Narrative:

Disassembling an instrument panel to prep for installing a garmin GNS-430W waas IFR GPS/glideslope; GIl06A (glideslope indicator) and moving other instruments in the panel I removed the static line from the airspeed indicator. I did not mark or make note of the static line being removed. At the time of the removal I figured I would be doing a static leak check while running the system up in altitude to check the gray code for the GNS 430W. Three days had passed and I started assembling the panel forgetting the static line connection. This was the last day of the install and I was feeling pressure to get it done; the pressure being the pilot standing outside the aircraft for the last three hours of the job. During testing we had other unrelated problems with the autopilot causing more delays. We finally finished with all the work running several hours behind schedule and forgetting to check the gray code for the GNS430W. At this time checking the GNS-430W would have been the only thing that would have caught the oversight of the static line. I had another individual check my work but there was no way they could see the static line. I was the only person who knew the line was off. We turned the aircraft over to the pilot and went home. Some time that evening I remembered the static line and called mechanic Y. I left a message that I had left the [static] line off. At this time I was considering calling the airport to see if there was any way to contact the pilot and tell him not to pressurize the aircraft. While this was going through my head; mechanic Y called me back and said the pilot was on the ground safely at ZZZ airport and asked if I would fix the problem in the morning. The next morning I went to work and removed the glare shield; reconnected the static line and perform a static leak check. I also checked the gray code for the GNS430W and looked every thing else over several more times. I told mechanic Y; I was happy with the aircraft at this time and went home. A few days later in the morning; we all got together and talked about what had happened and what we could do so that it would never happen again.

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Original NASA ASRS Text

Title: Two Repairman Technicians report about a Cessna C-414A aircraft that departed with one end of static line for the Captain's altimeter not reconnected after installation of a Garmin GNS-430W Glideslope and Glideslope Indicator. Pilot returned to airport one hour and fifty minutes later in emergency situation.

Narrative: Disassembling an instrument panel to prep for installing a Garmin GNS-430W WAAS IFR GPS/Glideslope; GIl06A (Glideslope Indicator) and moving other instruments in the panel I removed the static line from the airspeed indicator. I did not mark or make note of the static line being removed. At the time of the removal I figured I would be doing a Static Leak Check while running the system up in altitude to check the Gray Code for the GNS 430W. Three days had passed and I started assembling the panel forgetting the static line connection. This was the last day of the install and I was feeling pressure to get it done; the pressure being the pilot standing outside the aircraft for the last three hours of the job. During testing we had other unrelated problems with the autopilot causing more delays. We finally finished with all the work running several hours behind schedule and forgetting to check the Gray Code for the GNS430W. At this time checking the GNS-430W would have been the only thing that would have caught the oversight of the static line. I had another individual check my work but there was no way they could see the static line. I was the only person who knew the line was off. We turned the aircraft over to the pilot and went home. Some time that evening I remembered the static line and called Mechanic Y. I left a message that I had left the [static] line off. At this time I was considering calling the airport to see if there was any way to contact the pilot and tell him not to pressurize the aircraft. While this was going through my head; Mechanic Y called me back and said the pilot was on the ground safely at ZZZ airport and asked if I would fix the problem in the morning. The next morning I went to work and removed the glare shield; reconnected the static line and perform a Static Leak Check. I also checked the Gray Code for the GNS430W and looked every thing else over several more times. I told Mechanic Y; I was happy with the aircraft at this time and went home. A few days later in the morning; we all got together and talked about what had happened and what we could do so that it would never happen again.

Data retrieved from NASA's ASRS site as of April 2012 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.