AD 99-21-07
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | The Boeing Company | DC-9-11 | Airworthiness Directives; McDonnell Douglas Model DC-9, DC-9-80, and C-9 (Military) Series Airplanes, and Model MD-88 Airplanes |
| aircraft | The Boeing Company | DC-9-12 | Airworthiness Directives; McDonnell Douglas Model DC-9, DC-9-80, and C-9 (Military) Series Airplanes, and Model MD-88 Airplanes |
| aircraft | The Boeing Company | DC-9-13 | Airworthiness Directives; McDonnell Douglas Model DC-9, DC-9-80, and C-9 (Military) Series Airplanes, and Model MD-88 Airplanes |
| aircraft | The Boeing Company | DC-9-14 | Airworthiness Directives; McDonnell Douglas Model DC-9, DC-9-80, and C-9 (Military) Series Airplanes, and Model MD-88 Airplanes |
| aircraft | The Boeing Company | DC-9-15 | Airworthiness Directives; McDonnell Douglas Model DC-9, DC-9-80, and C-9 (Military) Series Airplanes, and Model MD-88 Airplanes |
| aircraft | The Boeing Company | DC-9-15F | Airworthiness Directives; McDonnell Douglas Model DC-9, DC-9-80, and C-9 (Military) Series Airplanes, and Model MD-88 Airplanes |
| aircraft | The Boeing Company | DC-9-21 | Airworthiness Directives; McDonnell Douglas Model DC-9, DC-9-80, and C-9 (Military) Series Airplanes, and Model MD-88 Airplanes |
| aircraft | The Boeing Company | DC-9-31 | Airworthiness Directives; McDonnell Douglas Model DC-9, DC-9-80, and C-9 (Military) Series Airplanes, and Model MD-88 Airplanes |
| aircraft | The Boeing Company | DC-9-32 | Airworthiness Directives; McDonnell Douglas Model DC-9, DC-9-80, and C-9 (Military) Series Airplanes, and Model MD-88 Airplanes |
| aircraft | The Boeing Company | DC-9-32 (VC-9C) | Airworthiness Directives; McDonnell Douglas Model DC-9, DC-9-80, and C-9 (Military) Series Airplanes, and Model MD-88 Airplanes |
Unsafe Condition
Failure of the hydraulic damper assemblies of the main landing gear (MLG), due to insufficient material thickness of the spring retainers, could result in vibration damage and collapse of the MLG.
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Required Actions
Modify the MLG hydraulic damper assemblies by removing shims, increasing bolt torque, and incorporating changes to increase fluid volume between damper chambers, or replace the assemblies with modified and reidentified units. Actions must be completed within specified timeframes based on prior compliance with superseded ADs.
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Compliance Time
Varies based on prior AD compliance: within 9, 24, or 36 months from effective dates of superseded ADs, or as indicated if previously done.
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Affected Aircraft
McDonnell Douglas Model DC-9, DC-9-80, C-9 (military) series, and MD-88 airplanes listed in specific service bulletins (MD80-32-276, MD80-32-278, DC9-32-289).
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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