EASA AD US-2018-22-01
Engine - Second Stage Turbine Rotors - Removal
Summary
The Federal Aviation Administration's Airworthiness Directive 2018-22-01 addresses Honeywell International Inc. TPE331 turboprop engines, specifically models TPE331-8, -10, -10N, -10R, -10U, -10UA, -10UF, -10UG, -10UGR, -10UR, and -11U equipped with certain second stage turbine rotor assemblies. This directive mandates the removal of specific second stage turbine rotors at reduced life limits to prevent unsafe conditions. It was issued following reports of uncontained rotor separation and discovery of cracks in the turbine rotors.
What Changed
This AD supersedes the previous AD 88-12-10 by further reducing the life limits for certain second stage turbine rotors and requiring their removal from service according to a new schedule based on cycles since new. It introduces specific removal timelines for rotor part numbers 3102106-1, -6, -8 and 3101514-1, -10, -12, reflecting updated safety findings. The directive also clarifies compliance requirements and rejects requests to extend rotor service life beyond the new limits.
Why It Matters
This directive is critical for aviation professionals as it addresses a significant safety risk involving uncontained rotor failures that can cause engine and aircraft damage. Operators and maintenance organizations must comply to ensure continued airworthiness and prevent catastrophic engine events. The updated removal schedules require careful tracking of rotor cycles and timely maintenance actions to maintain compliance and safety.
What To Do
Affected operators must remove the specified second stage turbine rotors from service according to the detailed cycle-based schedules provided in the AD. Compliance must be achieved by the effective date of December 10, 2018, with removal deadlines varying based on the rotor's cycles since new. Operators should consult Honeywell Service Bulletins TPE331-72-A2319 and TPE331-72-A2310 for replacement procedures and ensure all maintenance records reflect compliance.
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