NATOPS Flashcards
(219 cards)
Primary Fuel
A fuel that the aircraft is authorized to use for continuous unrestricted operations.
Restricted Fuel
A fuel that imposes operational restrictions on the aircraft.
Emergency Fuel
A fuel which may be used for a minimim time when no other primary or restricted fuel is available in case of emergency or operational necessity.
What are our primary fuels?
JP-5, JP-8, A++ (F-24), TS-1
What are our restricted fuels?
A1, A, JP-4, B
What are our emergency fuels?
JP8+100, F-27
What engine does the MH-60R have?
T700-GE-401C engine
5 sections: inlet, compressor, combustion, turbine, and exhaust.
Compressor Section
5 stage axial, single stage centrifugal
Where is TGT sensed?
Between the gas-generator and power turbine.
Engine Airflow Distribution
30% of total airflow used for the combustion process. The rest is utilized for:
- Compressor inlet temperature (T2) air
- Compressor discharge pressure (P3) air
- Combustor and turbine cooling
- Engine oil seal pressurization
What engine governing is retained with PCLs in LOCKOUT?
Np overspeed protection
TGT limiting, Np governing, and load shading are deactivated
Functions of the Engine-Driven Fuel Boost Pump
- Provide reliable suction feed from the aircraft fuel tank to the engine
- Provide discharge pressure to satisfy the minimum inlet pressure requirement of the HMU or high-pressure fuel pump.
HMU fuel is tapped off for what purposes?
- Positioning a metering valve to ensure proper fuel flow to the engine.
- Position a servo piston that actuate the variable geometry van servo and start bleed valve.
- Amplifying various signal (T2, P3, Ng) that influence fuel flow and variable geometry servo position.
HMU responds to the PCL for what?
- Fuel shutoff
- Setting engine start fuel flow with automatic acceleration to ground idle
- Setting permissible Ng up to maximum
- Fuel priming
- EDECU override capability (LOCKOUT)
Why is power available in FLY normally more than required?
- Fail-safe to high power (loss of torque motor electric signal)
- Power available with OEI (gas generator can increase power up to its limit
Functions of the HMU
RANNAF
- Rapid engine transient response through collective compensation
- Automatics fuel scheduling for engine star
- Ng overspeed protection (110 +- 2%, centrifugal valve secures fuel flow)
- Ng governing (T2, P3, Ng governing through 3D cam)
- Acceleration limiting (Ng governor protects PCL motion from damaging engine)
- Flameout and compressor stall protection (via VGV and AI/SBV position)
Functions of the ODV
- Provide main fuel flow to the 12 fuel injectors during engine start and operation
- Purge the main fuel manifold overboard, after engine shutdown, through a shutoff and drain valve to prevent coking of the fuel injectors
- Traps fuel upstream, which keeps the fuel/oil heat exchanger full, so that system priming is not required prior to the start
- Returns fuel back to the HMU if the Np overspeed is energized or if the EDECU hot start preventer is activated
Engine limiting definitions
Protect engine components and/or reaching a max possible outcome based on ambient conditions and collective setting
TGT-limiting is defined by reaching either IRP or CRP functions within the EDECU.
HMU-fuel flow limiting is defined by engine control system limiting the max power output under the following:
- Max fuel flow limited by the physical size of the fuel lines within the HMU and ODV
- HMU protecting compressor section by limiting fuel flow as a function of Ng and ambient temp
Increasing the collective during either of these will result in a droop in rotor speed below 100%, no increase in Ng or TGT, and a slight increase in torque within the range of continuous Np limits.
Engine limit condition definition
Torque limited condition is a transmission limit defined by reaching a Chapter 4 limit.
TGT-limited is an engine limit defined by reaching a Chapter 4 limit prior to reaching EDECU IRP, MRP, or CRP functions
Ng limited is an engine limit defined by reaching a Chapter 4 Ng limit.
If an engine is Ng limited and the collective is increased further, Nr will remain at 100% and Ng will increase (along with TGT and torque).
EDECU Operations
4N CHEF TASTEE
- Np governing - Actual Np compared to reference Np to compute speed error input signal
- Np overspeed protection - When Np>120%, ODV diverts fuel to inlet of HMU, causing flameout
- Np overspeed test - A/B buttons that re-reference Np to 96%
- Ng decay relight feature - turns on igniters for 5 seconds to attempt restart if Ng deceleration rate exceeded (>63%)
- Contingency power
- Manual: C-power switch on - TGT-limiting increased to 903, no further fuel flow increase at 891 +- 10
- Auto: enabled in OEI conditions (when one eng <50% torque); reset from 861 to 891 +- 10
- Dual-engine auto: requires Np <96%, greater than 3% droop between Np actual and reference, or 5%/sec Np droop rate - Hot start prevention - stops fuel flow when TGT >900 when Ng <60% and Np <50%; restored after TGT <300 or 25 sec
- Engine load sharing - torque matches lower torque engine by increasing power without affecting higher engine
- Fault diagnostic - displayed numerically on torque indicator (4 sec on/2 sec off); verify clear with TGT >425, PCL in IDLE/FLY
- TGT limiting - prevents further fuel flow to engine when TGT 866 +-10; Np/Nr will droop <100% and Ng governing will be sacrificed to protect against overtemp
- Auto-ignition system - turns on igniters for 5 sec when Np overspeed condition reached; will continue until Np/Nr controlled
- Cockpit Signals - provides Np, TGT, and torque to VIDS
- Transient droop improvement (TDI) - initiates power turbine acceleration why using anticipatory signals from TDI Nr sensor (good for autos)
- Eng speed trim - INCR/DECR switch, adjust Np between 96-101%
- EDECU lockout - PCL manually controls Ng and Np; deactivates TGT limiting, Np governing, and load sharing; keeps Np overspeed protection
CEDECU Operational Modes
incorporates a discrete application selection (DAS) plug, which mates with the E-4 connector
Navy code: 35 +-2.9%
Army Black Hawk code: 15 +-2.9%
EDECU: 0%
Ways to anti-ice the engine
- Vent bleed air from engine swirl vanes and engine IGVs by the engine AI/SBV
- Vent bleed air into the airframe engine inlet by the engine inlet anti-ice valve
- Continuously pump engine oil through scroll vanes
What indicates a malfunctioning anti-ice/start bleed valve?
- Appeareance or disapperance of the ENG ANTI-ICE ON advisory when outside of the range specified in the chart (<80.5: Off, 80.5 - 96.5: On, >96.5: Off)
- No illumination of ENG ANTI-ICE ON advisory when switch is selected on
- No rise in TGT when ENG ANTI-ICE turned on (30-100 increase)
Max torque available is reduced by up to 18% per engine with ENG ANTI-ICE on
How to tell in engine inlet anti-ice valve is not working properly?
Appearance of INLET ANTI-ICE On when OAT >13 (should be fully closed by 13, variable between 4 and 13, fully open <4)
The resultant loss of torque could be a maximum of 49%
Advisory comes on when inlet temp reaches 93