101-380024-1 - Textron Aviation OEM Preload Indicated Washer Assembly

101-380024-1 – Textron Aviation OEM Preload Indicated Washer Assembly

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Overview

The Textron Aviation 101-380024-1 is a flight-critical, OEM Preload Indicating (PLI) washer assembly, an advanced structural fastener component for the propeller mounting systems of the Beechcraft King Air series. This is not a standard washer; it is a sophisticated, single-use mechanical force indicator, also known as a Direct Tension Indicating (DTI) or "squish" washer. The sole purpose of the 101-380024-1 is to provide a simple, yet highly accurate, visual and tactile method of verifying that the propeller mounting bolts have been tensioned to the correct preload. Its use is fundamental to the safety and integrity of the propeller installation.

Manufactured to Textron's exacting specifications, this washer assembly ensures that the critical clamp load, which is essential for preventing propeller movement and bolt fatigue, is achieved and verified during installation.

Key Features

• Direct Tension Indication: The washer is engineered with precisely machined protrusions on one face. As the mounting bolt is tightened, these protrusions are compressed or "squished." The mechanic uses a feeler gauge to measure the remaining gap, which directly corresponds to the tension (preload) in the bolt, providing a direct measurement of clamp load rather than an indirect one from torque.

• Ensures Accurate Preload: Provides a more accurate method of achieving the correct clamp load than relying on torque wrenches alone, as it is not affected by variables like thread friction or lubrication. This is critical for the propeller-to-engine flange joint.

• Single-Use for Guaranteed Accuracy: This is a mandatory single-use component. The controlled deformation of the washer is a permanent, one-time event. Reusing the washer will result in a dangerously inaccurate preload reading.

• High-Strength, Hardened Steel: Fabricated from a high-strength, heat-treated steel alloy. This ensures the washer body can withstand the immense clamp loads while the indicator protrusions deform in a predictable and repeatable manner.

• Genuine Textron OEM Part: As a genuine factory component, it guarantees the correct material composition, heat treatment, and precisely engineered deformation characteristics required for this flight-critical safety application.

Technical Specifications

• Part Number: 101-380024-1

• Component Type: Preload Indicating (PLI) / Direct Tension Indicating (DTI) Washer

• Material: High-Strength, Heat-Treated Steel Alloy

• Primary Function: Provides a verifiable indication of correct bolt tension/preload.

• Installation: Used under the head of a propeller mounting bolt. Requires a feeler gauge for inspection.

• Serviceability: Single-use only; must be replaced if the bolt is ever loosened.

• Certification: FAA Production Approval

Aircraft Compatibility

The 101-380024-1 is the specified OEM PLI washer for the propeller installations on the highly successful Beechcraft King Air family of turboprop aircraft.

• Primary Aircraft Models:

  • Beechcraft King Air: 90, 100, 200, 300/350 Series

Applications

The 101-380024-1 has a singular, flight-critical application:

• Propeller Installation: The essential component for ensuring that the propeller mounting bolts have been tightened to the precise preload specified by the manufacturer, which is critical for preventing catastrophic failure of the propeller attachment.

Why Choose 101-380024-1?

The joint between the propeller and the engine is subjected to the full thrust of the engine, immense centrifugal forces, and complex vibratory loads. A failure of any component in this joint would be catastrophic. The Textron Aviation 101-380024-1 is the only component certified by the manufacturer to verify the most critical factor in this joint's integrity—the bolt preload. For a component this vital to safety, there is no substitute for a genuine, fully traceable OEM part.

The Textron 101-380024-1 is an application of Hooke's Law and material plasticity. A bolted joint's integrity comes from stretching the bolt like a very stiff spring, which creates a powerful clamping force (preload). A torque wrench provides an indirect and often inaccurate estimation of this preload due to friction variables. The PLI washer provides a direct measurement. The protrusions on the washer are designed to deform plastically (squish) at a specific compressive load, which is directly related to the tensile load (stretch) in the bolt. The installation procedure involves tightening the bolt while periodically checking the gap under the washer with a feeler gauge. When the gap is reduced to a specific, specified dimension (e.g., 0.006 inches), the mechanic knows that the bolt has been stretched to its target preload, regardless of the torque required to get there. This provides a far more accurate and reliable method for a joint where the correct preload is a matter of flight safety.

Note: This is a single-use, flight-critical structural component. It must be installed by a certified A&P or AME mechanic with experience in King Air propeller systems, in strict accordance with the current Textron Aviation (Beechcraft) maintenance manual. A calibrated torque wrench and a feeler gauge are required for proper installation. The washer must be replaced any time the propeller is removed.