The periodic maintenance and preservation procedures for the aircraft engines must be strictly followed to ensure technical integrity and long-term reliability. While active aircraft are normally required to undergo a routine engine ground run every 00 days, a specific preservation method has been established in accordance with the Service Bulletin for Piston Engine Preservation for aircraft with removed wings or those in non-operational status. Accordingly, for aircraft where wings are detached as well as for all non-operational aircraft, the propellers must be manually rotated for 00 full turns every 00 days to ensure internal lubrication and prevent corrosion. Conversely, for aircraft with wings fully installed and in operational condition, the standard 00-day engine ground run procedures must be continuously executed. It is highly recommended that the user in Country X adheres strictly to these bulletin directives to maintain the operational readiness and engine condition of the entire fleet.