AS350 B3e course · Flying the Astar
Start, run-up and shutdown
What each check proves
The essentials
Before start, the configuration must be right: collective locked, controls and switches set, the area clear, and the twist grip or engine controls where this variant needs them.
During run-up, each check proves something: that the hydraulic accumulators hold, that the warnings work, that the FADEC is healthy, that the engine and gearbox are within limits.
Before lift-off, look at the configuration itself — not at the checklist you just finished.
Before start: the configuration
Each item before start is there because of what happens if it's wrong when the engine lights:
- Collective locked — so it cannot rise as pressure changes.
- Rotor brake released, where fitted, and the fuel shut-off in its normal position.
- Engine controls set as this variant's RFM requires — the next card.
- Area clear, blades untied, doors and belts secure, rotor disc clear of people.
The start is the first time all of these matter at once.
Engine controls, variant by variant
- B2 (Arriel 1D1) — hydromechanical fuel control, set with a fuel flow control lever on the floor quadrant beside the pilot.
- B3 with Arriel 2B — Airbus's information notice 2976-I-76 says the twist grip must be in FLIGHT before the aircraft is energised and started, with the twist-grip and governor lights out, and that the grip must not be used with the engine control unpowered.
- B3 with Arriel 2B1, B3e with Arriel 2D — dual-channel FADECs with their own start procedures; on the 2B1, investigators note, the start is made with the grip in IDLE.
These are not interchangeable. Configure for the engine in front of you, from its RFM.
Mixed fleet, wrong habit
An operator flew AS350 B3s with both the Arriel 2B and the 2B1, which differ in how flight mode is selected. A pilot with little time on the 2B, and more on the 2B1, flew a 2B.
The aircraft yawed, rose about a metre, touched down hard with a tail-rotor strike and rolled onto its side. The engine data recorded rotor overspeeds.
"I know the B3" isn't enough. When a fleet mixes engine controls, the start configuration is the place where the habit from the other aircraft shows up.
Watching the start
Each indication in the start proves one link in the chain:
- Ng rising — the starter is turning the gas generator.
- TOT rising — fuel and ignition have lit it. Watch the peak against the start limit.
- Engine oil pressure — the bearings are lubricated before load arrives.
- Rotor turning — the free turbine is driving through the gearbox.
- Generator on line, start sequence ended — the electrical system is back to normal.
Automatic doesn't mean unattended: a hand ready to abort, eyes on Ng and TOT.
Why the order matters
Checks are sequenced so that each one leaves the aircraft ready for the next. The hydraulic check, for example, deliberately removes pressure — so it has to be followed by restoring it, and the restore has to be confirmed.
Skipping, reordering or being interrupted mid-sequence is how a check becomes a trap.
The accumulator check
The hydraulic check cuts system pressure with a cockpit control, so the main servos run on their accumulators alone. Moving the controls then proves the accumulators are charged and holding — the time you'll have after a real pump failure.
It is done with the collective locked: with pressure gone, the collective can rise by itself. And it ends by restoring pressure and confirming the warning has gone out. A check that removes something you need is only finished when you've proved it's back.
The yaw load compensator check — moved after Frisco
On dual-hydraulic AS350 B3s, a pre-take-off check drained the yaw load compensator using the yaw servo hydraulic switch on the collective. If the switch wasn't put back, the tail rotor had no boost — and the aircraft yawed anticlockwise, nose left, just after lift-off. Two accidents and an incident followed that pattern, Frisco among them.
FAA emergency AD 2015-22-53 moved the check to after landing, once the rotor has stopped, and requires the switch on before take-off. The trap was removed by moving the check, not by asking pilots to be more careful.
Warnings and the lamp test
The lamp test proves every warning light can actually light. During power-up and start, many lights come on and go out as systems come on line — a light that stays on is the first sign of a problem.
Where your aircraft has tests for the gong or the rotor-rpm horn, they prove the sounds will reach you when you're looking outside. A warning that can't reach you isn't a warning.
FADEC and governor checks
A FADEC tests itself at power-up and monitors itself continuously. What the pilot checks — and which lights must be out before flight — depends on the engine: the Arriel 2B's manual twist-grip backup comes with its own indications, and the 2B1 and 2D have automatic backup channels with theirs.
The principle is the same on all of them: an engine-control caution on the ground means you don't fly until it's understood. The RFM says what each one means.
