![]()
In private aviation, maintenance records are more than paperwork; they are a critical reflection of compliance and a major driver of aircraft value. Every detail, from understanding what is required and why, to the accurate and complete documentation of maintenance once it has been accomplished, establishes the compliance status of the aircraft at any given time.
While records themselves do not make an aircraft safe, they provide the necessary proof that maintenance has been completed correctly and on schedule. Just as important, they preserve an aircraft's market value by giving future buyers confidence in its history and condition.
This article explores how the foundation of airworthiness begins with the Type Certificate Data Sheet (TCDS) and extends through Instructions for Continued Airworthiness (ICA), maintenance manuals, inspection programs, and accurate maintenance records. It also explains what is required, where those requirements come from, and how an aircraft's specific operational structure affects what must be complied with. Proper documentation is essential for protecting one of the owner's most valuable assets: the aircraft.
Type Certificate Data Sheet (TCDS)
It all starts with the Type Certificate Data Sheet (TCDS) or aircraft specifications. The TCDS is issued by the FAA when a manufacturer meets all the requirements to certify and produce an aircraft. It contains critical details and serves as the foundation for the aircraft's airworthiness. While there is no formal definition of airworthiness in the regulations, Part 21.183 states that an aircraft must "conform to type design" and be "in a condition for safe operation" to receive an airworthiness certificate. This is why everything in maintenance begins with the TCDS.
Each aircraft, engine and propeller must receive a Type Certificate, with the resulting TCDS outlining the specifications and requirements for maintaining airworthiness. These "Products," defined in Part 21.1 and commonly referred to as "Class I Products," are required to have their logbooks in which total time and cycles are independently tracked, as specified in Part 91.417.
Certain details within the TCDS form the basis of maintenance requirements, such as retirement times for life-limited components. These references often direct us to the aircraft, engine and propeller Instructions for Continued Airworthiness and maintenance manuals, as well as other documents that specify these limitations. Each manufacturer has the flexibility to present this information in its own format, which results in some inconsistency, but the TCDS is where it all begins.
Notably, any requirements referenced in a TCDS are considered mandatory by the FAA. This is important to highlight because some TCDSs reference Service Bulletins (SBs) issued by manufacturers for life-limited parts. While service bulletins are typically considered optional unless incorporated into an Airworthiness Directive (AD), references in the TCDS make them mandatory.
Maintenance Manuals and Inspection Programs
The next key resource is the maintenance manual. While the aircraft maintenance manual is not always FAA-approved, maintaining an aircraft's airworthiness requires following the manufacturer's instructions. FAR Part 43.13 mandates that maintenance must be performed using the methods, techniques and practices outlined in the current manufacturer's maintenance manual or Instructions for Continued Airworthiness, or other methods approved by the FAA.
FAR Part 91.409 further specifies that no person may operate large airplanes (to which Part 125 is not applicable), turbojet multiengine airplanes, turbopropeller-powered multiengine airplanes, or turbine-powered rotorcraft unless the replacement times for life-limited parts specified in the aircraft specifications or TCDS are complied with, and that the aircraft is inspected according to a program chosen under paragraph (f).
The most common inspection program under Part 91.409(f) is outlined in 91.409(f)(3), which refers to a current inspection program recommended by the manufacturer, the same program found in the manufacturer's maintenance manual.
Aircraft maintenance manuals are organized using the ATA 100 coding system developed by the Air Transport Association of America. This system breaks down manuals into chapters, sections, and subsections for specific parts of the aircraft, making maintenance more efficient. For example, Chapter 21 refers to air conditioning, Chapter 23 to communications and Chapter 32 to landing gear. Chapter 5 contains the time limits and maintenance checks, which outline the inspection program recommended by the manufacturer. Some manufacturers also include life-limited parts in Chapter 5, while others list them in Chapter 4 (airworthiness limitations) in an entirely separate FAA-approved document.
Maintenance Tracking Systems and Records
When reviewing a maintenance tracking report from systems like CAMP or Traxxall, you should expect to see all the maintenance requirements for the aircraft, including its engines and, if applicable, propellers. These "Class I Products" collectively make up the aircraft, and their requirements, including total time and cycles, should be reflected in both the maintenance tracking system and the logbooks.
The maintenance tracking system is simply a reflection of the aircraft's logbooks, ensuring that you can easily verify when maintenance tasks were last completed and when they are due again. This ties directly into the regulatory maintenance record-keeping requirements. FAR Part 91.417(b)(1) specifies that inspection and maintenance records—including descriptions of the work, dates, and signatures—must be kept for at least one year or until the work is superseded, whichever comes first. FAR Part 91.417(b)(2) outlines certain records that must be retained indefinitely and transferred with the aircraft when ownership changes or during inspections. These records include:
• The total time (and cycles) in service for each airframe, engine, propeller, and rotor.
