The new Grand Caravan EX brings numerous other benefits beyond the addition of the Pratt & Whitney PT6A-140 engine. Some of the changes we will outline in this article are a direct result of the higher horsepower and the new requirements associated with the new power-plant, but our purpose here is to shed light on the comprehensive changes made to the Grand Caravan during its evolution to the EX model.
Two prominent items that have changed directly related to the new engine and its increased power are the propeller change and the new flap settings.
The switch from McCauley to a Hartzell propeller is due to the additional horsepower, which creates a condition where the McCauley propeller can not adequately perform in crosswinds conditions at horsepower settings beyond the original 675 horsepower of the Grand Caravan. McCauley did not have a product ready that would meet the EX certification schedule. With Cessna owning McCauley, we should expect a McCauley propeller to eventually replace the Hartzell on the Grand Caravan EX.
The new flap settings are a result of the impact the additional power has on handling and longitudinal stability. Specifically, the additional 192 horsepower cannot meet the requirements of FAR 23.145 without the addition of a gated flap position. The familiar Cessna preselect flaps do not meet the FAA criteria of “gated flaps”. In the case of the EX, a single gate position of 15 degrees was chosen and is now labeled “Takeoff and Approach”. The decision was to install only one gate position in place of using two gated positions for 10 degrees and 20 degrees, which could create a potentially confusing flap operation. In terms of performance the change of flap travel for takeoff impacts runway takeoff performance that is highlighted by comparing the gross weight sea level takeoff distances for the new EX and the Grand Caravan. There is little difference in the ground roll distance because the stall speed at 15 degrees of flap for takeoff on the EX is higher than the 20 degrees setting used by the Grand Caravan creating a longer rolling distance even with the additional power.
Non Power Increase Related Improvements
- Air Conditioning: The Grand Caravan EX has a new air conditioning compressor and drive assembly that will provide higher reliability. Additionally, the bleed air heat flow control valve is a new design to handle the higher P3 temperatures of the PT6A-140 engine.
- Autopilot: The updated GSM 86 servos replace the GSM 85A’s – an improvement to reliability. The clutch torque setting test is much less invasive lowering the cost of maintenance.
- AC Power: A new convenience option for the EX is a 115 VAC 500 watt inverter that will provide 4 outlet locations in the Cabin of the Grand Caravan. This is in addition to the 12 volt DC system currently offered.
- Starter Generator: As a result of the 300 AMP starter/generator being such a popular option, both the installation of the 200 AMP and 300 AMP units are now identical, making it as simple as a normal starter/generator change to switch to the other size.
- Passenger Comfort: A passenger comfort item is the seat belt design change. The new Grand Caravan EX seats will now have a shoulder harness that is detachable from the lap belt. This allows passengers to remove the harness for comfort but still be able to keep the lap belt on for safety.
- Prist Elimination: Operationally, a great improvement is not having to use fuel blended with anti-ice additives. This is a result of fuel system changes along with the large capacity of the fuel oil heater on the PT6A-140 engine. Anti-ice additive is an added cost, and in some parts of the world, it is impossible to acquire.
- Brakes: Probably unnoticed by most pilots is a change to the brake system return spring, giving a more positive brake return. Look for the change to be incorporated by Service Bulletin to earlier Caravans.
- Lighting: All lights – both interior and exterior – in the EX are now LED. This is a huge improvement to lighting reliability and brighter landing and taxi lighting. The cockpit lighting has also undergone a major transformation to LED. Gone are all post lights and flood lights. Circuit breaker panels and control panels are now all backlit LED’s improving readability and controllability.
- Remote Entertainment: Another new convenience option is a remote for the cabin controlling the XM entertainment selections, allowing passengers to hear the favorite stations without having to bother the pilot. Not unlike a TV remote, it shows the channel and programing information, controls volume, and can mute the sound.
The extra horsepower wasn’t just to go fast and climb better. It is also the key to the Grand Caravan becoming a float-plane. The development of the amphibious floats for the aircraft are courtesy of Wipaire, but to make the installation significantly easier, all EX’s will have the firewall reinforcement needed for float operations. Without this reinforcement, it would complicate and add more time to fitting the floats at Wipaire. Now, virtually every Grand Caravan EX is float eligible.