Air carrier light transport power surging on final approach in-flight engine shutdown.

Attributes
ACN	84748
Time
Date	198803
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : dtw
State Reference	MI
Altitude	msl bound lower : 1100 msl bound upper : 1100
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : dtw
Operator	common carrier : air carrier
Make Model Name	Light Transport, High Wing, 2 Turboprop Eng
Flight Phase	descent : approach
Route In Use	approach : straight in
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : cfi pilot : commercial pilot : instrument
Experience	flight time last 90 days : 250 flight time total : 2450 flight time type : 320
ASRS Report	84748
Person 2
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	other flight crewa
Resolutory Action	flight crew : overcame equipment problem flight crew : declared emergency
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

On short final (500' AGL) power surges were noted in left engine. Torque was oscillating between 0 and 2000'/pounds. The captain immediately shut down left engine (fully feathered by 300' AGL). Mechanics were unable to reproduce problem and sent the propeller governor back for analysis to the mfr. Other company pilots have reported the problem (although with 0-1000'/pound torque oscillations) with other planes. They attributed it to a stuck autofeather arming contact in the power levers (the contact arms the automatic-feather system when the power is advanced). Their theory is that when the power was reduced, the autofeather system remained armed and our engine was cycling in and out of feather. They solved their problems in flight by jockeying the power levers and unsticking the contact. Had there been more communication among pilots our shut down may have been avoided. We may have known about a common problem and its cure. Part of the reluctance of pilots to discuss problems such as this is a paranoia of being violated whenever an incident of any type occurs.

Original NASA ASRS Text

Title: ACR LTT POWER SURGING ON FINAL APCH INFLT ENGINE SHUTDOWN.

Narrative: ON SHORT FINAL (500' AGL) PWR SURGES WERE NOTED IN LEFT ENG. TORQUE WAS OSCILLATING BTWN 0 AND 2000'/LBS. THE CAPT IMMEDIATELY SHUT DOWN LEFT ENG (FULLY FEATHERED BY 300' AGL). MECHS WERE UNABLE TO REPRODUCE PROB AND SENT THE PROP GOVERNOR BACK FOR ANALYSIS TO THE MFR. OTHER COMPANY PLTS HAVE RPTED THE PROB (ALTHOUGH WITH 0-1000'/LB TORQUE OSCILLATIONS) WITH OTHER PLANES. THEY ATTRIBUTED IT TO A STUCK AUTOFEATHER ARMING CONTACT IN THE PWR LEVERS (THE CONTACT ARMS THE AUTO-FEATHER SYS WHEN THE PWR IS ADVANCED). THEIR THEORY IS THAT WHEN THE PWR WAS REDUCED, THE AUTOFEATHER SYS REMAINED ARMED AND OUR ENG WAS CYCLING IN AND OUT OF FEATHER. THEY SOLVED THEIR PROBS IN FLT BY JOCKEYING THE PWR LEVERS AND UNSTICKING THE CONTACT. HAD THERE BEEN MORE COM AMONG PLTS OUR SHUT DOWN MAY HAVE BEEN AVOIDED. WE MAY HAVE KNOWN ABOUT A COMMON PROB AND ITS CURE. PART OF THE RELUCTANCE OF PLTS TO DISCUSS PROBS SUCH AS THIS IS A PARANOIA OF BEING VIOLATED WHENEVER AN INCIDENT OF ANY TYPE OCCURS.

Data retrieved from NASA's ASRS site as of August 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.