Rotorcraft Flight Manual — N2 Speed Avoidance Range Limitation — Amendment / Placard — Installation
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AI-generated summary of the official EASA document. Verify against the PDF before acting.
What to do
Operators must amend the applicable Rotorcraft Flight Manual or Supplement within 50 flight hours or 30 days after 22 December 2020, whichever occurs first, and inform all flight crews of the changes. Concurrently, a placard depicting the N2 speed avoidance range must be installed on the instrument panel in full view of both pilots. Continued operation must comply with these updated procedures.
Summary
EASA Airworthiness Directive 2020-0266 addresses a safety issue affecting Airbus Helicopters AS 355 E, F, F1, and F2 models equipped with Rolls-Royce Corporation 250-C20F engines. The directive mandates amendments to the Rotorcraft Flight Manual and installation of a placard to avoid a specific N2 turbine speed range that can cause fatigue failures in power turbine 3rd stage wheels. This AD aims to prevent engine power loss and potential helicopter control issues.
What changed
This new Airworthiness Directive introduces a limitation on the N2 turbine speed range to be avoided during flight operations. It requires updating the Normal Procedures section of the Rotorcraft Flight Manual or Supplement and installing a visible placard on the instrument panel to warn pilots of the restricted speed range. These measures are based on findings of fatigue failures linked to detrimental vibrations within the affected speed range.
Why it matters
The directive is critical for aviation professionals as it directly addresses a safety risk that could lead to engine failure and loss of helicopter control. Operators and maintenance organizations must ensure compliance to maintain airworthiness and prevent costly damage or accidents. The clear procedural updates and placard installation help flight crews avoid operating conditions that could cause component fatigue and failure.
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