EASA SIB AIR-20-15: Boeing 787 Airplanes - Navigation Localizer System

What to do

Operators of Boeing 787-8, -9, and -10 airplanes should notify flight crews about the AFDS localizer capture issue and incorporate the procedures outlined in Boeing's Flight Crew Operations Manual Bulletin TBC-106 as soon as possible. They should monitor for Boeing's forthcoming software update to address the problem. No mandatory compliance deadline is specified, but early implementation of recommended actions is advised.

Summary

The Special Airworthiness Information Bulletin SAIB: AIR-20-15 is an FAA informational bulletin addressing a potential issue with the autopilot flight director system (AFDS) on Boeing 787-8, -9, and -10 airplanes. It warns that the AFDS may fail to properly capture the localizer during ILS approaches when intercepting at large angles, potentially leading to incorrect heading alignment. This bulletin provides background on the issue and references Boeing's Flight Crew Operations Manual Bulletin TBC-106 for guidance.

What changed

This bulletin introduces awareness of a specific AFDS failure mode on Boeing 787 models during ILS localizer capture at large intercept angles. It informs operators of the issue and Boeing's ongoing development of updated software to correct the erroneous localizer mode behavior. It also directs operators to Boeing's existing operational procedures to mitigate the risk.

Why it matters

This issue is critical for flight crews and operators because it can cause the airplane to deviate from the runway centerline during approach without any failure indication on the primary flight display. Understanding and mitigating this behavior is essential to maintain safe and accurate ILS approaches, preventing potential approach and landing hazards. Compliance teams and maintenance organizations need to be aware of the software update in development and operational guidance to ensure continued airworthiness and safety.