Cessna C525C Citation, CJ4

The CJ4 is fitted with Two Williams FJ44-4A turbofan engines with Full Authority Digital Engine Control (FADEC). The engines are twin-spool (co-rotational) medium bypass turbofans with mixed exhaust and high-cycle pressure ratio. Each engine produces 3,621 lbs of thrust at sea level up to 26°C providing a considerable weight to thrust ratio of less than two and a half to one. There is no thrust reverse or thrust attenuation system.
Engine start sequence, power control, and shutdown are managed by the respective FADEC unit, each of which is independently powered by its own engine driven Permanent Magnet Alternator (PMA). Back-up electrical power for the FADEC is the main aircraft electrical system. If a complete loss of aircraft electrical power occurs, each PMA will power its respective FADEC unit to maintain engine operation. Engine start, required thrust and shut down are selected by the pilot through the cockpit engine starter control buttons, thrust lever position and run/stop buttons respectively. Distinctive detents are provided at take-off, climb and maximum cruise power settings for ease of operation. There is no separate fuel cut-off other than through the FIRE buttons, which also isolate the hydraulic pump and the generator field circuit on the respective side for emergency engine shutdown.
Eachenginehasadualignitionsystemwith2igniterscontrolledbytheFADEC fired either singly or together as required by the FADEC. Ignition is activated automatically for starting and on approach to land and whenever a loss of combustion, excessively low engine speed or rapid deceleration is detected by the FADEC. The pilot may also select ignition manually to on at any time. Whenever ignition is active the message IGN appears in the EICAS display beside the N1 tapes.
1.7.2Avionics / Cockpit Layout

The CJ4 is equipped with dual Primary Flight Displays (PFD) and dual Multi-function Displays (MFD) Collins Proline 21 EFIS displays and Collins 3000 series Flight Management System (FMS). The aircraft is fitted with two CDUs for the FMS. A second FMS computer is a sales option. The subject aircraft and simulator during the OEB evaluation was fitted with the optional, second FMS.
The avionics and the FMS are fully integrated and some of the aircraft main systems are also operated through the FMS CDU (e.g. pressurisation). Other main and ancillary aircraft systems are monitored and controlled through menus available from within the PFD or MFD screens (e.g. TAWS, weather radar, ACAS, electrical system status and Crew Alerting System (CAS).
The systems and avionics integration of the CJ4 means much of the information available to the pilot is via sub-menus from within a main PFD or MFD control panel selection. The availability of this information is not immediately intuitive and pilots must have specific knowledge and systems familiarity to be able to access to the information quickly, when required.
The standby instrument display is a single ESIS unit in the centre of the instrument panel. The instrument is powered by its own dry-cell battery. This instrument receives information from its own (standby) AHRS and ADC and is designed to provide attitude, heading, airspeed and altitude indications for 55 minutes following the loss of the main aircraft power supply.
The CJ4 is equipped with a fitted ELT.
Electronic Flight Bag:
The CJ4 is equipped with the Rockwell Collins IFIS-5000 including electronic terminal charts (en route charts are not available from the system). Chart prioritisation is offered according to the FMS flight plan, with origin and destination charts immediately available on either MFD, however, it is not possible to view a full chart page on the MFD due to the screen size. Only approximately 3⁄4 of the chart is visible, although it is possible to scroll the chart to see the top or bottom.
The IFIS system is powered through the aircraft main DC power system. The system is not on the emergency bus and there is no standby power for the system. Therefore, the system is not suitable for approval of a ‘paperless’ operation and a suitable backup must be carried on board.
Own ship position (FMS position) is presented on many of these charts. Where own ship position is not available the ø symbol is presented in the top right corner. A digital reproduction of the chart title is continuously displayed when the chart is in view whether scrolled, zoomed or rotated.
Many of the charts are not drawn exactly to scale and the aircraft position may therefore appear incorrect. Unless a digital Airport Moving Map (AMM) has been used for the taxi chart, the error in the chart can be so large as to present the incorrect taxiway under the aircraft position symbol. This can be misleading and pilots must be made aware that, when referring to the aircraft symbol, the apparent position may be incorrect.
Crew Alerting System:
The CJ4 systems are monitored through the Crew Alerting System (CAS). There are over 100 CAS messages that could appear (normally appearing in the upper part of the MFD) either on the ground or during flight. The messages are colour-coded cyan (blue) amber and red to reflect normal, cautionary and emergency conditions as appropriate. It is not reasonable for the pilot to remember all the appropriate actions for each of these and a comprehensive QRH needs to be immediately available in the cockpit for every flight.
The systems architecture is such that emergency memory items are few, however the inter- relationship between systems and their automation means that a series of messages may appear at one time, revealing a number of symptoms that may be the result of a single system fault.

