An A319's captain seat horizontal control switch was MEL'ed but the circuit breaker not pulled. Duri...

Attributes
ACN	794926
Time
Date	200807
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	agl single value : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : zzz.tower
Operator	common carrier : air carrier
Make Model Name	A319
Operating Under FAR Part	Part 121
Flight Phase	ground : taxi
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	794926
Events
Anomaly	aircraft equipment problem : less severe maintenance problem : improper maintenance
Independent Detector	other flight crewa
Resolutory Action	none taken : unable
Supplementary
Problem Areas	Chart Or Publication Maintenance Human Performance Aircraft
Primary Problem	Aircraft

Narrative:

During taxi I experienced an uncommanded electric motor movement of the captain's seat. My seat moved; uncommanded; to the full aft and outboard position. We located and opened the captain's seat control circuit breaker. The captain's seat horizontal electric control was on MEL as a result of being written up as inoperative. This was a result of the horizontal control switch failing. The switch would not work in the forward position and would not center to off when in the aft position. Either vibration or perhaps my movements in the seat would cause the switch to move to the aft position. At present there is no requirement to open the seat control circuit breaker when any part or the seat electric control system is on MEL. Considering the ramifications of uncommanded seat movement it may be prudent to require collaring the seat control circuit breaker anytime the electric system is placed on MEL.

Original NASA ASRS Text

Title: AN A319'S CAPT SEAT HORIZONTAL CONTROL SWITCH WAS MEL'ED BUT THE CIRCUIT BREAKER NOT PULLED. DURING TAXI THE SEAT MOVED FULL AFT AND OUT; UNCOMMANDED.

Narrative: DURING TAXI I EXPERIENCED AN UNCOMMANDED ELECTRIC MOTOR MOVEMENT OF THE CAPT'S SEAT. MY SEAT MOVED; UNCOMMANDED; TO THE FULL AFT AND OUTBOARD POS. WE LOCATED AND OPENED THE CAPT'S SEAT CTL CIRCUIT BREAKER. THE CAPT'S SEAT HORIZ ELECTRIC CTL WAS ON MEL AS A RESULT OF BEING WRITTEN UP AS INOP. THIS WAS A RESULT OF THE HORIZ CTL SWITCH FAILING. THE SWITCH WOULD NOT WORK IN THE FORWARD POS AND WOULD NOT CTR TO OFF WHEN IN THE AFT POS. EITHER VIBRATION OR PERHAPS MY MOVEMENTS IN THE SEAT WOULD CAUSE THE SWITCH TO MOVE TO THE AFT POS. AT PRESENT THERE IS NO REQUIREMENT TO OPEN THE SEAT CTL CIRCUIT BREAKER WHEN ANY PART OR THE SEAT ELECTRIC CTL SYS IS ON MEL. CONSIDERING THE RAMIFICATIONS OF UNCOMMANDED SEAT MOVEMENT IT MAY BE PRUDENT TO REQUIRE COLLARING THE SEAT CTL CIRCUIT BREAKER ANYTIME THE ELECTRIC SYS IS PLACED ON MEL.

Data retrieved from NASA's ASRS site as of May 2009 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.

An A319's captain seat horizontal control switch was MEL'ed but the circuit breaker not pulled. During taxi the seat moved full aft and out; uncommanded.