TPE331 and the Short Skyvan

[Aeroflight]

I would like a bit of help with clarifying the exact engine models used on the Short Skyvan.

I believe all Skyvan 3s were originally delivered with Garrett TPE331-2-201A engines.

The TPE331-2-251A with identical performance is also quoted as being fitted to the Skyvan - as a retrofit or very late production?

A few US-registered aircraft were retrofitted with TPE331-6-252T under a STC (number ?) - this engine has an uprated gas generator with increased air flow & pressure ratio

Several (nearly all those still in service) have had the 'Super 2' upgrade which fits a -6 compressor to a -2-201A engine under STC SE383CH (issued circa 1996) held by National Flight Systems Inc.

The following performance figures are quoted:
TO SHP -2: 755, -6: 750 -- sfc -2: 0.556, -6: 0.577 -- OPR -2: 8.3, -6: 10.3 -- weight -2: 336 kg, -6: 355 kg

So the -6 is heavier and gives less power for a higher fuel consumption. What is the point of the 'Super 2' mod?

All comments and corrections are appreciated!

 

[Kiltonge]

What is the point of the 'Super 2' mod?

The -6 compressor was substantially improved over that of the -1 / -2 and gives much higher pressure ratio, when joined to the original hot section the output is maintained much better when hot / high.

Super-1 / Super-2 conversions were quite common in early 80s for that reason.

 

[Apophenia]

... A few US-registered aircraft were retrofitted with TPE331-6-252T under a STC (number ?)...

Skyvan TPE331-6-252T conversion was under STC SA02059AK.

 

[Aeroflight]

In addition to the above, it seems that the TPE331-2-201A was not fitted with any overspeed protection, and such a device had to be retrofitted after a number of uncontained engine failures.