What percentage of access covers or plates installed on MRG casings with fewer than 12 fasteners must be secured with a lockable cover?

The requirement that a percentage of access covers or plates installed on Main Reduction Gear (MRG) casings with fewer than 12 fasteners must be secured with a lockable cover stems from safety protocols designed to prevent unauthorized access and ensure operational integrity. Specifically, having 25 percent of these covers secured with a lockable mechanism serves as a balance between accessibility for maintenance and security against accidental or unauthorized openings.

This requirement enhances safety by ensuring that even if some covers are easily accessible due to the limited number of fasteners, a significant portion remains secure, minimizing potential risks associated with accidental exposure to sensitive components or systems. This focus on security and safety is essential in operational environments, particularly where heavy machinery operates.

The other options may not offer sufficient security or may impose unnecessary restrictions on maintenance processes, hence, 25 percent is the appropriate standard in aligning safety with accessibility.