AD 81-22-51
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | The Boeing Company | 747-100 Series | BOEING Model 747 Series Airplanes |
| aircraft | The Boeing Company | 747-100B Series | BOEING Model 747 Series Airplanes |
| aircraft | The Boeing Company | 747-100B SUD Series | BOEING Model 747 Series Airplanes |
| aircraft | The Boeing Company | 747-200B Series | BOEING Model 747 Series Airplanes |
| aircraft | The Boeing Company | 747-200C Series | BOEING Model 747 Series Airplanes |
| aircraft | The Boeing Company | 747-200F Series | BOEING Model 747 Series Airplanes |
| aircraft | The Boeing Company | 747-300 Series | BOEING Model 747 Series Airplanes |
| aircraft | The Boeing Company | 747-400 Series | BOEING Model 747 Series Airplanes |
| aircraft | The Boeing Company | 747-400D Series | BOEING Model 747 Series Airplanes |
| aircraft | The Boeing Company | 747-400F Series | BOEING Model 747 Series Airplanes |
Unsafe Condition
Failure of the Airborne Vibration Monitor (AVM) system or engine oil system could lead to engine failure or other engine malfunction without timely crew awareness.
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Required Actions
Revise the Airplane Flight Manual (AFM) to include AVM system operational requirements and emergency procedures, install an amber repeater light for vibration meter alarm lights within 60 days, and perform specified maintenance actions on engines after specific AVM or oil indications.
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Compliance Time
Within 25 hours time in service after the receipt of this AD, or within 3 calendar days, whichever occurs later for AFM revision; within 60 days calendar time after effective date for installing the repeater light.
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Affected Aircraft
Boeing Model 747 series airplanes with Rolls Royce RB.211 engines, including 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, and other 747-200 series models.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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