A pc-12 flight crew departing on a maintenance ferry in marginal weather returned to their departure...

Narrative:

After deferring an ahrs B failure; the aircraft was scheduled to return to base to undergo maintenance. Prior to taxi out; the airplane was configured to have the co-pilot's side pfd utilize the pilot's side adahrs computer. Upon takeoff and just prior to passing through 1;000 AGL; both pilot and co-pilot pfds failed; displaying att fail; heading fail and various red xs on altitude and airspeed indications. There were; however; no abnormalities on the systems mfd or the situational awareness mfd. We decided to return to our departure airport. We advised tower that we required a precautionary landing due to an avionics issue and would need to keep the airport in sight. On entering left downwind; both pfds returned to normal. Turning base; both pfds reverted to failure status. Tower then issued a landing clearance and the before landing checklist was then completed. After turning onto final for runway 4L; both pfds returned to normal. A normal landing was made and the aircraft returned to the ramp uneventfully.I recommend the aircraft not be flown in IMC whenever an adahrs computer is inoperative.

Original NASA ASRS Text

Title: A PC-12 flight crew departing on a maintenance ferry in marginal weather returned to their departure airport when the one operative ADAHRS failed intermittently shortly after takeoff.

Narrative: After deferring an AHRS B failure; the aircraft was scheduled to return to base to undergo maintenance. Prior to taxi out; the airplane was configured to have the co-pilot's side PFD utilize the pilot's side ADAHRS computer. Upon takeoff and just prior to passing through 1;000 AGL; both pilot and co-pilot PFDs failed; displaying ATT FAIL; HDG FAIL and various red Xs on altitude and airspeed indications. There were; however; no abnormalities on the systems MFD or the situational awareness MFD. We decided to return to our departure airport. We advised Tower that we required a precautionary landing due to an avionics issue and would need to keep the airport in sight. On entering left downwind; both PFDs returned to normal. Turning base; both PFDs reverted to failure status. Tower then issued a landing clearance and the before landing checklist was then completed. After turning onto final for Runway 4L; both PFDs returned to normal. A normal landing was made and the aircraft returned to the ramp uneventfully.I recommend the aircraft not be flown in IMC whenever an ADAHRS computer is inoperative.

Data retrieved from NASA's ASRS site as of July 2013 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.

Attributes
ACN	1047978
Time
Date	201211
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	Marginal
Light	Daylight
Aircraft 1
Make Model Name	PC-12
Operating Under FAR Part	Part 91
Flight Phase	Initial Climb
Component
Aircraft Component	Air Data Computer
Person 1
Function	Captain Pilot Flying
Events
Anomaly	Aircraft Equipment Problem Critical Flight Deck / Cabin / Aircraft Event Other / Unknown Inflight Event / Encounter Weather / Turbulence

A pc-12 flight crew departing on a maintenance ferry in marginal weather returned to their departure airport when the one operative adahrs failed intermittently shortly after takeoff.