AD 84-02-05
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 to maintain specified minimum N1 engine rpm during icing conditions could result in engine surge, flameout, or foreign object damage due to ingestion of ice or slush. Improper operation of the nacelle anti-ice system in icing conditions may lead to ice accretion on engines, nacelles, or engine sensor probes, impairing engine performance or reliability.
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Required Actions
Revise the AFM Certificate Limitations Section to specify minimum N1 rpm requirements for icing conditions within 120 days. Install a LOW N1 caution indication system within 24 months to alert crews if N1 falls below required levels. Use approved Boeing Service Bulletins for installation.
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Compliance Time
Within 120 days from the effective date of this AD for AFM revision; within 24 months from the effective date for LOW N1 indication installation.
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Affected Aircraft
Boeing Model 747 series airplanes certificated in all categories, 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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