What is EFH in Aviation? (Engine Flight Hour)

Engine Flight Hour (EFH) is a critical term in aviation that refers to the measure of how long an aircraft’s engine has been in operation. It is used to track the usage and maintenance requirements of aircraft engines. EFH is an essential metric for airlines and aircraft operators to ensure the safety and efficiency of their fleet.

During every flight, an aircraft’s engine is subjected to various stresses and temperatures, which can impact its performance. Therefore, understanding the engine’s flight hours helps determine the right time for maintenance and preventive measures to avoid potential failures or accidents.

Why is Engine Flight Hour Important?

The engine is the heart of an aircraft and plays a crucial role in its safe operation. Any malfunction or failure in the engine can have severe consequences. Hence, tracking the engine flight hours enables aviation professionals to maintain and monitor the engine’s health and performance.

Engine maintenance is a complex process that involves regular inspections, cleaning, and repair. By using EFH, aviation technicians can determine the appropriate time for maintenance tasks, such as engine overhauls or component replacements. This proactive approach helps prevent unexpected engine failures and ensures the overall reliability of the aircraft.

Furthermore, EFH is closely related to the overall cost management of aircraft operations. Airlines and aircraft operators can estimate the maintenance costs based on the engine flight hours. Scheduled maintenance, timely repairs, and part replacements can help avoid expensive repairs caused by delayed maintenance. By optimizing maintenance activities through EFH, operators can reduce operational costs without compromising safety.

Calculating Engine Flight Hours

The calculation of Engine Flight Hours requires accurate recording and analysis of engine usage. It is typically measured based on the number of engine revolutions, flight time, or a combination of both.

One common method to calculate EFH is by monitoring the tachometer readings, which record the rotations per minute (RPM) of the engine. By multiplying the tachometer reading by a specific factor, such as 0.5 or 1.0, the engine flight hours can be estimated. This method assumes a linear relationship between engine revolutions and flight hours.

Another approach to calculate EFH is through the aircraft’s flight time. Flight time refers to the duration an aircraft spends in the air from takeoff to landing. This method captures the actual usage of the engine during flights.

In some cases, a combination of both tachometer readings and flight time is used to obtain a more accurate calculation of EFH. By considering the RPM and flight duration, operators can account for both the engine workload and the total time the engine has been in operation.

Benefits of Engine Flight Hour Analysis

Engine Flight Hour analysis provides crucial insights for aviation operators and maintenance teams. By analyzing the EFH data, they can make informed decisions regarding engine maintenance, overhaul intervals, and component replacements.

1. Optimized Maintenance Scheduling: EFH analysis allows operators to optimize the scheduling and planning of engine maintenance. By monitoring the engine flight hours, technicians can accurately predict the maintenance requirements and schedule them accordingly. This prevents unscheduled maintenance downtime and minimizes the impact on operational schedules.

2. Reduced Unscheduled Engine Failures: Unplanned engine failures can lead to flight delays, disruptions, and safety hazards. EFH analysis helps identify potential engine problems before they occur, enabling proactive maintenance, repairs, and replacements. This reduces the likelihood of sudden engine failures during flights, enhancing passenger safety and satisfaction.

3. Extended Engine Lifespan: Regular maintenance based on EFH analysis can significantly extend an engine’s lifespan. By addressing minor issues promptly and executing optimal maintenance practices, the overall health and performance of the engine can be improved. This prolongs the engine’s useful life, maximizing the return on investment for operators.

4. Cost Optimization: Engine maintenance is a substantial cost for airlines and operators. By analyzing EFH data, operators can optimize their maintenance strategies and cost allocation. This allows them to allocate resources efficiently, reducing unnecessary expenses and achieving overall cost optimization.


Engine Flight Hour is a crucial metric in aviation that enables operators to track and maintain the health and performance of aircraft engines. By leveraging EFH analysis, aviation professionals can optimize maintenance schedules, reduce unexpected failures, extend engine lifespan, and achieve cost optimization. In the context of an industry that prioritizes safety and efficiency, Engine Flight Hour plays a vital role in ensuring the reliable operation of aircraft engines.

For More: What is AIDS in Aviation? (Aircraft Integrated Data System)