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Systems and Equipment Malfunctions

Not one dramatic event but a list — an alternator that quits, a gyro that lies, smoke in the cabin, flaps that stay up. What is tested is whether you notice early, do the immediate actions your airplane expects you to know by heart, confirm with the checklist, and keep flying the whole way through.

Emergency Operations — FI.XII.C

Why this task exists

A PFD that goes dark halfway through a night cross-country and a cabin door that pops open just after rotation have almost nothing in common as pieces of hardware. As emergencies they are the same problem: something has changed, and the airplane has to keep flying while you work out what. Most of the answer is not knowledge of the system. It is whether you notice, and whether the flying stops while you think.

Four things are being tested. That you recognize the malfunction early. That you respond in the order the airplane requires — the immediate actions your airplane expects you to know by heart, then the POH and the checklist to confirm what you did and finish what you did not. That you keep control throughout. And that you can say what risk the failure has created for the rest of the flight.

That order matters more than it sounds. Some of these failures give you the whole afternoon; an engine fire, an engine failure after takeoff or a runaway trim gives you seconds, and those are the ones the handbooks and your POH expect you to have committed to memory and to perform before you open anything. Memory items are not a way around the checklist — they buy the time in which the checklist is still useful. What you must not do is diagnose first. A theory about what broke is the most expensive thing you can carry while the airplane descends.

Engine power loss

The causes group into three families. Fuel — starvation from a tank you stopped managing, exhaustion, or contamination from water or the wrong grade. The environment — carburetor ice and induction icing, produced by conditions that look harmless. Maintenance — something that had been wearing out for a while and finished on your flight.

Sometimes it announces itself first: a drop in RPM or manifold pressure, roughness, a change in the sound you have stopped consciously hearing. Often it does not. Fuel exhaustion, a selector left on a tank that has run dry, and sudden mechanical failure routinely arrive with no warning at all. Notice what there is to notice, but never read a smooth-running engine as evidence that nothing is wrong — that is what fuel planning, a tank-switching habit and the gauges you actually scan are for.

Whatever caused it, the first action is the same. Pitch for best glide and fly the airplane; nothing you do with the fuel selector matters if the nose drops and the speed decays while you do it. Best glide speed comes from your POH. Establish the glide, pick somewhere to land, and then go after the engine: fuel selector to the fullest tank or the other tank, boost pump on, mixture rich, carburetor heat on if the engine has a carburetor, ignition on both and then tried on each. In most training airplanes those are memory items, and yours may order them differently or leave one out — learn the flow for the airplane you fly. The printed engine failure or partial power loss checklist follows, to confirm what you have already done and to cover what you have not.

Carburetor heat is worth saying out loud, because carb ice gets named as a cause and then forgotten as a response. Apply it early and apply it fully, and expect the engine to run rougher and the RPM to drop further before anything improves — that roughness is melted ice going through the engine, and it is the sign that you were right.

Partial power is the harder case, because an engine still making something invites you to press on toward the airport you wanted rather than the field you can reach. Treat partial power as a failure that has not finished happening yet.

Oil pressure and engine temperature

Falling oil pressure, especially with oil temperature climbing to meet it, is an engine failure that has not happened yet. Reduce power to the least that keeps you moving toward somewhere useful, turn toward the nearest suitable airport, and fly the arrival on the assumption that the engine will stop before you finish it — high, close in, and within gliding distance of the runway if you can manage it. It may be only a gauge or a sender, and that is a comforting thought to have on the ground afterward rather than a reason to keep flying on it now.

Smoke and fire

This is the failure that does not wait, and the one that makes the memory-item argument concrete. An engine fire in flight is fought by taking its fuel away — mixture to idle cutoff, fuel shutoff closed, cabin heat and defrost closed so the smoke has no route into the cabin — and then by getting down quickly, which is what the emergency descent exists for. An electrical fire usually smells before it shows: hot insulation, then haze. Take the power away, use the extinguisher if the airplane carries one, and ventilate deliberately rather than by reflex, because a vent opened onto a live fire feeds it.

The exact switches and their order are in your POH, and this is the one page in this lesson you should be able to recite without reading. Both cases end the same way: land as soon as possible, at the nearest place you can put the airplane down rather than the nicest one, and tell someone on the radio while you still have a radio.

Electrical failure

When the alternator quits the airplane does not stop flying — it starts a countdown, and the battery endurance you have is shorter than most pilots assume. The early signs are a low-voltage annunciator or a discharging ammeter; the late ones are screens dimming, radios going quiet, and equipment dropping off in an order you never chose.

Run the checklist, shed every load you do not need, and land while you still have the equipment to do it comfortably. Some airplanes carry an emergency or essential bus that keeps a minimal set of instruments and one radio alive, and some DA40s are among them. Whether yours has one, what it feeds, how you select it and how long it lasts are questions only your POH answers, and the time to read that page is on the ground.

The instruments that lie

Vacuum and pressure gyros

In a legacy panel the attitude and heading indicators are spun by an engine-driven vacuum pump, and the characteristic failure is gradual. The gyro spools down slowly, so the attitude indicator keeps presenting a confident answer well after it stopped being a true one. That is what makes it dangerous in cloud: it does not go blank, it goes wrong.

Do not assume a glass panel has retired this. Many G1000 airplanes, the C172S and 182T among them, still carry a vacuum or pressure pump driving a standby attitude indicator, so the pump, its gauge and its annunciator are still yours to check on preflight and to scan in flight. What your airplane has, and what fails with it, comes from the POH and the avionics supplement.

