What Qualifies as a Major Repair or Alteration on Aircraft? Understanding FAA Form 337

What is FAA Form 337?

FAA Form 337, officially titled “Major Repair and Alteration (Airframe, Powerplant, Propeller, or Appliance),” is a crucial document in aviation maintenance. This form is used to record significant repairs or modifications made to an aircraft, its airframe, engine, propeller, or related appliances.

When is Form 337 Required?

Form 337 is necessary when performing major repairs or alterations on aircraft. But what exactly qualifies as “major”? Here are some key points to consider:
• Structural changes that affect the aircraft’s weight and balance
• Modifications that significantly alter flight characteristics
• Installations of new equipment that affect the aircraft’s operation
• Repairs that deviate from approved methods or require special techniques

It’s important to note that not all repairs or alterations require Form 337. Routine maintenance and minor repairs typically don’t necessitate this documentation.

Completing and Filing Form 337

When a major repair or alteration is performed, the mechanic or repair station must:

Execute the form in at least duplicate
Provide detailed information about the work accomplished
Certify that the repair or alteration complies with FAA regulations
Obtain approval for return to service from an authorized individual

One copy of the completed form must be sent to the FAA Aircraft Registration Branch in Oklahoma City, while another is given to the aircraft owner.

The Importance of Proper Documentation

Accurate completion of Form 337 is crucial for several reasons:
• It provides a clear record of major work done on the aircraft
• It ensures compliance with FAA regulations
• It can affect the aircraft’s airworthiness and value
• It serves as a reference for future maintenance or inspections

Improper documentation or failure to file Form 337 when required can result in penalties and compromise the aircraft’s airworthiness status.