The retaining nut threads onto the threaded section of the control on the back side of the instrument panel to secure the control. Replacement retaining lock washer p/n EC111 for all McFarlane controls that attach to the instrument panel with a 1/2-20 thread.
- FAA-PMA (Sub-Component of Approved Article) Approved
- Manufactured by McFarlane Aviation, Inc.

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553-256 Piper Bolt, FAA-TC Approved | 553256 