When a gyro goes, the technique has substance to it. Cross-check first — an attitude indicator that disagrees with the turn coordinator, the altimeter and the airspeed is the one that is wrong. Cover it, so your eyes stop going back to a picture you have decided not to believe. Then fly partial panel: the electric turn coordinator or turn and slip for bank and rate, the magnetic compass for heading, and the airspeed indicator, altimeter and vertical speed for pitch, with small power changes and timed turns instead of large attitude changes. Ask for help early and tell the controller what you have lost.

Pitot-static

A blocked static port freezes the altimeter where the blockage happened, pins the VSI at zero, and leaves airspeed inaccurate everywhere except that altitude. The fix is the alternate static source, which vents to the cabin — where pressure is usually slightly lower than outside, so the altimeter and airspeed both read a little high and the VSI shows a brief false climb as you switch. Know where that selector is before you need it; in the DA40 it is typically under the left side of the panel, but the variants differ and your POH is what settles it for the airplane you are sitting in.

A blocked pitot behaves differently depending on the drain. If the ram opening blocks and the drain stays clear, airspeed falls toward zero. If both block, the trapped pressure makes the airspeed indicator act like an altimeter — reading higher as you climb and lower as you descend, whatever you are actually doing. Pitot heat is the defense, and it belongs on before you need it rather than after the needle moves.

Glass panel failure

A screen going dark is the obvious failure and the easy one. The harder one is the same failure the vacuum gyro taught: an AHRS or air data computer can degrade and hand you wrong attitude, heading or airspeed, with or without a red X to warn you. So the cross-check does not go away because the panel got newer. Standby instruments and a disagreement you take seriously are still the defense.

Reversion is how you get the missing information onto the display you still have, and it is not the same on every airplane. Some installations revert automatically when a display fails; others need the display backup button pressed; Aspen, G5, G3X and Avidyne panels each do it their own way, and what appears on the surviving screen differs too. Learn the sequence for your installation on the ground and press it in flight with your instructor at least once — hunting for it in weather with one screen out is not when you want to be reading labels.

Flaps and trim

Flaps that will not extend cost you nothing but planning. Fly the no-flap approach speed from your POH, expect a flatter approach, a longer float and a meaningfully longer ground roll, and choose a runway that accommodates all three. Flaps stuck part way down are the same trade at a different point: fly the configuration the airplane gave you.

Asymmetric flaps are the case that bites. If selecting flaps produces a roll, stop moving them immediately and hold the wings level with aileron — and understand that your roll authority against a split flap shrinks as the airspeed decays, so this is the approach you fly faster than normal, not slower. Where the POH allows it, returning the flaps to the position where control was restored is usually the better airplane to land. Then pick the longest runway you have, keep the speed up until the flare, and accept the float rather than trading it for control you no longer have.

Trim failure leaves you flying against a control force that will not go away. It is manageable but tiring: use both hands if you need them, and remember that changing power and airspeed changes how hard the airplane pushes back. If electric trim runs away, stop it first — the disconnect, then the breaker or the switch your POH names — and stopping it is a memory item, not something to look up. Then hold what you have, retrim manually if the airplane still lets you, and fly a long, stable approach with no configuration surprises left in it.

Doors, ice and landing gear

A door or window that pops open after rotation is loud, startling and, in most training airplanes, almost harmless to the flying. It has still killed people, because the pilot tried to close it at 200 feet with a hand off the controls and a head inside the cabin. Fly the airplane, tell the tower, fly a normal pattern, land, and close it on the ground.

Structural icing is the malfunction you cause rather than suffer. Training airplanes are not approved for flight into known icing, so the response is not a technique but an exit: leave the visible moisture, climb or descend to air where ice cannot form, turn pitot heat on, and tell ATC what you need rather than asking whether it is available. Expect a higher stall speed, degraded climb and heavier controls, fly the approach faster than normal, and consider leaving the flaps up if the POH warns about tailplane icing. The real decision was made before takeoff, with the freezing level and the temperature and dew point in front of you.

Landing gear malfunctions belong here too, even if your trainer's wheels are welded down. In a retractable, separate the indication from the gear: a green light can fail while three wheels are locked, and a mirror pass or another set of eyes can tell you which problem you have. Use the alternate extension procedure from the POH, do it high and with fuel in hand rather than on short final, and if the gear will not come down, make the landing a planned one — longest runway, emergency services standing by, and the airplane flown all the way to the ground.

Where you meet it next

Every one of these has the same first moves: fly the airplane, do the immediate actions you know by heart, then open the checklist and work out what actually broke rather than what you assumed broke. The failure is almost never the thing that hurts you; the fixation is.

On the checkride this arrives as a scenario rather than a maneuver. The examiner describes a symptom or changes something, and expects you to say what you see, what you think it is, what you would do from memory and what the checklist says — without the altitude or heading wandering while you talk.

The pieces then scatter into the rest of the syllabus. Fire and rapid descent are the Emergency Descent lesson; a quiet engine and a chosen field are Emergency Approach and Landing; the vacuum and pitot-static material comes back as partial panel in Instrument Straight-and-Level Flight and Recovery from Unusual Flight Attitudes; the no-flap and faster-than-normal approaches are the landing lessons you already fly. All of them are in Learn. And if you have never sat in your own airplane and traced where the fuel shutoff, the alternate static source, the reversion control and the trim disconnect are, that is the homework this lesson is really setting.