PA27 on flight plans for NATS/EUROCONTROL – for correct route charges. For continuity in the system once you are nominated a PA27 – you stay one.
PA23 outside EUROCONTROL area.
PAZT – for flight plans originally but now changed to PA27 so that charges can be levied when flying under IFR/SVFR. VFR flights are free of route charges for PA27 > 2000kgs.
Apache < 2000kgs – no route charges. PAZT for FP's
Yer get used to it after a couple of years and get on with other issues that are far more perplexing.
It's quite easy to say "PA27 Aztec" and ATC can correlate with their strips. ATC know that an Aztec is a flexible beast and can provide 160 to 4 or 100 at 10 - so Aztec drivers tend to "fit in"
Lovely aeroplane - whatever yer call it.