AD 91-21-13
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | The Boeing Company | 737-300 Series | Airworthiness Directives; BOEING Model 737-300, -400, and -500 Series Airplanes |
| aircraft | The Boeing Company | 737-400 Series | Airworthiness Directives; BOEING Model 737-300, -400, and -500 Series Airplanes |
| aircraft | The Boeing Company | 737-500 Series | Airworthiness Directives; BOEING Model 737-300, -400, and -500 Series Airplanes |
Unsafe Condition
Potential for cable separation due to the Number 2 engine throttle cable chafing against the right wing front spar bracket, and potential for Number 1 and Number 2 engine throttle control cable ratcheting feedback.
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Required Actions
Inspect the Number 2 engine throttle cable for wear near the right wing front spar station 124. Replace the cable before further flight if wear exceeds acceptable limits. Modify the engine throttle control cable system per Boeing Service Bulletin 737-76-1023 within 36 months after the AD's effective date. The modification terminates the repetitive inspections required by paragraphs A and B.
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Compliance Time
For Model 737-300 series: Prior to 300 flight hours after July 24, 1989, unless previously accomplished within previous 700 flight hours, then every 1,000 flight hours. For Model 737-400 series: Prior to 300 flight hours after November 27, 1989, unless previously accomplished within previous 700 flight hours, then every 1,000 flight hours. Modification required within 36 months after November 29, 1991.
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Affected Aircraft
Boeing Model 737-300, -400, and -500 series airplanes listed in Boeing Service Bulletin 737-76-1023 dated February 14, 1991.
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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