• The current status of life-limited parts.
• The current status of applicable airworthiness directives (ADs).
• The time since the last overhaul of all required items.
• The current inspection status.
• Copies of each FAA Form 337 or repair station work order documenting major repairs or alterations.
Maintaining these records is critical for demonstrating regulatory compliance, and the maintenance tracking system should help track these requirements and ensure the correct documentation is in place. Staying on top of compliance with Service Bulletins (SBs) or Customer Bulletins (CBs) issued by the manufacturer can also provide a comprehensive picture of the aircraft's maintenance history.
Supplemental Type Certificates (STCs)
Supplemental Type Certificates (STCs) are required when a significant modification or alteration is made to an aircraft, engine, or propeller that affects its type design. Some of the most common reasons for an STC include avionics upgrades, interior configuration changes, engine or propeller modifications, and aircraft performance enhancements.
An STC can be issued for a one-time installation on a specific aircraft or designed for use across several aircraft of the same make and model. Each STC must include three key components:
1. Documentation on FAA Form 337.
2. Instructions for Continued Airworthiness (ICA) when required.
3. An Aircraft Flight Manual Supplement to reflect any operational changes due to the modification.
A common issue during pre-buy inspections is the failure to identify STCs and their associated requirements. The ICAs provided with an STC are critical. They must be integrated into the aircraft's maintenance tracking system to ensure that all required inspections and maintenance are performed and properly documented.
Operations Under Part 135
It is important to understand what operations under Part 135 entail. On the surface, it may seem straightforward, but it becomes more complex when it comes to aircraft maintenance and inspection requirements. Operating under Part 135 essentially means operating under the umbrella of an FAA-issued air carrier certificate, which allows the aircraft to operate for hire under Part 135 regulations.
During the air carrier certification process, the applicant must demonstrate several key elements to the FAA. First, they must clearly define the organizational structure, outlining who is responsible for what within the operation. They must also establish how maintenance will be performed. This is not about the specific maintenance instructions, which still come from the OEM (Original Equipment Manufacturer).
Instead, the Part 135 Air Carrier maintenance manual focuses on procedures: it outlines who is responsible for specific tasks, how those tasks are to be completed, and what forms will be used to record actions and maintenance. The organization must convince the FAA that it can maintain the aircraft in an airworthy condition while handling the pressures of operating as a business to successfully obtain an air carrier certificate.
In most cases, under Part 135, the inspection program used for an aircraft will be the same as it is under Part 91. However, differences can emerge. Operators may seek efficiencies or extended inspection and overhaul intervals through approved program modifications. According to FAR Part 135.419, the FAA has the authority to require or approve an Approved Aircraft Inspection Program (AAIP). Specifically, the regulation states, "Whenever the Administrator finds that the aircraft inspections required or allowed under Part 91 are not adequate to meet this part, the Administrator may require or allow an approved aircraft inspection program."
While most aircraft operating under Part 135 will be maintained and inspected similarly to those under Part 91, occasionally an aircraft under Part 135 will be placed on an AAIP. In those cases, it is important to understand the need for a bridging process when the aircraft is removed from the Air Carrier certificate and placed back into operations under Part 91. The bridging process correlates identical maintenance and inspection requirements, aligns them for new "next due" calculations, and identifies any outliers that do not correlate for further resolution.
Conclusion
In private aviation, compliance begins and ends with proper recordkeeping. The TCDS establishes the type design, maintenance manuals and inspection programs define the requirements, and as work is accomplished, logbooks document the actions while tracking systems monitor compliance. Together, these elements provide the traceability and accountability needed to demonstrate compliance with maintenance requirements and, ultimately, the aircraft's airworthiness.
Whether under Part 91 or Part 135, operators must ensure that records are accurate, complete, and up to date, not only to satisfy regulators but also to preserve the value of the aircraft. Owners and operators at every level should make it a priority to maintain clear and accurate documentation of all required maintenance. The condition of an aircraft's maintenance records tells the story of how it has been cared for, and that story, good or bad, always carries significant weight in determining the aircraft's value at the time of sale. Joe Hertzler is a respected authority in aircraft maintenance operations, regulatory compliance and strategic innovation. As a strategic business advisor at Thoroughbred Aviation, Joe supports the company's growth through business development strategy, B2B collaboration and high-level client advisement.