Partial instrument failure shortly after takeoff.

Attributes
ACN	291211
Time
Date	199412
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : alb
State Reference	NY
Altitude	agl bound lower : 300 agl bound upper : 300
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : alb
Operator	common carrier : air carrier
Make Model Name	ATR 42
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	climbout : initial
Route In Use	departure other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 100 flight time total : 4400 flight time type : 170
ASRS Report	291211
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	other flight crewa
Resolutory Action	flight crew : declared emergency flight crew : overcame equipment problem flight crew : regained aircraft control
Consequence	Other
Supplementary
Primary Problem	Aircraft

Narrative:

After takeoff from runway 1 at alb, ny, and during initial climb out below 4000 ft, the master caution light went on. A flight controls light on the cap came on. I idented a stick pusher fault and canceled the master caution. We complied with all checklists and procedures, and then called ATC. After notifying ATC we returned to the airport, the landing was uneventful. Maintenance checked the aircraft and found a bad angle of attack vane. They replaced both vanes and a test flight was accomplished. The aircraft was returned to service. Aircraft was an ATR 42. Callback conversation with reporter revealed the following: master caution light is inhibited during takeoff roll so it came on immediately after liftoff. Flight crew analyzed and idented the problem as a faulty stick pusher. It activates when the aircraft is flown close to stall speed. A mechanical force pushes the yoke forward to prevent a stall from occurring. This system would activate if the flight crew were not observing the airspeed approaching stall speed. This fault occurred because one angle of attack vane disagreed with the other. Angle of attack was replaced and the aircraft test flown and then departed for original destination.

Original NASA ASRS Text

Title: PARTIAL INST FAILURE SHORTLY AFTER TKOF.

Narrative: AFTER TKOF FROM RWY 1 AT ALB, NY, AND DURING INITIAL CLBOUT BELOW 4000 FT, THE MASTER CAUTION LIGHT WENT ON. A FLT CTLS LIGHT ON THE CAP CAME ON. I IDENTED A STICK PUSHER FAULT AND CANCELED THE MASTER CAUTION. WE COMPLIED WITH ALL CHKLISTS AND PROCS, AND THEN CALLED ATC. AFTER NOTIFYING ATC WE RETURNED TO THE ARPT, THE LNDG WAS UNEVENTFUL. MAINT CHKED THE ACFT AND FOUND A BAD ANGLE OF ATTACK VANE. THEY REPLACED BOTH VANES AND A TEST FLT WAS ACCOMPLISHED. THE ACFT WAS RETURNED TO SVC. ACFT WAS AN ATR 42. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: MASTER CAUTION LIGHT IS INHIBITED DURING TKOF ROLL SO IT CAME ON IMMEDIATELY AFTER LIFTOFF. FLC ANALYZED AND IDENTED THE PROB AS A FAULTY STICK PUSHER. IT ACTIVATES WHEN THE ACFT IS FLOWN CLOSE TO STALL SPD. A MECHANICAL FORCE PUSHES THE YOKE FORWARD TO PREVENT A STALL FROM OCCURRING. THIS SYS WOULD ACTIVATE IF THE FLC WERE NOT OBSERVING THE AIRSPD APCHING STALL SPD. THIS FAULT OCCURRED BECAUSE ONE ANGLE OF ATTACK VANE DISAGREED WITH THE OTHER. ANGLE OF ATTACK WAS REPLACED AND THE ACFT TEST FLOWN AND THEN DEPARTED FOR ORIGINAL DEST.

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.