Narrative:

Mmu has no ASOS; teb and ewr were landing runway 6 and runway 4. ATC vectored us for RNAV 5 approach. WX was from cdw ASOS or ewr. We had no WX for mmu. During GPS missed approach to runway 5 at minimums (860 ft) we selected go around mode (gulfstream iv). We lost all navigation display data on both pfd's and navigation displays; both FMS's lost all data and FMS key pad locked (unable any inputs). Both flight guidance computers failed; fgcp; autoplt; electric trim; yaw damper; and autothrottles had failed. Fgcp heading went to 000 degree heading; altitude selector went to 100 ft. V-bars initially commanded a descent (the 100 ft) in the selector window. Missed approach altitude was 2300 ft as per fdc NOTAM. My altitude did vary some +/-200 ft handling an aircraft with now only manual trim during power and confign changes. Aircraft had been configured full flaps for landing and now full power for go around and flaps up to 20 degrees with no electric trim during the go around (hands full). As this is a standalone approach; charts do not show frequency of any land-based navaids (big mistake). We were to fly direct to moree; an NDB and hold. The copilot entered the frequency and we proceeded in the direction of the fix. ATC was advised of our missed approach and that we had lost equipment requesting a vector so we could sort out our failures and a plan of action. Once level; we reset our FGC circuit breakers and recovering autoplt; trim; and yaw damper; no autothrottle FMS or fgcp. We requested vectors to ewr; due to a level 5 thunderstorm they were closing operations. We were vectored back to mmu for the ILS 23 approach while working our way around level 4 and 5 cells. The ILS 23 approach would have been our first choice had we had mmu wind/WX. Mmu needs an ASOS; also RNAV approachs need frequencys listed as backup. Both gulfstream and honeywell spent several days checking out equipment and changing out units. I delayed in this report hoping for some answers. None yet!

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Original NASA ASRS Text

Title: GIV FLT CREW LOSES ALL PFD AND NAV DISPLAY INFO DURING MISSED APCH IN IMC CONDITIONS. RESTORE PARTIAL OPERATION AND LAND SAFELY ON ILS APCH.

Narrative: MMU HAS NO ASOS; TEB AND EWR WERE LNDG RWY 6 AND RWY 4. ATC VECTORED US FOR RNAV 5 APCH. WX WAS FROM CDW ASOS OR EWR. WE HAD NO WX FOR MMU. DURING GPS MISSED APCH TO RWY 5 AT MINIMUMS (860 FT) WE SELECTED GAR MODE (GULFSTREAM IV). WE LOST ALL NAV DISPLAY DATA ON BOTH PFD'S AND NAV DISPLAYS; BOTH FMS'S LOST ALL DATA AND FMS KEY PAD LOCKED (UNABLE ANY INPUTS). BOTH FLT GUIDANCE COMPUTERS FAILED; FGCP; AUTOPLT; ELECTRIC TRIM; YAW DAMPER; AND AUTOTHROTTLES HAD FAILED. FGCP HDG WENT TO 000 DEG HDG; ALT SELECTOR WENT TO 100 FT. V-BARS INITIALLY COMMANDED A DSCNT (THE 100 FT) IN THE SELECTOR WINDOW. MISSED APCH ALT WAS 2300 FT AS PER FDC NOTAM. MY ALT DID VARY SOME +/-200 FT HANDLING AN ACFT WITH NOW ONLY MANUAL TRIM DURING PWR AND CONFIGN CHANGES. ACFT HAD BEEN CONFIGURED FULL FLAPS FOR LNDG AND NOW FULL PWR FOR GAR AND FLAPS UP TO 20 DEGS WITH NO ELECTRIC TRIM DURING THE GAR (HANDS FULL). AS THIS IS A STANDALONE APCH; CHARTS DO NOT SHOW FREQ OF ANY LAND-BASED NAVAIDS (BIG MISTAKE). WE WERE TO FLY DIRECT TO MOREE; AN NDB AND HOLD. THE COPLT ENTERED THE FREQ AND WE PROCEEDED IN THE DIRECTION OF THE FIX. ATC WAS ADVISED OF OUR MISSED APCH AND THAT WE HAD LOST EQUIP REQUESTING A VECTOR SO WE COULD SORT OUT OUR FAILURES AND A PLAN OF ACTION. ONCE LEVEL; WE RESET OUR FGC CIRCUIT BREAKERS AND RECOVERING AUTOPLT; TRIM; AND YAW DAMPER; NO AUTOTHROTTLE FMS OR FGCP. WE REQUESTED VECTORS TO EWR; DUE TO A LEVEL 5 TSTM THEY WERE CLOSING OPS. WE WERE VECTORED BACK TO MMU FOR THE ILS 23 APCH WHILE WORKING OUR WAY AROUND LEVEL 4 AND 5 CELLS. THE ILS 23 APCH WOULD HAVE BEEN OUR FIRST CHOICE HAD WE HAD MMU WIND/WX. MMU NEEDS AN ASOS; ALSO RNAV APCHS NEED FREQS LISTED AS BACKUP. BOTH GULFSTREAM AND HONEYWELL SPENT SEVERAL DAYS CHKING OUT EQUIP AND CHANGING OUT UNITS. I DELAYED IN THIS RPT HOPING FOR SOME ANSWERS. NONE YET!

Data retrieved from NASA's ASRS site as of May 2009 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.