Narrative:

The first officer was flying the aircraft, at night IMC. Approximately 10 seconds after capturing the localizer, the autothrottles and autoplt kicked off, as well as the flight guidance control panel and flight mode annunciator (FMA) going blank. I took control of the aircraft and stabilized the approach using my flight guidance and FMA, (as we were in a 25-30 degree bank, descending at 1000-1500 FPM). I then gave the aircraft back to the first officer, who reengaged the autothrottles and autoplt. In approximately 2-5 seconds, the devices again kicked off and this time the FMA showed 'power up tst BX2.' (according to our flight manual this should only happen after the aircraft has been on the ground for 2 mins). I took the aircraft again and flew it until becoming VMC, then gave the aircraft back to the first officer, who completed the approach and landing visually. Callback conversation with reporter revealed the following information. This was his first experience with this type of autoplt disconnect/failure with loss of the first officer's loss of secondary flight information. First officer did not lose primary flight information such as hdi, etc, but did lose digital readout information on navigation frequency, actual altitude etc. Appears to reporter to be a flight guidance computer problem that kicked the autoplt and autothrust levers off.

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Original NASA ASRS Text

Title: ACFT EQUIP PROBLEM WITH FLT GUIDANCE SYS CREATES AN ELECTRICAL ELECTRONIC PANEL PROBLEM FOR FLT CREW DURING IAP ILS APCH.

Narrative: THE FO WAS FLYING THE ACFT, AT NIGHT IMC. APPROX 10 SECONDS AFTER CAPTURING THE LOC, THE AUTOTHROTTLES AND AUTOPLT KICKED OFF, AS WELL AS THE FLT GUIDANCE CTL PANEL AND FLT MODE ANNUNCIATOR (FMA) GOING BLANK. I TOOK CTL OF THE ACFT AND STABILIZED THE APCH USING MY FLT GUIDANCE AND FMA, (AS WE WERE IN A 25-30 DEG BANK, DSNDING AT 1000-1500 FPM). I THEN GAVE THE ACFT BACK TO THE FO, WHO REENGAGED THE AUTOTHROTTLES AND AUTOPLT. IN APPROX 2-5 SECONDS, THE DEVICES AGAIN KICKED OFF AND THIS TIME THE FMA SHOWED 'PWR UP TST BX2.' (ACCORDING TO OUR FLT MANUAL THIS SHOULD ONLY HAPPEN AFTER THE ACFT HAS BEEN ON THE GND FOR 2 MINS). I TOOK THE ACFT AGAIN AND FLEW IT UNTIL BECOMING VMC, THEN GAVE THE ACFT BACK TO THE FO, WHO COMPLETED THE APCH AND LNDG VISUALLY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO. THIS WAS HIS FIRST EXPERIENCE WITH THIS TYPE OF AUTOPLT DISCONNECT/FAILURE WITH LOSS OF THE FO'S LOSS OF SECONDARY FLT INFO. FO DID NOT LOSE PRIMARY FLT INFO SUCH AS HDI, ETC, BUT DID LOSE DIGITAL READOUT INFO ON NAV FREQ, ACTUAL ALT ETC. APPEARS TO RPTR TO BE A FLT GUIDANCE COMPUTER PROBLEM THAT KICKED THE AUTOPLT AND AUTOTHRUST LEVERS OFF.

Data retrieved from NASA's ASRS site as of July 2007 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.