Airworthiness Essentials

Four documents must be in the airplane before it moves under its own power. A fifth is added for a flight outside the United States. The mnemonic for the five is ARROW:

• Airworthiness certificate
• Registration certificate
• Radio station license, for international flight only
• Operating limitations
• Weight and balance data.

The airworthiness certificate

14 CFR 91.203(a)(1) requires "an appropriate and current airworthiness certificate" within the airplane 1. Paragraph (b) adds that the certificate is displayed at the cabin or cockpit entrance so that it is legible to passengers or crew. Each other document on the list is carried. The airworthiness certificate is displayed. In a Warrior it is in a clear pocket where a passenger can read it.

The registration certificate

91.203(a)(2) requires an effective U.S. registration certificate issued to the owner 1. The handbook says the certificate "must be carried in the aircraft at all times" 2. Registration has an expiration date and a renewal cycle.

The radio station license

A radio in an airplane is a station in the FCC's aviation service. The FCC rule is 47 CFR 87.18. An aircraft station is "licensed by rule and does not need an individual license" when two conditions hold 3. The first condition is that no statute or treaty requires the airplane to carry a radio. The second condition is that the station "does not make international flights or communications."

A Warrior flown inside the United States needs no individual license. A flight to Canada or Mexico needs the individual license aboard. The handbook lists the license as an owner responsibility "if operated outside of the United States" 4.

The operating limitations

14 CFR 91.9(b) is the O in ARROW. No person can operate a U.S.-registered airplane unless "a current approved Airplane or Rotorcraft Flight Manual, approved manual material, markings, and placards, or any combination thereof" is available in it 5. For a Warrior the combination is three things:

• the approved Pilot's Operating Handbook
• the placards on the panel and the doors
• the colored arcs on the airspeed indicator and the tachometer.

The handbook that belongs to the airplane stays in the airplane. A copy from the internet is not the approved manual for that serial number.

The weight and balance data

The current weight and balance data are part of the operating limitations for that airplane. The Airplane Flying Handbook lists "current weight and balance data" among the documents a pilot confirms on board before flight 6. Each repair or installation that changes the empty weight produces a new sheet. Only the newest sheet applies.

Two conditions in one word

14 CFR 3.5(a) defines the word. "Airworthy means the aircraft conforms to its type design and is in a condition for safe operation" 7. The definition has two conditions, joined by "and". An airplane in perfect mechanical condition with an unapproved part on it is not airworthy. An airplane that matches its type design in each detail with a cracked cylinder is not airworthy. Both conditions must be true at once.

Type design is the FAA-approved description of the airplane: the drawings, the parts, the limits. A mechanic answers the conformity question from the maintenance records. The pilot answers the condition question at the airplane.

The prohibition and the duty

14 CFR 91.7 has two paragraphs 8. Paragraph (a) says, "No person may operate a civil aircraft unless it is in an airworthy condition." Paragraph (b) names the person who decides. "The pilot in command of a civil aircraft is responsible for determining whether that aircraft is in condition for safe flight."

The second sentence of paragraph (b) extends the duty into flight. "The pilot in command shall discontinue the flight when unairworthy mechanical, electrical, or structural conditions occur." A decision made on the ramp does not end the duty. An oil pressure needle that falls in cruise makes the airplane unairworthy in cruise. The rule then requires the pilot to land.

Two people, two duties

14 CFR 91.403(a) names a different person. "The owner or operator of an aircraft is primarily responsible for maintaining that aircraft in an airworthy condition, including compliance with part 39 of this chapter" 9. Part 39 is airworthiness directives.

The owner maintains, and the pilot in command determines. The owner's duty covers months and years: inspections, directives, repairs, records. The PIC's duty is about this flight, today. A student on a solo flight holds the PIC's duty in full. The school holds the owner's duty. At the preflight the pilot reads the records of what the owner did and inspects what the owner maintains.

The Airplane Flying Handbook puts the two rules in one sentence. "The owner/operator is primarily responsible for maintenance, but in accordance with 14 CFR part 91, section 91.7(a) and (b) no person may operate a civil aircraft unless it is in an airworthy condition and the pilot in command of a civil aircraft is responsible for determining whether the aircraft is in condition for safe flight" 10.

