EASA AD CF-2021-36
Navigation — Head-up Display (HUD) and Synthetic Vision System (SVS) Misalignment
Summary
The Canadian Airworthiness Directive CF-2021-36 addresses a misalignment issue between the Head-up Display (HUD) and Synthetic Vision System (SVS) on Bombardier BD-700-2A12 aircraft with serial numbers 70006 to 70084. This directive mandates calibration of the HUD and updates to the Aircraft Flight Manual (AFM) to correct lateral offset errors observed during production. The directive aims to ensure accurate HUD and SVS alignment to maintain safe landing operations.
What Changed
CF-2021-36 introduces requirements to calibrate the HUD and integrate specific revisions into the AFM, prohibiting steep approach landings (SAL) and the use of the Enhanced Flight Vision System (EFVS) until calibration is completed. It also requires retroactive calibration measures for aircraft previously calibrated under earlier service bulletin revisions. These changes address mechanical misalignment discovered during manufacturing that affects HUD and SVS accuracy.
Why It Matters
This directive is critical for operators and maintenance personnel because uncorrected HUD misalignment can lead to incorrect aircraft position display, increasing the risk of excessive deviation during landing. This is especially important for operations involving steep approach procedures or EFVS use, where precise visual references are essential for safety. Compliance ensures continued airworthiness and operational safety of affected Bombardier BD-700-2A12 aircraft.
What To Do
Operators must update the AFM with approved revisions within 30 days of the directive's effective date and inform flight crews of the changes. HUD calibration must be completed within 27 months following the directive's effective date, following Bombardier service bulletins SB 700-34-7521 revision 3 and SB 700-34-7523 or later approved revisions. Aircraft previously calibrated under earlier revisions must perform retroactive calibration measures within the same 27-month period.
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