Systems 2 and System Emergencies

The Warrior's electrical system is a 14-volt alternator-and-battery system. The manual describes it: "a 14 volt 60 ampere alternator, voltage regulator, overvoltage relay, battery contactor and a standard 12 volt 25 ampere hour or an optional 12 volt 35 ampere hour battery" 1. The manual says "primary electrical power is provided by the 14 volt 60 amp alternator" and "secondary electrical power is provided by the standard or optional battery." The alternator carries the load in flight. The battery starts the engine and is the reserve.

Why an alternator

Older airplanes had generators. The handbook says "most DC generators do not produce a sufficient amount of electrical current at low engine rpm to operate the entire electrical system," so at low rpm "the electrical needs must be drawn from the battery, which can quickly be depleted" 2. An alternator "produces sufficient current to operate the entire electrical system, even at slower engine speeds," and its output "is more constant throughout a wide range of engine speeds." An alternator needs the engine turning and a field current from the battery to make electricity. It makes usable output at low engine speeds.

The ammeter

The ammeter shows the state of the electrical system. The handbook says "the ammeter shows if the alternator/generator is producing an adequate supply of electrical power. It also indicates whether or not the battery is receiving an electrical charge" 3. The Warrior's ammeter "does not show battery discharge; rather, it indicates the electrical load on the alternator in amperes" 1.

After a start the ammeter reads high, because the alternator recharges the battery that the starter discharged. In cruise it reads the load of whatever is switched on. A reading of zero in cruise with the radios on means the alternator has failed. From that moment the battery powers the electrical system. A battery is a reserve with a known capacity, not a supply.

The master switch and the breakers

The master switch turns the electrical system on and off. The handbook says "turning the master switch to the ON position provides electrical energy to all the electrical equipment circuits except the ignition system" 4. The Warrior's master is a split rocker: the BAT side closes the battery contactor and the ALT side energizes the alternator field 1.

Circuit breakers protect each circuit, and "each circuit breaker on the panel is of the push to reset type and is clearly marked as to its function and amperage." The pilot resets a popped breaker once at most, after the manual's cooling period: "before attempting to reset any circuit breaker, allow a two to five minute cooling off period" 5. A breaker that pops again stays out. A breaker held in by hand keeps current flowing through the fault and can start a fire.

The engine keeps running

A total electrical failure does not stop the engine. The magnetos generate the ignition spark without the electrical system, and the handbook's list of what the master switch powers excludes the ignition system 4. The equipment on the list stops:

• the radios
• the transponder
• the lights
• the electric fuel pump
• the stall warning horn
• the turn coordinator
• the fuel gauges
• the flaps, in an airplane with electric flaps.

The Warrior's flaps are manual and keep working after an electrical failure. An airplane with no electrical power has no radio, so the lost-communications procedure applies after an electrical failure.

Alternator failure

A zero reading on the ammeter is the sign of alternator failure. The Warrior's manual says "Loss of alternator output is detected through a zero reading on the ammeter. Before executing the following procedure, insure that the reading is zero and not merely low by actuating an electrically powered device, such as the landing light. If no increase in the ammeter reading is noted, alternator failure can be assumed" 6. The procedure has three steps:

• reduce electrical load
• alternator circuit breakers, check
• ALT switch off for 1 second, then on.

"If the ammeter continues to indicate no output, or alternator will not stay reset, turn off 'Alt' switch, maintain minimum electrical load, and land as soon as practical. All electrical power is being supplied by the battery." The pilot resets the alternator once. Then the pilot plans the battery's remaining minutes against the flight that remains. In daylight VFR, with the radio and transponder off and the battery saved for the pattern, the airplane lands at the nearest suitable airport. At night the battery also powers the lights, so the landing must come sooner.

The avionics master

The avionics run on the electrical bus behind a switch of their own. The switch keeps the radios off the bus while the starter turns. The bus voltage drops while the starter turns and spikes when the starter disengages. The Warrior's manual says "before starting the engine, check that all radio switches, light switches and the pitot heat switch are in the off position to prevent an overloaded condition when the starter is engaged" 5. The pilot turns the avionics off before start and before shutdown, so they are off at the next start.

The flight of N5343C

On July 29, 2024, a 70-year-old private pilot and his passenger flew a Piper Saratoga from Hendersonville, North Carolina, toward North Myrtle Beach at night. The alternator belt broke in cruise. The pilot misread the warning light, the battery ran down, and the airplane lost all electrical power. He continued to his destination, entered the pattern in the dark with an unpowered panel, and landed with the gear up. Nobody was hurt 7.

