[OS X TeX] Incompatibilty between T1 and LY1 encoding

[André Bellaïche]

I need some very narrow font for some marginal notes, and for that use I have installed HelveticaNeue Thin Condensed fonts.

Following the advice of John Owens in his document "Installing Opentype fonts with the LCDF typetools", I have declared the fontenc of the new fonts as LY1. 

But there seems to be some incompatibiltiy preventing to use these fonts together with the main font of the document which is Times, or rather Nimbus (\usepackage{ptm}), which has T1 as fontenc. I use the thin font only when needed, with a special command, but the LY1 fontenc must be loaded in the preamble. Right ? 

So, if I use the command

\usepackage[T1,LY1]{fontenc}

the small capitals in Times disappear (they are replaced by normal text --- I know they are fake small capitals, this is not the point).

And if I use 

\usepackage[LY1,T1]{fontenc}

in this order, the HelveticaNeue Thin Condensed font is replaced by Times, the default font of the document.

Any idea how to fix it?

The LaTeX Companion tells us explicitly that it is possible to load several font encodings. 

André Bellaïche
Université Paris-Diderot