AD 84-26-01
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | The Boeing Company | DC-9-11 | Airworthiness Directives; McDONNELL DOUGLAS DC-9-10, -20, -30, -40, -50, C-9 (Military) Series Airplanes |
| aircraft | The Boeing Company | DC-9-12 | Airworthiness Directives; McDONNELL DOUGLAS DC-9-10, -20, -30, -40, -50, C-9 (Military) Series Airplanes |
| aircraft | The Boeing Company | DC-9-13 | Airworthiness Directives; McDONNELL DOUGLAS DC-9-10, -20, -30, -40, -50, C-9 (Military) Series Airplanes |
| aircraft | The Boeing Company | DC-9-14 | Airworthiness Directives; McDONNELL DOUGLAS DC-9-10, -20, -30, -40, -50, C-9 (Military) Series Airplanes |
| aircraft | The Boeing Company | DC-9-15 | Airworthiness Directives; McDONNELL DOUGLAS DC-9-10, -20, -30, -40, -50, C-9 (Military) Series Airplanes |
| aircraft | The Boeing Company | DC-9-15F | Airworthiness Directives; McDONNELL DOUGLAS DC-9-10, -20, -30, -40, -50, C-9 (Military) Series Airplanes |
| aircraft | The Boeing Company | DC-9-21 | Airworthiness Directives; McDONNELL DOUGLAS DC-9-10, -20, -30, -40, -50, C-9 (Military) Series Airplanes |
| aircraft | The Boeing Company | DC-9-31 | Airworthiness Directives; McDONNELL DOUGLAS DC-9-10, -20, -30, -40, -50, C-9 (Military) Series Airplanes |
| aircraft | The Boeing Company | DC-9-32 | Airworthiness Directives; McDONNELL DOUGLAS DC-9-10, -20, -30, -40, -50, C-9 (Military) Series Airplanes |
| aircraft | The Boeing Company | DC-9-32 (VC-9C) | Airworthiness Directives; McDONNELL DOUGLAS DC-9-10, -20, -30, -40, -50, C-9 (Military) Series Airplanes |
Unsafe Condition
Cracks in the MLG attach fitting and its interrelated structure could lead to failure of the fitting.
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Required Actions
Inspect MLG attach fittings for cracks within specified landing intervals (3,600 or 1,800 additional landings) based on landing count. Repetitive inspections must be performed at 3,600 landing intervals until replaced or modified. If cracks are found, rework or replace the fitting before further flight. Preventative modification per SB 57-148, R1, or replacement constitutes terminating action.
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Compliance Time
Compliance is required as indicated, unless previously accomplished.
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Affected Aircraft
McDonnell Douglas Model DC-9-10, -20, -30, -40, -50, C-9 (Military) series airplanes with MLG attach fittings from forging alloy 7075-T73 and which have accomplished Option I of Service Bulletin 57-125, Revision 2 or prior issues.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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