AD 99-08-10
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | The Boeing Company | 747-100 Series | Airworthiness Directives; Boeing Model 747-100, -200, -300, -SP, and -400F Series Airplanes |
| aircraft | The Boeing Company | 747-100B Series | Airworthiness Directives; Boeing Model 747-100, -200, -300, -SP, and -400F Series Airplanes |
| aircraft | The Boeing Company | 747-100B SUD Series | Airworthiness Directives; Boeing Model 747-100, -200, -300, -SP, and -400F Series Airplanes |
| aircraft | The Boeing Company | 747-200B Series | Airworthiness Directives; Boeing Model 747-100, -200, -300, -SP, and -400F Series Airplanes |
| aircraft | The Boeing Company | 747-200C Series | Airworthiness Directives; Boeing Model 747-100, -200, -300, -SP, and -400F Series Airplanes |
| aircraft | The Boeing Company | 747-200F Series | Airworthiness Directives; Boeing Model 747-100, -200, -300, -SP, and -400F Series Airplanes |
| aircraft | The Boeing Company | 747-300 Series | Airworthiness Directives; Boeing Model 747-100, -200, -300, -SP, and -400F Series Airplanes |
| aircraft | The Boeing Company | 747-400F Series | Airworthiness Directives; Boeing Model 747-100, -200, -300, -SP, and -400F Series Airplanes |
| aircraft | The Boeing Company | 747SP Series | Airworthiness Directives; Boeing Model 747-100, -200, -300, -SP, and -400F Series Airplanes |
Unsafe Condition
Damage to airframes and property on the ground caused by 'blue ice' forming from leaking lavatory drain systems and dislodging from the airplane fuselage.
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Required Actions
Conduct repetitive leak tests of the lavatory drain system and repair as necessary. Install a cap or flush/fill line ball valve on the flush/fill line. Perform periodic seal changes. Replace any 'donut' type valves in the waste drain system.
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Compliance Time
Within 50 flight hours after May 17, 1999, or at the next scheduled maintenance, whichever occurs later.
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Affected Aircraft
Boeing Model 747-100, -200, -300, -SP, and -400F series airplanes.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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