What is TSN in Aviation? (Time Since New)

Time since new (TSN) is a crucial term in the aviation industry used to measure the total running time or usage of an aircraft, engine, or component since it was brand new. It refers to the duration of time the equipment has been in operation, serving as an important metric for maintenance and performance evaluation. TSN provides valuable information about the wear and tear an aircraft has endured and helps determine maintenance requirements, life expectancy, and overall asset value.

In aviation, TSN is measured in hours, minutes, or cycles, depending on the specific component being assessed. For example, the TSN for an aircraft typically refers to the total flight hours and cycles it has accumulated since it was manufactured. Flight hours are calculated based on the time the engines are running, while cycles take into account the number of takeoffs and landings the aircraft has completed. This data is meticulously recorded and tracked to ensure accurate maintenance scheduling and compliance with aviation regulations.

Importance of Time since new in Aviation

TSN plays a vital role in the aviation industry for various reasons:

1. Maintenance Planning and Component Lifespan: Knowing the TSN of aircraft and its components helps determine when maintenance, repairs, or replacements are needed. Regular maintenance is essential for ensuring the safety and reliability of the aircraft, and TSN provides a factual basis for scheduling these activities. It helps determine the lifespan of critical components, such as engines, landing gear, and avionics, based on their usage and recommended maintenance intervals. By monitoring TSN, aircraft operators can proactively address potential issues and minimize downtime.

2. Asset Valuation and Resale: Time since new also plays a significant role in determining the value of aircraft and components, especially when it comes to resale or lease transactions. Potential buyers or lessees consider the TSN as a key parameter to evaluate the asset’s condition and remaining lifespan. A lower TSN typically indicates a younger and less heavily used aircraft, making it more attractive for resale or lease. On the other hand, a higher TSN might affect the asset’s value, as potential buyers may perceive it as having a shorter remaining lifespan.

3. Safety and Reliability: TSN is directly linked to the safety and reliability of an aircraft. Regular maintenance and inspections are conducted based on the accumulated TSN to identify any potential issues or deterioration in the components. By adhering to maintenance schedules based on TSN, operators can ensure that the aircraft remains in optimal condition, minimizing the risk of in-flight failures due to worn-out or malfunctioning parts. Furthermore, TSN allows operators to track the reliability of specific components, helping identify patterns or trends that may require further investigation.

TSN Management and Tracking

Effective TSN management involves accurate tracking and recording of operating times for aircraft and its components. This is typically done using advanced maintenance tracking systems and software. These systems capture data from various sources, such as flight data recorders, engine data monitoring systems, and logbook entries, to compile the TSN for each specific asset or component.

Additionally, aircraft manufacturers and engine suppliers often provide TSN tables or guidelines, specifying recommended maintenance intervals, overhauls, or replacements based on TSN thresholds. These guidelines help operators plan their maintenance activities and ensure compliance with industry standards.

To monitor and track TSN effectively, aircraft operators must maintain thorough and accurate records. This includes diligently recording flight hours, cycles, landings, and any other relevant operational data in a centralized database or maintenance software. The data is then regularly reviewed and analyzed to assess maintenance requirements, identify trends, and make informed decisions.


Time since new (TSN) is a critical concept in aviation, measuring the total running time or usage of an aircraft, engine, or component since it was brand new. It provides essential information for maintenance planning, asset valuation, and ensuring safety and reliability. Accurate tracking and management of TSN is vital for maintaining the airworthiness of aircraft and optimizing maintenance schedules.

By leveraging advanced maintenance tracking systems and adhering to manufacturer guidelines, operators can effectively monitor TSN and make informed decisions regarding maintenance, inspections, and component replacements. This proactive approach helps keep the aviation industry safe, efficient, and reliable for both passengers and operators.

For More: What is LORAN in Aviation? (Long-Range Navigation)