AMC 25.733(f) Tyre inflation pressure check

• ED Decision 2020/024/R found in: CS-25 Amdt 27 - Large Aeroplanes (Jan 2023)

AMC 25.733(f) Tyre inflation pressure check ED Decision 2020/024/R **1. General** ‘Minimum serviceable inflation pressure’ means a tyre inflation pressure specified by the aeroplane type certificate holder below which damage to the tyre, potentially leading to a tyre failure, may occur. In order to demonstrate compliance with [CS 25.733(f)](#_DxCrossRefBm1709821159), the applicant should use one, or a combination, of the following means: (a) Provide a task in the Instructions for Continued Airworthiness (ICA) that requires tyres inflation pressure checks to be performed at a suitable time interval, (b) Install a system that monitors the tyres inflation pressures and: (1) provides an alert to the flight crew, in compliance with [CS 25.1322](#_DxCrossRefBm1709821114), whenever a tyre inflation pressure is below the minimum serviceable inflation pressure, or (2) allows the tyres inflation pressures to be checked prior to the dispatch of the aeroplane, and a tyre inflation pressure check task is included in the Aeroplane Flight Manual (AFM) pre-flight procedures. **2. ICA Tyre inflation pressure check** A ‘suitable time interval’ is the maximum time interval between two consecutive tyre inflation pressure checks. Checks should be conducted daily in order to ensure that the elapsed clock time between two consecutive tyre inflation pressure checks does not exceed 48 hours. Time intervals longer than 48 hours may be used if they are substantiated and agreed by EASA. This substantiation should at least include an analysis of the expected loss of tyre pressure during operation, taking into account the environmental and operational factors, including the potential for pressure loss at a rate that exceeds the normal diffusion resulting from damage to or degradation of the tyre/wheel assembly. If available, statistical data related to pressure losses gathered from the service experience of aeroplanes equipped with equivalent wheel designs should also be used. The substantiation should be made in cooperation with the tyre manufacturer(s). In addition, the applicant may take credit from an installed system monitoring the tyre inflation pressures. **3. Tyre inflation pressure monitoring systems** If a system is installed, its development assurance level should be commensurate with the potential consequences of an alert not being provided, as well as with the consequences of false alerts. If the system includes the indication of tyre pressure levels, the consequence of a false indication should also be taken into account. The assessment of these consequences should include the effects of the failure of one or more tyres (including simultaneous tyre failures) that may be caused by the operation of the aeroplane with under‑inflated tyres. Instructions for Continued Airworthiness should be provided to ensure that the calibration of the tyre pressure monitoring system is maintained. [Amdt 25/26]