A B757-200 flight crew was informed they may have operated a flight with an improper deferral a week...

Attributes
ACN	1051508
Time
Date	201211
Local Time Of Day	0001-0600
Place
Locale Reference	ATL.Airport
State Reference	GA
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Flight Phase	Parked
Flight Plan	IFR
Component
Aircraft Component	Electrical Distribution
Person 1
Function	First Officer Pilot Flying
Experience	Flight Crew Last 90 Days 100 Flight Crew Total 9800 Flight Crew Type 3500
Person 2
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 100 Flight Crew Total 22000 Flight Crew Type 4000
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Procedural MEL Deviation - Procedural Published Material / Policy

Narrative:

I've recently been advised that I may have flown an aircraft with an improper deferral a week ago. During my cockpit pre-flight I found the stby bus light on the overhead panel on. We called maintenance and two mechanics came on board to work the problem. They found a reference to the problem in the MEL and did the MEL procedures and called; I assumed; maintenance control to verify what they had done and to receive a deferral number. Just to make sure that we had the ability to power the standby buses in the event of the loss of both engine driven generators and the APU generator we took all power off of the airplane and switched the stby batt switch to on and found that we had stby power to the items on the standby buses. We felt that we had a safe and airworthy airplane and were not aware that the deferral may have been done improperly.

Original NASA ASRS Text

Title: A B757-200 flight crew was informed they may have operated a flight with an improper deferral a week after the flight.

Narrative: I've recently been advised that I may have flown an aircraft with an improper deferral a week ago. During my cockpit pre-flight I found the STBY BUS light on the overhead panel on. We called Maintenance and two mechanics came on board to work the problem. They found a reference to the problem in the MEL and did the MEL procedures and called; I assumed; Maintenance Control to verify what they had done and to receive a deferral number. Just to make sure that we had the ability to power the standby buses in the event of the loss of both engine driven generators and the APU generator we took all power off of the airplane and switched the STBY BATT switch to ON and found that we had STBY power to the items on the standby buses. We felt that we had a safe and airworthy airplane and were not aware that the deferral may have been done improperly.

Data retrieved from NASA's ASRS site as of July 2013 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.