Pilatus PC-24 Notes

Williams International FJ44-4A-QPM

Specifications

• Takeoff Power: 3,420 Lbf (855 C for 5 minutes)

• Automatic Thrust Reserve (ATR): 3,600 Lbf (10 minutes OEI, 5 minutes AEI)

• Maximum Continuous Thrust (MCT): limited to 835 C.

• Approved oil:

  • Mobile Jet II (preferred)
  • Mobile 254

• Approved fuel:

  • Jet A
  • Jet A-1
  • JP-8
  • TS-1
  • China No. 3

General

Medium-bypass jet engine with quiet power mode (QPM) for ground power operations in lieu of dedicated auxillary power unit.

• QPM generates 250A @ 45% N2.
• Engine must idle for 2 minutes prior to shutdown and prior to entering or exiting QPM.
• QPM must be disengaged prior to second engine start.
• QPM may not be used in icing conditions (no nacelle anti-ice available).

Engine comprised of N1 (low + intermediate pressure) and N2 (high pressure) sections.

• N1 extends throughout the entire engine, starting at engine intake with 1x low pressure compressor + 3x intermediate pressure compressors and ending at engine exhaust with 2x low pressure turbines.

• N2 comprises the center portion of engine, with hollow shaft overlapping N1 shaft, spinning 1x high pressure compressor and 1x high pressure turbine.

  • [Intake]
    • [N1]
      • low pressure compressor
      • 3x intermediate pressure compressors
    • [N2]
      • high pressure compressor
      • high pressure turbine
    • [N2 cont.]
      • 2x low pressure turbines
  • [Exhaust]

Air bypass section surrounds the N1 and N2 sections of the engine, containing a burn chamber around and behind N2’s high pressure compressor. The burn chamber includes fuel injectors and dual spark ignitors. Fuel and air are mixed and ignited, resulting in gas expansion which is forced over N2’s high pressure turbine and N1’s 2x low pressure turbines.

Engine ignitors are on during:

• Ground start
• Air start
• Flameout
• Gear down and locked on approach
• Manually turned on by pilots

Starter generator units (SGU) mounted underneath each engine use AC power from power conversion units (PCU) for engine start by spinning N2 high pressure compressor via tower gearbox assembly. After start, SGU generates AC power delivered back to PCUs. Thereafter, tower gear assembly delivers rotational energy to drive accessory gearbox.

The accessory gearbox is powered by rotational energy captured from the N2 high pressure compressor and delivered via the tower gearbox assembly. The accessory gearbox powers:

• fuel control unit (FCU)
  • fuel pump
  • fuel filter
  • fuel metering valve
  • fuel shutoff valve
  • permanent magnet alternator
  • magnetic pickup (measuring N2)
• oil pump
• fuel oil heat exchanger

Self-contained permanent magnet alternator (PMA) located within FCU provides power to full authority digital engine control (FADEC) unit after start during normal operations.

• Engines will continue operation regardless of ship electrical failure.

FADEC controls FCU. FCU controls fuel delivery to engine.

Limitations

• All engine fire protection systems must be operative.
• Positive Gs limited to 10 seconds.
• Engines idle 2 minutes with bleeds off prior to shutdown.
• Oil levels must not be below “ADD” mark.

Electrical

28 V DC electrical system provided by 2x PCUs generated via SGUs diverted down 2x power-lines to 4x electrical power distribution unit (EDPU) with 3x primary electrical busses and 2x batteries.

Engine > 53% N2 ==> SGU generates unregulated AC output ==> delivered to associated PCU ==> PCU converts to regulated 28 V DC output ==> powers respective power-line, EDPUs, electrical busses, and battery.

• 2x power-lines.
  • left
  • right
• 3x primary electrical busses.
  • left
  • right
  • essential
    • primarily powered by left bus during normal operations.
• 4x electrical power distribution units.
  • 1–4
  • controlled by utility management systems (UMS).
  • 41 electronic circuit breaks (ECB) each.
  • automatic load shedding.

Breakdown

• [Left engine]
  • Left SGU (unregulated AC)
    • Left PCU (28 V DC [max. 29.5 V DC], 400 A)
      • EDPU 1 + 3
      • Left electrical bus
      • Essential bus
    • Left battery (LiIon = 26.4 V DC / NiCad = 24 V DC)
• [Right engine]
  • Right SGU (unregulated AC)
    • Right PCU (28 V DC [max. 29.5 V DC], 400 A)
      • EDPU 2 + 4
      • Right electrical bus
    • Right battery (LiIon = 26.4 V DC / NiCad = 24 V DC)

Power distributed along both power-lines to all electrical components. Connected together by various bus ties which can open and close based on power delivery modes or load shedding schedules.

The system may be powered by a single generator via cross-tie contactor XC. In the event of a dual generator failure, the batteries will provide emergency power to the essential bus.

Batteries

The PC-24 has 2 batteries: BAT 1 located in the nose compartment and BAT 2 located to the bottom right aft of the fuselage in a battery compartment on the wing fairing.

In normal operation with both generators online, BAT 1 is charged from the left bus and BAT 2 is charged from the right bus.

When only one source of generated power is available bus ties are closed together to allow both BATs to remain charged from their respective buses by a single available power source.

• BAT 2 is the only BAT utilized for engine starting.

The two types of batteries used on the PC-24 are Nickel-Cadmium (NiCad) and Lithium-Ion (LiIon). LiIon is more popular. Older aircraft utilized NiCad batteries. The two battery series have different specifications and limitations.

• Nickel-Cadmium (NiCad)

  • Voltage: 24 V DC
  • Ampere Hours: 44 Ah
  • Min voltage start:
    • BAT 1: 22 V
    • BAT 2: 23.5 V
  • Min temp start: -20 C

• Lithium-Ion (LiIon)

  • Voltage: 26.4 V DC
  • Ampere Hours: 40 Ah
  • Min voltage start: green status indicators
  • Min temp start: -5 C

Limitations

• Min battery temp for flight = 0 C.
• Battery charging not to exceed 32 V.
• Charge rate before takeoff BAT 1 + BAT 2 = 50 A and decreasing.

Utility Management Systems (UMS)

UMS is a multi-processor computing platform functioning as the “brain” of the PC-24’s systems. During normal operations, UMS controls and monitors almost all of the PC-24’s onboard systems.

UMS is comprised of 4x dual-channel data concentration and processing unit (DCPU) spread throughout the aircraft. These can be considered “lobes” of UMS’s “brain”. Each DCPU is powered by either the left, right, or essential bus.

• DCPU 1
  • essential bus
• DCPU 2
  • right bus
• DCPU 3
  • left bus
• DCPU 4
  • left + right bus

In the event of power loss or disruption, DCPUs are able to, to some extent, utilize power from different electrical busses through various bus ties. In the event of total generated power loss only DCPU 1 is powered via the essential bus for a period of approximately 60 minutes.

UMS monitors and controls most aircraft systems via the 4x EDPUs and various aircraft control units (FADEC, etc.). Essentially, if a system or sub-system component contains the term “control” or “control unit” in the name, UMS is responsible for managing it.