NATOPS Flashcards
Requires Operational Necessity
Night HIFR
Night VERTREP
Rescue Via One or Two Wheels
Operating with Emergency Fuel
NATOPS acronym and purpose
NAVAL AIR TRAINING AND OP PROCEDURE STANDARDIZATION.
It is a positive approach towards improving combat readiness and achieving a substantial reduction in the aircraft mishap rate.
Where is TGT sensed?
TGT is sensed between the gas-generator and power turbine.
What percentages of airflow through the engine are used for what?
30% for the combustion process
70% for:
- compressor inlet temp (T2) air
- compressor discharge pressure (P3) air
- combustion and turbine cooling
- engine oil seal pressurization
What does Ng drive?
Compressor and Accessory Gearbox (AGB)
How does the Engine connect to the Rotor system?
Np turbine turns the power turbine driveshaft which extends through the front of the engine and connects to the high speed shaft which connects to the diaphragm coupling in the input module. Then… freewheeling unit and reduction gears and the main transmission
DECU vs HMU
Basic interaction
The HMU provides gas generator control while the DECU trims the HMU to satisfy the requirements of the power turbine load and reduce pilot workload.
The HMU provides functions essential to safe engine operation while the DECU performs fine trim to reduce pilot workload.
PCL position, what’s happening?
OFF- the power available spindle (PAS) mechanically shuts off fuel at the shut off valve within the HMU.
IDLE- the HMU automatically controls start sequence fuel flow allowing the engine to achieve self sustaining combustion.
FLY- sets the max level of power that could be supplied, if demanded.
LOCKOUT- PCL is used to manually control Np and Ng. TGT limiting, Np governing and load sharing functions are deactivated and must be manually controlled. The Np overspeed protection system is retained via a direct link between the DECU and ODV.
What do the T2, P3 and Ng signals aid the HMU in doing?
Controlling variable stator vanes and anti-ice/start bleed valve position during engine start and normal operation, reducing the chance of a compressor stall.
Also used for minimum and maximum fuel flow.
What linkages/signals does the HMU respond to?
Mechanical- Load Demand Spindle: coordinates Ng speed to the approximate power required by the rotor system based on collective position.
Mechanical- Power Available Spindle: the position of the PCL manipulates the PAS at the HMU setting the desired power setting.
Electrical- signal from the DECU which actuates the torque motor servo in the HMU to precisely trim Ng speed for power turbine control and load sharing.
What does the HMU respond to the PCL for?
Fuel shutoff
Setting engine start fuel flow with automatic acceleration to ground idle
Setting permissible Ng up to maximum
Fuel priming
DECU override capability (lockout)
What equipment in the HMU trims the amount of fuel supplies to the engine?
The Metering Valve schedules engine fuel flow commensurate with current power demand and is trimmed to the required level by the torque motor servo in response to DECU signals.
Ng OVSPD
What is happening?
110+/-2
A spring loaded ball valve ports fuel pressure causing the minimum pressure valve to secure flow to the engine.
What does the HMU provide?
Rapid engine transient response through collective compensation.
Automatic fuel scheduling for engine start.
Ng overspeed protection.
Ng governing.
Acceleration limiting.
Flameout and compressor stall protection.
Overspeed and drain Valve Functions
Provides fuel flow to the 12 fuel injectors during engine start and operation.
Purges 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 next start.
Returns fuel back to the HMU if the Np overspeed is energized or if the DECU hot start preventer is activated.
DECU Functions
400hz backup power
Np governing (left side power turb sect)
Np ovspd protection (120)
Np ovspd test (reref 96)
Ng decay rate relight (disabled Ng<62)
Contingency power (891+/-10)
Hot start prevention (Ng<60, Np<50,TGT>900)
Engine load Sharing
Fault diag system (codes interfere AFCS grnd check)
TGT Limiting (839 for IRP, 866 for MRP)
Auto Ignition System (Np ovspd reref and relight)
Cockpit Signals (Np, TGT, TRQ)
Transient Droop Improvement (left acc module)
Engine Speed Trim (96-101 Np)
DECU Lockout (TGT Limit, Np gov, Load share)
Primary Missions
SUW
ASW
EW
C2
NCO
Secondary missions
Amphibious Warfare
Air Warfare
Health Services
Fleet Support Ops
Intelligence Ops
Logistics
Naval Special Warfare
How can we fit four people in the back?
Three rear seats and instructor seat, SO seat unoccupied.
Abort Start Criteria
Ng does not reach 14% within 6 seconds after starter initiation
No oil pressure within 30 seconds after starter initiation.
No light-off within 30 seconds after moving PCL to idle.
ENG STARTER advisory disappears prior to reaching 52% Ng.
TGT is likely to exceed 851c before idle speed is attained.
After start Ng ground idle split is greater than 3%.
Indication of possible LDS rollpin failure. Do not fly until maintenance action is performed.
Minimum pressure to jettison full sono launcher
1100psi
Normally charged to 1175+/-25
System secured at 250psi to ensure safe launch separation from aircraft.
APU essential operations
Emergency procedures
Single engine training
Practice autorotations
Powering ECS during extreme temperature ops
Go/No-go canister pressure differential and rating
10,000lbs of fuel (or replace after ever evolution)
20psi differential for fuel flow to stop
APU Types
Turbomach/sundstrand
Garrett (we have this, 2 eng, 20 min, 2 quarts to refill from fill line)
Minimum Hyd Press to start APU
2650psi
APU CTRL Switch
Selecting ON opens the APU airframe fuel shutoff valve and sends a start signal to the digital electronic sequence unit.
Selecting OFF removes electrical power from the system, closing the airframe fuel shutoff valve.
To maintain BIT codes after a failure the APU CTRL must stay in the on positions and Battery power must stay on.
General preflight checks (four things)
Corrosion
FOD
Condition
Security
Visual Approach
Intercept ship final approach course at 200’ and 0.5nm to achieve a 3degree glideslope. Utilize a coordinated descent and deceleration to arrive 15’ above the deck.
Alternate Instrument Approach
Begins at least 1.5 nm astern the ship at 200’ and 80kias.
When established on final approach course begin a descent and deceleration at 0.5dme (MAP) at no less than 200’ and 50kias (we actually use closure not kias).
If no visual contact at 0.5dme go missed approach, otherwise utilize visual approach procedures to arrive 15’ above the deck with a controlled rate of closure.