Pilot of a C425 turboprop exceeded the maximum airspeed at or below 2500 ft, within a 4 mi radius of an airport, when he increased the aircraft airspeed to compensate for loss of indicated airspeed because of an iced over pitot tube. The pilot's pitot tube heat had failed.

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Attributes
ACN	363838
Time
Date	199703
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : ord
State Reference	IL
Altitude	msl bound lower : 850 msl bound upper : 2100
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : ord tower : phx
Operator	general aviation : corporate
Make Model Name	Corsair
Operating Under FAR Part	Part 91
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	other other : other pilot : atp pilot : cfi pilot : commercial pilot : instrument
Experience	flight time last 90 days : 100 flight time total : 7200
ASRS Report	363838
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	aircraft equipment problem : less severe inflight encounter : weather non adherence : far other anomaly other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course flight crew : overcame equipment problem
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

Assigned 170 KTS on radar vectors to ILS runway 27L ord. Ord wind 290 degrees, 25 KTS, gusting to 35 KTS. LLWS advisories. LLWS reported by several aircraft. I was following a B757, descending through overcast layer with light icing. As I entered the overcast on the GS, the airspeed began to drop slowly. Increased power to recover airspeed. Airspeed stabilized, then dropped again 10 KTS. Assuming wake turbulence or windshear, I increased power to recover again. Airspeed stabilized then dropped another 10 KTS. Now indicating 30 KTS slow, increased power, checked confign and ice, no ice on wings. Checked copilot IAS, now 220 KTS. Pilot's pitot heat had failed and ice blocked. Recovered airspeed to assigned. Landing uneventful. This occurred in only 2 or 3 mins. I was expecting to see airspeed deviations due to wake turbulence or windshear. Assumed that was the case, when actually pitot heat failed at very inconvenient time, on ILS, in IMC, light icing conditions. Including copilot instruments in scan (we fly single pilot) or using a copilot would have caught the discrepancy sooner.

Original NASA ASRS Text

Title: PLT OF A C425 TURBOPROP EXCEEDED THE MAX AIRSPD AT OR BELOW 2500 FT, WITHIN A 4 MI RADIUS OF AN ARPT, WHEN HE INCREASED THE ACFT AIRSPD TO COMPENSATE FOR LOSS OF INDICATED AIRSPD BECAUSE OF AN ICED OVER PITOT TUBE. THE PLT'S PITOT TUBE HEAT HAD FAILED.

Narrative: ASSIGNED 170 KTS ON RADAR VECTORS TO ILS RWY 27L ORD. ORD WIND 290 DEGS, 25 KTS, GUSTING TO 35 KTS. LLWS ADVISORIES. LLWS RPTED BY SEVERAL ACFT. I WAS FOLLOWING A B757, DSNDING THROUGH OVCST LAYER WITH LIGHT ICING. AS I ENTERED THE OVCST ON THE GS, THE AIRSPD BEGAN TO DROP SLOWLY. INCREASED PWR TO RECOVER AIRSPD. AIRSPD STABILIZED, THEN DROPPED AGAIN 10 KTS. ASSUMING WAKE TURB OR WINDSHEAR, I INCREASED PWR TO RECOVER AGAIN. AIRSPD STABILIZED THEN DROPPED ANOTHER 10 KTS. NOW INDICATING 30 KTS SLOW, INCREASED PWR, CHKED CONFIGN AND ICE, NO ICE ON WINGS. CHKED COPLT IAS, NOW 220 KTS. PLT'S PITOT HEAT HAD FAILED AND ICE BLOCKED. RECOVERED AIRSPD TO ASSIGNED. LNDG UNEVENTFUL. THIS OCCURRED IN ONLY 2 OR 3 MINS. I WAS EXPECTING TO SEE AIRSPD DEVS DUE TO WAKE TURB OR WINDSHEAR. ASSUMED THAT WAS THE CASE, WHEN ACTUALLY PITOT HEAT FAILED AT VERY INCONVENIENT TIME, ON ILS, IN IMC, LIGHT ICING CONDITIONS. INCLUDING COPLT INSTS IN SCAN (WE FLY SINGLE PLT) OR USING A COPLT WOULD HAVE CAUGHT THE DISCREPANCY SOONER.

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.