Narrative:

On the night of feb/xx/96, I was PIC on a scheduled freight run into helena, mt. The WX at hln was fairly decent, 1500 ft overcast, 7 mi and snow. There was a front passing through and flight service called for occasional light to moderate icing from the surface to 16000 ft. ZLC handed me off to hln approach. I was cleared to hauser NDB via the 15 mi arc at 13000 ft. As I started to intercept the arc, I was cleared for the ILS runway 27 approach at hln. At this point, ice began to build on the aircraft at an alarming rate to the point that I was having to maintain cruise power to hold the GS. I was also experiencing the worst st elmo's fire I have ever seen. The left engine encountered induction icing and began to quit, also the GS began to become intermittent and flag. I had tried to boot the ice off the wings but to no avail. I decided to break off the approach and intercept victor 247 which I had been on before receiving approach clearance because I know the route was VFR to the east 20 DME. It was sometime during the intercept to victor 247 that I managed to get the left engine back to full power by pulling the alternate air door. I was talking to approach all of the way but there was some misunderstanding about altitude and position, I also failed to declare an emergency which I should have. I was not the only one to have problems. 2 other aircraft declared emergencys. I feel I made the best possible decision by turning around and leaving the area. The ILS runway 27 approach into hln is well known for pockets of severe icing. With the static electricity affecting the navigation radios, I had begun to doubt my situational awareness. The left engine was probably only making 35-40 percent power, and I felt with the moderate to severe turbulence involved with the passage of this front, continuation of the approach would produce disastrous results. I feel this situation was caused by unforecast severe icing conditions and may not have been prevented but the danger was intensified by hln not having radar. If radar would have been in place at hln there would not have been a doubt to the controllers of my position at any time. I also failed to declare an emergency, which should have been the first thing that happened before I deviated back to VFR conditions. In my mind, I made the right moves because I had began to doubt myself and equipment. Hln is surrounded by mountainous terrain and is not a place to doubt one's equipment. I should have been in better contact with ATC. I was overloaded with emergencys and too busy to let ATC know I was in trouble.

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Original NASA ASRS Text

Title: PLT OF AN ATX TWIN MADE A MISSED APCH AND TURNED BACK TO VFR CONDITIONS AFTER LOSING PWR ON 1 ENG DUE TO ICE AND NOTICING THE EFFECTS OF ICE ON THE ACFT. HOWEVER, HE FAILED TO NOTIFY ATC OF HIS ABANDONMENT OF HIS APCH AND CHANGE IN DIRECTION OR EMER STATUS.

Narrative: ON THE NIGHT OF FEB/XX/96, I WAS PIC ON A SCHEDULED FREIGHT RUN INTO HELENA, MT. THE WX AT HLN WAS FAIRLY DECENT, 1500 FT OVCST, 7 MI AND SNOW. THERE WAS A FRONT PASSING THROUGH AND FLT SVC CALLED FOR OCCASIONAL LIGHT TO MODERATE ICING FROM THE SURFACE TO 16000 FT. ZLC HANDED ME OFF TO HLN APCH. I WAS CLRED TO HAUSER NDB VIA THE 15 MI ARC AT 13000 FT. AS I STARTED TO INTERCEPT THE ARC, I WAS CLRED FOR THE ILS RWY 27 APCH AT HLN. AT THIS POINT, ICE BEGAN TO BUILD ON THE ACFT AT AN ALARMING RATE TO THE POINT THAT I WAS HAVING TO MAINTAIN CRUISE PWR TO HOLD THE GS. I WAS ALSO EXPERIENCING THE WORST ST ELMO'S FIRE I HAVE EVER SEEN. THE L ENG ENCOUNTERED INDUCTION ICING AND BEGAN TO QUIT, ALSO THE GS BEGAN TO BECOME INTERMITTENT AND FLAG. I HAD TRIED TO BOOT THE ICE OFF THE WINGS BUT TO NO AVAIL. I DECIDED TO BREAK OFF THE APCH AND INTERCEPT VICTOR 247 WHICH I HAD BEEN ON BEFORE RECEIVING APCH CLRNC BECAUSE I KNOW THE RTE WAS VFR TO THE E 20 DME. IT WAS SOMETIME DURING THE INTERCEPT TO VICTOR 247 THAT I MANAGED TO GET THE L ENG BACK TO FULL PWR BY PULLING THE ALTERNATE AIR DOOR. I WAS TALKING TO APCH ALL OF THE WAY BUT THERE WAS SOME MISUNDERSTANDING ABOUT ALT AND POS, I ALSO FAILED TO DECLARE AN EMER WHICH I SHOULD HAVE. I WAS NOT THE ONLY ONE TO HAVE PROBS. 2 OTHER ACFT DECLARED EMERS. I FEEL I MADE THE BEST POSSIBLE DECISION BY TURNING AROUND AND LEAVING THE AREA. THE ILS RWY 27 APCH INTO HLN IS WELL KNOWN FOR POCKETS OF SEVERE ICING. WITH THE STATIC ELECTRICITY AFFECTING THE NAV RADIOS, I HAD BEGUN TO DOUBT MY SITUATIONAL AWARENESS. THE L ENG WAS PROBABLY ONLY MAKING 35-40 PERCENT PWR, AND I FELT WITH THE MODERATE TO SEVERE TURB INVOLVED WITH THE PASSAGE OF THIS FRONT, CONTINUATION OF THE APCH WOULD PRODUCE DISASTROUS RESULTS. I FEEL THIS SIT WAS CAUSED BY UNFORECAST SEVERE ICING CONDITIONS AND MAY NOT HAVE BEEN PREVENTED BUT THE DANGER WAS INTENSIFIED BY HLN NOT HAVING RADAR. IF RADAR WOULD HAVE BEEN IN PLACE AT HLN THERE WOULD NOT HAVE BEEN A DOUBT TO THE CTLRS OF MY POS AT ANY TIME. I ALSO FAILED TO DECLARE AN EMER, WHICH SHOULD HAVE BEEN THE FIRST THING THAT HAPPENED BEFORE I DEVIATED BACK TO VFR CONDITIONS. IN MY MIND, I MADE THE RIGHT MOVES BECAUSE I HAD BEGAN TO DOUBT MYSELF AND EQUIP. HLN IS SURROUNDED BY MOUNTAINOUS TERRAIN AND IS NOT A PLACE TO DOUBT ONE'S EQUIP. I SHOULD HAVE BEEN IN BETTER CONTACT WITH ATC. I WAS OVERLOADED WITH EMERS AND TOO BUSY TO LET ATC KNOW I WAS IN TROUBLE.

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.