<< >> NASA ASRS Report 474951, June 2000

A B757-200 in cruise at FL410 diverts due to #2 engine loss of power for 5 seconds on 4 events caused by an intermittent alternator pwring the electronic fuel control.

Attributes
ACN	474951
Time
Date	200006
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : bis.airport
State Reference	ND
Altitude	msl single value : 41000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zmp.artcc tower : ord.tower
Operator	common carrier : air carrier
Make Model Name	B757-200
Operating Under FAR Part	Part 91
Navigation In Use	other
Flight Phase	cruise : level
Route In Use	enroute airway : j36.airway
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 100 flight time total : 22000 flight time type : 100
ASRS Report	474951
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument pilot : multi engine
Events
Anomaly	aircraft equipment problem : less severe other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : #2 engine n1,n2 indications other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance flight crew : diverted to another airport
Consequence	other
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

During a no passenger ferry flight, level at FL410, right engine experienced a brief loss of power for 5 seconds and recovered to normal. This occurred 4 times in a 30 min period. We decided to divert to minneapolis for maintenance. During descent and landing, the engine operated normally. I chose to not declare an emergency and divert to a nearer suitable field like far or bis because the engine was operating normally (except for the 4 brief events at cruise altitude). We did not shut down the engine or perform any abnormal procedures nor did we declare an emergency. On the ground in msp, maintenance told us the problem was most likely a bad permanent magnetic alternator in the right engine electronic engine control unit. During engine events, the engine only lost partial power -- EPR from 1.3 to 1.14 -- and was so brief as to not be noticeable except on instruments.

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Original NASA ASRS Text

Title: A B757-200 IN CRUISE AT FL410 DIVERTS DUE TO #2 ENG LOSS OF PWR FOR 5 SECONDS ON 4 EVENTS CAUSED BY AN INTERMITTENT ALTERNATOR PWRING THE ELECTRONIC FUEL CTL.

Narrative: DURING A NO PAX FERRY FLT, LEVEL AT FL410, R ENG EXPERIENCED A BRIEF LOSS OF PWR FOR 5 SECONDS AND RECOVERED TO NORMAL. THIS OCCURRED 4 TIMES IN A 30 MIN PERIOD. WE DECIDED TO DIVERT TO MINNEAPOLIS FOR MAINT. DURING DSCNT AND LNDG, THE ENG OPERATED NORMALLY. I CHOSE TO NOT DECLARE AN EMER AND DIVERT TO A NEARER SUITABLE FIELD LIKE FAR OR BIS BECAUSE THE ENG WAS OPERATING NORMALLY (EXCEPT FOR THE 4 BRIEF EVENTS AT CRUISE ALT). WE DID NOT SHUT DOWN THE ENG OR PERFORM ANY ABNORMAL PROCS NOR DID WE DECLARE AN EMER. ON THE GND IN MSP, MAINT TOLD US THE PROB WAS MOST LIKELY A BAD PERMANENT MAGNETIC ALTERNATOR IN THE R ENG ELECTRONIC ENG CTL UNIT. DURING ENG EVENTS, THE ENG ONLY LOST PARTIAL PWR -- EPR FROM 1.3 TO 1.14 -- AND WAS SO BRIEF AS TO NOT BE NOTICEABLE EXCEPT ON INSTS.

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.