AD 66-23-01
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | The Boeing Company | 727-100 Series | BOEING Model 727 Series Airplanes |
| aircraft | The Boeing Company | 727-100C Series | BOEING Model 727 Series Airplanes |
| aircraft | The Boeing Company | 727-200 Series | BOEING Model 727 Series Airplanes |
| aircraft | The Boeing Company | 727-200F Series | BOEING Model 727 Series Airplanes |
| aircraft | The Boeing Company | 727 Series | BOEING Model 727 Series Airplanes |
| aircraft | The Boeing Company | 727C Series | BOEING Model 727 Series Airplanes |
Unsafe Condition
B-nuts at the engine firewall, specifically part number NAS596, are susceptible to cracking due to being manufactured by AFCO (Aircraft Fitting, Inc.).
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Required Actions
Inspect the engine fuel feed system B-nuts using a 10-power glass, dye penetrant, or ultrasonic method. If cracks are found, replace the fuel line tube assembly with a new part per Boeing Service Bulletin 28-25. Repeat inspections every 600 hours' time in service until AFCO B-nuts are replaced within 3,000 hours' time in service after the AD's effective date.
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Compliance Time
Within the next 600 hours' time in service after the effective date of this AD
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Affected Aircraft
Boeing Model 727 Series airplanes listed in Boeing Service Bulletin 28-25, Revision 1, dated January 19, 1966.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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