Narrative:

While en route on victor 8 at an assigned altitude of 16000' MSL on an instrument flight plan in instrument conditions, I experienced intermittent loss of radio communications with the den ARTCC. The effect of the radio problem was to completely mask incoming voice with an extremely loud static noise which I was unable to reduce with manipulation of the vol control on the radios--each episode would last for about 1 minute, then slack off for about 10-20 seconds and then return to a loud noise. I was not in radar contact at that time and in order to inform ATC I was experiencing radio problem I switched my transponder from my assigned code to 7700. As I flew out of the area of precipitation I was able to re-establish communications with ATC and advised them of the static problem was the reason for the 7700 code. As ATC was replying a flew back into snow precipitation and the loud static noise returned. I switched the transponder to code 7600. Upon resumption of communication a few mins later, ATC asked me to continue squawk of 7700 and asked my intention. I requested a vector to the nearest airport and after determining which airports were free of thunderstorms I accepted a routing to meeker airport. I dodged a # of thunderstorms en route west/O further communication problems and was able to make my approach in VFR conditions. Ground examination revealed no apparent problems with the radios. A phone call to the avionics firm that installed the radios, offered the opinion the problem was caused by atmospheric conditions which could result in the creation of precipitation static on the VOR receiving antenna. This induced static build-up is then transmitted throughout the rest of the radio circuitry. In the 6 yrs I have been flying with these radios I had never experienced this problem before. The avionics shop suggested the installation of static wicks and a different style VOR antenna. I have ordered high grade wicks and they will be installed upon receipt. After this experience I feel more emphasis should be placed on a requirement to install anti-static devices on airplanes which are certified for flight into actual instrument conditions.

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Original NASA ASRS Text

Title: PLT OF SMA LOST RADIO COM IN PRECIPITATION CONDITION.

Narrative: WHILE ENRTE ON VICTOR 8 AT AN ASSIGNED ALT OF 16000' MSL ON AN INSTRUMENT FLT PLAN IN INSTRUMENT CONDITIONS, I EXPERIENCED INTERMITTENT LOSS OF RADIO COMS WITH THE DEN ARTCC. THE EFFECT OF THE RADIO PROB WAS TO COMPLETELY MASK INCOMING VOICE WITH AN EXTREMELY LOUD STATIC NOISE WHICH I WAS UNABLE TO REDUCE WITH MANIPULATION OF THE VOL CTL ON THE RADIOS--EACH EPISODE WOULD LAST FOR ABOUT 1 MINUTE, THEN SLACK OFF FOR ABOUT 10-20 SECS AND THEN RETURN TO A LOUD NOISE. I WAS NOT IN RADAR CONTACT AT THAT TIME AND IN ORDER TO INFORM ATC I WAS EXPERIENCING RADIO PROB I SWITCHED MY XPONDER FROM MY ASSIGNED CODE TO 7700. AS I FLEW OUT OF THE AREA OF PRECIPITATION I WAS ABLE TO RE-ESTABLISH COMS WITH ATC AND ADVISED THEM OF THE STATIC PROB WAS THE REASON FOR THE 7700 CODE. AS ATC WAS REPLYING A FLEW BACK INTO SNOW PRECIPITATION AND THE LOUD STATIC NOISE RETURNED. I SWITCHED THE XPONDER TO CODE 7600. UPON RESUMPTION OF COM A FEW MINS LATER, ATC ASKED ME TO CONTINUE SQUAWK OF 7700 AND ASKED MY INTENTION. I REQUESTED A VECTOR TO THE NEAREST ARPT AND AFTER DETERMINING WHICH ARPTS WERE FREE OF TSTMS I ACCEPTED A ROUTING TO MEEKER ARPT. I DODGED A # OF TSTMS ENRTE W/O FURTHER COM PROBS AND WAS ABLE TO MAKE MY APCH IN VFR CONDITIONS. GND EXAMINATION REVEALED NO APPARENT PROBS WITH THE RADIOS. A PHONE CALL TO THE AVIONICS FIRM THAT INSTALLED THE RADIOS, OFFERED THE OPINION THE PROB WAS CAUSED BY ATMOSPHERIC CONDITIONS WHICH COULD RESULT IN THE CREATION OF PRECIPITATION STATIC ON THE VOR RECEIVING ANTENNA. THIS INDUCED STATIC BUILD-UP IS THEN XMITTED THROUGHOUT THE REST OF THE RADIO CIRCUITRY. IN THE 6 YRS I HAVE BEEN FLYING WITH THESE RADIOS I HAD NEVER EXPERIENCED THIS PROB BEFORE. THE AVIONICS SHOP SUGGESTED THE INSTALLATION OF STATIC WICKS AND A DIFFERENT STYLE VOR ANTENNA. I HAVE ORDERED HIGH GRADE WICKS AND THEY WILL BE INSTALLED UPON RECEIPT. AFTER THIS EXPERIENCE I FEEL MORE EMPHASIS SHOULD BE PLACED ON A REQUIREMENT TO INSTALL ANTI-STATIC DEVICES ON AIRPLANES WHICH ARE CERTIFIED FOR FLT INTO ACTUAL INSTRUMENT CONDITIONS.

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