Engineers are troubleshooting a possibly faulty chamber pressure transducer on the right hand solid rocket booster for Atlantis to determine whether or not it needs to be replaced before the shuttle's launch Oct. 10.

A NASA spokesman says that, if the sensor needs to be replaced, it can be done at the pad in parallel with normal prelaunch processing without delaying Atlantis' launch.

The sensor exhibited unexpected electrical readings during routine prelaunch testing. Subsequent testing failed to reproduce the anomaly, however.

The readings were within allowable tolerances, but NASA wants to make sure it's not a sign of a failing sensor.

The sensor measures the pressure inside the SRB's combustion chamber during launch. At burnout, when the sensors in the boosters detect the pressure has fallen to below 50 PSI, the signal is given to deparate the boosters from the shuttle tank.

The sensors are also used to monitor the booster's performance and ensure that a fault in the booster combustion will be detected.