‘Sit on your hands’

I’m in the left seat of Garmin’s Cessna Citation CJ2 level at 14,500 feet and cruising along over the pancake-flat Kansas prairie when company pilot Jessica Koss directs me to pull both throttles to idle and leave them there.

I comply and the autopilot dutifully holds the moderately loaded airplane’s altitude rock steady while airspeed diminishes, pitch attitude increases, and the elevator trim wheel spins. The pitch attitude is 10 degrees nose-up and airspeed has bled off to just 110 KIAS as the low-speed/high angle-of-attack warnings on the G600 retrofit panel flash and make aural “airspeed” and “landing gear” callouts.

“The hardest thing about this demo is that you’ve got to sit on your hands,” Koss says cooly. “Don’t touch anything. Just let it happen.”

The only Citation stalls I’ve ever done were in a flight simulator—not a real airplane. This Citation practically begs the pilot to avoid the impending stall, yet I continue to disregard its warnings. Finally, the airframe rumbles and the stick-shaker rattles with an unignorable high-frequency buzz.

In other Citations, stick-shaker activation is the last straw for the autopilot. It gives up, clicks itself off, and leaves it to the pilot to avoid, or recover from, an aerodynamic stall. But the GFC 600 autopilot in this highly integrated panel stays engaged and keeps flying the airplane.

The nose pitches down slightly while the stick-shaker buzzes and the warning lights blink red. The airplane settles into a steady, 800-foot-per-minute descent about five knots above its idle-power stall speed and remains there. The pitch attitude doesn’t oscillate, and there’s no aerodynamic buffeting.

“This slow descent will continue until the pilot finally steps in,” Koss says. “The Electronic Stability and Protection (ESP) system has under-speed protection that prevents aerodynamic stalls, and that’s what it’s doing here.”

Recovery is a simple matter of adding engine power. The stick-shaker stops rattling, the warning lights extinguish, and the airplane climbs to its preprogrammed altitude. The pitch change is smooth and mild when establishing the descent, and it’s equally undramatic during recovery.

Stress-free missed approach

Elaborate retrofit panels like this one are an increasingly popular way of reviving the legacy fleet of aging jets and turboprops. With the Textron Aviation Citation line, it began in 2021 with 30-something-year-old CitationJets in the form of supplemental type certificates (STCs) from JetTech and Columbia Avionics that installed Garmin equipment. Now, retrofits are gaining even more traction with Garmin offering its own STCs for the CJ2 and beyond and G5000 retrofits now available for the Citation XLS series.

The CJ2 retrofit involves a pair of G600 TXi PFD/MFDs, two GTN 750Xi navigators, a GI 275 standby instrument, a GFC 600 autopilot, and a digital TXi Engine Information System that replaces the airplane’s cluster of analog engine gauges. Retrofits are expected to cost about $600,000 per airplane, take about six weeks to complete, and reduce each airplane’s total weight about 85 pounds.

Garmin estimates about 70 percent of the CJ2s currently flying in the United States already have Garmin GTN 750 navigators installed, and that could reduce the total price for full panel upgrades. The company says the value of each upgraded airframe is likely to rise by an amount equal to the retail price of the avionics upgrade, and maintainability, pilot situational awareness, and dispatch reliability will improve.

Unlike Garmin’s G3000 and G5000 avionics suites, the CJ2 panel upgrade comprises multiple stand-alone units. Even so, the all-Garmin panel is tightly integrated, and each unit communicates with the others. In case of an attitude and heading reference system failure in the primary flight displays, the standby instrument automatically steps in and populates the larger PFD screens with attitude, airspeed, and altitude information. Citations are commonly flown by single pilots, and that fact puts a premium on avionics integration and automation.

The CJ2 has non-FADEC Williams engines, and the retrofit engine information system greatly simplifies the process of determining and setting takeoff, climb, and maximum continuous power settings. Instead of the pilot calculating those values manually, the EIS does it through built-in sensors and then displays them graphically with a red line on the N1 scale.

The G600 TXi screens also have the advantage of touch controls which enable pilots to simply reach out and press items such as barometric pressure or the CDI source to change them, as well as a dedicated controller with knobs. In this way, the retrofit panel is simpler to use than ultra-high-end avionics suites.

The retrofit upgrade’s most impressive safety feature takes place during go-arounds and missed approaches. These are busy, sometimes stressful, and potentially confusing events that the retrofit panel does a great deal to tame. Flying in visual conditions with Koss, we programmed the GTN 750s and GFC 600 autopilot to fly an LPV approach to Runway 17 at Ottawa Municipal Airport (OWI) in Kansas. The aircraft was soon locked onto the lateral and vertical guidance and following it down to decision altitude. When we got there and began a missed approach, however, it was a remarkably simple process: push the takeoff/go-around button and shove the power levers forward for takeoff power. Then raise the landing gear and flaps while the airplane accelerates and climbs.

The autopilot remains engaged and initiates a 10-degree nose-up pitch attitude and that matches the flight director command bars and the airplane climbs to the preset missed approach altitude of 4,000 feet. Push the Nav button on the autopilot to follow the published missed approach course. The airplane levels off at the preset altitude, flies to a holding point, and can even enter the appropriate holding pattern automatically when it gets there.

Unlike other Citations in which pressing the takeoff/go-around button disengages the autopilot, there’s no need with the retrofit panel to re-engage the autopilot or unsuspend navigation. All these actions take place automatically. The retrofit panel vastly simplifies a critical, multi-step process that takes place close to the ground.

New life

Garmin wasn’t the first to develop thoughtful STCs for legacy jets, but its enthusiastic entry into the retrofit avionics market brings many more Garmin service centers into the mix and gives new life to Cessna’s pioneering Citation line.

A few years ago, it was uncertain whether early Citations would have a future beyond the ADS-B mandate. Then many owners adopted Garmin GTN 750s as WAAS navigators that could easily be made to comply with reduced vertical separation minimum requirements at 29,000 feet and above. Now, those GPS units are the building blocks for more capable avionics upgrades that can transform the utility of legacy jets and allow them to keep up with the demands of flying in complex airspace for a few more decades.

These retrofits are expensive—but far less so than buying newer airframes. The eager adoption of new avionics by existing legacy aircraft owners—as well as used aircraft buyers—shows this could be one of those rare cases in which avionics upgrades hold their value. And the safety enhancements that come with envelope protection and simplified go-arounds are hard to overstate.

Buyers have long been willing to pay a premium for the G3000-equipped CJ3+ over otherwise identical CJ3s. Now, that phenomenon is coming to the used jet market where the entire Citation line may someday carry an unofficial “plus” designation by virtue of their Garmin retrofits. Citations are the low-hanging fruit in the legacy jet world due to their popularity and the large size of the existing fleet. If this Garmin retrofit program is successful in the marketplace, however, other legacy jet types are virtually certain to follow.

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