407 FADEC question
407 FADEC question
Referring specifically to the GXi, the FADEC has full control of the engine from idle to fly. With that said how can we manipulate the throttle for emergency situations i.e tail rotor failures, stuck pedals etc. I understand that when the throttle is rolled off it goes to idle 63Ng, but if I slightly reduce throttle will the FADEC keep Nr,Np and Ng at 100% until it gets to a point the fuel flow from the throttle reduction won’t allow the FADEC to keep it at 100%? Thank you in advance!
Referring specifically to the GXi, the FADEC has full control of the engine from idle to fly. With that said how can we manipulate the throttle for emergency situations i.e tail rotor failures, stuck pedals etc. I understand that when the throttle is rolled off it goes to idle 63Ng, but if I slightly reduce throttle will the FADEC keep Nr,Np and Ng at 100% until it gets to a point the fuel flow from the throttle reduction won’t allow the FADEC to keep it at 100%? Thank you in advance!
Referring specifically to the GXi, the FADEC has full control of the engine from idle to fly. With that said how can we manipulate the throttle for emergency situations i.e tail rotor failures, stuck pedals etc. I understand that when the throttle is rolled off it goes to idle 63Ng, but if I slightly reduce throttle will the FADEC keep Nr,Np and Ng at 100% until it gets to a point the fuel flow from the throttle reduction won’t allow the FADEC to keep it at 100%? Thank you in advance!
"1-12-G. IN-FLIGHT AUTO MODE
OPERATION
NOTE
If throttle is not maintained in FLY detent position during normal flight operations, available engine power may be limited. This will occur if throttle is positioned from the FLY detent (PLA 70°) to a setting which is less than 62° PLA.
Although any throttle position from 62° PLA to full open will provide the FADEC with complete control to maintain NR within limits, the approved throttle position for flight is the FLY detent position (PLA 70°).
During flight in AUTO mode with the throttle in FLY detent position (PLA 70°), the FADEC has complete control over engine operation to maintain NR within limits.
The ECU receives engine and airframe parameter inputs and cockpit command signals, processes them, and modulates the HMU stepper motor driven fuel metering valve to achieve desired engine performance.
If required, as may be the case in certain Emergency Procedures, an alternate means of engine control is also available to the pilot in AUTO mode. This can be achieved by manipulating the throttle below FLY detent position until the required engine performance is achieved. As the throttle is positioned between HMU Power Lever Angles of 40 to 62°, electrical signals are sent to the ECU from the HMU-PLA potentiometer. These signals dictate the amount of authority the ECU has to control maximum fuel flow (NG limiting), and in turn, engine NG speed.
Therefore, as throttle is increased or decreased, the maximum NG speed is regulated electrically by limiting the fuel flow."
Last edited by T28B; 12th Jun 2023 at 20:53. Reason: format adjustment for readability
Yes, that is correct. The following is a quote from the Manufacturers Data.
"1-12-G. IN-FLIGHT AUTO MODE
OPERATION
NOTE
If throttle is not maintained in FLY detent position during normal flight operations, available engine power may be limited. This will occur if throttle is positioned from the FLY detent (PLA 70°) to a setting which is less than 62° PLA.
Although any throttle position from 62° PLA to full open will provide the FADEC with complete control to maintain NR within limits, the approved throttle position for flight is the FLY detent position (PLA 70°).
During flight in AUTO mode with the throttle in FLY detent position (PLA 70°), the FADEC has complete control over engine operation to maintain NR within limits.
The ECU receives engine and airframe parameter inputs and cockpit command signals, processes them, and modulates the HMU stepper motor driven fuel metering valve to achieve desired engine performance.
If required, as may be the case in certain Emergency Procedures, an alternate means of engine control is also available to the pilot in AUTO mode. This can be achieved by manipulating the throttle below FLY detent position until the required engine performance is achieved. As the throttle is positioned between HMU Power Lever Angles of 40 to 62°, electrical signals are sent to the ECU from the HMU-PLA potentiometer. These signals dictate the amount of authority the ECU has to control maximum fuel flow (NG limiting), and in turn, engine NG speed.
Therefore, as throttle is increased or decreased, the maximum NG speed is regulated electrically by limiting the fuel flow."
"1-12-G. IN-FLIGHT AUTO MODE
OPERATION
NOTE
If throttle is not maintained in FLY detent position during normal flight operations, available engine power may be limited. This will occur if throttle is positioned from the FLY detent (PLA 70°) to a setting which is less than 62° PLA.
Although any throttle position from 62° PLA to full open will provide the FADEC with complete control to maintain NR within limits, the approved throttle position for flight is the FLY detent position (PLA 70°).
During flight in AUTO mode with the throttle in FLY detent position (PLA 70°), the FADEC has complete control over engine operation to maintain NR within limits.
The ECU receives engine and airframe parameter inputs and cockpit command signals, processes them, and modulates the HMU stepper motor driven fuel metering valve to achieve desired engine performance.
