What is DEL on Boeing 737? (Diagram Equipment List)

The Diagram Equipment List (DEL) on the Boeing 737 is an essential document that provides detailed information about the various equipment and systems installed on the aircraft. It serves as a comprehensive reference for maintenance personnel, pilots, and other aviation professionals to identify and locate specific components and their associated part numbers.

The DEL is a crucial part of the aircraft’s technical documentation and is used throughout its life cycle, from production to operation and maintenance. It plays a vital role in ensuring the safety and efficiency of the Boeing 737, allowing for accurate identification and troubleshooting of equipment issues.

The Importance of the Diagram Equipment List

Understanding the Diagram Equipment List is essential for aviation professionals involved in aircraft maintenance and operation. Here are a few key reasons why the DEL holds such importance:

The DEL as a Maintenance Reference

For maintenance personnel, the DEL serves as a valuable reference tool. It contains detailed diagrams and descriptions of the aircraft’s equipment, including relevant technical specifications and part numbers. This allows technicians to quickly locate and identify components during routine inspections, maintenance tasks, or troubleshooting procedures.

Furthermore, the DEL provides information regarding equipment replacement and modification procedures, ensuring that any changes made are in compliance with Boeing’s standards and guidelines. By following the DEL, maintenance personnel can effectively maintain the aircraft’s systems, ensuring optimal performance and safety.

The DEL for Component Localization

Pilots and other aviation professionals also benefit from the DEL, as it helps them identify and locate specific components in the aircraft. In the event of a malfunction or system failure, pilots can refer to the DEL to quickly understand the affected equipment and its potential impact on flight operations.

The DEL provides clear visual representations of the aircraft’s systems, ensuring that pilots can easily identify crucial components during both normal operations and emergency situations. This knowledge is vital for timely decision-making and appropriate response actions.

How to Utilize the Diagram Equipment List

Effectively utilizing the Diagram Equipment List requires a thorough understanding of its structure and content. Here are some guidelines to get the most out of this essential document:

Familiarize Yourself with the DEL Format

The DEL typically consists of multiple sections, each dedicated to a specific system or category of equipment. These sections are further divided into subsections, with each containing detailed diagrams, descriptions, and part numbers.

It is important to familiarize yourself with the DEL’s structure to quickly locate the information you need. Take note of section titles, page numbers, and any cross-references provided. This will help you navigate the document efficiently and save time during maintenance or troubleshooting tasks.

Use the DEL in Conjunction with Other Documents

While the DEL is a comprehensive reference document, it is not the only source of information. It is crucial to use the DEL in conjunction with other technical publications, such as the Aircraft Maintenance Manual (AMM) and the Illustrated Parts Catalog (IPC).

The AMM provides detailed procedures for maintenance tasks, including step-by-step instructions and reference diagrams. The IPC, on the other hand, focuses on the identification and ordering of replacement parts. By using these documents together, you can ensure a more comprehensive understanding of the aircraft’s systems and components.

Keep the DEL Updated

The Diagram Equipment List is subject to revisions and updates as new equipment is introduced or modifications are made to existing systems. It is crucial to stay informed and keep the DEL up to date to ensure accurate information is available when needed.

Regularly check for updates or revisions provided by the aircraft manufacturer or regulatory authorities. Keeping the DEL current will help you stay informed of any changes that may impact maintenance procedures or operational considerations.


The Diagram Equipment List (DEL) on the Boeing 737 is a valuable resource for aviation professionals involved in maintenance, operation, and troubleshooting of the aircraft’s systems. It provides detailed information about the equipment and allows for accurate identification and localization of components. By utilizing the DEL effectively, aviation professionals can ensure the safety, efficiency, and reliability of the Boeing 737.

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