EASA SIB NM-12-25
Hawker Beechcraft 400/400A and Learjet 60 Aeroplanes — Rockwell Collins Altitude Awareness Panel 115VAC Power Transient Failures
Summary
The Special Airworthiness Information Bulletin SAIB: NM-12-25 is an FAA informational bulletin addressing 115VAC power transient failures in Rockwell Collins Altitude Awareness Panels installed on Hawker Beechcraft 400/400A and Learjet 60 airplanes. It informs operators about issues related to the AAP-850 and AAP-851 altitude awareness panels that may cause smoke in the cockpit due to a varistor protection device failure. The bulletin provides guidance but does not mandate corrective action.
What Changed
This bulletin introduces awareness of a power transient failure issue in specific Rockwell Collins altitude awareness panels and recommends compliance with Rockwell Collins Service Bulletin AAP-850/851-34-3 to replace the varistor with a de-rated protection device. It clarifies that the smoke produced is minimal and the loss of panel function does not compromise safe flight or landing. No airworthiness directive is issued as the condition is not deemed unsafe.
Why It Matters
This information is important for aviation professionals because it highlights a potential electrical failure that could cause smoke in the cockpit, which may concern flight crews and maintenance personnel. Understanding the issue helps operators and maintenance teams manage the risk without unnecessary grounding or regulatory burden. It ensures continued safe operation while addressing the root cause through recommended service bulletin compliance.
What To Do
Operators of Hawker Beechcraft 400/400A and Learjet 60 airplanes should review and follow the guidelines in Rockwell Collins Service Bulletin AAP-850/851-34-3 dated January 18, 2012, to remove and replace the varistor in affected altitude awareness panels. There is no mandatory compliance deadline, but timely action is recommended to mitigate the risk of power transient failures.