Maintenance & TBO Explained
Maintenance & Time Before Overhaul (TBO): Understanding the Technical Clock
Owning an aircraft means managing a technical ‘clock’ that ensures safety and preserves the value of your asset. At Samera Sky, we believe informed owners are safer owners. This page breaks down the essential maintenance requirements and the concept of TBO in clear, grounded terms.
The Maintenance Schedule
In the UK, light aircraft follow a structured maintenance program (often based on a Self-Declared Maintenance Programme or Part-ML) to ensure airworthiness.
01
The 50-Hour Check
A routine “oil and filter” style inspection. Here, the aircraft is checked for leaks, spark plugs inspected, and the overall health of the engine in verified.
02
The 100-Hour/Annual Inspection
A deep-dive audit of the entire airframe and engine. Even if not flown 100 hours in a year, this inspection must be completed annually to maintain your Certificate of Airworthiness (CofA) or Permit to Fly.
03
ARC (Airworthiness Review Certificate)
An annual high-level review of the aircraft’s records and physical condition to ensure all mandatory Airworthiness Directives (ADs) have been met. This can be valid for up to three years if the necessary extensions are approved and added.
What is TBO? (Time Between Overhauls)
TBO is the manufacturer’s recommended limit on how many hours an engine should run before it undergoes an overhaul.
- The Numbers: For most common piston engines, TBO is typically between 1800 and 2400 hours, or 12 years – whichever comes first.
- The Goal: An overhaul involves taking the engine apart to its smallest components, inspecting every part against factory limits, and replacing worn items. It resets the “clock” to zero.
For more information on Aircraft Ownership & Maintenance, visit the CAA website.
“On-Condition” vs. Mandatory Overhauls
Private Use
For many private pilots in the UK, TBO is a recommendation. If the engine is healthy, has good compression, and clean oil, it can often be flown “on condition” beyond the hourly limit, provided a qualified engineer certifies it at every annual check.
Commercial/Training
If the aircraft is used for flight instruction or commercial work, TBO limits are usually much stricter and often mandatory.
Samera Sky views maintenance as part of our commitment to sustainable aviation as a well-maintained engine is an efficient engine. Through our connections with lenders, we can help our clients with engine financing, advocating with them to recognise the value of a “low-time” or a freshly overhauled engine. A healthy engine is a lower-risk asset, and we believe that should be reflected in the financing.
Managing the Costs
Maintenance is a predictable part of flying. Most pilots use an “Engine Fund” approach, setting aside a small amount for every hour flown. This ensures that when the “big clock” hits TBO, the capital is ready.
If you need to fund an upcoming overhaul, we can help you navigate the costs. Contact us today.
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