The pilot held a private certificate with 1,365 hours, 690 of them in the Saratoga, and 2.9 hours in the last 30 days. His flight review was ten months old and his medical six.

The airplane was a 2001 PA-32R-301T, a six-seat retractable with a 300-horsepower turbocharged engine. Its landing gear is hydraulic, driven by an electric pump, with a manual emergency extension. Its flaps are electric.

The weather at Grand Strand was 10 miles and an overcast at 5,500 feet, with the wind from 210 degrees at 9 knots. The runway was 5,997 feet long.

He departed at 9:00 in the evening. Somewhere in cruise the alternator belt broke and the alternator stopped. The alternator warning light came on. The pilot told investigators that he "misinterpreted the alternator warning light illuminating, and did not realize that the alternator had failed." The flight continued on battery power. "Some time later the battery failed, resulting in a total loss of electrical power."

He "recalled making the decision to continue to his originally intended destination because of his familiarity with the airport." On the downwind leg at Grand Strand he began the emergency checklists. He noticed the airplane was too fast and reached for the flaps, and "upon activation, he realized they would not function without electrical power." Working the checklist, he pulled "what he thought was the hydraulic system circuit breaker," which the investigators found was "actually the standby vacuum pump circuit breaker." He did not use the emergency gear extension. The airplane landed on its belly, and the landing substantially damaged the lower fuselage longerons.

Investigators found the emergency gear extension handle in the stowed position. On jacks, the emergency extension system "was found to function satisfactorily." With power restored the normal gear system worked. The alternator belt was broken. The probable cause is "the pilot's failure to use the emergency landing gear extension system, resulting in a gear-up landing. Contributing to the accident was an alternator belt failure" 7.

Where the accident could have been prevented

The accident was three decisions. The airplane was flyable after each of them. Each is listed below with its PAVE category and the decision that would have ended the flight safely at that point.

What feeds what

The pitot tube feeds ram air to the airspeed indicator only. The static ports feed the airspeed indicator, the altimeter, and the vertical speed indicator 8. A pitot blockage affects one instrument. A static blockage affects three.

A blocked pitot tube

With the ram opening blocked and the drain hole clear, the airspeed indicator reads zero. The handbook says "ram air is no longer able to enter the pitot system. Air already in the system vents through the drain hole, and the remaining pressure drops to ambient (outside) air pressure. Under these circumstances, the ASI reading decreases to zero" 9.

With both the opening and the drain blocked, "the pressure in the pitot tube is trapped." The airspeed then changes only when the static pressure does: it rises in a climb and falls in a descent. The Instrument Flying Handbook says "the ASI operates like an altimeter as the aircraft climbs and descends" 10. An insect nest or ice in the tube produces that indication. An airspeed indication that rises and falls with the altimeter is not a measure of airspeed.

Blocked static ports

Blocked static ports fix the altimeter at the altitude of the blockage and hold the VSI at zero. The airspeed indicator continues to move but reads incorrectly. The handbook says "the airspeed indicates lower than the actual airspeed when the aircraft is operated above the altitude where the static ports became blocked because the trapped static pressure is higher than normal for that altitude. When operating at a lower altitude, a faster than actual airspeed is displayed" 11. Above the blockage the airplane is faster than the indication. Below the blockage it is slower.

The alternate static source

An alternate static source valve, where installed, feeds the instruments from cabin air. Cabin pressure in flight is a little lower than outside pressure, and the handbook lists the effect: "the altimeter indicates a slightly higher altitude than actual," "the ASI indicates an airspeed greater than the actual airspeed," and "the VSI shows a momentary climb and then stabilizes" 12. The POH supplement gives the correction for the airplane. In an airplane with no alternate source, the same passage says a pilot can break the glass on the VSI. Cabin air then enters the static system through the broken glass, and the VSI reads backwards.

Two power sources

The engine-driven vacuum pump spins the gyros in the attitude indicator and the heading indicator. The turn coordinator is electric. The handbook says "vacuum or pressure systems provide the power for the heading and attitude indicators, while the electrical system provides the power for the turn coordinator. Most aircraft have at least two sources of power to ensure at least one source of bank information is available if one power source fails" 13.

The Warrior's manual describes its system. The pump is a dry pump with a shear drive. A regulator is set so "the normal vacuum reads 5.0 ± .1 inches of mercury," and a gauge is on the right side of the panel 14. "If the drive shears, the gyros will become inoperative." Zero on the gauge "would indicate a sheared pump drive, defective pump, possibly a defective gauge or collapsed line."

