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How Lycoming (and Rotax, and Continental) build engines

They used to make 8000 engines a year at their peak; now down to 1500 new and 1500 overhauls.

They appear to buy in the crankshaft forgings and heat treat them in-house. This is relevant to the debacle 15 years ago where the wrong heat treatment was done by a subcontractor. They then machine them in-house.

The annual sales work out in the region of $100M.

Shoreham EGKA, United Kingdom

It’s still amazing how hands-on the manufacturing process is. In automotive today, they’ll produce at least the same number of engines in a day that Lycoming do in a year and the assembly process is fully automated from start to end.

It would be interesting to see how their failure rate has changed with their more ‘modern’ processes although this would be difficult as stuff such as engine monitoring has also contributed.


The automotive engine builder probably spends more on the plant producing these engines than Lycoming makes in engine revenues in a decade.

Light Aviation is at a completely different scale – around 0.003% of the car industry (really. 90 MILLION cars versus 1 THOUSAND light piston aircraft per year, or around 3,000 including turbines and light jets, according to GAMA).

Last Edited by Cobalt at 13 Jan 11:56
Biggin Hill

I’ve been in business (manufacturing) since 1978, and [un]fortunately if you properly organise your line and use computer controlled machine tools as far as possible, the labour cost doesn’t come to much as a % of the price tag.

And in this case the investment required to reduce the labour cost significantly would be completely out of any reasonable range.

What would interest me is whether they are making e.g. cranks to closer balance tolerances. Their out of balance specs used to be atrocious, hence some engines would vibrate a lot while others didn’t.

Shoreham EGKA, United Kingdom

Does this mean that we shall now see an end to manufacturing faults that sometimes get reported? What about the people like Superior will they still be in business if Lycoming can produce real top quality engines? 2 very simplistic questions obviously.

UK, United Kingdom

I think one needs to distinguish between the different issues.

Before the roller tappets came in (7 years ago?) the weakest spot was the cam follower / cam interface, which needs very good lubrication, and on a Lyco it doesn’t get much oil until the engine is running and splashing plenty of oil up onto the camshaft. The roller tappets solve this, supposedly, but obviously very few engines as a % of those currently running have them.

The pre-roller cam interface is hugely vulnerable to corrosion through a lack of use, and there are extremely few verified data points to the contrary, especially from Europe.

The next weak spot was the valve guides, which was solved c. 15 years ago with the chrome plated guides – the cylinders marked with a “C”.

The above is in the context of the engine making the 2000hr TBO. No engine will run for ever and something has to fail eventually…

I don’t know what are the biggest causes of engines not making TBO today.

Also better manufacturing techniques are unlikely to deliver a lower risk of catastrophic failure, but that’s rare anyway. Better QA is always good, however.

Shoreham EGKA, United Kingdom

Peter wrote:

what are the biggest causes of engines not making TBO today.

That’s easy – it’s the owners euthanizeing good engines ‘cause "it’s time"


We had some people visiting an engine plant today. It is small in automotive terms, only making 30k – 40k engines a year. However the numbers of staff are low and labour is less than 5% of the finished product.

Darley Moor, Gamston (UK)

Look at this from 3:00 onwards. Compare and contrast with Lycoming….

Darley Moor, Gamston (UK)

one man one engine

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