Page 28 - Dec23T

controlled engine with FADEC or PWC’s EPECS, but it is very close.
The Garmin Autothrottle has two modes – power and airspeed. For example, the system is in power mode for takeoff, providing control over power and torque – within the King Air’s engine limits. In the climb, I selected FMS mode for the autothrottle, FLC for the climb, and now it was under speed control, com- manding an IAS, as I hand flew the King Air, also still maintaining power within limits.
Engines are not always matched on an aircraft. When one engine reaches an operating limit, for ex- ample, torque/ITT, etc., before the other, the system will reduce the throttles to maintain the limits and match. If the difference is significant, more than 5%, Garmin Autothrottle match will be limited to that 5%. The matching capability is also inhibited in certain phases of flight that would be detrimental, for example, takeoff or operating at less than 80% torque. The Garmin Autothrottle will also activate an ‘AT HOLD’ if the system notices a reduction in engine power on one engine during takeoff, leav- ing that lever fixed and maintaining speed with the other engine.
Another fascinating capability of the Garmin Autothrottle is that it pro- vides overspeed and underspeed pro- tection and power limit protection,
even when the system is disengaged, by automatically activating the capa- bility. The same capability controls engine parameters when the King Air is above 200 feet. The Garmin Au- tothrottle installation also includes a radar altimeter, which precludes underspeed protection below 50 ft AGL – an Autoland feature integrated into the system. At 45 ft AGL, the AT system enters ‘AT IDLE’ and moves the levers to idle; on touchdown, the system disengages.
The pilot can still override any AT function, just like overriding an autopilot. The Garmin Autothrottle has additional modes, such as climb (‘AT CLIMB’), which controls the power levers for torque, which are automatic depending upon the phase of flight. The pilot selects other func- tions to fit a particular mission. In cruise, the pilot can decide whether to cruise at maximum or normal power.
After departure and climbing over the Wisconsin countryside, I en- gaged the autopilot to follow our FMS flight plan to the practice area. Once there, I also wanted to evaluate the Electronic Stability Protection (ESP) feature and talk with Aaron about the Emergency Descent Mode (EDM).
I disconnected the autopilot and started my maneuvers, banking in excess of 45 degrees; the ESP progres- sively nudges you back to 30 degrees. Go beyond 45 degrees, and the force
increases to encourage you to reduce your bank. The same activation oc- curs when exceeding pitch angles or speed envelopes. Exceed these envelope limits for more than 10 sec- onds within a 20-second timeframe, and the autopilot engages. Of course, if you are intentionally outside of the normal envelope, you can either disable the system or temporarily interrupt it, the latter useful when practicing steep turns.
ESP is cool; many of us have seen it operate in single-engine aircraft. What does it do when you lose an engine in the King Air? It helps con- siderably. Aaron had me reduce one throttle to idle to simulate a failed engine. The One Engine Inoperative (OEI) function within ESP offers unique capabilities to assist the pi- lot with engine failures. OEI-ESP, as Garmin has named it, can be selec- tively enabled by the pilot. However, it makes sense to keep it enabled in most situations to offer automatic assistance. It is activated by the King Air rudder boost, supplementing the capabilities. It reduces the normal ESP envelope parameters; the bank limit is now 10 degrees, and pitch limits are decreased to 10 degrees up / 5 degrees down. The low-speed limit is now 15 knots above Vmc. If the pilot is slow to recover the plane to level flight, in a short period of non- compliance, the autopilot automati- cally activates to level the aircraft.
Too many lives have been lost to pilots improperly responding to en- gine failures, including some of my friends. Many instances were surviv- able. OEI-ESP is another feature that could dramatically improve safety in these situations.
Emergency Descent Mode (EDM) is optional with G1000 NXi but included with Autothrottle and Emergency Autoland. EDM is armed when the autopilot is engaged and the aircraft is above 20,000 feet. It is activated when the cabin pressure is above 12,500 – prime conditions for hypoxia. When triggered, the AP changes to heading (HDG) mode and turns left 90 degrees. In aircraft equipped with the autothrottle op- tion, Flight Level Change (FLC) mode
Garmin King Air Emergency Autoland Button – Active
26 • TWIN & TURBINE / December 2023