AD 91-15-24
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | The Boeing Company | 747-100 Series | Airworthiness Directives; BOEING Model 747 Series Airplanes |
| aircraft | The Boeing Company | 747-100B Series | Airworthiness Directives; BOEING Model 747 Series Airplanes |
| aircraft | The Boeing Company | 747-100B SUD Series | Airworthiness Directives; BOEING Model 747 Series Airplanes |
| aircraft | The Boeing Company | 747-200B Series | Airworthiness Directives; BOEING Model 747 Series Airplanes |
| aircraft | The Boeing Company | 747-200C Series | Airworthiness Directives; BOEING Model 747 Series Airplanes |
| aircraft | The Boeing Company | 747-200F Series | Airworthiness Directives; BOEING Model 747 Series Airplanes |
| aircraft | The Boeing Company | 747-300 Series | Airworthiness Directives; BOEING Model 747 Series Airplanes |
| aircraft | The Boeing Company | 747-400 Series | Airworthiness Directives; BOEING Model 747 Series Airplanes |
| aircraft | The Boeing Company | 747-400D Series | Airworthiness Directives; BOEING Model 747 Series Airplanes |
| aircraft | The Boeing Company | 747-400F Series | Airworthiness Directives; BOEING Model 747 Series Airplanes |
Unsafe Condition
Failure of Auxiliary Power Unit (APU) pneumatic ducts could damage adjacent structure, pneumatic ducts, hydraulic lines, and/or electrical wiring.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Conduct penetrant inspections, proof pressure tests, and stress relieve APU pneumatic ducts per Boeing Service Bulletin 747-36-2081. Repair or replace ducts if cracks or ruptures are found. Replacement must follow SB 747-36-2081 or 747-36-2092.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Prior to the accumulation of 7,000 flight cycles, or within the next 3,000 flight cycles after the effective date of this AD, whichever occurs later.
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Affected Aircraft
Boeing Model 747 series airplanes with APU pneumatic ducts in body sections 44, 46, and 48 (line positions 2 through 720) and sections 44 and 48 (line positions 721 through 734).
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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