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DAS2138-2 – Meggitt ABS Hydraulic O-Ring Seal
Part Number: DAS2138-2
Manufacturer: Meggitt Aircraft Braking Systems (MABS / Parker Meggitt)
Common Synonyms: Brake Piston Seal, Hydraulic Packing, MABS O-Ring
Overview Section
The DAS2138-2 is a high-specification OEM Hydraulic O-Ring engineered specifically for the wheel and brake assemblies of high-performance business and regional aircraft. Manufactured by Meggitt Aircraft Braking Systems, this component is a critical element in the hydraulic actuator (piston) assembly of the main landing gear brakes.
As a primary seal, the DAS2138-2 is designed to contain hydraulic pressures exceeding 3,000 PSI while facilitating the rapid reciprocating movement required for modern antiskid systems. It is typically paired with a DAS2100 series backup ring to prevent extrusion and ensure a leak-free interface during the high-thermal energy events of a landing roll.
Enhanced Technical Data
| Technical Metric | Specification Data |
| Material Compound | Nitrile (NBR) / Specialized High-Modulus Elastomer |
| Durometer (Hardness) | 80–90 Shore A (Optimized for high-pressure retention) |
| Inside Diameter (ID) | 0.489 in (Nominal) |
| Cross-Section (CS) | 0.070 in (Nominal) |
| Operating Pressure | Rated for high-pressure aviation circuits (3,000+ PSI) |
| Service Temperature | $-65°F$ to $+275°F$ ($-54°C$ to $+135°C$) |
| Fluid Compatibility | MIL-PRF-5606 and MIL-PRF-83282 |
| Shelf Life | 84 Months (7 Years) from Cure Date |
| ATA Chapter | ATA 32 (Landing Gear - Wheels and Brakes) |
Advanced Engineering & Structural Application
The DAS2138-2 is engineered for Dynamic Sealing Integrity. Unlike static airframe seals, a brake piston seal must maintain its "squeeze" while the piston moves forward to apply the brake and retracts to release it.
Engineering Insight: Resistance to Compression Set
In a landing gear environment, seals are subjected to "cold soak" during high-altitude cruise and extreme heat during braking. The DAS2138-2 is formulated with a high resistance to Compression Set. This ensures that the O-ring does not remain permanently flattened after a long flight, which would allow fluid to "weep" or bypass the seal when the brakes are first applied upon landing.
Friction and Wear Performance
The surface of the DAS2138-2 is engineered to have a controlled coefficient of friction. In a Meggitt antiskid system, the piston must move with near-zero latency. This seal provides the necessary elasticity to allow for "piston return" (the slight retraction of the brake pads) without sticking to the cylinder wall.
Aircraft Compatibility
The DAS2138-2 is a proprietary component for Meggitt-equipped braking systems:
Hawker 800/800XP/850XP/900XP: Found in the main gear brake piston housings.
Beechcraft Premier I/IA: A standard seal in the hydraulic braking circuit.
Regional Aircraft: Utilized in various commuter aircraft using Meggitt ABS technology (verify by serial number in the IPC).
The Meggitt DAS2138-2 is the industry standard for maintaining the hydraulic precision of your aircraft's braking system. Engineering a safe stop begins with the smallest components; this OEM O-ring ensures that your hydraulic system maintains the necessary pressure for effective braking and antiskid performance. With a verified 84-month shelf life and full compliance with Meggitt ABS engineering standards, the DAS2138-2 provides the reliability required for corporate and charter operations. Don't risk your braking performance with generic seals—trust the precision of Meggitt OEM hardware.
Installation & Maintenance Addendum
Cure Date Verification: Always check the Cure Date on the sealed packaging. Do not install DAS2138-2 seals that have exceeded their 84-month shelf life.
Anti-Spiral Lube: Apply a thin layer of clean MIL-PRF-5606 hydraulic fluid to the seal before installation. This prevents "spiral failure" (twisting of the O-ring) as the piston is pressed into the brake housing.
Gland Inspection: Inspect the brake piston bore for microscopic scoring. A damaged bore will "nibble" the surface of a new DAS2138-2, leading to a slow hydraulic leak.
