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Part# 05-26516
MFR Model# MCVAC299505-0102
OEM PNEligible Aircraft
Eligible Aircraft
(Series / Model)
MCVAC299505-0102Cessna172: I, K, L, M, F172M05-26516


Vernier-Assist for non-certified aircraft and an extended line of FAA-PMA approved controls, the breakthrough design is now approved on throttle controls for Cessna, Piper, Beechcraft, Grumman, and Bellanca.

McFarlane’s patented Vernier-Assist™ offers the pilot precision control of the engine, unlike anything else on the market! The Vernier-Assist assembly operates on friction alone by simply turning the knob, with no threads or locking balls/pins. It also allows for normal coarse movement by pushing in or out on the knob. Unlike standard threaded vernier controls, this design cannot be jammed. The friction control provides smoothness and precision when operating the throttle and a friction lock secures the control in position, but it can be easily overridden in the case of an emergency. It is SAFE!

These light weight controls use a patented roller action and do not use a positive lock thread engagement. Coarse adjustments are made by pushing the knob inwards or pulling the knob outwards. Fine adjustments are made by rotating the knob clockwise or counterclockwise. For extreme conduit routing or heavy carburetor load installation, slight inward or outward assist pressure could be required during rotation.
California Prop 65 Warning Symbol

WARNING: Cancer and Reproductive Harm -

Part Numbering Note

Part numbers for Vernier-Assist™ are the same as McFarlane's original push-pull FAA-PMA approved controls, except the "MC" prefix changes to "MCVA".
Part Numbering MCA: (add a A after the MC):
See examples below:
  • Standard Throttle: MC0411091-2
  • Vernier-Assist Throttle: MCVA041191-2
  • Standard Throttle: MCS1222-1S
  • Vernier-Assist Throttle: MCVAS1222-1S
  • Standard Throttle: MCC299505-0101
  • Vernier-Assist Throttle: MCVAC299505-0101


  • FAA-PMA Approved


  • Jam-proof safety
  • Precision power adjustments
  • Smooth friction control
  • Light and compact
  • Standard Vernier performance without the button!


Metal Contruction
  • Unlike the controls of McFarlane competitors that use plastic, McFarlane control fittings and components are made from stainless steel, plated steel, anodized aluminum, and brass. McFarlane Vernier control locking devices are precision formed and heat treated in critical wear areas.
A Superior Conduit System
  • McFarlane controls have low-friction smoothness and flexibility, even when routed with multiple tight bends. McFarlane conduits are made from carbon steel wire, specially formed for increased strength and smooth inside diameter. Two of these wires are coiled in tandem for increased tensile strength. A Teflon jacket extruded over the coiled housing provides additional strength and wear-resistance. A virgin Teflon® liner in the center of the conduit reduces friction and ensures reliable operation.
Knobs Make A Difference
  • McFarlane “pilot friendly” knobs are all compression molded from a reinforced phenolic or a reinforced melamine-phenol resin. Unlike the soft injection molded knobs of McFarlane competitors, McFarlane knobs are hard and thermally stable. They’re scratch-resistant and do not deteriorate. McFarlane knobs meet the latest F.A.R. requirements for shape and color.
Vibration Dampening Featues
  • McFarlane metal swivel joints have a unique Viton® rubber vibration dampening sleeve with a spring load system that dampens engine induced vibration in the push rod guide tube and metal swivel joint. Molded Viton® boots are also used on the push rod guides to seal out contaminates. The Viton® rubber withstands the high temperature of the engine environment while resisting degradation from oil and solvents. This system drastically reduces the wear that leads to premature control failure.
Special Lubrication
  • McFarlane controls have a special lifetime lubrication applied to critical sliding surfaces, made from a molybdenum disulfide and Teflon® based lubricant with a synthetic grease base. McFarlane lubricant will reduce friction and prevent galling and contamination locking of the control components from -70 deg F to over 1000 deg F.
Consistent Quality
  • The assembly of McFarlane engine controls is interrupted many times for inspections of all critical elements to ensure only the highest quality controls are produced. Each inner wire swage, each push rod, each conduit fitting and terminal is inspected by McFarlane assembly team. As a further measure of quality, a second inspector also checks each critical detail to make sure only controls of the highest quality pass inspection. Attention is given to every detail at McFarlane Aviation. For instance, we verify the torque required to operate every vernier control to ensure it operates properly and has that smooth feel McFarlane customers have come to expect.
Tough in an Enviornment
  • The McFarlane controls have an outstanding performance and reliability record in all environments; we test them in the harshest environments to ensure they will provide a long and reliable service life. Bush pilots prefer McFarlane controls because they work freely at 50 deg below zero and have proven solidarity in harsh salt-water. Temperatures approaching the melting point of the steel components cannot stop McFarlane controls from functioning.
Time Tested
  • With over 25 years of experience building aircraft engine controls and with thousands of units in airplanes flying on every continent (yes, even Antarctica), McFarlane controls are universally recognized for their high quality products and proven track record.
Recommended Service Life
  • Considering the operating environment and criticalness of engine controls, McFarlane maximum recommended in-service time for McFarlane engine controls is equal to the maximum time between engine overhauls, as recommended by the engine manufacturer.
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Please note, Aircraft Spruce's personnel are not certified aircraft mechanics and can only provide general support and ideas, which should not be relied upon or implemented in lieu of consulting an A&P or other qualified technician. Aircraft Spruce assumes no responsibility or liability for any issue or problem which may arise from any repair, modification or other work done from this knowledge base. Any product eligibility information provided here is based on general application guides and we recommend always referring to your specific aircraft parts manual, the parts manufacturer or consulting with a qualified mechanic.

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