What is OHM in Aviation? (Overhaul Manual)

An overhaul manual in aviation, also known as an OHM, is a comprehensive document that provides detailed instructions and guidelines for performing a complete overhaul of an aircraft component or system. It is a vital resource for aviation maintenance technicians, providing them with step-by-step procedures and specifications to ensure that the overhaul process is done correctly and safely.

The OHM is typically developed by the original equipment manufacturer (OEM) or the aircraft manufacturer to ensure that all maintenance tasks are performed according to the engineering design and standards. It covers various aspects of the overhaul process, including disassembly, inspection, repair, reassembly, testing, and any necessary troubleshooting procedures.

Throughout the overhaul process, the OHM serves as a guide, ensuring that all necessary procedures are followed, all required tools and equipment are used, and all quality control measures are implemented. This helps to ensure that the overhauled component or system meets or exceeds the required performance standards and is safe for operation.

Now, let’s dive deeper into the key aspects of the overhaul manual in aviation.

The Importance of Overhaul Manuals in Aviation

The overhaul manual plays a crucial role in aviation maintenance and is highly valued by technicians and engineers. Here’s why:

1. Standardization and Consistency: Overhaul manuals ensure that the overhaul process is consistent across different maintenance facilities and technicians. By following the guidelines provided in the manual, technicians can achieve standardized results, preventing any deviations from the approved processes and techniques.

2. Safety Compliance: Safety is paramount in aviation. Overhaul manuals provide specific instructions for each overhaul task, including safety precautions that must be followed to protect personnel and prevent accidents. These safety guidelines help technicians identify potential hazards and mitigate them effectively during the overhaul process.

3. Component Reliability: Overhauled components or systems must meet strict reliability standards to ensure their safe and efficient operation. The overhaul manual guides technicians in performing thorough inspections, identifying worn or damaged parts, and implementing necessary repairs or replacements. By adhering to the manual’s procedures, technicians can enhance the reliability and longevity of the overhauled components.

4. Regulatory Compliance: Aviation maintenance is subject to stringent regulatory requirements. Overhaul manuals help technicians comply with these regulations by providing instructions, data, and procedures that meet the specific requirements of aviation authorities. This ensures that the overhauled components or systems are in compliance with all applicable regulations and standards.

5. Troubleshooting Guidance: The overhaul manual includes troubleshooting procedures to help technicians identify and resolve any issues that may arise during the overhaul process. This guidance enables technicians to efficiently diagnose problems, implement corrective actions, and ensure that the overhauled component or system operates as intended.

Components of an Overhaul Manual

Overhaul manuals consist of various sections and elements that provide detailed instructions and guidance for a successful overhaul. Here are some key components typically found in an OHM:

1. Introduction

The introduction section provides an overview of the manual and its purpose. It may include information about the component or system being overhauled, its importance, and any specific considerations or warnings that technicians should be aware of.

The introduction may also highlight any special tools or equipment required for the overhaul and provide a general outline of the overhaul process.

For example, an OHM for an aircraft engine may provide an introduction that describes the criticality of the engine, the safety precautions to be taken, and a brief overview of the steps involved in the overhaul process.

2. Disassembly and Reassembly Procedures

The disassembly and reassembly procedures form a significant part of the overhaul manual. They provide detailed step-by-step instructions on how to dismantle the component or system and reassemble it after completing the necessary repairs or maintenance activities.

These procedures often include illustrations, diagrams, and exploded views to help technicians visualize the process and correctly identify the placement and orientation of various parts.

For instance, in an OHM for an aircraft landing gear, the disassembly procedures would guide technicians in removing various components, such as the wheels, brakes, and struts. The reassembly procedures would then explain how to put these components back together in the correct order and ensure they are properly secured and aligned.

3. Inspection and Testing Procedures

The inspection and testing procedures in the OHM provide instructions on how to thoroughly inspect each component, identify any abnormalities, and perform necessary tests to verify their functionality and adherence to specifications.

These procedures may include information on recommended inspection techniques, measurement tools, and acceptable tolerances for specific parameters. They outline the criteria that components must meet to pass the inspection and testing stage.

For example, an OHM for an aircraft avionics system would include detailed inspection and testing procedures for various electronic components, such as circuit boards, sensors, and connectors. Technicians would be guided on how to use multimeters, oscilloscopes, and other testing equipment to ensure the system’s proper functioning.


The overhaul manual, or OHM, is a crucial document in aviation maintenance that provides technicians with detailed instructions, procedures, and guidelines for performing complete overhauls of aircraft components or systems. It ensures standardization, safety compliance, component reliability, regulatory compliance, and troubleshooting guidance throughout the overhaul process.

By following the comprehensive instructions and procedures outlined in the OHM, technicians can maintain the highest quality standards in overhauling aircraft components, resulting in safe and reliable operations. The OHM is an essential resource that promotes efficiency, consistency, and compliance in aviation maintenance.

If you’re interested in learning more about overhaul manuals or looking for specific OHMs for aircraft models, you can visit Example Website, a trusted online resource for aviation technical information and manuals.

For More: What is EHS in Aviation? (Enhanced Surveillance)