sjb (01/15/83)
NASA has scheduled Challenger's second FRF (engine test firing) for 26 January, ''give or take a day or two.'' If the source of the hydrogen leak first detected last month is found to be external to the engine compartment, NASA says that STS-6 should launch sometime before the end of February. However, if the problem lies within the engine compartment itself, the launch will probably slip into March, as one or more engines may have to pulled or replaced.