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Airworthiness Flowchart

How the “Airworthiness Flowchart." Works.


All questions regarding determinations of airworthiness can be answered using this flowchart. Just follow along now, and we will build it together. You can either watch it being built on the video or follow along below with all the appropriate FARs linked directly to the FAA's website. Each block will lead you to the appropriate result. If you stay on the appropriate paths, and do not deviate regardless of the situation confronting you, you will never be violated by the FAA for an incorrect decision.

Airworthiness Flowchart Video

Inspection Authorization Refresher Training

"How the Airworthiness Flowchart work".

So; when is a product or a part airworthy and when is it not?

Standard Airworthiness  Certificate

The ultimate end in determining airworthiness is to remain in compliance with the standard airworthiness certificate issued under FAR 21.183 for a new aircraft. It is the birth certificate for a new aircraft. Reviewing the standard airworthiness certificate indicates in Block 5 "Authority And Bass For Issuance" that the FAA has inspected the new aircraft and has found it to be airworthy. In addition, Block 6 of that certificate states that the certificate remains valid if the operations and maintenance are in compliance with FARs. FAR 21.183 and the standard airworthiness certificate define the airworthiness conditions.


In addition Block 6, "terms and conditions" of that certificate states that the certificate remains valid if the operations and maintenance are in compliance with FARs. FAR 21.183 and the standard airworthiness certificate, define the airworthiness conditions.

Let's take a look at FAR 21.183 "Airworthy"!

Legal airworthiness depends upon two conditions.

  • The first is that the aircraft or product involved be inspected. This means that all components must be within service limits. This is determined through proper inspection under FAR 43.15, rules for inspections:
  • The second is that each component of the aircraft or product meets its approved type design. Type design is defined in FAR 21.31. It includes all the data, drawings, manuals, and processes that define the aircraft or product.

If either or both of these conditions are not met, the aircraft or product is not "airworthy"! If either or “Both of these Conditions” are not met, the Aircraft or Product is not "Airworthy"! Type design is defined in FAR 21.31. It includes all the data, drawings, manuals, and processes that define the aircraft or product.


 How determination of airworthiness Condition are Concluded 

This page describes the condition questions. If condition one and two are determined to be airworthy, then the aircraft\product is airworthy. If either condition is determined to be unairworthy, then the entire aircraft or product is unairworthy until it can be rendered airworthy by clearing the defect.

Condition for Safe Operation

Let’s begin clarifying the two conditions.

We will begin with rules for inspections; an important condition for safe operation. We will develop the attributes that result in that condition being airworthy. So far we have;

What is the product or part’s condition?

Rules for inspections

We will start by taking a look at Condition One. Rules for inspections, an important condition for safe operation, depends upon inspecting the aircraft or product. The IA performs inspections in accordance with FAR 43.15. The IA inspects for attributes such as worn parts beyond specified limits, loose parts, corrosion, smoking rivets, fuel leaks, worn tires and brakes and the like.

Maintenance FAR 43.13

We have been focused on Inspection, now let’s look at Maintenance FAR 43.13

If the rules for inspections reveals unairworthy conditions, they must be repaired to their original condition.

These repairs are accomplished in accordance with FAR 43.13. This FAR defines all of the requirements for performing maintenance. This includes using the proper manuals and repair equipment.

Overhaul, Repair, and Replacement. 

Maintaining aircraft consists of three elements; overhaul, repair, and replacement. 

  • Products can be overhauled in accordance with FAR 43.2.
  • Parts can be repaired restoring them to their original condition in accordance with FAR 43.13.
  • Finally, parts can be replaced in accordance with FAR 21.9.

Replacement

If parts are to be replaced, there are only four ways to do it if they are to be airworthy.

  • The first is to obtain the replacement part from the type certificate holder.
  • The second is to use an appropriate and indicated TSO part in accordance with FAR 21.9. 
  • The third is to use a PMA part in accordance with FAR 21.9. 
  • The final way is to install a part approved by the FAA on a Form 337 Major Repair and Alteration.