Vacuum failure is slow

A vacuum failure does not stop the attitude indicator at once. The gyro spins down over minutes, and as it slows the horizon bar tilts gradually. A pilot who follows the bar rolls with it. The Instrument Flying Handbook describes the gyro coming up to speed after a start: "this erection can take as long as 5 minutes, but is normally done within 2 to 3 minutes" 15. The spin-down is the same process in reverse, and just as gradual.

The signs are two. The suction gauge reads low or zero. The attitude indicator disagrees with the instruments that do not use vacuum: the turn coordinator, the altimeter, and the airspeed indicator.

A suspected failure

The procedure for a suspected instrument failure is the cross-check. The Instrument Flying Handbook's rule for reading the panel is to trust no single instrument until another instrument confirms its indication 16. An attitude indicator that shows a bank while the turn coordinator shows wings level and the heading holds is the failed instrument. The pilot then covers the failed instrument with a hand, a sticky note, or a suction cup. A pilot's scan returns repeatedly to a false indication in the center of the panel unless the instrument is covered.

Cabin heat

The Warrior's cabin heat is ram air warmed by a shroud around the muffler. The manual says the exhaust system "incorporates a single muffler with heater shrouds to supply heated air for the cabin, the defroster system and the carburetor deicing system" 17. The design is simple, and only the muffler wall separates the cabin air from the exhaust gas. A cracked muffler puts carbon monoxide into the heated air. The response to carbon monoxide in the cabin is heat off, vents open, land.

No ice protection

The Warrior has no airframe ice protection, and it is prohibited from flight into known icing. Its anti-ice equipment is carburetor heat and, where installed, pitot heat. Structural icing needs visible moisture and a surface near or below freezing. The Aviation Weather Handbook says structural icing "occurs when supercooled water droplets strike the airframe and freeze" 18. The AIM says a pilot "can expect icing when flying in visible precipitation, such as rain or cloud droplets, and the temperature is between +02 and −10 degrees Celsius" 19. The effects "are cumulative-thrust is reduced, drag increases, lift lessens, and weight increases," and "it takes but 1/2 inch of ice to reduce the lifting power of some aircraft by 50 percent."

The escape from icing is an immediate change of course or altitude. The AIM's two choices are "get out of the area of precipitation; or go to an altitude where the temperature is above freezing," and it adds that the warmer altitude "may not always be a lower altitude." For a Warrior the change is a 180-degree turn, a new altitude, or both. The pilot makes it at the first sign of ice on the strut or the windshield.

Supplemental oxygen

14 CFR 91.211(a) sets three altitudes 20:

• above 12,500 feet cabin pressure altitude up to 14,000, the required flight crew must use supplemental oxygen "for that part of the flight at those altitudes that is of more than 30 minutes duration"
• above 14,000 feet, the required flight crew must use it "during the entire flight time at those altitudes"
• above 15,000 feet, "each occupant of the aircraft is provided with supplemental oxygen."

The rule says provided, not use, for passengers. The pilot must have oxygen available for them. They need not use it.

The numbers are minimums

The 91.211 altitudes are legal minimums, and the effects of altitude begin lower. The AIM says "a deterioration in night vision occurs at a cabin pressure altitude as low as 5,000 feet," and that significant hypoxia effects begin for a healthy pilot at 12,000 21. A smoker, a tired pilot, or a pilot at night has less margin than the rule provides. A pilot who flies a Warrior at 9,500 feet across mountains at night is legal without oxygen and would fly better with it.

The checklist, not memory

The pilot works an abnormal indication with the checklist. The Warrior's emergency section exists for that purpose. Its introduction says the procedures "are suggested as the best course of action for coping with the particular condition described, but are not a substitute for sound judgment and common sense," and that "since emergencies rarely happen in modern aircraft, their occurrence is usually unexpected, and the best corrective action may not always be obvious" 22. Troubleshooting from memory under stress produces wrong answers. The pilot of N5343C pulled the vacuum pump breaker instead of the hydraulic pump breaker. A pilot who reads the printed checklist does not make that error.

Startle

The first response to any bang, light, or silence is to fly the airplane. Startle is expected, and it lasts seconds. In those seconds the pilot holds pitch, holds power, and trims, and only then diagnoses. The pilot works an oil pressure gauge that reads zero after the airplane is level and headed toward a landing site. The Warrior's manual gives the diagnosis for that gauge: a complete loss "may signify oil exhaustion or may be the result of a faulty gauge. In either case, proceed toward the nearest airport, and be prepared for a forced landing" 23.

