A B737 flight crew reports frequent failures of emergency instrument panel lighting.

Attributes
ACN	471432
Time
Date	200005
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : iad.airport
State Reference	VA
Altitude	agl single value : 0
Environment
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	ground : parked ground : preflight
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : multi engine pilot : commercial pilot : cfi pilot : atp
Experience	flight time last 90 days : 250 flight time total : 11000 flight time type : 2000
ASRS Report	471432
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : critical maintenance problem : improper maintenance non adherence : published procedure non adherence : far
Independent Detector	other flight crewa other flight crewb
Resolutory Action	none taken : detected after the fact
Consequence	other
Supplementary
Problem Areas	Cabin Crew Human Performance Flight Crew Human Performance Aircraft
Primary Problem	Flight Crew Human Performance

Narrative:

During preflight inspection we discovered an emergency cockpit illumination problem. On the B737, if normal power is lost, a standby power system will provide basic emergency functions. One of these is instrument panel lighting. Under standby power, instrument panel background flood lighting is supposed to come on at a dim level. This light has a separate ballast for the standby power function. This light worked under normal power but did not work on standby power. (It normally comes on dim during standby power.) my first officer said he had noticed several similar problems over the past few months. It is easy to miss the lights during the standby power check, and the checklist does not require specifically checking them. This could lead to a situation where if a loss of normal power occurred at night, instrument panel lighting would not be available. We briefed our fleet capts on the issue.

Original NASA ASRS Text

Title: A B737 FLC RPTS FREQUENT FAILURES OF EMER INST PANEL LIGHTING.

Narrative: DURING PREFLT INSPECTION WE DISCOVERED AN EMER COCKPIT ILLUMINATION PROB. ON THE B737, IF NORMAL PWR IS LOST, A STANDBY PWR SYS WILL PROVIDE BASIC EMER FUNCTIONS. ONE OF THESE IS INST PANEL LIGHTING. UNDER STANDBY PWR, INST PANEL BACKGROUND FLOOD LIGHTING IS SUPPOSED TO COME ON AT A DIM LEVEL. THIS LIGHT HAS A SEPARATE BALLAST FOR THE STANDBY PWR FUNCTION. THIS LIGHT WORKED UNDER NORMAL PWR BUT DID NOT WORK ON STANDBY PWR. (IT NORMALLY COMES ON DIM DURING STANDBY PWR.) MY FO SAID HE HAD NOTICED SEVERAL SIMILAR PROBS OVER THE PAST FEW MONTHS. IT IS EASY TO MISS THE LIGHTS DURING THE STANDBY PWR CHK, AND THE CHKLIST DOES NOT REQUIRE SPECIFICALLY CHKING THEM. THIS COULD LEAD TO A SIT WHERE IF A LOSS OF NORMAL PWR OCCURRED AT NIGHT, INST PANEL LIGHTING WOULD NOT BE AVAILABLE. WE BRIEFED OUR FLEET CAPTS ON THE ISSUE.

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.