Narrative:

The deviation occurred while the aircraft was in the climb phase after taking off. I was acting second in command pilot occupying the right seat in the cockpit. The aircraft was being flown on a left course deviation. All the settings were performed by the pilot in command.at some point; the flight attendant came to the cockpit and asked for some instructions from the pilot in command with regards to the operation of equipment in the galley. While in the climb phase; prior to level off; the pilot in command left the cockpit to help the flight attendant with the galley equipment. I kept on monitoring the engine and flight instruments while in the climb. After passing FL280; both engines' tgt (turbine gas temperature) gauges jumped from normal operation to the very bottom of the amber arc (warning area). At this point; I disconnected the auto throttles and reduced the power/fuel flow so the tgt indication would come down into the normal operation range.as soon as the tgt gauges came down into normal; our right engine lp (low pressure) gauge spiked to the warning - red - zone. These deviations were momentary not lasting more than couple of seconds. The autopilot was disconnected thus preventing the aircraft from leveling off at the 30;000 ft assigned altitude. As I cross-referenced all the instruments; I noticed the altitude deviation and proceeded to correct it. According to my observations; flying the plane from the right side and after cross referencing all the instruments; the deviation was not larger than 200 ft and we did not interfere with any other aircraft either vertically or laterally.

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Original NASA ASRS Text

Title: An altitude deviation ensued following the departure of the Captain to investigate a coffee maker and the reaction of the First Officer to apparently momentary engine parameter spikes which caused him to disconnect the autoflight systems immediately prior to reaching the programmed cruise altitude.

Narrative: The deviation occurred while the aircraft was in the climb phase after taking off. I was acting second in command pilot occupying the right seat in the cockpit. The aircraft was being flown on a left course deviation. All the settings were performed by the pilot in command.At some point; the Flight Attendant came to the cockpit and asked for some instructions from the pilot in command with regards to the operation of equipment in the galley. While in the climb phase; prior to level off; the pilot in command left the cockpit to help the Flight Attendant with the galley equipment. I kept on monitoring the engine and flight instruments while in the climb. After passing FL280; both engines' TGT (Turbine Gas Temperature) gauges jumped from normal operation to the very bottom of the amber arc (warning area). At this point; I disconnected the Auto Throttles and reduced the power/fuel flow so the TGT indication would come down into the normal operation range.As soon as the TGT gauges came down into normal; our right engine LP (low pressure) gauge spiked to the warning - red - zone. These deviations were momentary not lasting more than couple of seconds. The autopilot was disconnected thus preventing the aircraft from leveling off at the 30;000 FT assigned altitude. As I cross-referenced all the instruments; I noticed the altitude deviation and proceeded to correct it. According to my observations; flying the plane from the right side and after cross referencing all the instruments; the deviation was not larger than 200 FT and we did not interfere with any other aircraft either vertically or laterally.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.