The hover check
The first few seconds in the hover are a test flight. Do the controls respond normally, in every axis? Any unusual vibration? Warnings still clear?
And the power: compare what the hover takes with what the charts said it would. More than expected means something is wrong — the mass, the density altitude, or the engine — and the time to find out is now, a metre off the ground, not leaving a confined area.
The engine power check
The performance charts assume an engine making at least a minimum power. The engine power check, run in stable flight on the schedule your operator sets, measures the margin your engine actually has. The VEMD chapter covers how.
It belongs in this sequence because it is what makes the hover check's comparison honest: a chart is only as good as the engine it assumes.
Shutdown
A turbine needs to stabilise at idle before it's shut off, so the hot section and bearings cool evenly. The RFM sets the time.
After the engine stops, the rotor coasts down. In wind, a slowing rotor's blades can flap low; keep people away from the disc until it has stopped, and use the rotor brake within its limits where fitted.
Using the rotor brake
The rotor brake shortens the coast-down — the time the blades spend slow, low and vulnerable to the wind. On many AS350s its lever is on the floor quadrant, beside the fuel shut-off.
It may only be applied below a rotor speed set in the RFM. Applied early, it heats and wears the brake and loads the drive. It is not a way to hurry a shutdown, and it is released before the next start.
Wind for start and stop
Strong or gusty wind during start and stop is a blade-sailing risk — slow blades flap up and down far enough to hit the tail boom or a person.
At low rotor speed there is little centrifugal force to keep the blades stiff, so a gust lifts one side of the disc and drops the other. The less time spent at low rpm, the less exposure.
The RFM gives wind limits for rotor start and stop. Turning the aircraft into wind and keeping the cyclic where the RFM says help.
Source 3
Post-flight
The post-flight is the next flight's first preflight:
- on dual-hydraulic B3s, the yaw load compensator check, now done here;
- the VEMD flight report — any exceedance is a maintenance item;
- a walk round while it's hot: fresh leaks, bird or debris damage, the tail rotor;
- blades tied, covers on, and the log written up.
What does the pre-flight hydraulic check prove?
That the accumulators hold — and its restore step proves pressure comes back. The restore is where Frisco went wrong.
Why does a turbine need time at idle before shutdown?
Stabilising at idle lets temperatures even out before the engine stops.
On a dual-hydraulic AS350 B3, when is the yaw load compensator check done since AD 2015-22-53?
After landing with the rotor stopped, so a switch left off can't follow you into the air.
On a B3 with the Arriel 2B, where does Airbus say the twist grip must be before start?
FLIGHT, per Information Notice 2976-I-76. The 2B1 and 2D have their own procedures — another reason not to fly one from habits learned on the other.
In the hover check, the aircraft needs noticeably more power than the chart predicted. What does it tell you?
Something in the calculation is wrong. Find out a metre off the ground, before you commit to anything.
Sources
- Aircraft Accident Report AAR-17/01, Airbus AS350 B3e N390LG, Frisco, Colorado · NTSB · 3 July 2015
- AS350B3 rolls — engine controls · Aerossurance
- Helicopter Flying Handbook (FAA-H-8083-21B) · FAA · Chapter 8, Ground Procedures and Flight Preparations
- Interagency Aviation Accident Prevention Bulletin 19-02, AS 350 throttle quadrant · USDA Forest Service / U.S. Department of the Interior · 16 November 2018
- Information Notice 2976-I-76 · Airbus Helicopters · Revision 0, 23 February 2016
- Helicopter Flying Handbook (FAA-H-8083-21B) · FAA · Chapter 4, Helicopter Components, Sections, and Systems
- Arriel 2D — Airbus H125 engine · Safran Helicopter Engines
- Airworthiness Directive 2015-22-53 · FAA · 80 FR 74982, 1 December 2015 (superseded in 2018, 83 FR 2039)
- AS-350 Hydraulic System (investigation docket document) · NTSB
- FAA issues emergency AD for dual-hydraulic AS350 helicopters · Vertical · October 2015
- AAIB report: AS350 B3e Ecureuil, G-MATH · UK AAIB
- Helicopter Flying Handbook (FAA-H-8083-21B) · FAA · Chapter 7, Helicopter Performance
- Helicopter Flying Handbook (FAA-H-8083-21B) · FAA · Chapter 9, Basic Flight Maneuvers
- Aviation Investigation Report A04A0050 (AS350 B3) · Transportation Safety Board of Canada
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.