Airworthiness & inspections

Airworthiness & the AVIATE inspections

Definition

Before every flight, the pilot in command is responsible for determining that the aircraft is airworthy (14 CFR 91.7) — meaning it conforms to its approved type design and is in condition for safe operation. Keeping it that way is the owner/operator's job (91.403). The recurring inspections and checks that keep an aircraft legal are remembered with AVIATE: Airworthiness Directives, VOR check, Inspections (annual and 100-hour), Altimeter and pitot-static, Transponder, and ELT. Some apply to every flight; a couple apply only to IFR.

Explanation

Airworthy has two parts: it matches its approved design (no unapproved alterations, all ADs complied with) AND it's safe to operate (nothing broken that matters). Both must be true, and confirming it is on you as PIC — not just the mechanic.

AVIATE	Interval / note
A — Airworthiness Directives	Comply as issued (mandatory)
V — VOR check	Every 30 days — IFR only
I — Inspections (annual & 100-hour)	See the inspection slides
A — Altimeter & pitot-static	Every 24 calendar months — IFR only
T — Transponder	Every 24 calendar months
E — ELT	Inspect every 12 months (battery: 121.5)

Why it matters

Flying an un-airworthy airplane — an overdue inspection, an uncomplied AD — is illegal and unsafe, and it's the PIC who's responsible, not just the shop.

From the Right Seat

I have students actually open the logbooks on an early lesson and find each AVIATE item themselves — it demystifies 'is this airplane legal?' fast.

A DPE might ask

Who is responsible for determining an aircraft is airworthy?
What does AVIATE stand for, and which items are IFR-only?

14 CFR 91.7, 91.403 & 91.409 — Airworthiness & required inspections

Airworthiness Directives (ADs)

Definition

An Airworthiness Directive is a legally binding order the FAA issues when an unsafe condition is found in a type of aircraft, engine, propeller, or appliance. Complying is mandatory, and the owner/operator is responsible for making sure every applicable AD is done and recorded (91.403). There are two main kinds. An Emergency AD is effective immediately — sometimes before it's even published in the Federal Register — because the condition is urgent. A Final Rule AD is the standard published directive with an effective date and a compliance time, and it may be a one-time fix or a recurring inspection. You find the ADs for a specific airplane on the FAA's Dynamic Regulatory System (DRS) at drs.faa.gov, searched by make and model.

Explanation

ADs are how the FAA fixes a known problem across a whole fleet. An open (uncomplied) applicable AD makes the airplane un-airworthy — you can't legally fly it until it's done. Compliance is recorded in the maintenance logbooks: which AD, the date, the method, and whether it recurs.

Emergency AD

Effective immediately
May apply before Federal Register publication
For an urgent unsafe condition
May require action before further flight

Final Rule AD

Published with an effective date
Has a stated compliance time
The standard, most common AD
One-time or recurring

Why it matters

As PIC you're responsible for knowing the airplane's ADs are complied with — an overlooked AD is a common, serious airworthiness violation, and DRS is where you (or your mechanic) verify them.

From the Right Seat

Search your training airplane on drs.faa.gov once — seeing its real ADs makes the concept concrete and shows you exactly what your mechanic tracks.

A DPE might ask

What is an Airworthiness Directive, and who must comply?
What are the two types of AD, and where do you find them?

14 CFR 91.403 — Airworthiness Directives & responsibility FAA Dynamic Regulatory System — Find ADs by aircraft make & model

Annual vs. 100-hour

Definition

Two inspections cover the 'I' in AVIATE. An annual inspection is required for every aircraft every 12 calendar months, and must be signed off by a mechanic holding an Inspection Authorization (IA). A 100-hour inspection is required only when an aircraft is operated for hire or used for flight instruction for hire — then it must be inspected every 100 hours of time in service. So if a student owns their airplane and flies it for their own training, it needs only annuals; but that same airplane at a flight school, rented out or used for paid instruction, also needs 100-hour inspections. An annual inspection counts as a 100-hour, but a 100-hour does not count as an annual.

Explanation

The dividing line is 'for hire.' Personal flying — even training in your own airplane — needs only the annual. The moment the airplane earns money carrying people or giving instruction, the 100-hour applies. A 100-hour may be exceeded by up to 10 hours only to reach a place of inspection, and that overage comes off the next interval.

Annual

Required for every aircraft
Every 12 calendar months
Signed off by an IA mechanic
Counts as a 100-hour too

100-hour

Only if for hire or instruction for hire
Every 100 hours in service
e.g. flight-school & rental airplanes
Does NOT count as an annual

Why it matters

Knowing which applies keeps you legal: renting from a school you rely on the 100-hour; in your own airplane you track the annual. Flying past either makes the airplane un-airworthy.

