Eaton 155S9-5D - Dust Plug Assembly for -4/-5 Coupling

The Eaton 155S9-5D Dust Plug Assembly is a protective closure designed for size -4 and -5 hose-attaching halves of the Aeroquip 145 and 155 Series self-sealing hydraulic quick-disconnect couplings. Engineered to keep dirt, moisture, and other contaminants out of disconnected coupling halves, this dust plug is an essential maintenance accessory for any aircraft hydraulic system that uses MIL-H-5606 or MIL-H-83282 petroleum-based hydraulic fluid.

Originally produced under the Aeroquip brand and now part of Eaton's Aerospace Group portfolio, the 155S9-5D is fully interchangeable with all fielded Aeroquip 145/155 Series hardware. The plug threads onto the coupling's union nut using the same quick-lead blunt-start thread engagement as the mating coupling halves, allowing technicians to install or remove it by hand with a simple turning motion — no tools required.

Key Features

• Sized for -4 and -5 145/155 Series self-sealing couplings
• Compatible with MIL-H-5606 and MIL-H-83282 petroleum-based hydraulic fluids
• Quick-lead blunt-start thread for hand installation and removal
• Protects internal coupling components from dust, debris, and moisture ingress
• Pairs with chain assembly 5100-S8 for tethered retention to the coupling half
• Fully interchangeable with fielded Eaton Aeroquip 145/155 Series hardware

Specifications

• Manufacturer: Eaton (Aeroquip Aerospace Group)
• Part Number: 155S9-5D
• Type: Dust Plug Assembly
• Coupling Series: 145/155 Series Self-Sealing
• Size: -4 / -5
• Fluid Compatibility: MIL-H-5606, MIL-H-83282 (Hydraulic)
• Skydrol Equivalent Part: 015567S9-5D (for phosphate-ester systems)
• Chain Assembly: 5100-S8 (sold separately)
• CAGE Code: 00624

Applications

The 155S9-5D dust plug is used across military and commercial aircraft hydraulic systems anywhere a -4 or -5 Aeroquip 145/155 Series self-sealing coupling needs protection during maintenance, ground handling, or storage. Common applications include hydraulic test stands, line servicing, hose assembly storage, and aircraft on ground (AOG) protection. MROs, FBOs, repair stations, and military maintenance shops rely on these dust plugs as standard consumable inventory to prevent costly hydraulic system contamination.