The flight of N53EM

On April 22, 2024, a 62-year-old private pilot took off alone from Flying W Airport in Lumberton Township, New Jersey, in his own Beech Sierra. The purpose of the flight was an annual inspection at another airport. The last annual inspection was in May 2014, almost ten years earlier. The engine lost part of its power on takeoff. The airplane stalled into a field beyond the end of the runway. The pilot had minor injuries, and the airplane was substantially damaged 11.

Beech built the Sierra in 1976. It has retractable landing gear, a controllable-pitch propeller, and a 200-horsepower Lycoming IO-360 engine. The pilot held a private pilot certificate with airplane single-engine land and helicopter ratings. He had 267 hours in total and 19 hours in this make and model. His last flight review was on July 16, 2012.

The maintenance records showed the last annual inspection on May 14, 2014, at 1,469.2 hours since the engine's last overhaul. Between that inspection and the accident the airplane flew about 16 hours. The sky was clear that afternoon, with 10 miles of visibility, a 4-knot wind, and a temperature of 16 degrees Celsius. The runway was 3,496 feet long.

The pilot told investigators that he performed a preflight inspection, started the engine, and checked the magnetos before departing. After liftoff the airplane "did not climb very well and began to settle back towards the ground with the landing gear still extended." A witness heard the engine "sputtering" as the airplane climbed, and heard what sounded like a significant drop in rpm. The airplane stalled and struck a field off the end of the runway.

Investigators found low compression on the No. 2 cylinder. A borescope showed carbon build-up around the intake valve. The valve was not sealing, and the valve seat appeared to be cracked. The NTSB wrote that had the airplane undergone the required annual inspection before the flight, "it is likely that the deficient condition of the cylinder would have been detected and corrected, thus preventing the accident."

The probable cause is "the pilot/owner's failure to ensure adequate maintenance of the airplane, which resulted in a partial loss of engine power during takeoff" 11. The report names 14 CFR 91.409(a) and Appendix D to Part 43 by number. Appendix D is the inspection checklist, and item (d)(3) on it is cylinder compression.

Where the accident chain could have been broken

The accident was five decisions. Each is listed below with its PAVE category and the decision that would have ended the flight safely at that point. Four of the five were about the airplane, and a regulation applied to each.

Why the certificate has a blank where the date goes

A standard airworthiness certificate carries no expiration date. 14 CFR 21.181(a)(1) says why. Standard certificates "are effective as long as the maintenance, preventive maintenance, and alterations are performed in accordance with parts 43 and 91 of this chapter" 12. The rule also requires that the airplane stay registered in the United States, and that the FAA has not suspended, revoked, or terminated the certificate.

The blank means the certificate has no fixed term. The certificate is effective only while its conditions are met. The Sierra's certificate stopped being effective on the day its annual expired, and nothing printed on it changed. The certificate in the pocket looks the same on an airplane ten years past its annual as on one inspected last week. The handbook says a standard certificate "remains in effect if the aircraft receives the required maintenance and is properly registered in the United States" 13.

Standard and special

14 CFR 21.175 divides airworthiness certificates into two classes 14. The FAA issues a standard airworthiness certificate for one of these:

• an airplane type certificated in the normal, utility, acrobatic, commuter, or transport category
• a manned free balloon
• a special class of aircraft, as the FAA designates it.

A Warrior holds a standard certificate in the normal category. The certificate is white, FAA Form 8100-2, and the category is printed on it.

The FAA issues a special airworthiness certificate for one of these:

• an airplane type certificated in the primary, restricted, provisional, or limited category
• an airplane certificated in the light-sport category
• an airplane operating for an experimental purpose
• an airplane operating under a special flight permit.

The special certificate is pink, FAA Form 8130-7. A homebuilt airplane holds an experimental certificate. A crop duster holds a restricted certificate. Each special certificate comes with operating limitations of its own, and those limitations are part of the certificate.

The special flight permit

The fourth item on the special list is a permit, not a category. 14 CFR 21.197(a) says a special flight permit "may be issued for an aircraft that may not currently meet applicable airworthiness requirements but is capable of safe flight" 15. The first purpose on its list is "flying the aircraft to a base where repairs, alterations, or maintenance are to be performed." Pilots call it a ferry permit. It is the document the Sierra needed for its flight to the shop. The permit is effective for the period written on it 12.

