What Is an Airworthiness Directive?

Understanding airworthiness directives is vital for every pilot, especially airplane owners.

Many people are familiar with recalls in the car world.

Car makers work with their mechanics to develop service bulletins when a problem is noticed. If it’s a safety issue, the National Highway Traffic Safety Administration may get involved and require that all cars be recalled. 

Airworthiness Directives, or AD, is the aviation world equivalent of a recall. It’s a mandate that you must have your aircraft inspected or fixed. If you don’t comply with an AD, it is no longer legal to fly it. 

What Is an Airworthiness Directive?

An Airworthiness Directive is a rule issued by the FAA for required maintenance or inspection on a specific aircraft type.

They come about after conditions have been noticed that could pose a hazard to flight.

Sometimes, the problem was discovered due to an accident investigation, but many other times, they address things that have been noticed during routine maintenance inspections.

Airworthiness Directives vs Mandatory Service Bulletins

Aircraft manufacturers often issue their own Mandatory Service Bulletin (MSB) when problems are discovered.

These MSBs tell mechanics of a problem with other aircraft and provide steps to inspect for the condition and repair it. MSBs are non-regulatory—they come from aircraft builders like Cessna or Piper. 

But if the issue is serious enough, or there have already been incidents or accidents, the FAA will get involved.

Making an MSB mandatory through the regulations is when it becomes an airworthiness directive (AD). Many ADs incorporate or refer to a service bulletin, thereby making it mandatory.

What Is the Purpose of an Airworthiness Directive?

Airworthiness Directives are a basic safety tool governments use to ensure operators fix unsafe conditions on their aircraft.

The FAA issues ADs in the US, while the EASA in Europe issues them there.

Often, these government organization units work together so that when one issues an AD, the others follow suit. 

Airworthiness directives can be issued for specific aircraft makes and models, engine models, propellers, or equipment installed in a plane, like avionics or STC modifications.

Why Are Airworthiness Directives Important?

Once an airworthiness directive is issued, owners and operators of the aircraft must comply with it.

As their name suggests, ADs are airworthiness items that, if not complied with, put the operator in violation of FAR 91.403. So, while many maintenance issues are the responsibility of the aircraft’s mechanic, ADs are particularly important to owners and operators. 

At the same time, the inspections and repairs required by an airwrothiness directive must be completed by a mechanic. The exact requirements are specified in the AD itself.

Even though licensed pilots can perform some preventative maintenance tasks, they’re only allowed to comply with an AD if the AD specifically allows it.

Pilots must establish that all ADs are complied with as part of their routine pre-flight inspections.

Unfortunately, this is often easier said than done.

Owners are notified when a new AD may affect their plane. But they are often complicated, involving specific model years, serial numbers, or individual pieces of optional equipment. 

During every major inspection, the mechanic signing off on the work will complete an audit of all of the ADs that could apply to a particular aircraft. They print an airworthiness directive compliance record that gets kept in the aircraft logbooks, and each AD is marked off. 

This record is the primary tool that pilots can use to ensure compliance.

The signing mechanic will inspect each AD that applies to the aircraft, engines, propellers, and onboard equipment. They will sign it off as complied with (C/W), previously complied with (PCW), or not applicable (N/A).

Reoccurring ADs will also list the time and date when they must be complied with again.

It’s important to note that some airworthiness directives require routine inspections or maintenance work more often than other inspections.

You might have an aircraft that requires you to track compliance with an AD every 25 or 50 hours. This will have to be a new line item on your dispatch sheets to ensure that the aircraft never over flies the allowable time limits.

Emergency Airworthiness Directives

An airworthiness directive usually requires inspection or repair of an item at the next service interval. For small planes, that’s usually the next 100-hour or annual inspection. That means an aircraft could fly for quite a while before the AD is addressed. 

In cases with a high risk of accidents, the FAA may issue an Emergency airworthiness directive. In these situations, the aircraft is basically grounded until the issue is resolved. Emergency ADs are fairly rare.

Boeing aircraft have been subject to a few high-profile Emergency ADs in the last few years.

First, the grounding of the Boeing 787 fleet in 2013 happened after two lithium-ion battery fires. Then, in 2018, an Emergency AD grounded the worldwide fleet of 737 MAX planes due to software issues. 

Finding ADs for Your Plane

There’s nothing secret about the ADs that might affect your plane. It’s always best to work with your mechanic to ensure compliance and that you have a completed AD Compliance Log filled out as part of your aircraft’s maintenance records.

You can search for ADs independently using the FAA’s DRS (Dynamic Regulatory System). There are sections for Final Rule ADs, Emergency ADs, proposed ADs, and biweekly ADs.

You can also organize your query based on manufacturer or specific type, and the database includes equipment ADs.

While it would be difficult to perform a full audit for an aircraft using this tool, it’s a great way to read some example ADs and see what issues have affected your plane model in the past.