Narrative:

En route to pick up a patient. Around lovelock; nv (lol); I started having the attitude indicator flag show itself. It would then retract. The a/I appeared to read correctly compared to the copilot's and standby attitude indicator. I was on top of a solid overcast. This continued for several mins and then the HSI heading flag started doing the same thing. I switched inverters and checked for circuit breakers out. No change and progressively worse. I elected to return to O43 as it was good VMC when I had left; but it has no WX reporting. I told ZOA of my problems and started towards O43. The attitude indicator finally had a hard failure and I covered it up (sticky pads are great!). The HSI heading flag would stay retracted for a while and appeared correct compared to the copilot's directional gyro and magnetic compass. Nearing O43; I was still on top of an overcast. Center was vectoring me around for other traffic so I had a good look at the overcast. I found a large hole and saw the airport. Cleared for the visual but I lost the airport and told center I wanted to go to rno. Direct to reno and descend; now into IMC. Everything is going ok albeit a lot of concentration and hard work. After a while; I ask for priority so I don't keep getting vectored. Shortly after mustang VOR (fmg); I break out into VMC and see rno. Landing is uneventful. The first time in 20 yrs I have actually had to fly partial panel in IMC. A handful after yrs of glass and lots of redundancy in instruments; crew and system. There is a reason for all that redundancy and single pilot IFR with partial panel is truly a high workload I don't want to repeat any time soon! Training; training and practice truly make the difference! The instrument had a hard failure and was replaced later that day. It had been overhauled 3 times before.

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Original NASA ASRS Text

Title: SINGLE PLT ABOARD AC690B HAS COMPLETE GYRO FAILURE ENROUTE IFR. DIVERTS IN IMC TO RNO FLYING BASIC INSTRUMENTS.

Narrative: ENRTE TO PICK UP A PATIENT. AROUND LOVELOCK; NV (LOL); I STARTED HAVING THE ATTITUDE INDICATOR FLAG SHOW ITSELF. IT WOULD THEN RETRACT. THE A/I APPEARED TO READ CORRECTLY COMPARED TO THE COPLT'S AND STANDBY ATTITUDE INDICATOR. I WAS ON TOP OF A SOLID OVCST. THIS CONTINUED FOR SEVERAL MINS AND THEN THE HSI HDG FLAG STARTED DOING THE SAME THING. I SWITCHED INVERTERS AND CHKED FOR CIRCUIT BREAKERS OUT. NO CHANGE AND PROGRESSIVELY WORSE. I ELECTED TO RETURN TO O43 AS IT WAS GOOD VMC WHEN I HAD LEFT; BUT IT HAS NO WX RPTING. I TOLD ZOA OF MY PROBS AND STARTED TOWARDS O43. THE ATTITUDE INDICATOR FINALLY HAD A HARD FAILURE AND I COVERED IT UP (STICKY PADS ARE GREAT!). THE HSI HDG FLAG WOULD STAY RETRACTED FOR A WHILE AND APPEARED CORRECT COMPARED TO THE COPLT'S DIRECTIONAL GYRO AND MAGNETIC COMPASS. NEARING O43; I WAS STILL ON TOP OF AN OVCST. CTR WAS VECTORING ME AROUND FOR OTHER TFC SO I HAD A GOOD LOOK AT THE OVCST. I FOUND A LARGE HOLE AND SAW THE ARPT. CLRED FOR THE VISUAL BUT I LOST THE ARPT AND TOLD CTR I WANTED TO GO TO RNO. DIRECT TO RENO AND DSND; NOW INTO IMC. EVERYTHING IS GOING OK ALBEIT A LOT OF CONCENTRATION AND HARD WORK. AFTER A WHILE; I ASK FOR PRIORITY SO I DON'T KEEP GETTING VECTORED. SHORTLY AFTER MUSTANG VOR (FMG); I BREAK OUT INTO VMC AND SEE RNO. LNDG IS UNEVENTFUL. THE FIRST TIME IN 20 YRS I HAVE ACTUALLY HAD TO FLY PARTIAL PANEL IN IMC. A HANDFUL AFTER YRS OF GLASS AND LOTS OF REDUNDANCY IN INSTS; CREW AND SYS. THERE IS A REASON FOR ALL THAT REDUNDANCY AND SINGLE PLT IFR WITH PARTIAL PANEL IS TRULY A HIGH WORKLOAD I DON'T WANT TO REPEAT ANY TIME SOON! TRAINING; TRAINING AND PRACTICE TRULY MAKE THE DIFFERENCE! THE INST HAD A HARD FAILURE AND WAS REPLACED LATER THAT DAY. IT HAD BEEN OVERHAULED 3 TIMES BEFORE.

Data retrieved from NASA's ASRS site as of January 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.