Common error

A common misconception is that every airplane needs a 100-hour inspection. It doesn't — the 100-hour is required only when the airplane is flown for hire or for flight instruction for hire. A privately owned airplane flown for personal use (even personal training) needs only the annual.

A pilot owns an airplane and flies it only for personal use. Which inspection is required?

A DPE might ask

What's the difference between an annual and a 100-hour inspection?
Which aircraft are required to have 100-hour inspections?

14 CFR 91.409 — Annual & 100-hour inspections

Recording a VOR check & the ELT

Definition

Two AVIATE items have details worth knowing. If you'll fly IFR using VOR navigation, the VOR equipment must be checked within the preceding 30 days, and the check is logged with four things: the date, the place, the amount of bearing error, and the signature of the person who made the check (14 CFR 91.171). The Emergency Locator Transmitter (ELT) is inspected every 12 calendar months, and its battery must be replaced after one cumulative hour of use, or when 50% of its useful life has expired (91.207).

Explanation

The VOR-check log is one line — date, place, bearing error, signature — and it's the pilot's responsibility, not the shop's, since it's done before IFR flight. For the ELT, the 121.5 memory aid captures it: 12 months, 1 hour, half the battery life — and 121.5 MHz is the emergency 'guard' frequency an ELT transmits on.

VOR check — record (91.171)	What it is
Date	When the check was made
Place	Where / the checkpoint used
Bearing error	The amount of error found
Signature	Who made the check

Why it matters

A VOR check is the pilot's job before IFR VOR navigation, and an out-of-date ELT battery is a common squawk — 121.5 makes the ELT rule easy to recall on a checkride and in practice.

Mnemonic

121.5

12 — inspect the ELT every 12 calendar months
1 — replace the battery after 1 cumulative hour of use
.5 — replace the battery at 50% of useful life

121.5 MHz is also the emergency 'guard' frequency.

From the Right Seat

Have a passenger read you the checkpoint while you note the bearing error — a VOR check on the ground before an IFR trip takes 30 seconds and one logbook line.

A DPE might ask

What must be recorded for a VOR equipment check?
When must an ELT battery be replaced?

14 CFR 91.171 & 91.207 — VOR checks & ELT

Logbooks & inoperative equipment

Definition

All of this — inspections, AD compliance, repairs — is recorded in the aircraft's maintenance records. Most aircraft keep three separate logbooks: one for the airframe, one for the engine, and one for the propeller. That's where you (or your mechanic) confirm the annual, 100-hour, transponder, altimeter, and AD entries are current. If a piece of equipment is inoperative, 14 CFR 91.213 tells you what to do: first find out whether that item is required — check the MEL if the aircraft has one, the Kinds of Operation Equipment List (KOEL), the Type Certificate Data Sheet (TCDS), the required-equipment rule 91.205, and any AD. If it's required, the airplane isn't airworthy until it's fixed. If it isn't required and isn't a hazard, the item must be deactivated or removed, placarded 'INOPERATIVE,' and recorded — then you may fly.

Explanation

Inoperative equipment isn't automatically a no-go, but you can't ignore it either. The 91.213 flow is: is it required (MEL / KOEL / TCDS / 91.205 / AD)? If yes, fix it. If no, deactivate or remove it, placard it inoperative, log it, and go. Aircraft with an approved MEL follow the MEL instead.

Is the item required? Check…	Source
Minimum Equipment List (if the aircraft has one)	MEL
Kinds of Operation Equipment List	KOEL
Type Certificate Data Sheet	TCDS
Required equipment for the flight	14 CFR 91.205
Airworthiness Directives	ADs

Why it matters

This is a real preflight decision — a burned-out landing light, an inop gauge. Knowing the 91.213 steps and where to look is the difference between a legal go and an illegal one.

Common error

Some pilots think any inoperative item grounds the airplane, and others think you can just ignore a broken gauge. Both are wrong. 91.213 is a decision: if the item is required (by the MEL, KOEL, TCDS, 91.205, or an AD) you can't fly until it's fixed; if it isn't required and isn't a hazard, you deactivate or remove it, placard it 'INOPERATIVE,' log it, and go.

You find one inoperative instrument that is NOT required for your flight. Under 91.213 you may fly after...

Safety

On preflight, if something's inop, resist 'it's probably fine.' Run the 91.213 check — required or not? — and if you're unsure, call your mechanic before you fly.

A DPE might ask

What maintenance records does an aircraft have, and what's in each?
Walk through 91.213 for an inoperative instrument.

14 CFR 91.213 & 91.417 — Inoperative equipment & maintenance records