DC9 crew had uncommanded flap extension, during cruise.

Attributes
ACN	413116
Time
Date	199808
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : eck
State Reference	MI
Altitude	msl bound lower : 33000 msl bound upper : 33000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zob
Operator	common carrier : air carrier
Make Model Name	DC-9 30
Flight Phase	cruise other other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : commercial pilot : atp
Experience	flight time last 90 days : 200 flight time total : 6000 flight time type : 1200
ASRS Report	413116
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : overcame equipment problem other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

In cruise at FL330 after about 30-45 mins, I noticed that it was taking significantly more power (+.10 EPR) to remain at cruise mach (mach .75) than scheduled. I noted that the flap indicator showed 5 degrees flap extension, handle up, slats retracted. I sent the first officer back to visually check flap position and he reported that the flaps appeared to be extended 5 degrees. I then went back to see, and also felt they were extended to at or near 5 degrees. I requested a lower altitude from ATC and was cleared initially to FL250. I kept the airspeed as low as safely possible during descent until we reached an altitude where the flap/mach airspeed limits were no longer exceeded. We initiated a divert into dtw. At 12000 ft, I noted that the flaps appeared to have retracted on their own. At no time did we move the handle out of the 'up' detent during this event. On approach, landing and taxi in, the flaps extended and retracted normally. The DC9 has old, electro-mechanical type flap indicators and it is common for these to not read 'exactly' on the selected flap position. Most DC9 pilots learn to ignore indications up to several degrees off of what is selected. If extra power had not been required (and my suspicions raised) I might not have noted the 5 degree indication at all as being abnormal.

Original NASA ASRS Text

Title: DC9 CREW HAD UNCOMMANDED FLAP EXTENSION, DURING CRUISE.

Narrative: IN CRUISE AT FL330 AFTER ABOUT 30-45 MINS, I NOTICED THAT IT WAS TAKING SIGNIFICANTLY MORE PWR (+.10 EPR) TO REMAIN AT CRUISE MACH (MACH .75) THAN SCHEDULED. I NOTED THAT THE FLAP INDICATOR SHOWED 5 DEGS FLAP EXTENSION, HANDLE UP, SLATS RETRACTED. I SENT THE FO BACK TO VISUALLY CHK FLAP POS AND HE RPTED THAT THE FLAPS APPEARED TO BE EXTENDED 5 DEGS. I THEN WENT BACK TO SEE, AND ALSO FELT THEY WERE EXTENDED TO AT OR NEAR 5 DEGS. I REQUESTED A LOWER ALT FROM ATC AND WAS CLRED INITIALLY TO FL250. I KEPT THE AIRSPD AS LOW AS SAFELY POSSIBLE DURING DSCNT UNTIL WE REACHED AN ALT WHERE THE FLAP/MACH AIRSPD LIMITS WERE NO LONGER EXCEEDED. WE INITIATED A DIVERT INTO DTW. AT 12000 FT, I NOTED THAT THE FLAPS APPEARED TO HAVE RETRACTED ON THEIR OWN. AT NO TIME DID WE MOVE THE HANDLE OUT OF THE 'UP' DETENT DURING THIS EVENT. ON APCH, LNDG AND TAXI IN, THE FLAPS EXTENDED AND RETRACTED NORMALLY. THE DC9 HAS OLD, ELECTRO-MECHANICAL TYPE FLAP INDICATORS AND IT IS COMMON FOR THESE TO NOT READ 'EXACTLY' ON THE SELECTED FLAP POS. MOST DC9 PLTS LEARN TO IGNORE INDICATIONS UP TO SEVERAL DEGS OFF OF WHAT IS SELECTED. IF EXTRA PWR HAD NOT BEEN REQUIRED (AND MY SUSPICIONS RAISED) I MIGHT NOT HAVE NOTED THE 5 DEG INDICATION AT ALL AS BEING ABNORMAL.

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.