The day-VFR list

14 CFR 91.205(b) lists the instruments and equipment required for VFR flight during the day 16. The mnemonic for the list is ATOMATOFLAMES, one letter per item. The engine and flight instruments come first:

• Airspeed indicator
• Tachometer for each engine
• Oil pressure gauge for each engine using a pressure system
• Manifold pressure gauge for each altitude engine
• Altimeter
• Temperature gauge for each liquid-cooled engine
• Oil temperature gauge for each air-cooled engine.

The next letters are the rest of the equipment:

• Fuel gauge for each tank
• Landing gear position indicator
• Anticollision lights
• Magnetic direction indicator
• ELT
• Safety belts.

Three flight instruments

Items (1) to (3) are the airspeed indicator, the altimeter, and a magnetic direction indicator. The rule says "magnetic direction indicator," not "compass," so a certified electronic magnetometer satisfies it. A heading indicator does not. The heading indicator is a gyro, and the rule requires an instrument that senses magnetic north.

The engine gauges

Item (4) is a tachometer for each engine. Item (5) is an oil pressure gauge for each engine that uses a pressure system. Item (7) is an oil temperature gauge for each air-cooled engine. A Warrior's Lycoming O-320 is air-cooled and has a pressure oil system, so all three apply.

Items (6) and (8) do not apply to a Warrior. Item (6) requires a temperature gauge "for each liquid-cooled engine." Air over its fins cools the O-320, so there is no coolant to measure.

Item (8) requires a manifold pressure gauge "for each altitude engine." An altitude engine is turbocharged or supercharged to hold its power as the air thins. The O-320 is normally aspirated. The rule requires each gauge only for the engine design that uses it. A pilot who moves to a turbocharged airplane must have item (8) in it.

Operable, not installed

Paragraph (a) of 91.205 requires that the listed items "are in operable condition" 17. An installed gauge that reads wrong fails the rule. An airplane can carry each item on the list and still be illegal for day VFR because one of them does not work.

The fuel gauge

Item (9) requires a "fuel gauge indicating the quantity of fuel in each tank" 16. A Warrior has two tanks and two gauges. One dead gauge grounds the airplane for day VFR until the 91.213 flow is worked. A pilot who knows the tank is full by looking into it still cannot take off with a required gauge inoperative.

The gauge is required to work. It is not required to be accurate at each reading. The Airplane Flying Handbook says to "always positively confirm the fuel quantity indicated on the fuel gauges by visually inspecting the level of fuel in each tank" 18. The gauge satisfies the rule. A look into the tank and a dipstick give the pilot the quantity.

The landing gear indicator

Item (10) requires a landing gear position indicator "if the aircraft has a retractable landing gear." A Warrior's gear is fixed, so the item does not apply. The Sierra's gear retracts, and its indicator is the three green lights the pilot checks after the gear comes down. On the accident flight the gear never came up.

Anticollision lights by date

Item (11) requires "an approved aviation red or aviation white anticollision light system" for small airplanes certificated after March 11, 1996, under Part 23. A Warrior type certificated in the 1970s is outside that date, so item (11) does not require the strobe or beacon for day VFR. The night list requires anticollision lights on all airplanes, whatever the date.

Item (11) includes an exception. "In the event of failure of any light of the anticollision light system, operation of the aircraft may continue to a location where repairs or replacement can be made." A strobe that fails in flight does not require a landing at the nearest airport.

Over water, for hire

Item (12) applies only when the airplane "is operated for hire over water and beyond power-off gliding distance from shore." It then requires approved flotation gear readily available to each occupant and at least one pyrotechnic signaling device. A private pilot carrying a friend along the coast is not for hire, and the item does not apply. A flight instructor giving instruction for hire in the school's airplane over the ocean is a different flight. Power-off gliding distance is the test, and the POH glide chart gives the distance for the altitude.

Safety belts and shoulder harnesses

Item (13) requires "an approved safety belt with an approved metal-to-metal latching device, or other approved restraint system for each occupant 2 years of age or older" 16. A child under 2 can be held. Each other person needs a belt of their own.

Item (14) adds shoulder harnesses by manufacture date:

• for small airplanes manufactured after July 18, 1978, a shoulder harness for each front seat
• for small airplanes manufactured after December 12, 1986, a shoulder harness for all seats.

