It’s one of the most frequently asked questions my office receives daily, and it’s a topic that will only generate more confusion as technology and 100LL regulations change; so what is the difference between a factory rebuild, a factory overhaul, and a field overhauled engine? More importantly, how does it affect the value of my aircraft? And is opting for a factory new engine worth the extra money? As labor rates continue to climb, combined with inflation at the highest levels in over 30 years, there’s even more confusion about the difference between a field overhaul, factory new engine, or rebuild.

Let’s learn more about the meaning behind these terms, their definitions, and additional helpful details.

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Breaking Down The Differences Between An Aircraft Factory Rebuild & Engine Overhaul

Understand the difference between an aircraft factory rebuild and an engine overhaul by first reviewing their meanings. One of the reasons these and related terms are used interchangeably is that there is no set definition used across the aviation industry.

What Is An Engine Overhaul?

In general aviation, an engine overhaul refers to a major or a top overhaul. Choosing when to work on an aircraft engine will depend on the FAA’s definition of “time in service” and the manufacturer’s recommended time between overhauls (TBO).

A major overhaul requires an engine’s complete deconstruction. After the work is done, your aircraft engine should receive facility approval. This means that the overhauled engine should perform within the fits and limits specified by the manufacturer’s overhaul data. As an aircraft owner, you should know which parts are replaced through the manufacturer’s overhaul data, SB, or Airworthiness Directive (AD).

A top overhaul only requires repairs to parts outside of the crankcase or on the “top” of the engine, and this can be done without completely disassembling the entire engine. While someone may refer to any or all of these as simple maintenance, repairs, etc., refined meanings of each do exist.

What Constitutes An Aircraft Factory Rebuild?

Rebuilding an engine through the manufacturer of that engine uses different wording than an overhaul. As mentioned above, an overhaul ensures an engine can return to service. The difference between this and a factory rebuild is that it must test to “the same tolerances and limits as a new item,” according to Federal Aviation Regulations (FAR).

Cost Variation

According to the AOPA, “There is little operational difference between a rebuilt and an overhauled engine, but there is a definite legal difference. This difference influences the cost of the rebuilt engine, and it can increase the aircraft’s value, although probably not in proportion to the cost of the engine.”

If you decide to sell your aircraft, you may be able to up your asking price because its engine is “factory rebuilt” rather than overhauled. Regardless of your choice, you’re still looking at an additional expense that needs to be worked into your yearly aviation budget.

Shop Around For Quality

Don’t simply trust any shop to do your aircraft engine overhaul. The outcome or ideal results depend on the individual working on your aircraft. Your best bet is to shop around, ask for recommendations, and inquire about previous successful engine overhauls performed on other aircraft. You want the best person for the job – not just anyone who says they can do the work.

Understanding The Process

Below are the general processes for an overhaul versus an engine rebuild.

Steps Of An Overhaul

Broken down into simple steps, an overhaul facility will do the following for major overhauls:

  • Inspect and deconstruct the engine
  • Make repairs as necessary
  • Reassemble the engine
  • Test and approve the engine for its return to service

A top overhaul means a facility may:

  • Remove cylinders
  • Inspect and repair cylinders, cylinder walls, and other necessary parts

Again, a top overhaul doesn’t require an engine’s total deconstruction.

Steps Of An Engine Rebuild

Rebuilding an engine is typically done directly through the engine’s manufacturer, and this is because only the manufacturer or approved-by-manufacturer facilities can perform a rebuild. Most engine facilities will work with your engine throughout its lifecycle.

Aligned with FAR standards, a facility will rebuild an engine by:

  • Disassembling the engine
  • Cleaning all parts
  • Inspecting all parts
  • Making repairs as necessary
  • Reassembling the engine
  • Testing

With an engine rebuild, FAR Part 43.2 says it needs to operate like new after being disassembled and put back together. Testing should ensure its operation follows “the same tolerances and limits as a new item.”

Determining A Timeline

The time it takes to have your engine overhauled or rebuilt will depend significantly on several factors, including the following:

  • Labor available
  • Supply chain or parts readily available
  • Additional problems revealed with inspection
  • Facility workload

Minimize aircraft downtime by planning financially with your insurance and financial advisor. You can also prepare for potential repairs and pre-order any expected parts needed. Taking care of these tasks before it’s time to take in your aircraft will get you in and out of the facility faster.

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Largest Commercial Aircraft Engine Manufacturers

As you consider an aircraft factory rebuild or engine overhaul, here is a list of the most common names you’ll see when working with engine manufacturers.

General Electric / GE Aviation

Founded in 1917, GE Aviation is a subsidiary of General Electric, headquartered in Evendale, Ohio. GE Aviation offers engines for the majority of commercial aircraft and military aircraft.

Pratt & Whitney

Pratt & Whitney is a subsidiary of Raytheon Technologies, founded in 1925 with headquarters in East Hartford, Connecticut. Pratt & Whitney aircraft engines are used for civil and military aviation.

Engine Alliance

Founded in 1996, Engine Alliance is a 50/50 joint venture between GE Aviation and Pratt & Whitney, with headquarters in East Hartford, Connecticut.


Generally well-known for its luxury cars, Rolls Royce is also a major player in the aviation industry. Founded in 1904, Rolls Royce produces turbofan aircraft engines for commercial aircraft.


PowerJet is a Franco-Russian 50/50 joint venture founded in 2004 by aeronautical engine manufacturers Snecma and NPO Saturn. It is in charge of the SaM146 program – the sole power plant for the Sukhoi Superjet 100 airliner.

CFM International

CFM International is also a 50/50 Franco-American joint venture. This particular venture is between GE Aviation and Safran Aircraft Engines – formed to build and support the CFM56 series of turbofan engines.

Honeywell Aerospace

Founded in 1936, Honeywell Aerospace manufactures aircraft engines, avionics, and other aviation products. It is a part of the Honeywell International conglomerate, with headquarters in Phoenix, Arizona.

VREF – Your Trusted Guide In Aviation

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