AS350 B3e course · The aircraft
The family tree
B2, B3, B3e — and why it matters which one you're in
The essentials
Fifty years of production means many versions of the same airframe. The ones you are most likely to fly are the B2 (Arriel 1D1), the B3 (Arriel 2B or 2B1) and the B3e / H125 (Arriel 2D).
They look nearly identical. The biggest differences are the engine and its control, and those change start procedures, failure behaviour and emergency actions.
Before flying any Astar, ask: which engine, which engine control, and which modifications? Then fly that aircraft's RFM.
The variants you'll meet
| AS350 B2 | Arriel 1D1 — hydromechanical fuel control1 |
|---|---|
| AS350 B3 (early) | Arriel 2B — single-channel digital control, manual backup2 |
| AS350 B3 (later) | Arriel 2B1 — dual-channel, automatic backup2 |
| AS350 B3e / H125 | Arriel 2D — dual-channel FADEC, automatic backup4 |
| Type certificate | EASA R.008 — shared with the EC1301 |
Checking an unfamiliar airframe
Treat every Astar as a new type until you have answered these:
- Variant and engine. The type certificate lists the 2B, 2B1 and 2D all under AS350 B3. The engine logbook and the RFM tell you which you have.
- Engine control. Backup type, twist grip, mode switches — and what this one expects on start.
- Modifications. Hydraulics, yaw load compensator, fuel tank, tail-boom strakes, mass increases.
- RFM. The current revision, with a supplement for each item of equipment fitted.
- Open items. Airworthiness directives that add placards or limits.
- Cockpit. Any switch you cannot explain — ask before flight, not after.
Difference matrix: engine and control
| AS350 B (1977) | Arriel 1B · hydromechanical control1 |
|---|---|
| AS350 BA | Arriel 1B · wide-chord AS355 blades, higher max mass6 |
| AS350 B1 | Arriel 1D · hydromechanical control1 |
| AS350 B2 (1989) | Arriel 1D1 · hydromechanical control1 |
| AS350 C / D AStar | Lycoming LTS1016 |
| AS350 B3, Arriel 2B (1997) | Single-channel digital · manual backup via twist grip2 |
| AS350 B3, Arriel 2B1 | Dual-channel digital · automatic backup2 |
| AS350 B3e / H125 (2011) | Arriel 2D · dual-channel FADEC, automatic backup, engine data recorder7 |
Difference matrix: what else changed
| B2 → B3 | About 15% more power, FADEC, LCD instruments, upgraded main gearbox, AS355-type tail rotor8 |
|---|---|
| B3 → B3e | Arriel 2D, new FADEC, engine data recorder, tail-rotor control and blade modifications1 |
| B3e tail rotor | Balance weights instead of a yaw load compensator; compensator reinstated by MOD 07 5606 (2013)9 |
| Dual hydraulics | Option on later aircraft; Airbus quotes 2,370 kg internal max mass with it (a weight-extension mod in the type certificate)10 |
| 2020 H125 standard | More Arriel 2D power released by VEMD software; retrofit for VEMD-equipped B3e11 |
| Fuel tank | Crash-resistant on newer production and some retrofits — check the airframe4 |
The early Arriel aircraft
The first production AS350 B had the Arriel 1B and was certified in France in 1977. The B1 (1986) had the Arriel 1D; the BA (1991) kept the Arriel 1B but took the wider-chord main-rotor blades of the AS355 twin and a higher maximum mass. The B2, certified in 1989, combined the wide-chord blades with the Arriel 1D1.
The Arriel 1 family has a hydromechanical fuel control — no computer between your hand and the fuel. B2s remain common in utility and firefighting fleets, and B, B1 and BA airframes can be converted to B2 standard by service bulletin, so the paperwork matters more than the year of build.
The North American AStar
For the US market Aérospatiale built the AS350 C (FAA-certified 1977) and then the AS350 D AStar (1978), powered by the Lycoming LTS101. They are the same airframe family with a different engine, different engine handling and different limitations.
