SAFRAN (TURBOMECA) ARRIEL 1D1 · FREE-TURBINE TURBOSHAFT · AS350 B2

Arriel 1D1 Engine Lab

Start the engine, fly it, and break it. The cutaway follows the air from intake to exhaust while a simple physics model drives the cockpit gauges. Limits come from the EASA type-certificate data sheet. Click any numbered part to learn what it does.

Upper half: section · Lower half: outside view · Schematic, not to scale t 00:00
Governing

Upper half: section · Lower half: outside view · Swipe the drawing to pan

Gas temperature−40 °C1,250 °C

Instrument panel

Green, amber and red bands use TCDS limits
Shaft power–
Output shaft–
Gas generator–
Free turbine–
Fuel flow–
Air mass flow–
Pressure ratio–
Thermal efficiency–
Part 1 of 11 · Module M01

Air intake

Follow the air

The cycle, live

Temperature–entropy diagram of the Brayton cycle. Compress (1→2), burn at near-constant pressure (2→4), expand through both turbines (4→5). The faint loop is take-off power at sea level, ISA.

StnLocationP barT °C

Where the fuel energy goes

Shaft power to rotor–
Hot exhaust and losses–

Turbine work split

Spent driving the compressors–
Sent to the rotor–

Reduction gearbox

Free turbine 41,420 rpm → output 5,976 rpm (6.93 : 1). Drawn slowed down.

Free turbine torque–
Output shaft torque–

Lab sheet

Each task ticks itself when the sim sees you do it.

    Exceedance log

    Limits passed, with the peak value reached. A real exceedance means a maintenance inspection.

    • No exceedances yet.

    Arriel 1D1 data

    From EASA TCDS E.073, Issue 05 (20 February 2025). The TCDS is the certified reference. Manufacturer brochures quote slightly different power figures.

    TypeFree-turbine turboshaft, single-engine helicopters
    Part number0 292 00 522 0
    EASA certification19 July 1988 (applied 10 May 1988)
    Gas generator1 axial + 1 centrifugal compressor, annular combustor, 2-stage turbine
    Power turbine1 stage, free; reduction gearbox at rear; accessory gearbox at front
    Take-off power531 kW (712 shp)*
    Max continuous power466 kW (625 shp)
    Output shaft speed5,976 rpm
    N1 (100%)51,800 rpm
    N1 limitsMCP 98% · TO 101.9%* · 103.1% 20 s** · 107.5% 5 s · min 67%
    N2 (100%)41,420 rpm
    N2 limits108.5% stabilized · 120.5% / 86% for 5 s
    TOT limitsMCP 795 °C · TO 845 °C · start 865 °C · 870 °C <20 s**
    Torque83 m·daN max · 91.5 m·daN for 20 s
    Oil temperaturemax 115 °C · power application from −10 °C (3 cSt oil) / 0 °C (5 cSt)
    Oil pressuremin 1,300 hPa (70–85% N1) · 1,800 hPa (N1 ≥ 85%) · max 5,000 hPa
    P2 air bleedmax 100 g/s at take-off
    Control systemHydromechanical FCU: proportional N2 + proportional-integral N1 control
    Size (L × H × W)1.20 × 0.61 × 0.47 m
    Dry weight122 kg

    * Restricted by the installation's fuel-flow limit; N1 take-off limit follows a de-rating law with OAT and altitude. A Safran brochure quotes 546 kW (732 shp) at sea level, ISA. ** Only on helicopters with the VEMD digital display.

    How the sim works

    The limits above are certified data. The engine behaviour between them is a teaching model, not a performance model. Assumptions:

    • Shaft power rises with corrected N1 and falls with air density (δ/√θ). It reaches 531 kW at 101.9% N1 at sea level, ISA.
    • TOT follows corrected N1, calibrated so take-off power sits at 845 °C and max continuous near 795 °C.
    • Air mass flow about 2.5 kg/s and pressure ratio about 8 : 1 at take-off. Component efficiencies are 78–85%.
    • Rotor power demand runs from 140 kW (flat pitch) to 600 kW (full collective) at 100% rotor speed.
    • Generic start sequence: ignition at 10% N1, light-off at 12%, starter cut-out at 45%, idle near 68%. Follow the flight manual for real procedures.
    • The governor holds N2 at 100% with a proportional loop plus collective feed-forward. The fuel stop limits N1 to 104.5%.

    References