1.7.4Weight & Balance
Refer to AFM, Weight and Balance Data, Section VI.
1. Max Ramp Weight: 17.230 lbs 2. Max Take Off Weight: 17.111 lbs 3. Max Landing Weight: 15.660 lbs 4. Max Zero Fuel Weight: 12.500 lbs 5. Basic Operating Weight: 10.280 lbs 6. Useful Load: 6.980 lbs 7. Useful Fuel Capacity: 5828 lbs
1.7.5Flight Controls
The main (dual) flight controls are all cable operated. Electrically operated aerodynamic trim tabs are fitted to the right aileron, right elevator and the rudder. A secondary power circuit and control system is provided for the elevator trim, there is no manual trim mechanism available. A rudder bias system uses engine bleed air to assist in directional control during engine-out operation.
A single autopilot is able to follow commands from one of 2 Flight Guidance Computer s (FGC) and is controlled through a single flight guidance panel (FGP) at the top centre of the main instrument panel. The FGP is equally accessible from either cockpit seat. The active FGC will take roll, pitch and yaw inputs from the selected PFD and accompanying AHRS, and compute flight guidance commands for the flight director and autopilot. Lateral flight guidance modes include roll, heading, navigation and approach modes, with a half-bank function available. ‘Back-course’ approach mode is also available for use where these approaches are authorised. Vertical guidance is computed by the active FGC and is available in pitch, flight level change (speed hold) and vertical speed modes. A vertical navigation mode is also available when the primary navigation data is derived from the FMS.
As the only aircraft in the CE-525 family, the CJ4 does not feature ground flaps.
1.7.6Hydraulic System
The CJ4 has a single, closed-centre hydraulic system. This is unlike all the other C525 aeroplanes, which have an open system that is pressurised on demand by the closing of a single bypass valve. The CJ4 system is continually pressurised to 3000 psi by two engine-driven pumps providing hydraulic power on demand to the four hydraulic aircraft sub-systems. Landing gear actuation, wing flaps, speed brakes and ground spoilers all use this hydraulic pressure for operation. Wheel brakes use their own dedicated hydraulic supply and accumulator and are not part of this system.
1.7.7Fuel System
Each wing houses an integral tank which feeds, via return fuel motive flow and ejector pumps, into a feeder ‘hopper’ for the respective engine. Each side has a 434.9 USG capacity providing 2,914 lbs of useable fuel per side (= 5,828 lbs total useable capacity).
There is no cross-flow system but fuel can be transferred from one hopper to the opposite hopper by the pilot moving the Fuel Transfer selector knob in the cockpit. Maximum fuel imbalance for normal operations is 200lbs.

A Single Point Refuelling (SPR) system is available through an access panel in the fuselage, just ahead of the right wing leading edge root. Normal, over-wing refuelling caps are also provided on top of the outboard end of each wing tank. Standby boost pumps are activated by FADEC for starting or if a low fuel pressure condition is detected, automatically during fuel transfer and if selected manually to ‘on’ by the pilot.
Additional Limitations:
Lithium battery - min. temperature for engine start: -10°C
Nickel-cadmium & lead-acid battery min temp. for engine start: -20°C
Minimum time prior to power increase above 80% N2: 2 minutes
Ground operation with engine anti ice ON and N2 >75% 2 minutes
Max. operating altitude with WING XFLOW ON: FL410
Max. operating altitude with DC GEN OFF L/R: FL350
Min. weight in RVSM airspace: 11.050 lbs
The ground control lock must NOT be set if the airplane will be exposed to temperatures below -10°C.