# Minimization of Material Waste Through Maintenance Interval Optimization in Transport Systems
## 1 Introduction
### Origin of the Research Problem
It includes a basic examination of key systems, such as engines, landing gear, control surfaces, lighting, fuel status, and general external condition;
* Line Maintenance Check: Typically conducted every 24-48 h of operation or after specific flight cycles. It is more thorough than a pre-flight inspection and performed mainly at airports by specialized maintenance personnel;* Periodic Checks (Base Maintenance--A, B, C, D Checks): A Check: Conducted every 500-800 flight hours or every 1-3 months, depending on usage. It involves inspecting systems such as hydraulics and electrical systems; B Check: Conducted less frequently than A Check (every few months). Today, most airlines no longer perform B Checks, focusing instead on A and C Checks; C Check: Carried out every 12-18 months, requiring more detailed examination and maintenance of structural components, often taking the aircraft out of service for several days; D Check: The most comprehensive check performed every 6-10 years, involving extensive inspection and overhaul, including dismantling many parts of the aircraft. It is often called a \"General Overhaul\". Special Inspections: These include checks following specific events like hard landings or bird strikes, as well as calendar inspections of components with time limits. Regulation Sources:
* Aircraft Manufacturer: Provides detailed guidelines for inspection;
* National and EASA Regulations: Define minimum inspection frequency requirements to ensure airworthiness. Regular compliance with inspection schedules is crucial for maintaining flight safety. Maritime vessels undergo rigorous technical inspections to ensure safety, environmental protection, and compliance with regulations. In Poland, these inspections are overseen by Maritime Offices and recognized classification societies like the Polish Register of Shipping (PRS). Key aspects of technical inspections of maritime vessels:
* Classification Inspections:
* Initial Survey: Conducted during construction or before the first operation, assessing compliance with regulations;
* Periodic Surveys: Regular inspections confirming the vessel meets classification standards, typically every five years;
* Special Surveys: Extra inspections due to incidents, damages, or modifications. * Statutory Inspections:
* Safety Certificates: Ensuring vessels comply with conventions such as SOLAS or MARPOL;
* Port State Control Inspections: Conducted by port authorities to verify international compliance. * Equipment Inspections:
* Life-Saving Appliances: Routine checks and maintenance of rescue devices;
* Fire-Fighting Equipment: Inspections of fire extinguishing systems and detectors. * Navigation and Communication System Inspections:
* Navigational Equipment: Inspection of radars, GPS, and other devices;
* Communication Systems: Verification of radio stations and GMDSS systems. * Hull and Structural Inspections:
* Underwater Inspections: Regular checks of the hull below the waterline;
* Hull Thickness Measurements: To detect corrosion or damage. Technical inspections are essential for maintaining valid certificates and safe operation. Failure to comply may result in detention, fines, or loss of certificates. Detailed requirements are set by national regulations and international conventions, such as SOLAS, MARPOL, and STCW. The requirements for the railway sector are presented in Sections 3.1 and 3.2. The requirements for wheeled vehicles are much simpler; technical inspections are conducted once a year for both passenger cars and trucks. Based on the static determination of technical reviews in rail, which could be conducted simultaneously for different review levels, we conducted research to prepare a model for optimizing review planning. This type of problem does not play a crucial role in other modes of transport.