AD 90-17-20
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
Failure of the 5/16-inch bolts attaching the forward support fitting of the inboard and outboard flap tracks of the outboard flap could result in loss of the outboard flap.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Within 250 hours time-in-service after the effective date, and every 1,000 hours thereafter, torque check the 5/16-inch bolts. Replace bolts that fail or do not sustain the torque check before further flight. Replace 5/16-inch bolts with 3/8-inch stainless steel bolts to terminate AD requirements.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Within the next 250 hours time-in-service after the effective date of this AD, unless already accomplished within the last 750 hours time-in-service, and thereafter at intervals not to exceed 1,000 hours time-in-service from the last inspection
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Model 737 series airplanes listed in Boeing Alert Service Bulletin 737-57A1079, Revision 4, dated May 10, 1990, certificated in any category.
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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