Boeing 747-400 Aeroplanes — External Power System Connector
- Published
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What to do
Owners and operators of Boeing 747-400 series airplanes are recommended to replace the external power connector safety guide P/N 66-9236 with the improved P/N MS17845-1. This replacement typically requires one person for one hour and does not require follow-on testing. Additionally, maintenance procedures should be reinforced to ensure proper ground power connection practices. No mandatory compliance deadline is specified.
Summary
The FAA Special Airworthiness Information Bulletin SAIB: NM-12-40 addresses an airworthiness concern for Boeing 747-400 series airplanes related to the external power system connector. The bulletin highlights issues caused by damage to the safety guide on the external power receptacle, which can lead to incorrect connection and electrical short circuits. This information bulletin provides guidance to operators to prevent damage and potential fire risks associated with ground power connections.
What changed
This bulletin introduces a recommendation to replace the existing external power connector safety guide with part number 66-9236, which is plastic and encloses the receptacle on three sides, with an improved safety guide having part number MS17845-1. The new guide features a metallic housing enclosed on all four sides, providing a tighter fit and stronger protection against misalignment. This change was implemented in production starting at line number 1334.
Why it matters
This issue matters because incorrect external power connections can cause electrical short circuits, leading to smoke, fire, and significant damage to the airplane's electrical systems and structure. Although there is no in-flight risk, the damage can result in extensive aircraft downtime and costly repairs, affecting operational efficiency and safety for ground personnel and passengers. Proper maintenance and replacement of the safety guide help mitigate these risks.
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