Private small aircraft experiences airspeed and vsi instrument problems while IMC.

Attributes
ACN	170385
Time
Date	199102
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : ind
State Reference	IN
Altitude	msl bound lower : 4000 msl bound upper : 4000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : ind
Operator	general aviation : personal
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Fixed Gear
Flight Phase	descent : approach descent other landing other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : atp pilot : cfi
Experience	flight time last 90 days : 70 flight time total : 3770 flight time type : 15
ASRS Report	170385
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	aircraft equipment problem : critical altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	other controllera other flight crewa
Resolutory Action	flight crew : declared emergency other other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

Takeoff out of tell city to ind. Before takeoff, I preflted checking pitot heat by the increase in amps. Flew up at 7000' (on top) descended for approach, turned on pitot heat cleared to 4000'. While descending, the altimeter and vsi were jumping, plus and minus 2000' on the vsi, so I turned on alternate static source. After turning it on realized the altimeter was 400' low so I started climbing. The controller mentioned 'maintain 4000'.' 2 mins later, lost airspeed. I informed the controller. She gave me priority and vectored me for the approach. It (altimeter) then appeared to be working, but when I landed it stayed at 80 KT. I took the airplane to a mechanic and had it repaired finding a broken power wire and the pitot tube plugged up with what appeared to be rubber. The mechanic removed it, reinstalled the pitot tube and I flew home.

Original NASA ASRS Text

Title: PVT SMA EXPERIENCES AIRSPEED AND VSI INSTRUMENT PROBLEMS WHILE IMC.

Narrative: TKOF OUT OF TELL CITY TO IND. BEFORE TKOF, I PREFLTED CHKING PITOT HEAT BY THE INCREASE IN AMPS. FLEW UP AT 7000' (ON TOP) DSNDED FOR APCH, TURNED ON PITOT HEAT CLRED TO 4000'. WHILE DSNDING, THE ALTIMETER AND VSI WERE JUMPING, PLUS AND MINUS 2000' ON THE VSI, SO I TURNED ON ALTERNATE STATIC SOURCE. AFTER TURNING IT ON REALIZED THE ALTIMETER WAS 400' LOW SO I STARTED CLBING. THE CTLR MENTIONED 'MAINTAIN 4000'.' 2 MINS LATER, LOST AIRSPD. I INFORMED THE CTLR. SHE GAVE ME PRIORITY AND VECTORED ME FOR THE APCH. IT (ALTIMETER) THEN APPEARED TO BE WORKING, BUT WHEN I LANDED IT STAYED AT 80 KT. I TOOK THE AIRPLANE TO A MECH AND HAD IT REPAIRED FINDING A BROKEN PWR WIRE AND THE PITOT TUBE PLUGGED UP WITH WHAT APPEARED TO BE RUBBER. THE MECH REMOVED IT, REINSTALLED THE PITOT TUBE AND I FLEW HOME.

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.