AD 2018-19-10
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Airbus | Helicopters Model AS355E | Airworthiness Directives; Airbus Helicopters |
Unsafe Condition
Degradation of a main gearbox (MGB) oil cooler fan assembly bearing, which could result in loss of MGB and engine oil cooling function, loss of the rear transmission, and subsequent loss of control of the helicopter.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Measure the tail rotor (T/R) drive vibration level without balancing the T/R drive, and record the amplitude value. Clean the oil cooler fan. Measure the T/R drive vibration level without balancing the T/R drive, and record the amplitude value. Calculate the difference between the two amplitude values. If the difference is greater than 0.75 inch per second (ips), before further flight, replace each oil cooler fan assembly bearing. After the effective date of this AD, do not install an oil cooler fan assembly bearing with more than 0 hours TIS unless the requirements of this AD have been accomplished.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Within 165 hours time-in-service (TIS)
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Affected Aircraft
Airbus Helicopters Model AS355E, AS355F, AS355F1, AS355F2, and AS355N helicopters, certificated in any category.
AI-generated summary from the source AD text. Verify against the official source before acting.
Source: Official FAA Source ↗
Retrieved: Apr 6, 2026
Rights: U.S. Government Public Domain
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