PA28 pilot has a track heading deviation while en route.

Attributes
ACN	701420
Time
Date	200606
Local Time Of Day	0601 To 1200
Place
Locale Reference	navaid : pnh.vortac
State Reference	TX
Altitude	msl single value : 6000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zab.artcc
Operator	general aviation : personal
Make Model Name	PA-28 Cherokee/Archer II/Dakota/Pillan/Warrior
Operating Under FAR Part	Part 91
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	other
Function	flight crew : single pilot oversight : pic
Qualification	pilot : instrument pilot : commercial
Experience	flight time last 90 days : 80 flight time total : 720 flight time type : 600
ASRS Report	701420
Person 2
Affiliation	government : faa
Function	controller : radar
Events
Anomaly	aircraft equipment problem : less severe other spatial deviation
Independent Detector	other controllerb
Resolutory Action	controller : issued advisory controller : provided flight assist flight crew : returned to intended or assigned course flight crew : overcame equipment problem
Consequence	faa : reviewed incident with flight crew other
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance ATC Human Performance
Primary Problem	Aircraft

Narrative:

While in cruise flight level at 6000 ft MSL (on course from cds VOR to pnh VOR as assigned by ATC (ZAB) I deviated left (south) of assigned course due to loss of dry vacuum pump which caused attitude indicator to give progressively inaccurate indications and caused loss of directional gyro as well. Autoplt was flying at time and followed failing instruments resulting in a substantial deviation left of course. ATC (either ZAB or ama approach) called deviation from course to my attention via radio; after which aircraft was steered back to assigned course and continued in (no gyro) mode for normal visual approach and landing at ama. WX was cavu. No other aircraft involved. No violation of restr or prohibited airspace. Mechanical problem quickly repaired by replacement of dry vacuum pump.

Original NASA ASRS Text

Title: PA28 PLT HAS A TRACK HDG DEV WHILE ENRTE.

Narrative: WHILE IN CRUISE FLT LEVEL AT 6000 FT MSL (ON COURSE FROM CDS VOR TO PNH VOR AS ASSIGNED BY ATC (ZAB) I DEVIATED L (S) OF ASSIGNED COURSE DUE TO LOSS OF DRY VACUUM PUMP WHICH CAUSED ATTITUDE INDICATOR TO GIVE PROGRESSIVELY INACCURATE INDICATIONS AND CAUSED LOSS OF DIRECTIONAL GYRO AS WELL. AUTOPLT WAS FLYING AT TIME AND FOLLOWED FAILING INSTS RESULTING IN A SUBSTANTIAL DEV L OF COURSE. ATC (EITHER ZAB OR AMA APCH) CALLED DEV FROM COURSE TO MY ATTN VIA RADIO; AFTER WHICH ACFT WAS STEERED BACK TO ASSIGNED COURSE AND CONTINUED IN (NO GYRO) MODE FOR NORMAL VISUAL APCH AND LNDG AT AMA. WX WAS CAVU. NO OTHER ACFT INVOLVED. NO VIOLATION OF RESTR OR PROHIBITED AIRSPACE. MECHANICAL PROB QUICKLY REPAIRED BY REPLACEMENT OF DRY VACUUM PUMP.

Data retrieved from NASA's ASRS site as of January 2009 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.