AD 99-11-11
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Airbus Helicopters | AS-365N2 | Airworthiness Directives; Eurocopter France Model SA-365N, N1, N2, N3, and SA-366G1 Helicopters |
| aircraft | Airbus Helicopters | AS-365N3 | Airworthiness Directives; Eurocopter France Model SA-365N, N1, N2, N3, and SA-366G1 Helicopters |
| aircraft | Airbus Helicopters | SA-365N | Airworthiness Directives; Eurocopter France Model SA-365N, N1, N2, N3, and SA-366G1 Helicopters |
| aircraft | Airbus Helicopters | SA-365N1 | Airworthiness Directives; Eurocopter France Model SA-365N, N1, N2, N3, and SA-366G1 Helicopters |
| aircraft | Airbus Helicopters | SA-366G1 | Airworthiness Directives; Eurocopter France Model SA-365N, N1, N2, N3, and SA-366G1 Helicopters |
Unsafe Condition
Cracks in the main gearbox (MGB) planetary gear shaft could lead to failure of the MGB 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
Install a MGB planetary gear shaft vibration level monitoring unit (VLMU), revise the Rotorcraft Flight Manual (RFM) to include preflight vibration checks using the VLMU, emergency procedures for an inoperative VLMU, and limitations. If the VLMU is inoperative, inspect the MGB magnetic plug after every flight and oil filter daily (not exceeding 12 hours time-in-service between inspections).
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Within 25 hours time-in-service
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Affected Aircraft
Eurocopter France Model SA-365N, N1, N2, N3, and SA-366G1 helicopters with all variants of the MGB.
AI-generated summary from the source AD text. Verify against the official source before acting.
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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