Bell 407GX Systems

Question 1

What type of engine does the BH407GX have?

Answer 1

Rolls Royce 250-C47B
RFM System Description 1-14-A

Question 2

BH407GX
During operation in the AUTO mode, how is a FADEC failure condition indicated?

Answer 2

Activation of the FADEC FAIL warning tone and display of the FADEC FAIL warning and FADEC MANUAL caution messages on the CAS
RFM System Description 1-14-A-1

Question 3

BH407GX
What are the main components of the FADEC system?

Answer 3

The airframe mounted ECU (Electronic Control Unit)
The engine mounted HMU (Hydro-mechanical unit)
RFM System Description 1-14-A-2

Question 4

BH407GX
What are the 9 inputs monitored by the ECU?

Answer 4

1 - MGT
2 - NG
3 - NP
4 - NR
5 - TMOP (Torque Meter Oil Pressure)
6 - Collective Pitch and Rate
7 - CIT (Compressor Inlet Temperature)
8 - Ambient Pressure
9 - PLA (throttle Power Lever Angle)

RFM System Descriptions 1-14-A-2

Question 5

BH407GX
How does the HMU provide fuel modulation in the AUTO mode?
In the MANUAL mode?

Answer 5

AUTO = stepper motor
MANUAL = hydro mechanical actuator

RFM System Descriptions 1-14-A-2

Question 6

BH407GX
If a FADEC lamp test failure is identified by a system self-test, how will the system alert the pilot?

Answer 6

The FADEC MAINT advisory CAS message.

RFM System Descriptions 1-14-A-3

Question 7

BH407GX
From where does the FADEC ECU receive electrical power?

Answer 7

Below 85% NP, the aircraft supplies power via the 28 VDC bus.
Above 85% NP, the ECU selects between the 28 VDC bus and the engine-driven PMA as its primary power source. The higher voltage source is selected.

RFM System Descriptions 1-14-A-3

Question 8

BH407GX
During an automatic start procedure, how long after positioning the throttle to idle does the pilot have to engage the starter before the FADEC ECU prevents the starter from latching?

Answer 8

60 seconds

RFM System Descriptions 1-14-1-A-4

Question 9

BH407GX
If, during an automatic start procedure, the ECU has disabled the latching feature because the start switch was not activated in time, what must be done to reset the system?

Answer 9

Throttle must be positioned to cut-off and then back to idle.

RFM System Descriptions 1-14-A-4

Question 10

BH407GX
During a normal automatic start sequence, when does the ECU unlatch the starter?

Answer 10

Upon reaching an engine NG speed of 50%

RFM System Descriptions 1-14-A-4

Question 11

BH407GX
During a normal automatic start sequence, how long is the “Hot Start Abort Logic” incorporated?

Answer 11

Up to 50% NG

RFM System Descriptions 1-14-A-4

Question 12

BH407GX
What throttle PLA corresponds to the FLY position?

Answer 12

70 degrees

RFM System Descriptions 1-14-A-8

Question 13

BH407GX
Below what throttle PLA will the ECU’s degree of authority over fuel flow begin to decrease?

Answer 13

62 degrees

RFM System Descriptions 1-14-A-8

Question 14

BH407GX
After detecting a flameout, how long will the FADEC system continue the automatic relight sequence?

Answer 14

Until a relight is detected OR NG speed decays below 50%. The AUTO RELIGHT message will remain illuminated while the sequence is running.

RFM System Descriptions 1-14-A-8

Question 15

BH407GX
If a FADEC fault occurs while the engine is running, but the fault is minor in nature (i.e. Maintenance Advisory Faults), how and when is it communicated to the pilot?

Answer 15

These faults are identified as maintenance advisory faults and are display during shutdown when the throttle is placed in the cutoff position and the NG speed decays below 9.5%. This is in the form of a FADED DEGRADED message.

RFM System Description 1-14-A-9 and 19

Question 16

BH407GX
How many categories of FADEC faults are there and what are they?

Answer 16

Five categories - four relate to in-flight faults, one relates to maintenance advisory faults with engine shutdown.

They are:
1 - Direct Reversion to Manual (DRTM)
2 - FADEC DEGRADED
3 - FADEC FAULT
4 - RESTART FAULT
5 - Maintenance Advisory

RFM Systems Description 1-14-A-9 thru 19

Question 17

BH407GX
How long does it take to transition from AUTO to MANUAL mode? Is the use of throttle to control NR/NP effective during this time?

Answer 17

2 to 7 seconds.
No, use of throttle is ineffective until the transition to MANUAL mode is complete.

RFM Systems Description 1-14-A-11

Question 18

BH407GX
(TRUE/FALSE) - The NP Overspeed system is only available in the AUTO mode.

Answer 18

FALSE
NP Overspeed protection is available in both AUTO and MANUAL modes by independent analog circuits integral to the ECU.

RFM Systems Description 1-14-A-16

Question 19

BH407GX
At what NP speed does the NP Overspeed system activate the overspeed solenoid and reduce fuel flow?
At what NP speed does the solenoid deactivate?

Answer 19

Activates at 118.5% +/- 1%
Deactivates at 112.5 +/- 2 %

RFM Systems Description 1-14-A-16

Question 20

BH407GX
What cockpit indications would tell the pilot that FADEC was operating in the Reversionary Govenor mode?

Answer 20

Illumination of the FADEC FAULT, FADEC DEGRADED, and RESTART FAULT messages.

RFM Systems Description 1-14-A-15

Question 21

BH407GX
What avionics components are directly associated with activation and deactivation of the Airspeed Actuated Pedal Stop System?

Answer 21

• AIr Data Computer (ADC)
• GIA 2 (Garmin Integrated Avionics)

RFM Systems Description 1-20-D

Question 22

BH407GX
At what speed is the pedal stop restrictor extended?

Answer 22

55 +/- 5 KIAS.

RFM Systems Description 1-20-D

Question 23

BH407GX
At what speed is the pedal stop restrictor retracted?

Answer 23

50 +/- 5 KIAS.

RFM Systems Description 1-20-D

Question 24

BH407GX
When will the PEDAL STOP caution message be displayed?

Answer 24

1 - when the test button is pressed.

2 - any time the pedal stop restrictor remains extended and airspeed is below 50 +/- 5 KIAS.

3 - any time the pedal stop restrictor remains retracted and airspeed is above 55 +/- 5 KIAS.

RFM Systems Description 1-20-D