AT72 experiences unwanted propeller autofeather during descent in hrl airspace.

Attributes
ACN	426719
Time
Date	199901
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : hrl
State Reference	TX
Altitude	msl bound lower : 14000 msl bound upper : 14000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	ATR 72
Navigation In Use	Other
Flight Phase	descent other
Route In Use	arrival other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial
Experience	flight time last 90 days : 210 flight time total : 2400 flight time type : 640
ASRS Report	426719
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	other flight crewa
Resolutory Action	aircraft : equipment problem dissipated
Consequence	Other

Narrative:

In the descent from FL240 to 2000 ft at approximately 14000 ft, the #1 engine eec faulted and the #1 propeller feathered. The power was approximately 50-55% at the time and airspeed was approximately 240 KIAS -- smooth ride no turbulence. We ran the QRH for the eec, but it would not reset. We tried several times to unfeather the propeller, but it would not. (The engine was running at idle.) we decided to level off at 5000 ft and hold to call company and research the problem. I was flying and the captain was running the checklists. After 1 turn in the hold, the company and we decided the appropriate measures were to land the aircraft with the propeller feathered. At that time the engine spooled up and the propeller unfeathered by itself. We landed with no mishap. Callback conversation with reporter revealed the following information: the reporter stated that, following this incident the engine, propeller assembly, and autofeather computer were replaced, but the same problem occurred on subsequent test flts. Maintenance finally located the source of the problem in a wiring bundle behind the baggage compartment. To his knowledge, no other similar incidents have occurred on the AT72.

Original NASA ASRS Text

Title: AT72 EXPERIENCES UNWANTED PROP AUTOFEATHER DURING DSCNT IN HRL AIRSPACE.

Narrative: IN THE DSCNT FROM FL240 TO 2000 FT AT APPROX 14000 FT, THE #1 ENG EEC FAULTED AND THE #1 PROP FEATHERED. THE PWR WAS APPROX 50-55% AT THE TIME AND AIRSPD WAS APPROX 240 KIAS -- SMOOTH RIDE NO TURB. WE RAN THE QRH FOR THE EEC, BUT IT WOULD NOT RESET. WE TRIED SEVERAL TIMES TO UNFEATHER THE PROP, BUT IT WOULD NOT. (THE ENG WAS RUNNING AT IDLE.) WE DECIDED TO LEVEL OFF AT 5000 FT AND HOLD TO CALL COMPANY AND RESEARCH THE PROB. I WAS FLYING AND THE CAPT WAS RUNNING THE CHKLISTS. AFTER 1 TURN IN THE HOLD, THE COMPANY AND WE DECIDED THE APPROPRIATE MEASURES WERE TO LAND THE ACFT WITH THE PROP FEATHERED. AT THAT TIME THE ENG SPOOLED UP AND THE PROP UNFEATHERED BY ITSELF. WE LANDED WITH NO MISHAP. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THAT, FOLLOWING THIS INCIDENT THE ENG, PROP ASSEMBLY, AND AUTOFEATHER COMPUTER WERE REPLACED, BUT THE SAME PROB OCCURRED ON SUBSEQUENT TEST FLTS. MAINT FINALLY LOCATED THE SOURCE OF THE PROB IN A WIRING BUNDLE BEHIND THE BAGGAGE COMPARTMENT. TO HIS KNOWLEDGE, NO OTHER SIMILAR INCIDENTS HAVE OCCURRED ON THE AT72.

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.