The emergency descent

The pilot flies an emergency descent for an engine fire, a cabin fire, or smoke. The Airplane Flying Handbook says the maneuver is "for descending as rapidly as possible to a lower altitude or to the ground for an emergency landing," and that "the objective is to descend the airplane as soon and as rapidly as possible while not exceeding any structural limitations of the airplane" 24. The steps are:

• power to idle
• configure as the manual recommends
• bank "approximately 30 to 45°" so the pilot can see the airspace below.

The bank also keeps positive load on the wings. The ACS lists the situations: "depressurization, smoke, or engine fire" 25.

Speed discipline

Speed in an emergency descent shortens the time to the ground, and it has a limit. The handbook says "the pilot should not allow the airplane's airspeed to pass the never-exceed speed (VNE), the maximum landing gear extended speed (VLE), or the maximum flap extended speed (VFE), as applicable." In smooth air the Warrior can descend at the top of the green arc, 140 mph, or into the yellow arc with care. In rough air the limit is maneuvering speed, 124 mph, because a gust at high speed can break the airplane before the fire does 26.

Choose the target first

The pilot chooses the descent target before the descent begins. The pilot decides the altitude to level at, the direction to turn, and where the landing goes if the emergency continues. The ACS risk elements for the task are "altitude, wind, terrain, obstructions, gliding distance, and available landing distance" 25. A descent that ends at 1,000 feet over a lake with smoke still in the cabin has no landing site.

Engine fire in flight

The response to an engine fire in flight is to cut off the fuel. The Warrior's manual gives the steps: "Fuel Selector - OFF, Throttle - CLOSE, Mixture - IDLE CUT OFF, Heater - Off (In all cases of fire), Defroster - OFF (In all cases of fire), If terrain permits - Land Immediately" 27. The engine will stop. The flight is then a forced landing. The Airplane Flying Handbook says such a fire "is usually caused by a failure that allows a flammable substance, such as fuel, oil, or hydraulic fluid, to come in contact with a hot surface," and that "by the time a pilot becomes aware of an in-flight engine compartment fire, it usually is well developed" 28.

Electrical fire

The first sign of an electrical fire is usually a smell. The handbook says "the initial indication of an electrical fire is usually the distinct odor of burning insulation" 29. The Warrior's manual gives the response for smoke in the cabin: "Master Switch - Off, Vents - Open, Cabin Heat - Off, Land as soon as practicable" 27.

Master off removes the source. The extinguisher goes on the fire. Ventilation comes after the extinguisher, because the handbook says smoke "may be removed from the cabin by opening the cabin air vents. This should be done only after the fire extinguisher (if available) is used" 30. Then the pilot decides what, if anything, is switched back on to land.

A door opens

A door that opens in flight makes noise and does not affect control. The Warrior's manual says "an open door will not affect normal flight characteristics, and a normal landing can be made with the door open" 31. The Airplane Flying Handbook says the danger is the pilot's reaction: "if a pilot allows himself or herself to become distracted to the point where attention is focused on the open door rather than maintaining control of the airplane, loss of control may result even though disruption of airflow by the door is minimal" 32. The manual has a closing procedure, flown at 100 mph with the storm window open. The simpler procedure is to fly the pattern, land, and close the door on the ground.

No flaps

A flap failure means a no-flap landing. The handbook says "in light airplanes, a no-flap approach and landing is not particularly difficult or dangerous," but "a no-flap landing requires substantially more runway than normal. The increase in required landing distance could be as much as 50 percent" 33. The approach is faster and flatter, the float is longer, and the rollout is longer. A no-flap landing is an inconvenience with a procedure, and a Warrior student flies one in training.

Stuck trim

A trim tab stuck in one position leaves the pilot holding a control force. The handbook's discussion of control failures says "various combinations of power and flap extension offer a limited amount of pitch control" 34. The pilot chooses the flap setting and the airspeed that make the force smallest, and lands early rather than late. A pilot's arm tires over a long approach. A configuration that reduces the force holds for the whole approach.

What it does

The emergency locator transmitter activates on impact. The AIM says that "if 'armed' and when subject to crash-generated forces, ELTs are designed to automatically activate and continuously emit their respective signals, analog or digital," and that "the transmitters will operate continuously for at least 48 hours" 35.

The frequencies are 121.5 MHz, 243.0 MHz, and 406 MHz. The older ELTs are analog on 121.5 and 243.0. The 406 MHz ELT "is a digital transmitter that can be encoded with the owner's contact information or aircraft data," and it "also transmits a stronger signal." The unit has a switch marked OFF, ARM, and ON, and the Warrior has a remote switch on the panel. The switch stays in ARM in the airplane.

