EASA AD G-2022-0005
Navigation — Inertial Reference Units Magnetic Variation - Inspection
Summary
UK Civil Aviation Authority Airworthiness Directive G-2022-0005 is a regulatory document addressing the inspection of magnetic variation data in Honeywell Inertial Reference Units (IRUs) installed on all models and serial numbers of AVRO 146-RJ aeroplanes. The directive focuses on IRUs with part numbers HG2001BC02 and HG2001BC04, which use outdated magnetic variation lookup tables from 1990 and 1995 respectively. It mandates assessment and updating of magnetic variation data to ensure navigation accuracy.
What Changed
This new Airworthiness Directive introduces mandatory assessments of the magnetic variation data tables in the affected IRUs to verify their accuracy against the current World Magnetic Model. It requires operators to take specific actions if the difference exceeds 2 degrees, including operational restrictions and amendments to the Minimum Equipment List (MEL). The directive also mandates providing flight crews with procedures for operating in areas with significant magnetic variation.
Why It Matters
This directive is critical for aviation professionals because outdated magnetic variation data can lead to inaccurate heading and navigation calculations, increasing the risk of controlled flight into terrain or collisions, especially when compass navigation is used and terrain awareness systems are inoperative. Operators and maintenance teams must ensure compliance to maintain safe navigation and avoid operational restrictions. Compliance also supports regulatory adherence and flight safety.
What To Do
Operators of AVRO 146-RJ aeroplanes equipped with the specified Honeywell IRUs must assess the accuracy of the installed magnetic variation data within three months of the effective date and subsequently at intervals not exceeding five years or upon issuance of a new World Magnetic Model. If the variation difference exceeds 2 degrees, operators must prohibit flight in affected areas without serviceable TAWS and TCAS, amend the MEL accordingly, and provide flight crews with approved procedures for handling significant magnetic variation. These actions must be completed by 10 June 2022, three months after the effective date of 10 March 2022.
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