Narrative:

I was doing overnight maintenance on a canadair regional jet. Our hangar was full, therefore, I was working on the ramp in front of the hangar where there was poor lighting. I noticed the seal missing from the l-hand engine pylon panel under the upper translating cowl stang fairing. In order to install a new seal, the upper translating cowl door had to be opened and the stang fairing removed to get the pylon panel off. I elected to leave the lower translating cowl door latched to minimize the chances of jet or propeller blast damage. I installed a new seal, reinstalled the panel and stang fairing, and closed the upper cowl door. Later, after the aircraft had been repositioned to the gate, I was reviewing on night's work in my mind as I cleaned up in the hangar. I could not recall whether I had relatched the upper cowl door. I immediately called the line supervisor and asked if there had been a crew call-in for finding the door unlatched on their walkaround. He said no. I then asked that he immediately send a mechanic out to check the door as this was right at scheduled departure time. He did so. 20 mins passed and I didn't hear anything back, so I called again. The supervisor told me the aircraft had departed when the mechanic arrived at the gate. Soon thereafter, the aircraft returned to the airport due to a rumbling sound that concerned the crew. They declared an emergency as a precaution. When they arrived at the gate the l-hand upper translating cowl door was found open.

Google
 

Original NASA ASRS Text

Title: A CANADAIR CL65 WAS DISPATCHED IN NON COMPLIANCE WITH THE L ENG REVERSER COWLING ACCESS DOOR OPEN.

Narrative: I WAS DOING OVERNIGHT MAINT ON A CANADAIR REGIONAL JET. OUR HANGAR WAS FULL, THEREFORE, I WAS WORKING ON THE RAMP IN FRONT OF THE HANGAR WHERE THERE WAS POOR LIGHTING. I NOTICED THE SEAL MISSING FROM THE L-HAND ENG PYLON PANEL UNDER THE UPPER TRANSLATING COWL STANG FAIRING. IN ORDER TO INSTALL A NEW SEAL, THE UPPER TRANSLATING COWL DOOR HAD TO BE OPENED AND THE STANG FAIRING REMOVED TO GET THE PYLON PANEL OFF. I ELECTED TO LEAVE THE LOWER TRANSLATING COWL DOOR LATCHED TO MINIMIZE THE CHANCES OF JET OR PROP BLAST DAMAGE. I INSTALLED A NEW SEAL, REINSTALLED THE PANEL AND STANG FAIRING, AND CLOSED THE UPPER COWL DOOR. LATER, AFTER THE ACFT HAD BEEN REPOSITIONED TO THE GATE, I WAS REVIEWING ON NIGHT'S WORK IN MY MIND AS I CLEANED UP IN THE HANGAR. I COULD NOT RECALL WHETHER I HAD RELATCHED THE UPPER COWL DOOR. I IMMEDIATELY CALLED THE LINE SUPVR AND ASKED IF THERE HAD BEEN A CREW CALL-IN FOR FINDING THE DOOR UNLATCHED ON THEIR WALKAROUND. HE SAID NO. I THEN ASKED THAT HE IMMEDIATELY SEND A MECH OUT TO CHK THE DOOR AS THIS WAS RIGHT AT SCHEDULED DEP TIME. HE DID SO. 20 MINS PASSED AND I DIDN'T HEAR ANYTHING BACK, SO I CALLED AGAIN. THE SUPVR TOLD ME THE ACFT HAD DEPARTED WHEN THE MECH ARRIVED AT THE GATE. SOON THEREAFTER, THE ACFT RETURNED TO THE ARPT DUE TO A RUMBLING SOUND THAT CONCERNED THE CREW. THEY DECLARED AN EMER AS A PRECAUTION. WHEN THEY ARRIVED AT THE GATE THE L-HAND UPPER TRANSLATING COWL DOOR WAS FOUND OPEN.

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.