Engine swaps under supplemental type certificates go in more than one direction. Soloy, for example, has converted Arriel-powered BA and B2 aircraft to Honeywell LTS101 engines — the converted B2 is designated AS350 SD2.
A logbook or RFM supplement, not the paint, tells you what you have.
The B3 and B3e
The B3 first flew on 1 March 1997 with the Arriel 2B and digital engine control, and was certified in France that December. Its engine control changed during production, by engine serial number:
- early 2B: single-channel control, with a manual backup through the twist grip
- from engine 073084: an automatic stop added to that backup arrangement
- from engine 073254, the 2B1: dual-channel control with an automatic backup
The B3e (flight manual EASA-approved 17 June 2011) brought the Arriel 2D, a new FADEC with an automatic backup, and an engine data recorder. It became the H125 in 2015 and is the version in production today.
B2 to B3: more than an engine
The B3 was not a simple re-engine. Flight International described about 15% more power, FADEC, LCD instruments, a main gearbox upgraded to carry the extra power, and a tail rotor of the type fitted to the AS355 twin.
For a pilot moving between them, the differences that matter are a different start, a different way of reading the engine, a different engine-control failure picture, and more power to manage with the pedals.
Mixed fleets are where start-up accidents have caught pilots out.
Gauges or VEMD
Most Arriel 1 aircraft show the engine on separate instruments: torque, gas-generator speed and turbine temperature each on its own gauge with its own markings. You scan three needles and judge which is closest to its limit.
The B3 brought the VEMD: two LCD screens, with the First Limit Indicator making that comparison for you. It also counts cycles and records exceedances. Late-production B2s can have a VEMD too — the type certificate lists a B2 VEMD modification — so check the panel.
Moving between them is a scan problem. On a VEMD a gauge pilot can stop seeing the individual parameters; on gauges a VEMD pilot can miss that a different limit is now first.
The compensator that came back
The B3e was meant to do without the yaw load compensator — a hydraulic device on the tail-rotor control that offsets pedal loads — and used extra balance weights on the tail rotor instead.
In service the tail rotor's laminated half-bearings deteriorated early. EASA's emergency ADs of 2012 imposed flight-envelope limits and repeated inspections. In February 2013 AD 2013-0029 required the fix, MOD 07 5606, within five months: remove the weights and fit a compensator — in effect, the B3 configuration again.
Two aircraft with the same name can differ because of where each sits in the modification history. Modification state is something to check, not assume.
Common STCs and options
Third-party supplemental type certificates change Astars too. Some you will meet:
- FastFin (BLR Aerospace) — a tail-boom strake, a reshaped tail-boom cowling and vortex generators, intended to improve tail-rotor margin in crosswind hovering. FAA-approved for the H125 family in December 2016, EASA in January 2017.
- Engine conversions, such as Soloy's LTS101 installations.
- Crash-resistant fuel tanks retrofitted to older airframes.
- Mission kits: cargo hook, floats, high skids, wire-strike cutters, hoist.
Each brings an RFM supplement, and some change limitations or performance charts.
Relatives, not variants
Some aircraft share the Astar's lineage but are different types to fly:
- AS355 Écureuil 2 / TwinStar — the twin-engine derivative.
- EC130 / H130 — a wider cabin and a Fenestron tail on the AS350's dynamic system. It shares the AS350's EASA type certificate, R.008.
- AS550 Fennec / H125M — the military versions; Airbus counts the H125M in the Écureuil family alongside the H125 and H130.
Experience transfers. Procedures, limitations and emergency handling do not.
What else changes between airframes
Beyond the engine, individual aircraft differ in ways that matter:
- hydraulics — single, or the optional dual system
- yaw load compensator — and its modification state
- fuel tank — original or crash-resistant
- instruments — round gauges or the VEMD, and the avionics fit
- mission equipment — floats, high skids, hook, cutters, each with an RFM supplement
Each can change limitations or emergency actions.
