P/N: MCS2550-8

All McFarlane PMA tachometer cable assemblies are manufactured as captive assemblies, meaning the inner core is secured with swaged terminals at both ends to prevent the core from being pulled out of the conduit. This design helps protect tachometers from damage and supports long-term reliability.

• Improved design over OEM
• Core withstands up to 3x the torsional load compared to OEM
• Thrust washers on both ends for longer life and smoother operation
• Captive assembly design prevents core pullout and tachometer damage
• Polymer-jacketed casing protects the core and improves durability
• McFarlane proprietary lubricant for smooth, consistent performance
• Left-lay core design matches OEM configuration

Common Tach Cable Failure Symptoms

Tach cables most commonly fail due to binding (seizing or jerking), caused by improper lubrication, contamination, sharp bends, kinks, conduit damage, or wear over time. Binding is often visible on the instrument panel as a jumpy or erratic tach needle and may worsen until the cable fails. There are specific instructions in the service manual for how to properly install the cable or troubleshoot any issues; visit our FAQs for more information or give our technical support team a phone call.

Why are the McFarlane Tach Cables Better? Our tach cable design has improved strength compared to the OEM. When testing torsional strength, our core exceeds the OEM core, which is exceptionally important with the functionality and reliability of the tach cable. Some may inquire about replacing the core of the tach cable only, rather than replacing the full assembly. When replacing the core only, your old casing will have wear, and sometimes the wear can be significant enough to prevent a brand-new c

with the old casing. Because of this, we do not offer replacement cores, and we highly recommend replacing your full tach cable assembly instead. Our full assemblies are an affordable alternative with better strength and reliability than a simple core replacement or a full assembly from the OEM.

Specifications

• Captive, pre-lubricated assembly
• Male ends only
• One end: 0.102" square
• Opposite end: keyed with 0.152" diameter
• 7/8-18 internal thread on one end
• 5/8-18 internal thread on the other end
• Left-lay core design (matches OEM)

Related Products

McFarlane also offers magnetos, alternators, starters, and additional engine accessory components to support your maintenance needs.

Installation Notes

Proper installation is critical for long service life. Tach cables should be routed as straight as possible from the tachometer through the firewall to the tach drive housing, with no sharp bends or kinks. Avoid bend radii smaller than six inches and avoid bends within three inches of either terminal. The tach cable should also be installed with the oil drain hole oriented downward to allow oil drainage if the tach drive housing seal fails. Refer to your aircraft service manual for specific torque requirements and routing guidance.