This document provides owners of aging single-engine airplanes guidance about maintaining the airworthiness of their airplanes. The general aviation (GA) fleet is aging. In 2000, the average age of the nation’s 150,000 single-engine fleet was more than 30 years. By 2020, the average age could approach 50 years. This guide for maintaining older airplanes consists of “best practices” that go beyond normal inspection requirements. A team made up of airplane manufacturers, owners, their representative organizations, and engineers and inspectors from the Federal Aviation Administration (FAA) developed these best practices. The Aircraft Owners and Pilots Association (AOPA), the Antique Airplane Association (AAA), the Experimental Aircraft Association (EAA), and the FAA endorse this guide. The intended primary users of this guide are owners of older, small single-engine airplanes. In this guide, owners will find useful tips for assessing the effects of aging on their airplane. They will also find that this guide provides excellent guidance for user groups or type clubs to use for developing a checklist and gathering reference information specific to a model type.