A contract repair station inspector reports about four lower fuselage drain valves that were not rei...

Narrative:

I gave an 'ok to close' on a work card for panel number 194e on a B737-700 aircraft [while] following a contract customer's air carrier maintenance procedures manual (mpm) procedures for that inspection. After the aircraft had been in service for several months; the flight crew experienced a pressurization issue and diverted the flight for investigation. During troubleshooting by the air carrier's mechanics; it was discovered that four drain valves under panel 194e were not installed. These valves were removed in april 2012; in accordance with (in accordance with) routine check card XXX. The installation of these valves were signed for by a mechanic and a quality control (qc) inspector (not myself); [approximately] five days later on the same card. The 'ok to close' inspection requirements for this area is to look for FOD and obvious damage; I found neither at that time. The area of the inspection was on the aircraft exterior skin just aft of the main wheel well. The belly drains in question are common to the aft cargo bay. I was made aware that there was an issue months later.

Original NASA ASRS Text

Title: A contract Repair Station Inspector reports about four lower fuselage drain valves that were not reinstalled on a customer Air Carrier's B737-700 aircraft. Flight crew had diverted due to a pressurization issue.

Narrative: I gave an 'OK to Close' on a work card for panel number 194e on a B737-700 aircraft [while] following a contract customer's Air Carrier Maintenance Procedures Manual (MPM) procedures for that inspection. After the aircraft had been in service for several months; the flight crew experienced a pressurization issue and diverted the flight for investigation. During troubleshooting by the air carrier's mechanics; it was discovered that four drain valves under panel 194e were not installed. These valves were removed in April 2012; In Accordance With (IAW) Routine Check Card XXX. The installation of these valves were signed for by a Mechanic and a Quality Control (QC) Inspector (not myself); [approximately] five days later on the same card. The 'OK to Close' inspection requirements for this area is to look for FOD and obvious damage; I found neither at that time. The area of the inspection was on the aircraft exterior skin just aft of the main wheel well. The belly drains in question are common to the aft cargo bay. I was made aware that there was an issue months later.

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.

Attributes
ACN	1024638
Time
Date	201204
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Light	Daylight
Aircraft 1
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	Parked
Component
Aircraft Component	Fuselage
Person 1
Function	Inspector
Qualification	Maintenance Airframe Maintenance Powerplant
Experience	Maintenance Inspector 3.5 Maintenance Lead Technician 17
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Procedural Published Material / Policy

A contract repair station inspector reports about four lower fuselage drain valves that were not reinstalled on a customer air carrier's B737-700 aircraft. Flight crew had diverted due to a pressurization issue.