Tag Archives: turbine engine overhaul

General Information about Aircraft Engine Overhaul

There are variables which can alter the TBO for an aircraft engine.


TBO (Time Between Overhauls) is determined by the manufacturer of the engine.  It is meant to suggest the service life between overhauls when flown at a minimum interval (40 hours per month for one manufacturer).  Aircraft power plants love to fly, the purpose for which they are built. If they are used less frequently than this suggested interval, they will become prone to moisture build up and corrosives in the oil, shortening the service life of the motor when not brought to operating temperature on a regular basis.  Also, some engines will be exposed to extreme conditions that should be taken into account.  Life for an engine operating primarily in dry, dusty conditions, near salt water, in varied climates or any combination of these is subject to extra wear.  There is a reason planes don’t come with roadside assistance. It’s the same reason to adhere to the TBO.

The reason for aircraft engine overhaul isn’t necessarily to prevent cataclysmic failure of the power plant.


An engine is built to tolerances.  When it is “fresh,” such as when new or after an overhaul, the tolerances are very close.  Normal wear on the metal parts causes these tolerances to widen.  There is a point in the design of the motor where the tolerances increase and performance is affected.  When this happens oil consumption can increase, power can decrease and the risk of failure of an engine component increases.  Overhaul is as much about inspection of the engine parts as it is about repair or replacement and this cannot be done during any other time of aircraft maintenance.  Inspection of the components and their interactions can play a major role in the diagnosis of a problem before it causes failure.  Inspection is the most precise and important part of an overhaul and cannot be performed in a careless manner.

What is entailed in an aircraft engine overhaul.

The term “engine overhaul” means the process of maintaining and restoring equipment, machines or systems to serviceable conditions.  This involves the disassembly, inspection to detect damaged, defective or worn parts, the repair or replacement of these parts and the reassembly, testing and trial-run prior to the return to its full operating level.  There are two types of overhaul: major or top overhaul.

What is performed in a major overhaul?

In a major overhaul, the engine is completely disassembled.  Every part is inspected, repaired as necessary, reassembled, tested and approved for return to service within the fits and limits specified by the manufacturer’s overhaul data.  This could be a return to the fits and limits of new, or to serviceable limits.

What is performed in a top overhaul.

The top overhaul consists of repairs to parts outside of the crankcase.  This can be accomplished without the complete disassembly of the engine.  It can include the removal, inspection and repair of cylinders, inspection and repair of cylinder walls, pistons, valve-operation mechanisms, valve guides, valve seats and the replacement of pistons and piston rings.  Reassembly and testing follow this to ensure that the return to service life is trouble-free.

The TBO is more than just a suggestion.

The life of aircraft engines isn’t easy.  There are many factors that come into play when determining the serviceable life.  The metals inside go through a great deal of heating and cooling cycles due to the internal combustion process as well as the cool-down period after flight.  Metals begin to degrade over time due to these cycles.  Metal-to-metal wear due to improper lubrication and during start up (running the short time before lubrication can make it to the parts) take a toll on the engine.  The very design of an engine is to allow for expansion to tolerances after operating temperature range has been achieved. This means that until this range is reached, the tolerances are operating at less than optimal, which allows extra wear to occur should anything but the minimum of power be applied.  Add to this operational conditions, such as interval of use and environmental conditions, and the need for regularly scheduled inspection of all working parts becomes quite clear.

With so much riding on the line, the very best of care should be taken when selecting the facility to perform service on aircraft.

Covington Aircraft is a Pratt & Whitney Canada certified distributor and designated overhaul facility, offering service on all their turbine and radial aircraft engines.  We also perform annuals, 100 hours and most service-related work on any airframe.  We have flight safety personnel ready to service your needs.  If for any reason we are unable to provide a service for you, we can provide you with contact information of someone who can.  In our 47,000-square-foot facility, we offer state-of-the-art engine testing, new engine installations, complete overhaul service using the latest equipment, and we maintain a complete line of engine parts and accessories so we can get you back in the air in the shortest time possible.  We are ready to perform all stages of engine repair and overhaul work in-house on both radial and turbine aircraft engines.  When you add to this the service, dependability, commitment to quality and competitive pricing that is part of our policy, you will understand why we have been in the business for nearly 40 years.

To read more about planes, engines and how much we care about our clients, please click here.  Learn more about us and our commitment to quality and dependability by clicking here.


Turbine Engines Education Series – Service, Overhaul and Things to Look For on your Turbine Aircraft Engine

Covington Aircraft is ranked among the world’s leading maintenance, repair and overhaul facilities, providing any service you need for your aircraft on the ground.  Specializing in PT6A turbine and R985 and R1340 radial engines, and a Pratt & Whitney Canada Distributor and Designated Overhaul Facility (DDOF), Covington can handle your turbine engine work.


What’s First?  How Do We Proceed From Here?


Representatives at Covington are only a phone call or email away.  Let them know where you and your engine stand.  David Hamilton, Vice President of the Turbine Facility can be reached by phone or email (www.covingtonaircraft.com).

Who Do I Speak To When I Have Questions?

Covington Aircraft is proud that those who answer questions at their facility have over 100 years of experience.  You can be sure that when you call Covington Aircraft that you will not be transferred repeatedly and that “your guy” is still there.  Call 918-756-8320 and ask for:

  • Robert Ramirez or Ted Neal for Parts
  • Ron Hollis for Customer Technical Support
  • Annette Stewart for Accounts Receivables and Payables
  • David Hamilton for General Questions and Quotes

What If You Are Not Listed on My Engine Model as P&WC approved?

Aircraft engine overhaul is not a necessary remedy for all engine issues.  Covington Aircraft does turbine maintenance on all PT6A engines and can usually take care of any maintenance issue.  If for some reason Covington can’t help you with your problem, they will point you in the right direction to someone who can.

What Kind of Treatment Will I Get If I Just Have One Aircraft?

Covington Aircraft has grown their business one aircraft and one customer at a time and not based on just a quick sale.  Covington prides itself on looking out for their customer’s best interests and builds a relationship that addresses more than just an engine.  Their goal is to make you feel appreciated whether you own one aircraft or a thousand.

Do You Do Airframe Work?

Having experienced, Flight Safety trained personnel, Covington Aircraft can do annuals, 100 hours and most service related work on almost any airframe.  If they are unable to do so, they will recommend someone who can to be sure your expectations are met.

Can You Take Care of My Engine Change?

With our new 47,000 square foot hangar facility in Okulmgee, Oklahoma engine changes are no problem.  However, if necessary, Covington Aircraft can come to your location.  Remember, if you have your aircraft engine overhaul done at our facility, removal and installation is labor free.

Can You Handle My Warranty Issue?

Whether it is a Covington Warranty or a Pratt & Whitney Canada Warranty, Covington is there to provide customers with whatever support they need.  As a Distributor and Designated Overhaul Facility for Pratt & Whitney Canada, Covington Aircraft is authorized to process your warranty and will work to provide you with the quality service you expect.

Founded in 1972, Covington Aircraft is a world-leading aircraft engine maintenance, repair and overhaul facility specializing in the PT6A turbine engine and R-985 and R-1340 radial engines.

Covington Aircraft, with 39 years of experience in aircraft engine overhaul and turbine engine maintenance, is ready to provide you the service you need for your operation.  For more information on how Covington can take care of your aircraft on the ground, visit www.covingtonaircraft.com.

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