Summary
We propose to adopt a new airworthiness directive (AD) for certain Boeing Model 747-400 series airplanes. This proposed AD was prompted by reports of water leaking into electrical and electronic equipment in the main equipment center, which could result in an electrical short and potential loss of several functions essential for safe flight. This proposed AD would require modifying the floor panels, removing drains; installing floor supports, floor drain trough doublers, drain troughs, and drains; and sealing and taping the floor panels. We are proposing this AD to correct the unsafe condition on these products.