A PA-28-151 Warrior left the factory between 1974 and 1977, so neither date applies to it. A shoulder harness installed on such an airplane is equipment the owner chose. A pilot who has one uses it. The rule counts the date the airplane was built.

The ELT

Item (15) requires "an emergency locator transmitter, if required by § 91.207" 16. The ELT's rules are in 91.207, not in 91.205. That section requires an approved ELT "in operable condition" attached to the airplane 19. It also lists the exceptions.

Paragraph (f)(3) exempts an airplane "engaged in training operations conducted entirely within a 50-nautical mile radius of the airport from which such local flight operations began." A training flight to the practice area needs no ELT by rule. A cross-country does. The ELT's battery and inspection rules are in the same section.

Whose list this is

The title of 91.205 says which airplanes the rule covers: "Powered civil aircraft with standard U.S. airworthiness certificates." Paragraph (a) repeats it 17. An airplane with a special certificate is outside the section.

An experimental airplane has its own operating limitations, issued with its certificate. 14 CFR 91.319 forbids operating it "for other than the purpose for which the certificate was issued" and requires the pilot to advise each person carried of the experimental nature of the airplane 20. Its equipment list is in its limitations. A pilot who moves from a Warrior to a homebuilt must read a different document. ATOMATOFLAMES is the Warrior's list, and the Warrior holds a standard certificate.

The night additions

14 CFR 91.205(c) lists what night VFR adds to the day list 21. Item (1) is "instruments and equipment specified in paragraph (b)." The rest is five items, and the mnemonic is FLAPS:

• Fuses: one spare set, or three spare fuses of each kind required, accessible to the pilot in flight
• Landing light: one electric landing light, if the airplane is operated for hire
• Anticollision lights: an approved aviation red or aviation white system, on each U.S.-registered airplane
• Position lights: approved
• Source of electrical energy: adequate for all installed electrical and radio equipment.

Lights

Position lights are the red light on the left wingtip, the green on the right, and the white on the tail. They are required at night on each airplane. They must be on from sunset to sunrise.

The anticollision system is the beacon or the strobes. By day, item (b)(11) required it only on airplanes certificated after 1996. By night, item (c)(3) requires it "on all U.S.-registered civil aircraft." The 1970s Warrior that needs no strobe for day VFR needs one for night VFR. The same relief applies at night: a failed light in the system lets the flight continue "to a stop where repairs or replacement can be made."

The landing light is required only "if the aircraft is operated for hire." A private pilot flying at night with no landing light is legal. That pilot lands without a landing light, and the rule leaves that judgment with the pilot.

Electricity

Item (5) requires an adequate source of electrical energy for all installed electrical and radio equipment. In a Warrior that source is the alternator, with the battery as the reserve. Night flight on the battery alone, after an alternator failure, is flight with the required source gone. The condition is unairworthy under 91.7(b), and the pilot must discontinue the flight at the nearest suitable airport.

Item (6) requires spare fuses "accessible to the pilot in flight." Most Warriors have circuit breakers, which reset, so the breakers satisfy the item. An airplane with fuses needs the spares in reach, not in the baggage compartment.

Before the flight

14 CFR 91.213 says when an airplane can take off with an item of installed equipment that does not work. For a small non-turbine airplane with no minimum equipment list, paragraph (d) gives four steps 22:

• The item is not required by the type certificate, the equipment list, 91.205, or an airworthiness directive.
• The item is removed or deactivated.
• The item is placarded.
• A certificated pilot or mechanic determines that it "does not constitute a hazard to the aircraft."

A student does not fly an airplane with a broken item until the school works the 91.213 flow. The handbook gives three choices when inoperative equipment is found before departure: "cancel the flight, obtain maintenance prior to flight, or to defer the item or equipment" 23. A takeoff is not on the list until the deferral is done. A student who finds a dead fuel gauge, a cracked windshield, or a flat strut calls the school before starting the engine.

After the flight

The pilot writes up a discrepancy found in flight or on the post-flight walkaround and reports it to the operator before the next flight. The Airplane Flying Handbook describes the post-flight inspection as a walk around the airplane for four things 24:

• oil or fuel streaks near the cowling
• fuel stains under the wings
• damage to the gear and tires
• obstructions in the cowling inlets.

