Automatic Power Reserve - C650 - pls. explain

[CMN]

Automatic power reserve - I know this is the A/C automatically adding power on the good engine in case of failure on the other. But that's very general.

Can someone please describe what APR on a C650 exactly does?

[bflyer]

hi
i don't know about the c650..but here's how it works on a B722 and it's called the AUTO PERFORMANCE RESERVE..hope it might be of some help
the system is armed when
1- main landing gear shock struts are compressed
2- wing flaps are in the T/O position(5-25 deg for the 722)
3- ALL engines are above approx 73% N1
now if the system detects that one or two engines rpm drops below 6000rpm(approx 73%N1)..the system will signal a solenoid valve in the operating engine(s) fuel control unit(s) to add 1000 lbs of extra thrust
the system will be disarmed after T/O when wing flaps are retracted from the T/O position OR when ALL engines thrust is reduced below 70% N1
however in the event of an engine failure..the system will remain active even when wing flaps are retracted from the T/O position

[sander82]

Hi, find below a description on the APR as (optionally) installed on the C650.

The automatic performance reserve system is used only on takeoff and operates regardless of the engine speed synchronizer switch position (FAN/OFF/TURB).

The automatic performance reserve system works in conjunction with both electronic engine controllers and the engine speed synchronizer.
Relays in the automatic performance reserve controller are controlled by engine speed detectors within the controller which sense N 2 between the two engines. When N 2 exceeds 5 percent and the automatic performance reserve system is activated, automatic performance reserve thrust is produced. Increasing thrust approximately 200 lbs on the operating engine.

The electronic engine controllers of airplanes incorporating the automatic performance reserve system are adjusted to allow a one percent in N 2 and a 45°F (25°C) increase in ITT operating limits. Under normal conditions (non activated automatic performance reserve system) the controller transmits trimmed signals to the electronic engine controllers which regulate the engines to normal limits. When automatic performance reserve thrust is required, the relays within the automatic performance reserve controller are de-energized. When de-energized, the N 2 and ITT trim signals are removed and the limits are increased to automatic performance reserve levels.

Hope this helps.

[CMN]

Very helpful - Thanks!