Registration

The owner registers a 406 MHz ELT with NOAA. The AIM says the FCC and the FAA's technical standard order both require it 35. When a registered beacon activates, the satellite system decodes the owner's information. The rescue coordination center "can then telephone or contact the owner to verify the status of the aircraft," and "if the aircraft is safely secured in a hangar, a costly ground or airborne search is avoided."

An unregistered 406 beacon is an anonymous signal. Satellites stopped monitoring 121.5 MHz in 2009. The owner renews the registration each two years, and the current registration is part of the airplane's paperwork.

Testing, and after a hard landing

Ground tests of an analog ELT are limited to a short window each hour. The AIM says they "should only be tested during the first 5 minutes after any hour," and "tests should be no longer than three audible sweeps" 36. The pilot tests a 406 MHz unit by the manufacturer's instructions. Airborne tests are not authorized.

The AIM also names the common false alarms: "aerobatics, hard landings, movement by ground crews and aircraft maintenance." After any hard landing the pilot tunes 121.5 before shutdown and listens. A sweeping tone means the ELT has activated. The pilot turns it off, tells the nearest air traffic facility, and writes a maintenance discrepancy.

The extinguisher

The cabin fire extinguisher is a preflight item. The pilot checks that it is charged, with the gauge needle in the green, and secured in its bracket within reach of the seat. PASS is the sequence for using it:

• pull the pin
• aim at the base of the fire
• squeeze the handle
• sweep.

The pilot ventilates the cabin after the extinguisher, because the Airplane Flying Handbook says the vents are opened "only after the fire extinguisher (if available) is used" 30. A halon extinguisher in a small cabin displaces air. The pilot opens the windows as soon as the fire is out.

Survival gear

The pilot packs survival gear for the terrain and the season under the route, not for the weather at the departure airport. The ACS names the planning figure: "survival gear (water, clothing, shelter) for 48 to 72 hours" 37. Water, clothing and shelter, and signaling are the three categories. A summer flight over the coast range in a light shirt ends in a cold night if the engine stops. The kit stays in the baggage compartment, and the pilot checks its contents each season.

Mountains and water

The ACS lists three environments: "climate extremes (hot/cold)," "mountainous terrain," and "overwater operations" 37. Mountains add shelter, insulation, and signaling weight to the kit, because a search in terrain takes longer and the nights are colder. Water beyond gliding distance from shore adds flotation for each occupant, and 14 CFR 91.205(b)(12) requires it when the flight is for hire 38. The gear list is a route decision, made when the pilot plans the route.

The parachute handle

Some airplanes carry a whole-airframe ballistic parachute. The ACS asks "when to deploy a ballistic parachute and associated passenger briefings, if equipped" 37. The manufacturer's supplement gives the envelope and the decision rule. The rule in the airplanes that have one has four triggers:

• loss of control
• structural failure
• pilot incapacitation
• a forced landing with no survivable field.

The pilot briefs passengers on the handle before engine start. A passenger who must find it after the pilot is unconscious has no time to be told. The Warrior has no parachute. A student who later flies an airplane with one learns its handle first.

The autoland button

Some airplanes carry an emergency autoland system that flies the airplane to a runway and lands it. The ACS asks "when to activate an emergency auto-land system and brief passengers, if equipped" 37. A passenger activates it when the pilot cannot fly. The passengers must know that the button exists and where it is. The system is built for the case where the pilot cannot press it.

Monitoring automation

An autopilot, a GPS, or a tablet is a system, and the pilot monitors it as a system. The handbook says "the pilot must know how to manage the course deviation indicator (CDI), the navigation source, and the autopilot," and that managing the autopilot "means knowing at all times which modes are engaged and which modes are armed to engage" 39. The rule has three parts:

• know which mode is engaged
• know what the system is set to do next
• know what you will do the moment it does anything else.

The pilot disconnects an autopilot that turns the wrong way and flies by hand. The transition advisory circular says the same about unfamiliar equipment: training on the specific installation, with an instructor current on it 40.

After a forced landing

The sequence after any forced landing is people, fire, signal. The pilot gets the occupants out and away from the airplane, checks for injuries, and treats what can be treated. Fuel and hot metal are the fire risk, and no one returns to the airplane until there is no fire. Then the signal:

• the ELT switch to ON, if the impact did not activate it
• the radio on 121.5, if the electrical system still works
• the airplane itself as the marker, because searchers look for a downed airplane.

The AIM says pilots and passengers "should know how to activate the aircraft's ELT if manual activation is required" 35. The occupants stay with the airplane, where searchers can find them.