Whatever the walkaround finds goes on the squawk sheet. The next pilot's preflight starts from that squawk. The next student finds an unreported rough magneto again at the runup, with a passenger aboard. 91.7(b) requires a pilot to discontinue a flight for an unairworthy condition 8. The written report is how that condition reaches the person who maintains the airplane.

Legal and safe are two questions

The last step of the 91.213(d) flow is a determination "that the inoperative instrument or equipment does not constitute a hazard to the aircraft" 22. The rule separates the legal question from the safety question. An airplane can pass each item of 91.205 and still be unsafe for this flight. A landing light is not required for a private night flight, but a night landing at an unlit strip without one is a hazard. The Risk Management Handbook says pilots who understand the difference between what is "smart" or "safe" and what is legal "establish personal minimums that are more restrictive than the regulatory requirements" 25. The pilot in command answers both questions before each flight, and both answers must be yes.

The inspections in the records

A pilot checks the inspections an airplane needs in the maintenance records, not on the ramp. The mnemonic is AV1ATE, with an S some pilots add:

• Annual inspection, each 12 calendar months
• VOR check, each 30 days, for IFR flight only
• 100-hour inspection, when carrying persons for hire or giving instruction for hire
• Altimeter and pitot-static system test, each 24 calendar months, for IFR flight only
• Transponder test, each 24 calendar months
• ELT inspection each 12 calendar months, plus the battery date
• Static system, the same 24-month test as the altimeter.

The Airplane Flying Handbook's sample airworthiness checklist lists the same items 6.

The annual

14 CFR 91.409(a) says no person can operate an airplane unless it has had an annual inspection "within the preceding 12 calendar months" 26. The inspection is under Part 43, and a mechanic approves the airplane for return to service after it. Twelve calendar months end on the last day of the month. The handbook says the period "extends from any day of a month to the last day of the same month the following year" 27. An annual signed on May 14, 2014, covers flying through May 31, 2015. The Sierra flew until April 2024 with no later annual.

The annual applies to each airplane, whatever it is used for. A mechanic who holds an inspection authorization signs it 28.

The 100-hour

Paragraph (b) adds a second inspection for two kinds of operation 26. The first is to operate an airplane "carrying any person (other than a crewmember) for hire." The second is to "give flight instruction for hire in an aircraft which that person provides." Neither is legal unless the airplane has had an annual or 100-hour inspection within the preceding 100 hours of time in service.

A school airplane used for instruction needs the 100-hour inspection. A privately owned Warrior flown by its owner does not need it. An owner who takes instruction in that Warrior from an instructor who does not provide the airplane does not need it either.

The 100 hours "may be exceeded by not more than 10 hours while en route to reach a place where the inspection can be done." The overrun counts toward the next inspection. "The excess time used to reach a place where the inspection can be done must be included in computing the next 100 hours of time in service." A school airplane inspected at 107 hours is due again at 200 hours, not at 207.

One substitution, not two

The two inspections use the same checklist, Appendix D to Part 43 29. The difference is the signer. An annual can substitute for a 100-hour, because the signer of an annual holds an inspection authorization. A 100-hour cannot substitute for an annual. The last sentence of 91.409(a) says no 100-hour inspection can be substituted for the annual "unless it is performed by a person authorized to perform annual inspections and is entered as an 'annual' inspection in the required maintenance records" 26. The handbook says the same in the other direction 27.

The ELT inspection

14 CFR 91.207(d) requires an inspection of the ELT "within 12 calendar months after the last inspection" for four things 19:

• proper installation
• battery corrosion
• operation of the controls and crash sensor
• the presence of a sufficient signal radiated from its antenna.

A mechanic usually does the inspection with the annual, and it is a separate entry in the records.

The ELT battery

Paragraph (c) sets the battery rule. The batteries "must be replaced (or recharged, if the batteries are rechargeable)" in two cases 19:

• when the transmitter has been in use for more than 1 cumulative hour
• when 50 percent of their useful life has expired, as established by the transmitter manufacturer.

The new expiration date "must be legibly marked on the outside of the transmitter and entered in the aircraft maintenance record." One cumulative hour includes each test transmission and each accidental activation on a hard landing. A pilot who hears the ELT on 121.5 after landing turns it off and tells the school, because the minutes count toward the hour.