If required, as may be the case in certain Emergency Procedures, an alternate means of engine control is also available to the pilot in AUTO mode. This can be achieved by manipulating the throttle below FLY detent position until the required engine performance is achieved. As the throttle is positioned between HMU Power Lever Angles of 40 to 62°, electrical signals are sent to the ECU from the HMU-PLA potentiometer. These signals dictate the amount of authority the ECU has to control maximum fuel flow (NG limiting), and in turn, engine NG speed.
Therefore, as throttle is increased or decreased, the maximum NG speed is regulated electrically by limiting the fuel flow."
Wonderful! Thank you so much for that information and the location on it!!! That explains why you have to reduce throttle quite a bit before you get an RPM droop. Thank you again!!
Yes, that is correct. The following is a quote from the Manufacturers Data.
"1-12-G. IN-FLIGHT AUTO MODE
OPERATION
NOTE
If throttle is not maintained in FLY detent position during normal flight operations, available engine power may be limited. This will occur if throttle is positioned from the FLY detent (PLA 70°) to a setting which is less than 62° PLA.
Although any throttle position from 62° PLA to full open will provide the FADEC with complete control to maintain NR within limits, the approved throttle position for flight is the FLY detent position (PLA 70°).
During flight in AUTO mode with the throttle in FLY detent position (PLA 70°), the FADEC has complete control over engine operation to maintain NR within limits.
The ECU receives engine and airframe parameter inputs and cockpit command signals, processes them, and modulates the HMU stepper motor driven fuel metering valve to achieve desired engine performance.
If required, as may be the case in certain Emergency Procedures, an alternate means of engine control is also available to the pilot in AUTO mode. This can be achieved by manipulating the throttle below FLY detent position until the required engine performance is achieved. As the throttle is positioned between HMU Power Lever Angles of 40 to 62°, electrical signals are sent to the ECU from the HMU-PLA potentiometer. These signals dictate the amount of authority the ECU has to control maximum fuel flow (NG limiting), and in turn, engine NG speed.
Therefore, as throttle is increased or decreased, the maximum NG speed is regulated electrically by limiting the fuel flow."
"1-12-G. IN-FLIGHT AUTO MODE
OPERATION
NOTE
If throttle is not maintained in FLY detent position during normal flight operations, available engine power may be limited. This will occur if throttle is positioned from the FLY detent (PLA 70°) to a setting which is less than 62° PLA.
Although any throttle position from 62° PLA to full open will provide the FADEC with complete control to maintain NR within limits, the approved throttle position for flight is the FLY detent position (PLA 70°).
During flight in AUTO mode with the throttle in FLY detent position (PLA 70°), the FADEC has complete control over engine operation to maintain NR within limits.
The ECU receives engine and airframe parameter inputs and cockpit command signals, processes them, and modulates the HMU stepper motor driven fuel metering valve to achieve desired engine performance.
If required, as may be the case in certain Emergency Procedures, an alternate means of engine control is also available to the pilot in AUTO mode. This can be achieved by manipulating the throttle below FLY detent position until the required engine performance is achieved. As the throttle is positioned between HMU Power Lever Angles of 40 to 62°, electrical signals are sent to the ECU from the HMU-PLA potentiometer. These signals dictate the amount of authority the ECU has to control maximum fuel flow (NG limiting), and in turn, engine NG speed.
Therefore, as throttle is increased or decreased, the maximum NG speed is regulated electrically by limiting the fuel flow."
LRP what you are quoting here is correct for the basic 407 and GX/P models. The GXi does not have an HMU anymore as everything is controlled by the EEC (Electronic Engine Control) which in turn controls the FMU (Fuel Metering Unit).
Here's what the 407 GXi Manufacturers Data states:
If necessary, as may be the case in certain emergency procedures, an alternate means of engine control is also available to the pilot. For example, in the event that the pilot needed to reduce the engine speed below 100% NP/ NR, this can be achieved by manipulating the throttle below the FLY detent position until the necessary engine performance is achieved. As the throttle is set below the FLY detent (for example: between Power Lever Angles (PLA) of 50° to 67.0°), electrical signals are sent to the EEC’s from the dual channel Linear Variable Differential Transducer (LVDT). These signals dictate the amount of authority the EEC channel in control has to control maximum fuel flow (for example: NG limiting), and in turn, engine NG speed. Therefore, as the throttle is increased or decreased in the range of 50° to 67.0° PLA, the maximum NG speed is regulated electrically by limiting the fuel flow. As mentioned previously, PLA angles of 67.1° and above will provide the EEC channel in charge with complete control to maintain 100% NP/NR.
LRP what you are quoting here is correct for the basic 407 and GX/P models. The GXi does not have an HMU anymore as everything is controlled by the EEC (Electronic Engine Control) which in turn controls the FMU (Fuel Metering Unit).
Here's what the 407 GXi Manufacturers Data states:
Hope this helps.
Here's what the 407 GXi Manufacturers Data states:
Hope this helps.
Thank you vertical spin. I caught on to that as well when I read the comment by LRP and went straight to the GXi’s manufactures data to see what the differences were. Thank you for pointing it out!
