NATOPS DECU Flashcards
What are the control parameters of the DECU?
- NP sensing
- NP overspeed and torque sensing
- TGT monitoring
The DECU receives what inputs from the cockpit?
- ENGINE SPD TRIM
- CONTGCY PWR
- ENG OVERSPEED TEST A and B
DECU receives what input signals from helicopter?
- TQ from other DECU
- NP demand
- 400hz backup power
- HMU (LVDT)
DECU sends what signals to the cockpit?
- Torque
- Np
- TGT
- Contingency Power
DECU functions:
4NCHEFTASTED
- 400 hz airframe power
- NP governing
- NP overspeed protection (@120% fuel diverted)
- NP overspeed test (resets overspeed limit to 96% Np)
- NG decay relight feature
- C-power (891 +- 10)
- Hot start prevention
- Engine load sharing
- Fault diagnostic System
- TGT limiting
- Auto ignition system
- Signals to cockpit
- transient droop improvement
- Engine speed trim (96-101%)
- DECU LOCKOUT
Never reset a popped ENG OVSP circuit breaker because _________.
It may initiate engine overspeed signal and cause the engine to fail
TGT limiting
DECU?
EDECU?
@ 851 and IRP limiter will limit fuel flow at 839 +- 10.
EDECU is at 866 +- 10
Rotor will start to droop if power is demanded beyond that.
C-power
Allows TGT up to 903 but limit fuel flow at 891 +- 10.
DECU LOCKOUT
Torque motor is disabled deactivating:
- TGT limiting
- Np governing
- load sharing
Keeps
- Np overspeed
Hot start prevention
When TGT hits 900C with NG below 60% and NP below 50%
The DECU trips the ODV to stop fuel flow.
FUEL flow is restored when TGT is below 300 or 25 seconds.
Overridden by holding the ENG OVRSPD test button during start.
Failure to clear DECU fault codes will prevent:
AFCS ground checks
Blade Fold
What is Transient droop improvement?
The DECU increases fuel flow to the HMU when
collective demand is increased rapidly or
in the event of rapid NR decay.
It does this by anticipating signals from the NR sensor and the collective position
Auto-ignition system
After an NP overspeed (120%) and the NP is below 120 the ODV closes and the igniters come on for 5 seconds. This process will continue until NP is controlled.
Might cause yaw kicks during relight.
NG decay rate relight feature
If an engine flames out and NG decay exceeds a certain rate
The auto relight feature will come on for 5 sec.
Disabled below 62 percent
EDECU has what differences?
TGT limiting is at 866+-10 instead of 839+-10.
Auto C-power in OEI conditions. (torque below 50%)
C- power advisories will not come on.