The transponder and the altimeter

14 CFR 91.413 says no person can use an ATC transponder unless "within the preceding 24 calendar months" it has been tested and inspected to Appendix F of Part 43 30. The rule applies to use of the transponder, VFR or IFR. An airplane with an expired transponder check can fly VFR where no transponder is required, with the transponder off.

14 CFR 91.411 requires the same 24-calendar-month test for the altimeter and static system, and the rule applies to flight "in controlled airspace under IFR" 31. A VFR-only airplane can fly with that check expired. The two tests are usually done together, and a school airplane has both in the records.

All available information

14 CFR 91.103 begins with one sentence. "Each pilot in command shall, before beginning a flight, become familiar with all available information concerning that flight" 32. Information the pilot could have obtained and did not is information the rule required. The two paragraphs that follow name the minimum.

For any flight

Paragraph (b) applies to each flight, including a lap around the pattern. It requires "runway lengths at airports of intended use," and the takeoff and landing distance data from the approved flight manual 32. For an airplane with no approved manual, the rule accepts "other reliable information" about performance at the expected airport elevation, runway slope, weight, wind, and temperature. A Warrior's POH has the takeoff and landing charts.

For a flight away from the airport

Paragraph (a) applies to "a flight under IFR or a flight not in the vicinity of an airport." It adds four items:

• weather reports and forecasts
• fuel requirements
• alternatives available if the planned flight cannot be completed
• any known traffic delays of which the pilot in command has been advised by ATC.

A cross-country requires all four before takeoff. Whether a lesson in the practice area is in the vicinity of the airport is a judgment, and a weather briefing is the safe answer.

The manufacturer's sequence

The preflight inspection follows the POH checklist for this airplane. The Airplane Flying Handbook says "the AFM/POH or a third party checklist based on the AFM/POH may be used to conduct the visual preflight inspection, and each manufacturer has a specified sequence for conducting the actions" 33. The school's Warrior checklist is that third-party checklist. It goes from the cabin, around the airplane in one direction, and back to the cabin. A pilot working from memory skips items, and skips a different item each time. A pilot working from the card does not.

The handbook's order is documents first, then airplane. The pilot inspects "the airplane's airworthiness status," then follows the POH for the visual inspection 10. The status is the five ARROW documents and the AV1ATE inspections.

The failure behind each item

Each checklist item exists to find one specific failure. A pilot who knows the failure behind the item inspects for it. A pilot who does not know it only follows the card. The handbook names the failures:

• Control surfaces: freedom and security. A control lock left in, or a hinge bolt working loose, causes a loss of control on rotation.
• Tires and struts: wear, cuts, and strut extension. A flat strut causes a landing on the wheel pant.
• Fuel vents: clear. "If outside air is unable to enter the tank as fuel is drawn into the engine, the eventual result is fuel starvation and engine failure" 18.
• Pitot tube and static ports: clear. A blocked pitot makes the airspeed indicator read zero on the takeoff roll, or read wrong in the climb.
• Oil quantity: within limits, on the dipstick, before each flight. The handbook says the level is "maintained to prevent the oil level from falling below the minimum required during engine operation."
• The cowling: no fresh stains. The handbook says a fuel stain "warrants further investigation" however old it looks.

Fuel

The pilot sumps the fuel to find water and sediment. The handbook says "sufficient fuel should be drained from the fuel strainer quick drain and from each fuel tank sump to check for fuel grade/color, water, dirt, and odor" 34. Water is heavier than fuel and collects at the low points. In the sample jar it "is usually in bubble or bead-like droplets, different in color (usually clear, sometimes muddy yellow to brown with specks of dirt), in the bottom." A pilot who finds water keeps sampling "until no water and contamination appears."

The pilot checks the sample for four things:

• color: 100LL is dyed blue, and jet fuel is clear or straw-colored
• smell: gasoline, not the oily kerosene smell of jet fuel
• grade: the blue of 100LL against a white background
• water and sediment: bubbles at the bottom, or dark specks.

"Each fuel tank sump should be drained during preflight and after refueling." A Warrior has three drains: one under each wing tank and the fuel strainer drain at the bottom of the engine compartment. Condensation forms overnight in a part-full tank, and a fuel truck can deliver water with the fuel. Water is most likely in the tanks before the first flight of the day and after each fueling.