There are no other methods.

Type Design

We have discussed condition one that the aircraft or product involved be in a condition for safe operation under FAR 43.15.

Let’s talk now about Condition number two type design FAR 21.31; does the product or part meet the manufacturer’s design specifications? The second element of airworthiness is, conformity to the type design. An IA will use various publications to determine conformity to type design. In short, the aircraft or product must meet the print to be airworthy.

Conforming to FAR 21.31

In conforming to FAR 21.31, the IA must determine if conformity to type design has been met.

To do this the IA must use at a minimum;

  • The type certificate data sheet,
  • Airworthiness directives, 
  • Aircraft flight manual,
  • Pilot’s operating handbook, and 
  • Approved aircraft equipment list.

 

Alterations under FAR 21.43

Alterations under FAR 21.43. If the IA determines that major alterations have been performed, complete inspection of such alterations must be made to assure continued conformity to the alteration data. If complete alteration data is not available, the IA must indicate that as a discrepancy, rendering a determination of un-airworthiness until it can be obtained.

Alterations FAR 21 & 43

There are only four ways to alter an aircraft or other product.

  • The first is an approved alteration provided by the type certificate holder.
  • The second is an alteration approved under a supplemental type certificate.
  • The third is any alteration in compliance with an airworthiness directive.
  • The last is a field approval by the FAA on a Form 337 Major Repair and Alteration .

All major alterations require the completion of FAA Form 337 Major Repair and Alteration. Airworthiness directives are always considered FAA approved data.

Now let us put the entire flowchart together.

All questions regarding determinations of airworthiness can be answered using this flowchart. Just follow the blocks to the appropriate result. Stay on the appropriate paths and do not deviate regardless of the situation confronting you. If you follow the chart you will never be violated by the FAA for an incorrect decision.


How exactly would you use this flowchart? 

A good example is, a piece of cracked engine baffle. Most mechanics will just fabricate a new piece using the cracked piece as a template. But is it airworthy? Following the flowchart and the first two conditions it probably is not. While it might meet the condition for safe operation, if the mechanic does not have the type certificate holder’s current approved data to produce the replacement part, conformity to type design FAR 21.31 can not be determined.

  • What is the required material and in what temper?
  • What corrosion preventive methods were applied?
  • Are the dimensions as precise as the original indicates on the drawing?

The end result is the simple engine baffle would not meet airworthiness requirements. 

Take a few minutes to look over the flowchart. Follow along the appropriate paths for any question you may have in mind, and see what the final conclusion is!


Each FAR is linked to the FAA's web site, so take a moments to check it out.

FAR 21.183 Airworthy

FAR 43.15 Rules of Inspection

FAR 21.31 Meets Type Design

FAR 43.13 Maintenance

FAR 43.2 Overhaul

FAR 21.9 Replacement Parts

FAR 21 TC

Far 39 AD

Form 337

FAR 21 & 43

 

 

To sum up 

When the FAA or an appropriately-rated designee supplies an airworthiness certificate for that product or part, it is certifying its airworthiness. For a product or a part to be considered airworthy, two separate conditions must exist at all times:

  1. It must be in a condition that assures its safe use during flight, and
  2. It must adhere to the type certificate holder’s drawings and specifications
Remember, The Type Design is defined by the 
  • Type Certificate Data Sheet,
  • Airworthiness Directives,
  • Aircraft Flight Manual,
  • or, Pilot’s Operating Handbook for older aircraft.
  • The "Illustrated Parts Catalog", and the required "Equipment List" (describes what is required to be installed on the aircraft).

If the parts or product are not original equipment, have alterations been made? Alterations alter the Type Design.

For that product, or part to be airworthy the two conditions and all of the subfactors must be in agreement and in sync.


If one of the subfactors produces a negative answer or is out of sync then the corresponding condition fails. The product, or part is not considered airworthy.


If all of the subfactors produce a positive result and are in sync, then the corresponding condition passes.

The product, or part is considered to be airworthy.

Download Airworthiness Flowchart Front - Flowchart Back

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