The permissible mass, also known as "Not-to-Exceed Weight" (NTEW), is a decisive limit value in aircraft development and design. It represents the upper weight limit set for a deliverable from the design group, including all tolerances and margins. This value is set at the beginning of a program and remains constant until requirements change.
Important aspects of the permissible mass (NTEW)
Determination and agreement
The allowable mass is defined at the beginning of an aircraft development program and is a confirmed, often contractually bound value between the parties involved, such as the design group and the client. This means that the design group is obliged to adhere to this value.
Purpose and meaning
Weight management: The NTEW serves as a critical limit for weight management during the design and development of the aircraft. It ensures that the final product remains within the specified weight limits.
Conformity and responsibility: Compliance with the NTEW is often contractually required, and non-compliance can result in penalties or other consequences for the design group.
Application examples
Contractor Not-to-Exceed Weight: A specific example of a permissible mass is the "Contractor Not-to-Exceed Weight", which is a contractually stipulated weight limit that must not be exceeded.
Informal mass assignment: In some cases, there may also be informal mass assignments to design organizations that serve as internal guidelines or goals.
Influence on the design
Tolerances and margins: The NTEW includes all tolerances and margins that must be taken into account during design and development. This ensures that the final product remains within the weight limits even when variations and uncertainties are taken into account.
Design decisions: Establishing an NTEW influences many design decisions, including material selection, structural design and system integration to ensure the aircraft meets weight requirements.
Importance of compliance
Safety and performance: Compliance with the permissible mass is crucial for the safety and performance of the aircraft. Exceeding the weight limits can impair flight performance and jeopardize structural integrity.
Contractual obligations: Compliance with the NTEW is often a contractual obligation, and non-compliance can lead to financial or legal consequences.
Overall, NTEW is a key aspect of aircraft development that ensures the final product is safe, efficient and in compliance with contractual and technical requirements.
English 
Deutsch