Certified reference manual specific to each aircraft model. Defines operational limitations, performance, emergency procedures, and regulatory compliance. In case of discrepancy, the AFM remains the controlling authority.

Provides operating procedures, system descriptions, performance data, and limitations required for safe aircraft operation.

Complementary training document providing operational philosophy, best practices, maneuver techniques and situational awareness guidance.

Configuration-specific operational procedures and emergency guidelines for cabin crew operations.

Regulatory-approved reference defining equipment that may be inoperative under specified conditions.

Aircraft-specific condensed procedures for rapid in-flight reference.

Defines aircraft weight, center of gravity limitations and operational loading procedures.

Primary maintenance reference including servicing, inspection, repair, replacement and continued airworthiness instructions.

Shop-level maintenance procedures for off-aircraft components.

Illustrated listings for identification and requisitioning of aircraft and engine components.

Structured diagnostic procedures for aircraft system faults.

Electrical system schematics, wiring installations and detailed wire listings.

Approved structural repair procedures and allowable damage limits.

Inspection procedures to detect structural damage and maintain airworthiness.

Repair and inspection procedures for ducts and fuel pipe assemblies.

Repetitive maintenance tasks and scheduling basis for operator-approved programs.

Approved consumables required for servicing and maintenance.

Recommended tools and test equipment required for maintenance and troubleshooting.

Airport and maintenance planning data.

Planning guidance for recovery of disabled aircraft and preparation for return to service.

An orphan aircraft is a type whose original manufacturer no longer exists and whose Type Certificate (TC) has either lapsed, been transferred, or is held by an entity with limited support capacity. The aircraft remains legally airworthy as long as it complies with its original TCDS and applicable Airworthiness Directives — but the owner bears full responsibility for sourcing documentation, parts, and qualified maintenance personnel. Many warbirds, vintage trainers, and post-war light aircraft fall into this category, including the Navion (TC held by Sierra Hotel Aero, Inc.), Aeronca, Luscombe, Taylorcraft, Ercoupe, and Stinson types.

Reference: FAA Regulatory Guidance Library · EASA Aircraft Certification

The Type Certificate is the FAA's formal approval that an aircraft design meets airworthiness standards. The TCDS is the public document attached to the TC — it defines approved engine models, weight limits, required equipment, and operating limitations. It is the legal foundation of the aircraft's airworthiness. If the TC holder disappears, the FAA may transfer the TC or place it in inactive status. The TCDS remains the controlling document regardless.

Reference: FAA TCDS Database

An Airworthiness Directive is a legally mandatory instruction issued by the FAA (or EASA/national authority) requiring a specific inspection, repair, or modification to be performed within a defined timeframe. ADs are not optional — non-compliance makes the aircraft unairworthy and uninsurable. For vintage types, ADs may be decades old but remain fully in force. Always check the FAA AD database for your specific make, model, and serial number.

Reference: FAA Dynamic Regulatory System (AD Search)

A Service Bulletin is a document issued by the manufacturer (or current TC holder) recommending a specific modification, inspection, or repair. Unlike an AD, an SB is not automatically mandatory — but it may become mandatory if the FAA incorporates it into an AD. For vintage aircraft, SBs issued decades ago by the original manufacturer remain relevant and are often the only source of approved repair data. Always check whether an SB has been superseded or incorporated into an AD.

A Service Letter is a manufacturer communication providing guidance, recommendations, or minor procedural updates — generally advisory in nature. A Mandatory Service Letter carries the same legal weight as a Service Bulletin and must be complied with. The distinction matters: always read the document header carefully to determine its compliance status. For orphan aircraft, these letters are often the only surviving source of approved procedural guidance.

A Technical Order is the U.S. military equivalent of a civilian maintenance manual. T.O.s cover everything from flight operations (Dash-1) to maintenance (Dash-2), parts (Dash-4), and inspection requirements. For aircraft that served in military roles — such as the L-17 Navion, T-6 Texan, or C-47 — the original T.O. series remains the most authoritative technical reference available, even after the aircraft transitions to civilian ownership.

Reference: Air Force Technical Order System

FAA Form 337 is the document used to record any major repair or alteration to an aircraft beyond standard maintenance. It must be completed by an A&P mechanic with Inspection Authorization (IA) and filed with the FAA. For vintage aircraft, the Form 337 archive is often the only record of engine swaps, structural repairs, and avionics upgrades performed over decades.

Reference: FAA Form 337 (official)

“On condition” means the component has no fixed overhaul interval — it is inspected regularly and replaced or overhauled only when it no longer meets serviceability standards. This is common for engines on vintage general aviation aircraft (e.g., Continental E-185/E-205 on the Navion). It contrasts with hard-time limits, where a component must be overhauled or replaced at a fixed number of hours regardless of condition.