<< >> NASA ASRS Report 579983, April 2003

While being vectored on an IFR training flight in IMC conditions, the flight instructor discovered they had a faulty directional gyroscope.

Attributes
ACN	579983
Time
Date	200304
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : mht.airport
State Reference	NH
Altitude	msl single value : 3500
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : mht.tracon
Operator	general aviation : instructional
Make Model Name	Cessna Aircraft Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Flight Phase	climbout : intermediate altitude
Route In Use	departure : on vectors
Flight Plan	IFR
Person 1
Affiliation	other
Function	instruction : instructor
Qualification	pilot : multi engine pilot : instrument pilot : commercial pilot : cfi
Experience	flight time last 90 days : 110 flight time total : 1640 flight time type : 138
ASRS Report	579983
Person 2
Affiliation	other
Function	instruction : trainee
Events
Anomaly	aircraft equipment problem : less severe non adherence : clearance other anomaly other other spatial deviation
Independent Detector	atc equipment other atc equipment : radar other controllera other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance flight crew : landed as precaution flight crew : took precautionary avoidance action other
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance
Primary Problem	Aircraft

Narrative:

We departed nashua (ash) on an IFR training flight to concord (con), with a climb heading of 320 degrees. Shortly after climb, the directional gyroscope began slowly rolling counterclockwise indicating a turn to the right. In response, my student turned to the left to maintain our assigned heading of 320 degrees. Climbing through about 2700 ft MSL, manchester approach assigned us a 360 degree heading for vectors to con. At this time, the directional gyroscope was indicating 320 degrees. However I noticed our direction on the GPS screen to be more westerly. Once we began turning to 360 degrees, manchester approach repeated their instruction of 360 degrees and said it looked like we turned left first. By now we were IMC level at 4000 ft MSL. I quickly crosschecked the magnetic compass, turn coordinator, and altitude indicator, also the suction gauge for a possible vacuum failure. I determined there was a problem with the directional gyroscope and reported it to manchester approach and requested an immediate descent to VMC conditions. We arrived in VMC conditions at 3000 ft MSL and canceled IFR and returned to ash. The directional gyroscope showed no signs of problems during our taxi checks or run-up. The problem wasn't evident until during flight.

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Original NASA ASRS Text

Title: WHILE BEING VECTORED ON AN IFR TRAINING FLT IN IMC CONDITIONS, THE FLT INSTRUCTOR DISCOVERED THEY HAD A FAULTY DIRECTIONAL GYROSCOPE.

Narrative: WE DEPARTED NASHUA (ASH) ON AN IFR TRAINING FLT TO CONCORD (CON), WITH A CLB HEADING OF 320 DEGS. SHORTLY AFTER CLB, THE DIRECTIONAL GYROSCOPE BEGAN SLOWLY ROLLING COUNTERCLOCKWISE INDICATING A TURN TO THE R. IN RESPONSE, MY STUDENT TURNED TO THE L TO MAINTAIN OUR ASSIGNED HEADING OF 320 DEGS. CLBING THROUGH ABOUT 2700 FT MSL, MANCHESTER APCH ASSIGNED US A 360 DEG HDG FOR VECTORS TO CON. AT THIS TIME, THE DIRECTIONAL GYROSCOPE WAS INDICATING 320 DEGS. HOWEVER I NOTICED OUR DIRECTION ON THE GPS SCREEN TO BE MORE WESTERLY. ONCE WE BEGAN TURNING TO 360 DEGS, MANCHESTER APCH REPEATED THEIR INSTRUCTION OF 360 DEGS AND SAID IT LOOKED LIKE WE TURNED L FIRST. BY NOW WE WERE IMC LEVEL AT 4000 FT MSL. I QUICKLY XCHKED THE MAGNETIC COMPASS, TURN COORDINATOR, AND ALT INDICATOR, ALSO THE SUCTION GAUGE FOR A POSSIBLE VACUUM FAILURE. I DETERMINED THERE WAS A PROB WITH THE DIRECTIONAL GYROSCOPE AND RPTED IT TO MANCHESTER APCH AND REQUESTED AN IMMEDIATE DSCNT TO VMC CONDITIONS. WE ARRIVED IN VMC CONDITIONS AT 3000 FT MSL AND CANCELED IFR AND RETURNED TO ASH. THE DIRECTIONAL GYROSCOPE SHOWED NO SIGNS OF PROBS DURING OUR TAXI CHKS OR RUN-UP. THE PROB WASN'T EVIDENT UNTIL DURING FLT.

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.