Broken Aileron Cable and Non-reversible Filtering of Control Position Data for Flight Data Recording
- Published
AI-generated summary of the official EASA document. Verify against the PDF before acting.
What to do
Operators of DHC-8-401 and DHC-8-402 aeroplanes should retrofit aileron and spoiler cables with wear protection as per Service Bulletin 84-27-68 Revision C or later. For aircraft with serial numbers below 4472 lacking the flight signal conditioning unit part number 1152862-5, operators should embody Service Bulletin 84-31-65 Revision B or replace the existing unit with the specified part number following the Aircraft Maintenance Manual and illustrated parts catalogue instructions. No mandatory compliance deadlines are specified.
Summary
EASA Safety Information Bulletin 2023-02 is an airworthiness bulletin addressing issues related to broken aileron cables and non-reversible filtering of control position data for flight data recording on De Havilland Aircraft of Canada Ltd. DHC-8-401 and DHC-8-402 aeroplanes. The bulletin highlights an incident involving a broken lower left aileron cable and discusses the impact of filtering on flight data recorder accuracy. It also references relevant Bombardier/De Havilland service bulletins and operator messages related to cable wear protection and flight data recording system updates.
What changed
This bulletin provides updated information on the susceptibility of aileron cables to premature wear and the introduction of modified cables with polymer sleeves and pulleys to reduce wear. It also clarifies that certain flight data recorder systems apply non-reversible filtering to control input data, which affects the accuracy of recorded control positions. The bulletin recommends retrofit actions for affected aircraft but does not mandate regulatory changes or airworthiness directives.
Why it matters
The information is important for operators and maintenance organizations to prevent potential flight control issues caused by worn or broken aileron cables, which could affect flight safety. Understanding the limitations of filtered flight data recorder parameters helps investigators and operators accurately interpret flight control inputs during incidents. Compliance with recommended retrofits can enhance aircraft reliability and data integrity without immediate regulatory enforcement.
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