to the 501 for an installed price of $187,000. FAA certification of the retrofit system was expected by the end of last month.

The first installations are being done by Temple Electronics at Houston Hobby Airport, Chelton’s top dealer in a network of about 60 shops. FAA pilots flew the first 501 to get the FlightLogic upgrade in late May, and approval of the STC was pending at press time. According to Chelton Flight Systems president Gordon Pratt, six more Citation I/SPs are in line for the upgrade at Temple Electronics as soon as the STC is in hand, and dozens more are likely to become early recipients of the cockpit.

“The interest level has been extremely strong,” Pratt said. “We have orders or interest from operators of nearly 100 Citation 501s who want to upgrade to this cockpit.”

‘Virtual VFR’

FlightLogic in the Citation 501 consists of four displays (two for the pilot and two for the copilot), each measuring 6.25 inches wide and 5.5 inches high.
Remote-mounted equipment includes an attitude and heading reference system (AHRS), air-data computer and GPS WAAS receiver. The system is RVSM ready and comes standard with class-B TAWS. (Operators can choose to upgrade to class-A TAWS for an extra $16,000, Pratt said.)

James Temple, president of Temple Electronics, said the FlightLogic upgrade not only helps prepare 501 operators for upcoming TAWS and RVSM mandates, it also greatly improves reliability and saves weight.

“Pulling out the old instruments and a lot of wiring, we saved about 35 pounds during the installation,” Temple said. “That was after adding a lot of capability to this airplane that it did not have before. And from a hardware standpoint, this is now a much more reliable airplane.”

Including the Citation 501 retrofit system, Temple Electronics has completed eight FlightLogic installations, the others in King Airs, Piaggio Avantis and Twin Commanders.

What sets FlightLogic apart is its synthetic-vision flight display with highway-in-the-sky (HITS) guidance cues. Pratt refers to the technology as “virtual VFR” because of its ability to depict a convincing electronic view of the outside world on the primary flight display. To create its virtual digital surroundings, the Chelton SVS combines an internal database of the earth’s topography, attitude and heading data, and position input from the GPS receiver. The result is a video-game-like view of the world ahead of the airplane.

Highway in the sky is one of the most useful features of FlightLogic, especially when used with the terrain display. Because pilots can fly approaches based on visual cues instead of interpreting instruments, track errors are reduced, even when low-time pilots who’ve had little or no instrument training are at the controls.

“There’s no more mental gymnastics; you just point it at the runway,” said a pilot who flies his own personal airplane equipped with FlightLogic. “If it drifts off, you just point it back at the runway, exactly like you would on a sunny day. The highway-in-the-sky tunnel is so valuable. You see where you’re supposed to be. You find yourself instinctively flying the GPS-based tunnel, and cross-checking your position with the ILS needles. It is that precise.”

The safety benefits of FlightLogic are not going unnoticed. Pratt said some insurance companies have started offering price breaks to operators in the Alaska Capstone program who are flying with the avionics system.

Flying with FlightLogic

Behind the scenes, FlightLogic is a powerful system. Three-dimensional terrain modeling; airspeed; groundspeed; altitude (both msl and agl); vertical speed; enhanced low-speed awareness; heading; decision height; actual winds aloft; crosswind component; OAT; and timers are constantly updated on the display while airborne. Other flight critical information appears as pop-ups when any unusual situations begin to develop. If conditions are normal, the screen declutters, providing only the essential information for keeping track of aircraft performance and navigation.

In addition to the synthetic-vision PFD, which depicts a 3-D flight path, there is also a navigation display that includes an array of powerful flight-management tools. The nav display consists of a moving map that uses Jeppesen NavData and can present weather and traffic data. The map displays flight path and terrain that is near or above the current altitude and satisfies the FAA TAWS mandate for all turbine-powered aircraft.

Two unique features of the moving-map display are a horizontal projected path showing a wind-corrected track of the aircraft up to one minute in the future, and a patented dead-stick glide-area depiction that is corrected for turns, wind and terrain. A conventional HSI/RMI presentation is also part of the package.

During a demo flight from Houston Hobby to nearby Beaumont, Texas, pilot John Smith put FlightLogic through its paces, flying coupled ILS and GPS approaches to Runway 12. The airplane flew the approaches precisely as the flight-path marker on the PFD passed through the middle of the HITS boxes as though it were a dart hitting a series of square bull’s-eyes. During level-off for cruise back to Houston, the autopilot showed a tendency to porpoise, a nuisance that engineers planned to remedy.

While most of its functions seem fairly straightforward, learning all of the features behind FlightLogic takes time. Pratt said Chelton is currently producing an instructional video for FlightLogic buyers and a Web-based training program with eight sections that takes about four or five hours to complete. Chelton has also launched the National Chelton Authorized Instructor Network, a program that allows flight instructors to get checked out with the system. The program includes a day of classroom instruction and a day in the airplane at Chelton’s facility in Prescott, Ariz.

Chelton will be showing a new version of FlightLogic for the first time at the EAA AirVenture airshow later this month in Oshkosh, Wis. The new package boasts 10.4-inch displays, which are the centerpiece of retrofit applications for Part 25 airplanes, next on Chelton’s list of targets for the cockpit upgrade.