Page 2-26
Pilot’s Operating Manual
Revision A1: Nov, 2002
Sub-section 2
ENGINES
Hawker 800XP Pro Line 21
Section III - SYSTEMS DESCRIPTION
Digital Electronic Engine Control (Fuel Computer)
Two Digital Electronic Engine Controls (DEECs) are located in the rear equipment bay.
Each DEEC controls the engine acceleration and deceleration. Separate ENG CMPTR switches on the
flight compartment overhead roof panel allow automatic (AUTO) or overspeed protection (OVSPD
PROT) mode selection. Both DEECs receive 28 VDC from the PE busbar in the automatic mode.
During acceleration and deceleration, the DEECs provide governing, limiting and scheduling response
to the thrust lever and engine inputs. Inputs to each computer are:
• Engine Inlet Pressure (Pt
2
)
• Engine Inlet Temperature (Tt
2
)
• Interstage Turbine Temperature (ITT)
• N
2
speed
• N
1
speed
• Thrust Lever Position
Each DEEC provides appropriate output current to the torque motor of the associated FCU based on
the various inputs. Circuits within the DEEC monitor N
1
and N
2
continuously to provide overspeed
protection. The computer commands the engine to shut down if the engine speed exceeds 109 or 110%
N
2
.
If an overspeed occurs, the primary overspeed circuit arms an electronic switch which energizes the
overspeed solenoid that cuts fuel to the engine. This function is called the
ultimate overspeed
protection.
A MANUAL/NORMAL switch on the front of the DEEC CASE (rear equipment bay) and the flight
compartment overhead roof panel ENG CMPTR switches control the overspeed protection.
ENG CMPTR
1
2
AUTO
O
F
F
OVSPD PROT
Overhead Roof Panel
