Flight Control System Maintenance: Trim Tab and Flap Actuators 

An Insider’s Guide to Airplane Parts and Maintenance – Part 3 


If you are an aircraft enthusiast with an interest in Beechcraft, Cessna, Citation, Piper, Cirrus, or Diamond aircraft, then you are in the right place. 

At AAI, we overhaul and exchange aircraft accessories (especially hard-to-find accessories) for these aircraft brands, which means we have an insider’s view that very few people in the entire world get to see. 

We get an up-close look at the wear and tear created by years of use and hours of flight time. We see the problem parts that are prone to failure, we see the high performing parts that rarely have issues, and we see everything in between. 

So, if you are an aircraft enthusiast (whether you own a private aircraft, are an aircraft mechanic, a pilot, or maybe just have dreams of flying someday) then you will find valuable information in our blog series, An Insider’s Guide to Airplane Parts and Maintenance

Here are all the articles in the series so far: 

Part 1 – Aircraft Fuel System Parts and Maintenance 

Part 2 – Aircraft Hydraulic System Parts and Maintenance  

Part 3 – Flight Control System Maintenance: Trim Tab and Flap Actuators (this article)

Be sure to subscribe to our Frequent Flyers Email Newsletter (sent monthly) so that you don’t miss any articles! 

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 and flap actuators.  
 
Trim tab actuators 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.   

Trim tab actuators commonly have a TBO of 1,000 hours or three years, and flap actuators are about the same. 

The Aircraft Owners and Pilots Association (AOPA) provides a great visual for the function of the trim tab.  
 

The AAI insider’s guide to trim tabs. 

Unfortunately, mechanics often don’t have the special tools or facilities to overhaul parts, which is where AAI comes in. It can be difficult to perform repairs in the field, and the smallest mistake can make a huge difference. The construction of these parts must be perfect; if the trim tab is too tight, the part can seize up midair. If it is too loose, the pilot can’t control the plane as precisely as they need to. AAI depends on mechanics to diagnose the problem so that your aircraft gets the right parts, and fast.  

With a tolerance from .004 to .010 inches (the thickness of a human hair!), trim tab actuators require detailed construction. AAI manufactures common replacement parts in-house to cut down on costs and simplify the supply chain. What does that mean for you? Shorter lead times and no sticker shock because replacing common worn parts is already built into the quote we give you.  

The AAI insider’s guide to flap actuators. 

Flap actuators adjust the flaps on an aircraft’s wings. It is used to reduce the stalling speed of an aircraft wing and is usually mounted on the wing trailing edges of a fixed-wing aircraft. Flap actuators have tight tolerances, high wear, commonly corrode, and are mostly mechanical. 

Like trim tab actuators, flap actuators are prone to high wear and corrosion, so maintaining them is crucial to avoid potential issues. 

Trim tab and flap actuators are prone to corrosion. 

When you’re at cruise speed, pressure and wear is inevitable. With trim tab and flap actuators, it is important that when you send your parts in to be overhauled, you’re getting more than just a pretty paint job.  

That’s where sacrificial coating comes in; it looks nice, but it is intended to protect. It can be removed and refinished to protect the base metal underneath. Because these details are important, AAI performs metal treatment, painting and manufactures commonly worn parts in-house to reduce costs and own the supply chain. AAI has also developed proprietary reconditioning processes, making your wait shorter and helping you avoid the headache that comes with ordering new parts.  

AAI provides FAA certified repairs on trim tab and flap actuators.

There’s no part too small when it comes to keeping your flight control systems maintained. Detailed, thorough, and expert work is required to get the job done the right way. At AAI, we know your ultimate goal is to get your plane fixed so you can fly. That’s why we go above and beyond to help you avoid extra costs by creating repairs and manufacturing the parts on your aircraft that are commonly worn, like trim tab and flap actuators. 

Do you have questions about AAI’s process or available parts? Check out our website or contact us for more information and be sure to sign up for our Frequent Flyers Email Newsletter to get our articles, updates about industry events, and links to our favorite online content delivered right to your inbox every month. 

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