Trim tab actuators control small, secondary flight control surfaces that are attached to the trailing edge of a larger, primary control surface such as an elevator or rudder. These actuators commonly have a time-between-overhaul (TBO) of 1,000 hours or three years.
In this article, we’re going to dive into flight control systems, how trim tab actuators work, when to overhaul, insider tips for maintenance, and why it is important to send your aircraft parts to a certified repair station to ensure precision and correct operation.
What are Flight Control Systems?
A conventional aircraft flight control system consists of flight control surfaces, cockpit controls, connecting linkages, and the necessary operating systems to control the aircraft’s direction in flight. There are primary controls, like a control yoke, rudder pedals, and throttle controls, and there are secondary controls, like trim tab controls and flap actuator control. In this blog, we are going to discuss trim tab actuators.
Trim tabs are small, secondary flight control surfaces that are attached to the trailing edge of a larger, primary control surface such as an elevator or rudder. Simply put, they are used to “trim” the aerodynamic force on the control surface and stabilize the aircraft. Flaps are mounted on the trailing edges of the wings and are used to reduce take-off distance and landing distance. Flap actuators extend flaps giving more lift area, but also create drag. Learn more about flap actuators in our blog article.
How Does the Pitch Trim System Work?
According to the Aircraft Owners and Pilots Association (AOPA), the pitch trim system works together to move the trim tab actuator, which moves the trim tab up or down. The most common trim system found on single engine aircraft is elevator trim, that controls pitch. Larger aircraft have rudder and aileron trim systems, but we will focus on pitch trim in this article. Here is the process:
- The trim wheel in the cockpit is attached to a sprocket and a chain ride in the sprocket’s teeth.
- The chain is swaged to a long, woven stainless-steel cable that runs through pulleys and guides under the panel and cabin floor.
- This cable goes all the way back to the tailcone, where it makes a couple right-angle turns through two more pulleys.
- Finally, it’s swaged to another chain. When the sprocket turns, it moves the trim tab actuator, which moves the trim tab up or down.
Check out this illustration for a helpful visual of how each part works together⤵️
What Does it Mean to Trim Your Plane?
Trimming, according to AOPA, “allows the pilot to fine-tune a flight condition so that it can be maintained in hands-off flight.” There are several steps involved in trimming:
This involves lowering the pitch attitude until the rate of climb reads zero.
Set the Power
Throttle back the RPM or manifold pressure to the value that your performance chart recommends for the desired cruise airspeed.
Add and Adjust
Apply nose-down trim in small but sure increments until your hand pressure on the yoke or stick is no longer required.
Watch What Happens
Monitor your instruments for constant ASI and altitude.
Read more about each of these steps in the AOPA article.
Check out this helpful video for more information about how trim works⤵️
Components of a Trim Tab Actuator
The trim tab actuator consists of several components:
↪️ External screw
↪️ Internal screw
Follow the manufacturer’s recommended lubrication and TBO (time between overhaul) requirements to ensure your Trim Tab Actuators last longer. Ignoring lubrication and overhauls can cause internal parts to be damaged past point of repair, leading to expensive bills and long lead times. This condition also leads to excessive wear and damage to the airframe itself.
AAI Can Repair and Overhaul Your Cessna Aircraft Trim Tab Actuator
When it comes to your Cessna trim tab actuator overhaul, it is extremely important to send your parts to a certified repair station who will do more than just a shiny paint job. Ignoring lubrication and overhauls can cause internal parts to be damaged past the point of repair, leading to expensive bills and long lead times.
AAI manufactures parts in house, which keeps costs down and lead times low. Not only that, but we’ll offer accurate, transparent pricing with no surprises and provide an option for rapid exchange whenever possible.
When you send your Cessna trim tab actuator to AAI it will undergo very detailed steps during overhaul to ensure it works as intended until your next TBO. Here are the steps AAI performs on your trim tab actuators:
- Receive to verify part number and conformity
- Cleaning to remove all grease, dirt and paint
- Visual and dimensional inspection
- Replacement of all bearings, hardware and any rejected parts found during inspection
- Corrosion treatment to include primer/paint, alodine and metal plating
- Final assembly and testing
- 8130-3 certification
AAI Works on Several Cessna Models
AAI can help you with several different Cessna aircraft:
- Cessna 100 Series
- Cessna 200 Series
- Cessna 300 Series
- Cessna 400 Series
- Cessna 500 Series
Learn more about our services for Cessna aircraft here.
We make it easy for you to get the parts you need:
1. Call AAI
2. Get a quote
3. Fix your plane and fly