Warning panel, gong and horn

A tour by system: engine

Expect the engine to report through several channels: oil pressure (a red light with the gong on the B3 TSB Canada describes — an engine losing oil is close to stopping), an engine chip detector (metal in the oil), and indications from the engine control — a FADEC or governor fault, graded by severity on the later engines.

What exactly each caption says, its colour and whether it brings the gong differ between the B2, B3 and B3e. Learn the panel of the aircraft you fly, not a generic one; the FADEC chapter explains what the engine-control warnings mean in principle.

Sources 2, 4, 5, 7

A tour by system: drive and rotor

The main gearbox reports oil pressure and oil temperature, and both gearboxes carry chip detectors. Loss of gearbox oil pressure — a red light with the gong — is among the most serious on the panel: the gearbox carries every bit of lift you have, and it does not run long without oil.

A chip light on its own is information — a detector has caught metal. A chip light together with rising temperature, falling pressure, noise or vibration is a failing gearbox.

Sources 2, 4, 5

A tour by system: hydraulics

Loss of hydraulic pressure brings a red hydraulic warning (HYDR on the B3e) and the gong. It is red not because the aircraft will fall out of the sky, but because the controls are about to become heavy and a hover without boost is not something to attempt.

The Hydraulics and Hydraulic failure chapters cover what the light means, the accumulators and why the procedure ends in a run-on landing.

Sources 4, 8, 9

A tour by system: fuel and electrics

Fuel warnings tell you about quantity — a low fuel caution — and about the system: a clogging fuel filter, fuel pressure where it's monitored. Low fuel means plan the landing now, not when the gauge reaches zero.

Electrical lights cover the generator going off-line and battery temperature — a red warning with the gong on the B3 TSB Canada describes. A generator light starts a clock: everything now runs on the battery. Which captions your aircraft has depends on the variant and its equipment.

Sources 2, 4, 5

Several lights at once

One failure can light several captions. An engine that stops takes its oil pressure and the generator with it, so you may see engine, generator and other lights together — and the horn as rotor rpm decays.

Look for the common cause rather than working through the lights one by one. Here the cause is the engine; the generator light is a symptom. The aircraft tells you what has failed by the pattern, and the rotor rpm tells you how urgent it is.

Sources 4, 5

Horn tones

The horn is one sound source that can say more than one thing: low rotor rpm and high rotor rpm may each have their own pattern, and some installations use it for other alerts.

Learn by ear, on the ground and in training, which pattern means which on your aircraft — the RFM states it. The response to low and high rpm is opposite (collective down for one, up for the other), so mistaking one for the other is the worst kind of error.

Sources 4, 6

Priorities

Warnings compete for attention, and the order is the same every time:

• Rotor rpm and control — fly the aircraft.
• Red — conditions that threaten the aircraft.
• Amber — degraded systems; fix, or plan around.

Then the landing decision: immediately, as soon as possible, or as soon as practicable. A light you have not yet read can wait one second while you keep the rotor in range.

Sources 4, 7

How urgent: the three landing phrases

Flight-manual emergency procedures grade how soon to land with a few standard phrases:

• Land immediately — the aircraft may not stay flying; land at the nearest place, accepting damage if necessary.
• Land as soon as possible — at the nearest site where a safe landing can be made.
• Land as soon as practicable — the flight can continue to a suitable site, but don't extend it.

These are the meanings in common use. Your RFM defines its own at the start of the emergency section, and its wording governs.

Source 6

Confirm before you act

A light is a sensor's opinion. Before a drastic action, look for a second indication: an oil pressure light should agree with the pressure on the VEMD; a chip light with no other symptom is a different situation from a chip light with rising temperature.

Confirming doesn't mean delaying. It means one glance at the right gauge on the way to the procedure.

Sources 4, 10

What a confirmation looks like

Pair each light with what would also be true if it were real:

• Engine failure — yaw, rotor rpm decaying, Ng and torque falling, the quiet.
• Oil pressure — the pressure reading itself, and temperature following it.
• Hydraulic loss — control forces building.
• Generator — the electrical load and battery indications.

Rotor rpm never needs a second opinion: if the horn sounds and the rpm agrees, act. If a light has no partner, it may be the sensor — but land and let maintenance decide.

Sources 4, 5