As PPRuNe Towers mentions above, the decision was made that searches would be made on words of four or more characters to ease on the server loads. However.... there are some two and three letter words that can be searched. These words or abbreviations are entered manually by yours truly and can be added to. The current list of searchable two and three letter words are:
BA BAe FCA TUI AA UA VMC IMC VFR IFR twr app rwy AOC A/P APU ATC CFI FMC HSI CAA FAA NVG
Please feel free to add your own suggestions below and they will be considered for inclusion into the list.