AD 2021-22-16
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Airbus | Helicopters Model EC 155B and EC155B1 | Airworthiness Directives; Airbus Helicopters |
Unsafe Condition
Failure of a main gearbox (MGB) second stage planet gear, which could result in failure of a MGB planet gear assembly, failure of the MGB, and subsequent loss of helicopter control.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Replacing the MGB, or as an alternative, replacing the epicyclic reduction gear module for certain serial numbered planet gear assemblies installed on the MGB. Inspecting the MGB magnetic plugs and MGB filter for particles, and for certain serial-numbered planet gear assemblies, inspecting the oil sump for particles. Depending on the outcome of these inspections, further inspections and replacing certain parts may be required.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Within 10 hours time-in-service (TIS) after the effective date of the AD and thereafter at intervals not to exceed 10 hours TIS, inspecting the MGB magnetic plugs for particles. Within 25 hours TIS after the effective date of the AD, inspecting the MGB filter for particles. Within 50 hours TIS after the effective date of the AD, replacing the MGB. As an alternative to replacing the MGB, replacing the epicyclic reduction gear in the affected MGB.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Airbus Helicopters Model EC 155B and EC155B1 helicopters with at least one Type Y planet gear assembly with a certain serial number installed, or at least one Type Z planet gear assembly with a certain serial number installed.
AI-generated summary from the source AD text. Verify against the official source before acting.
Source: Official FAA Source ↗
Retrieved: Apr 4, 2026
Rights: U.S. Government Public Domain
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