First of all, only Band A (left side) can be tuned to the aviation band; if you try to use Band B it will not work. Press the left "BAND SEL" button (volume knob). Then you should be able to use the tuning knob to tune to the frequency you want.
If it skips over the aviation band, then the first thing to check is that the aviation band is not masked. This is covered in the secondary "CD-ROM" manual, page "OTHER OP-1":
- Turn the transceiver power OFF.
- Press the left or right [BAND SEL] + Power ON.
- The band mask display appears.
- Rotate the Tuning control to select the band you want to hide (or return to normal).
- Press the Tuning control to set the selected band.
- Rotate the Tuning control to set the band to select USE or MASK.
- USE allows you to see and use the band as normal. MASK hides the band on the display.
- Press the Tuning control to set the selection.
- Press the [ESC] to exit.
(Caution: the paragraph at the beginning of the section about "hide the frequency display" has nothing whatsoever to do with the actual function being described. Evidently even Kenwood's technical writers were confused by the choice of "band" to refer both to frequency bands and what another radio might call VFOs.)
I checked that my own TM-D710G can receive 131.550 MHz as you mentioned (with the band not masked).