AD 90-21-15
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | The Boeing Company | 737-100 Series | Airworthiness Directives; BOEING Model 737 Series Airplanes |
| aircraft | The Boeing Company | 737-200 Series | Airworthiness Directives; BOEING Model 737 Series Airplanes |
| aircraft | The Boeing Company | 737-200C Series | Airworthiness Directives; BOEING Model 737 Series Airplanes |
| aircraft | The Boeing Company | 737-300 Series | Airworthiness Directives; BOEING Model 737 Series Airplanes |
| aircraft | The Boeing Company | 737-400 Series | Airworthiness Directives; BOEING Model 737 Series Airplanes |
| aircraft | The Boeing Company | 737-500 Series | Airworthiness Directives; BOEING Model 737 Series Airplanes |
| aircraft | The Boeing Company | 737-600 Series | Airworthiness Directives; BOEING Model 737 Series Airplanes |
| aircraft | The Boeing Company | 737-700 Series | Airworthiness Directives; BOEING Model 737 Series Airplanes |
| aircraft | The Boeing Company | 737-800 Series | Airworthiness Directives; BOEING Model 737 Series Airplanes |
Unsafe Condition
Cracking in the horizontal stabilizer center section rear spar upper chord near the beam gusset plates.
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Required Actions
Eddy current or dye penetrant inspect the upper surface of the forward flange of the horizontal stabilizer center section rear spar upper chord for cracks near each beam gusset plate. Repair, modify, or replace damaged chord before further flight if cracks are found. Resume repetitive inspections after repair, modification, or replacement as per specified landing intervals.
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Compliance Time
Prior to the accumulation of 35,000 landings, or within 350 landings after October 18, 1982, whichever occurs later, unless accomplished within the last 4,150 landings, and thereafter at intervals not to exceed 4,500 landings since the last inspection.
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Affected Aircraft
Boeing Model 737 series airplanes listed in Boeing Alert Service Bulletin 737-55A1031, Revision 2, dated November 30, 1989, certificated in any category.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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