AD 83-21-02 R1
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 trailing edge flap tracks due to cracks or corrosion penetration through the track web.
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Required Actions
Inspect the external surface of trailing edge flap tracks for cracks or corrosion penetration at intervals specified in Table I. Replace cracked tracks before further flight. Modify tracks by drilling drain holes within 500 landings or six months, whichever comes first. Perform internal borescope inspections and X-ray evaluations for corrosion. Apply corrosion inhibitor every 6 months. Adjust inspection intervals with FAA approval based on operator data.
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Compliance Time
Accomplish initial inspections after the effective date of this AD, with repetitive intervals not exceeding those in Table I. Modifications under paragraph D must be done within 500 landings or six months after the effective date, whichever occurs first. Compliance with other actions as specified in each paragraph's timing requirements.
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Affected Aircraft
Boeing Model 747 series airplanes certificated in categories listed in Boeing Alert Service Bulletin 747-57A2225, Revision 1, or later FAA-approved revision, 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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