When must an incident investigation be initiated for Program 2 and 3 processes?

When must a stationary source owner or operator begin conducting incident investigations as required under 40 CFR §68.60 (for Program 2 processes) or 40 CFR §68.81 (for Program 3 processes)?

For both Program 2 and Program 3 processes, the incident investigation must be initiated as soon as possible, but not later than 48 hours following the incident.