DHC8 captain experiences an auto-feather at acceleration height as the electronic control unit (ecu)...

Narrative:

We took off normally; upon reaching acceleration height I (PF) called for 'flaps up; set climb power; climb checklist' the pm brought up the flaps and turned the bleeds on and max; and the ecu to mcl. As she turned the aux pump off the number one engine auto-feathered. We ran the memory action items and looking at the gauges realized what happened and ran the engine failure/fire checklist and shut the engine down. We declared an emergency with departure and asked to go back. We tried to contact dispatch a couple of times but could not reach them. We had another company aircraft in the area who was able to relay the information to dispatch. They gave us an immediate turn back to the airport for vectors to the ILS. We asked for delay vectors to finish all our checklists. Upon completion of all required checklists we informed approach we were ready to come in. They gave us vectors for the approach and we proceeded to do the single engine ILS approach. We landed normally and taxied into the ramp and shutdown with no other further incident. Not aware of why the engine auto-feathered after acceleration height.

Original NASA ASRS Text

Title: DHC8 Captain experiences an auto-feather at acceleration height as the Electronic Control Unit (ECU) is switched to Maximum Climb Power (MCL). The engine is shut down and the flight returns to the departure airport.

Narrative: We took off normally; Upon reaching acceleration height I (PF) called for 'flaps up; set climb power; climb checklist' The PM brought up the flaps and turned the bleeds on and max; and the ECU to MCL. As she turned the aux pump off the number one engine auto-feathered. We ran the memory action items and looking at the gauges realized what happened and ran the engine failure/fire checklist and shut the engine down. We declared an emergency with Departure and asked to go back. We tried to contact dispatch a couple of times but could not reach them. We had another company aircraft in the area who was able to relay the information to dispatch. They gave us an immediate turn back to the airport for vectors to the ILS. We asked for delay vectors to finish all our checklists. Upon completion of all required checklists we informed Approach we were ready to come in. They gave us vectors for the approach and we proceeded to do the single engine ILS approach. We landed normally and taxied into the ramp and shutdown with no other further incident. Not aware of why the engine auto-feathered after acceleration height.

Data retrieved from NASA's ASRS site 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	1223459
Time
Date	201412
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Aircraft 1
Make Model Name	Dash 8-200
Operating Under FAR Part	Part 121
Flight Phase	Climb
Flight Plan	IFR
Component
Aircraft Component	Propeller Autofeather System
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Critical

DHC8 captain experiences an auto-feather at acceleration height as the electronic control unit (ecu) is switched to maximum climb power (mcl). The engine is shut down and the flight returns to the departure airport.