Can I visit the Huanghuacheng Great Wall on a 72-hour transit when staying in Beijing?

We arrive in Bejing at 05.30, plan to explore the city. The following day (day 2) we hoped to visit Huanghuacheng Great Wall. Day 3 we fly to Hong Kong at midday. Would we be able to visit the Great Wall or is this classed as 'leaving Beijing'?