AD 99-26-21
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | The Boeing Company | 737-300 Series | Airworthiness Directives; Boeing Model 737-300, -400, -500, -600, -700, and -800 Series Airplanes |
| aircraft | The Boeing Company | 737-400 Series | Airworthiness Directives; Boeing Model 737-300, -400, -500, -600, -700, and -800 Series Airplanes |
| aircraft | The Boeing Company | 737-500 Series | Airworthiness Directives; Boeing Model 737-300, -400, -500, -600, -700, and -800 Series Airplanes |
| aircraft | The Boeing Company | 737-600 Series | Airworthiness Directives; Boeing Model 737-300, -400, -500, -600, -700, and -800 Series Airplanes |
| aircraft | The Boeing Company | 737-700 Series | Airworthiness Directives; Boeing Model 737-300, -400, -500, -600, -700, and -800 Series Airplanes |
| aircraft | The Boeing Company | 737-800 Series | Airworthiness Directives; Boeing Model 737-300, -400, -500, -600, -700, and -800 Series Airplanes |
Unsafe Condition
Chafing between hydraulic case drain and pressure hoses could damage the hoses, causing hydraulic leaks and failure, while chafing between wire bundles W0334/W5230 and hydraulic hoses could damage components leading to electrical arcing and increased fire risk.
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Required Actions
Perform a one-time detailed visual inspection of wire bundles W0334/W5230 and hydraulic case drain/pressure hoses for the EMDP in hydraulic system B's right main wheel well. Correct discrepancies by repairing damaged wires, replacing hoses outside limits, adjusting support components, installing spacers/clamps for separation, and conducting required tests per Boeing service bulletins. Compliance must occur within 90 days of the effective date.
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Compliance Time
Within 90 days of the effective date
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Affected Aircraft
Boeing Model 737-300, -400, -500, -600, -700, and -800 series airplanes listed in specified Boeing Alert Service Bulletins.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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