Service difficulty report · Odor · Boeing 747422

Difficulty date
April 23, 2005
Submitted
May 3, 2005
Operation
Air carrier
Aircraft
N199UA
Make and model
Boeing 747422
Aircraft serial
28717
Aircraft time
30,407 hours, 3,784 cycles
Engine
Pwa PW4056
Part
Odor
Condition
Detected
Location
Cabin
Stage of operation
CR
How discovered
O
Nature of condition
B
Precautionary procedure
A, H

As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.

What was found

CREW ODOR IN CABIN, NOTICED IN AFT CREW REST AREA, SULPHUR LIKE SMELL. CHILLERS SHUT OFF, RECIRCS SHUT OFF & PAX ENT SYSTEM SHUT OFF ODOR STILL EVIDENT. UTILITY BUSSES SHUT OFF AND ODOR STILL EVIDENT. FOUND OUTBOARD OVERHEAD ELECTRONIC UNIT 46HJK BURNED. UNIT WAS REPLACED, DATABASE LOADED AND CHECKED OK. FURTHER DISCUSSION WITH INTERIORS ENGINEERING INDICATES UNIT WAS SCRAPPED. UNIT HAD AN INTERNAL SWITCH THAT FAILED. THE SWITCHES NORMALLY FAIL IN THE CLOSED POSITION BUT THIS ONE HAD A RARE FAILURE IN AN OPEN (CONNECTED) POSITION WHICH ALLOWED IT TO OVERHEAT AND BURN OUT. DRH