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Finding timed out (i.e. 0 TBO) turboprop engines is relatively easy, they are abundant, and not for without good reason. Having received an estimate from Walter GE recently, it became more apparent that after perhaps the 4th or 5th overhaul, a turboprop engine may see the rest of its days in darkness, at a museum or in the back of the warehouse - for sale - in perpetuity. 


By Alex Berry, 22nd June 2018

That’s not necessarily to say that it can’t be overhauled, quite to the contrary.  It’s just that, for many aircraft owners and operators, rising TTSNs start to become a very costly affair, especially for twins. A used King Air 100 with twin Garrett’s could be snapped up for $300-500k quite easily, then look at what you might pay for to acquire one with healthy TBO’s, most like a range of circa. $1.2-1.5m. A quick reminder then, that the value of an aircraft is largely based on its explicit resource remaining, especially when conducting public or commercial operations. This is the moment you realise that a $400k bargain is actually the same as a $1.1-1.2m bird if it had good engines and props.

So let’s consider what it might take to give the presumed bargain-buy some healthy TBOs. After an investment of circa. $320-350k (per engine) and at least 4 months turnaround time, a timed out engine could be properly replenished to an 1,800-2,000hr resource (depending on the model). Excluded in this estimate, is the cost of accommodating service bulletins that may have become due.

This can add significantly to the overall cost. Let’s also consider that Walter GE in the Czech Republic are the only authorised establishment that can perform this resource replenishment. This cost is understandable, when one appreciates what they do to overhaul an engine.

They essentially dismantle the entire engine, check, replace and rebuild to an exacting standard, replacing worn parts out of acceptable tolerance levels as they go - and of course – they really know their engines.   

Similarly, propellers are also a lifed resource and must be overhauled according to the manufacturer’s schedule. The Avia V508 3-blade and V510 5-blade propellers are commonly paired with Walter GE M601 variants and many of these blades can be found waiting patiently for someone to give them a new leash of life. Avia recently advised that a rough estimate of the cost of overhauling a 0 TBO prop. was circa. €10k vs. a new prop. costing circa. €30k with a 4 month wait for either option to deliver a 2,000hr resource.