You're about to fly an unfamiliar AS350 B3. What should you confirm first?
The engine control. B3s with the Arriel 2B and 2B1 have different start positions and different backup behaviour, and confusing them has caused accidents.
Which engine does the B3e / H125 use?
The Arriel 2D. The B2 has the 1D1, the B3 the 2B or 2B1, and the AS350 D the Lycoming LTS101.
The paperwork says 'AS350 B3'. Does that tell you its engine control?
No. The type designation covers the early 2B, the 2B1 and the B3e's 2D, which have three different engine controls. The engine logbook and the RFM tell you which one you have.
What did MOD 07 5606 do to the B3e?
It removed the extra tail-rotor balance weights and fitted a yaw load compensator, returning the yaw channel to the B3 arrangement after the tail-rotor bearing problems of 2012.
What kind of fuel control does the Arriel 1D1 in a B2 have?
Hydromechanical. Digital engine control arrived with the Arriel 2 in the B3 — which is why start and engine-control failure handling differ so much between B2 and B3.
Sources
- Type-Certificate Data Sheet R.008, AS 350 / EC 130 · EASA
- Eurocopter addresses AS 350B3 engine-control failure recovery · Aviation International News · 30 October 2006
- AS350B3 rolls — engine controls · Aerossurance
- H125 Technical Description 2025 (baseline aircraft definition) · Airbus Helicopters · 125 B3 25.100.04 E / 25.101.01 E — General, Cockpit/Cabin, Power plant, Transmission
- Helicopter Flying Handbook (FAA-H-8083-21B) · FAA · Chapter 5, Rotorcraft Flight Manual
- Eurocopter AS350 Écureuil — development and variants · Wikipedia · Development; Variants (AS350 BA, B1, B2, C, D)
- Turbomeca's Arriel 2D engine is certified by EASA (press release) · Turbomeca (Safran), via AviationPros · 16 May 2011
- Proven pedigree: low cost, low noise and low vibration led Eurocopter's design priorities for its AS350B3 · Flight International · 1 September 1999
- Eurocopter falls back on load compensator as fix for AS350 B3e · Vertical
- H125 — product page · Airbus Helicopters · Dual hydraulics / 2,370 kg internal MTOW; 1,400 kg sling load
- More power and enhanced aerial work capabilities for the H125 · Airbus Helicopters · January 2020
- Type-Certificate Data Sheet E.073, Arriel 1 series engines · EASA · Issue 05, 20 February 2025
- Soloy gets 100th LTS101 for its 350 re-engining program (AS 350BA and AS 350B2) · Aviation International News · 25 February 2008
- EASA awards STC for Soloy LTS101 helo mod (AS350BA) · Aviation International News · 14 July 2010
- New names for Airbus Helicopters models · Vertical · 2015
- Emergency Airworthiness Directive 2012-0217-E (tail rotor) · EASA
- EASA OKs Eurocopter fix for AStar/Ecureuil tail rotor · Aviation International News · 14 February 2013
- BLR secures FAA/EASA approvals for H125 FastFin · Aviation International News · 7 March 2017
- Crash-resistant fuel systems: uptake among civil helicopter operators · AirMed & Rescue
- Aérospatiale AS350 Écureuil / AStar — production history · Helis.com
- Airbus delivers the 7,000th Ecureuil helicopter · Airbus Helicopters · July 2022
- Information Notice 2976-I-76 · Airbus Helicopters · Revision 0, 23 February 2016
- Aircraft Accident Report AAR-17/01, Airbus AS350 B3e N390LG, Frisco, Colorado · NTSB · 3 July 2015
Educational only. Not approved training material, and never a substitute for the Rotorcraft Flight Manual, an instructor, or your operator's procedures. Figures marked as manufacturer data or test results are not limitations. This content is a draft and has not yet been reviewed by an instructor.