C414A aircraft encountered light icing in cruise. Reporter pilot had to use alternate air on the rig...

Attributes
ACN	363770
Time
Date	199703
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : zid
State Reference	IN
Altitude	msl bound lower : 13000 msl bound upper : 13000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Operator	general aviation : corporate
Make Model Name	Chancellor 414A & C414
Operating Under FAR Part	Part 91
Flight Phase	cruise other
Route In Use	enroute airway : zid
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : commercial pilot : instrument
Experience	flight time last 90 days : 15 flight time total : 10000 flight time type : 1300
ASRS Report	363770
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Events
Anomaly	inflight encounter : weather
Independent Detector	other flight crewa
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	Weather
Air Traffic Incident	other

Narrative:

Going from cgi-crp, WX briefing for thunder showers and moderate icing. Flying a C44A with full deicing and anti- icing. Cruising at 13000 ft and picking up a light amount of mixed on the lower part of the leading edge but with one oddity -- ice forming just above the stall warning sensor on the left wing. This ice was streaming back the leading edge. I assume this was from the heated stall warning although I had never seen this in any aircraft I have flown in 55 yrs. With the small amount of ice on the leading edge, I lost about 7 mi of IAS. Again odd. Then I started losing manifold pressure on right engine (left engine ok). Advanced throttle and mixture -- no help. Oh oh, intake is icing up, went to alternate air. Manifold pressure recovered and I went on my merry way. Not enough ice to use the boots and air inversion finally dissipated the wing ice, closed the alternate air and had ok manifold pressure. In thousands of hours of flying, I have never had to use alternate air or had a loss of that much IAS with so little wing ice. With the ice streaming back from the stall warning, I suspect I was picking it up on the lower part of the wing. Fly long enough, and you'll run into most everything.

Original NASA ASRS Text

Title: C414A ACFT ENCOUNTERED LIGHT ICING IN CRUISE. RPTR PLT HAD TO USE ALTERNATE AIR ON THE R ENG WHEN THE MANIFOLD PRESSURE STARTED DECREASING, BUT DID NOT USE WING ANTI- ICE BECAUSE THERE WAS NOT ENOUGH BUILDUP. TEMP INVERSION EVENTUALLY MELTED THE ICE.

Narrative: GOING FROM CGI-CRP, WX BRIEFING FOR THUNDER SHOWERS AND MODERATE ICING. FLYING A C44A WITH FULL DEICING AND ANTI- ICING. CRUISING AT 13000 FT AND PICKING UP A LIGHT AMOUNT OF MIXED ON THE LOWER PART OF THE LEADING EDGE BUT WITH ONE ODDITY -- ICE FORMING JUST ABOVE THE STALL WARNING SENSOR ON THE L WING. THIS ICE WAS STREAMING BACK THE LEADING EDGE. I ASSUME THIS WAS FROM THE HEATED STALL WARNING ALTHOUGH I HAD NEVER SEEN THIS IN ANY ACFT I HAVE FLOWN IN 55 YRS. WITH THE SMALL AMOUNT OF ICE ON THE LEADING EDGE, I LOST ABOUT 7 MI OF IAS. AGAIN ODD. THEN I STARTED LOSING MANIFOLD PRESSURE ON R ENG (L ENG OK). ADVANCED THROTTLE AND MIXTURE -- NO HELP. OH OH, INTAKE IS ICING UP, WENT TO ALTERNATE AIR. MANIFOLD PRESSURE RECOVERED AND I WENT ON MY MERRY WAY. NOT ENOUGH ICE TO USE THE BOOTS AND AIR INVERSION FINALLY DISSIPATED THE WING ICE, CLOSED THE ALTERNATE AIR AND HAD OK MANIFOLD PRESSURE. IN THOUSANDS OF HRS OF FLYING, I HAVE NEVER HAD TO USE ALTERNATE AIR OR HAD A LOSS OF THAT MUCH IAS WITH SO LITTLE WING ICE. WITH THE ICE STREAMING BACK FROM THE STALL WARNING, I SUSPECT I WAS PICKING IT UP ON THE LOWER PART OF THE WING. FLY LONG ENOUGH, AND YOU'LL RUN INTO MOST EVERYTHING.

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.

C414A aircraft encountered light icing in cruise. Reporter pilot had to use alternate air on the right engine when the manifold pressure started decreasing, but did not use wing anti- ice because there was not enough buildup. Temperature inversion eventually melted the ice.