EASA AD 2017-0247-E
Main Rotor — Blades — Inspection / Replacement
Summary
EASA Airworthiness Directive 2017-0247-E is an emergency directive addressing inspection and replacement requirements for main rotor blades, specifically part number 369D21120-505, installed on all serial numbers of NH-500D helicopters. The directive mandates repetitive inspections of the abrasion strips on these blades to detect delamination or disbonding that could lead to significant vibration and potential loss of control. It applies to blades with a 1.25 inch chord length abrasion strip and outlines corrective and terminating actions to ensure continued airworthiness.
What Changed
EASA Airworthiness Directive 2017-0247-E supersedes the previous emergency AD 2016-0237-E and expands the inspection requirements to include all serial numbers of the affected main rotor blades. It removes the previous requirement to replace the abrasion strip with a stainless steel version as a mandatory modification and instead focuses on repetitive inspections and conditional replacement based on findings. The directive also incorporates updated service bulletin revisions from the manufacturers.
Why It Matters
This directive is critical for operators and maintenance organizations of NH-500D helicopters to prevent in-flight loss of the abrasion strip on main rotor blades, which can cause severe vibrations and compromise flight safety. Compliance ensures the structural integrity of the rotor blades and reduces the risk of accidents related to blade failure. It also provides clear guidance on inspection intervals and corrective actions, aiding maintenance planning and regulatory compliance.
What To Do
Operators must inspect the abrasion strips of all affected main rotor blades before the next flight after the effective date or after installation, and then at intervals not exceeding five flight hours or daily inspections, whichever occurs first. If any discrepancies are found, the affected blade must be replaced before further flight. Terminating action includes either accumulating 700 flight hours without defects or replacing all affected blades with modified parts. Installation of affected blades is permitted only if inspections are performed as required.
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