A B737-300 PA switch on the captain's yoke was wired incorrectly causing PA system to malfunction.

Attributes
ACN	522539
Time
Date	200108
Day	Mon
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	agl single value : 0
Aircraft 1
Controlling Facilities	tracon : bwi.tracon
Operator	common carrier : air carrier
Make Model Name	B737-300
Flight Phase	ground : maintenance
Person 1
Affiliation	company : air carrier
Function	maintenance : technician
Qualification	technician : powerplant technician : airframe
Experience	maintenance technician : 12
ASRS Report	522539
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical maintenance problem : improper maintenance maintenance problem : improper documentation non adherence : published procedure non adherence : far
Independent Detector	other flight crewa
Resolutory Action	none taken : detected after the fact
Consequence	other
Factors
Maintenance	contributing factor : schedule pressure performance deficiency : logbook entry performance deficiency : testing performance deficiency : repair
Supplementary
Problem Areas	Maintenance Human Performance Aircraft
Primary Problem	Maintenance Human Performance

Narrative:

On aug/mon/01, I changed a PA microphone switch on the captain's yoke. After changing this switch I checked the PA system from captain's boom microphone. It appeared to work normally. I did not check the other microphone switch. On aug/tue/01, the crew found the PA to be hot all the time and the other microphone switch inoperative. It was discovered that I had inadvertently hooked 2 wires up wrong on the terminals. The mistake was corrected and the aircraft was dispatched without further difficulties. I hooked the wire up on the switch as they were on the old switch. 1 wire was disconnected and not labeled. I consulted procedures and thought I hooked it up correctly. I did not know of the problem until the following evening.

Original NASA ASRS Text

Title: A B737-300 PA SWITCH ON THE CAPT'S YOKE WAS WIRED INCORRECTLY CAUSING PA SYS TO MALFUNCTION.

Narrative: ON AUG/MON/01, I CHANGED A PA MIKE SWITCH ON THE CAPT'S YOKE. AFTER CHANGING THIS SWITCH I CHKED THE PA SYS FROM CAPT'S BOOM MIKE. IT APPEARED TO WORK NORMALLY. I DID NOT CHK THE OTHER MIKE SWITCH. ON AUG/TUE/01, THE CREW FOUND THE PA TO BE HOT ALL THE TIME AND THE OTHER MIKE SWITCH INOP. IT WAS DISCOVERED THAT I HAD INADVERTENTLY HOOKED 2 WIRES UP WRONG ON THE TERMINALS. THE MISTAKE WAS CORRECTED AND THE ACFT WAS DISPATCHED WITHOUT FURTHER DIFFICULTIES. I HOOKED THE WIRE UP ON THE SWITCH AS THEY WERE ON THE OLD SWITCH. 1 WIRE WAS DISCONNECTED AND NOT LABELED. I CONSULTED PROCS AND THOUGHT I HOOKED IT UP CORRECTLY. I DID NOT KNOW OF THE PROB UNTIL THE FOLLOWING EVENING.

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.